CN117642882A

CN117642882A - Electrochemical device and electronic apparatus

Info

Publication number: CN117642882A
Application number: CN202280049748.3A
Authority: CN
Inventors: 蔡晓生; 张楠
Original assignee: Ningde Amperex Technology Ltd
Current assignee: Ningde Amperex Technology Ltd
Priority date: 2022-09-29
Filing date: 2022-09-29
Publication date: 2024-03-01
Also published as: WO2024065396A1

Abstract

An electrochemical device and an electronic device, wherein the electrochemical device comprises a negative electrode plate, the negative electrode plate comprises a carbon nano tube array, and a first negative electrode active material is arranged in the carbon nano tube array; the negative electrode plate further comprises a current collector, the carbon nanotube array is located on the current collector, the first negative electrode active material is located between the carbon nanotubes, and the first negative electrode active material is a silicon-containing material. Through contacting the surfaces of the silicon-containing material and the carbon nano tube, the contact area of the current collector and the silicon-containing material is increased, the electronic resistance is reduced, an effective electronic path is ensured, the ion conduction rate in the electrochemical reaction process can be accelerated by the uniformly distributed carbon nano tube structure, the problem of lithium precipitation caused by uneven local lithium ion concentration is avoided, and the first discharge efficiency, multiplying power and cycle performance of the battery are improved.

Description

Electrochemical device and electronic apparatus

Technical Field

The present disclosure relates to lithium ion battery technology, and more particularly, to an electrochemical device and an electronic device.

Background

With the high-speed development of electric automobiles and mobile electronic devices in recent years, the demand of battery energy density is higher and higher, the silicon-based negative electrode material has gram capacity of up to 1500-4200 mAh/g, and is regarded as the next generation lithium ion negative electrode material with the highest application prospect for realizing a high-energy-density lithium battery, but the low conductivity (> 108 Ω & cm) of silicon and the volume expansion thereof in the charge and discharge process are overlarge (about 300% of volume expansion), so that the further application of the silicon-based negative electrode material is hindered to a certain extent; in addition, during initial charging, lithium is consumed to form the SEI, and the initial efficiency of the silicon-based anode material is low.

At present, the first effect of a silicon-based material is mainly improved by a lithium supplementing technology, lithium band lithium supplementing is the most common and low-cost lithium supplementing technology, but the lithium band lithium supplementing has the problems of low lithium supplementing efficiency and high lithium supplementing heating, namely potential safety hazard exists; the method mainly comprises the following steps of: designing a porous silicon-based material, reducing the size of the silicon material, adopting oxide/polymer coating, adopting plastic adhesive and the like; the design of the porous silicon-based material and the reduction of the size of the silicon material can improve the rate performance to a certain extent, but the occurrence of side reactions and the growth of an uncontrollable SEI film further limit the cycling stability of the silicon material along with the cycling; coating with oxides and polymers can avoid coating with electrolyte and electrode materials, but due to their poor conductivity (> 105 Ω.cm) can increase electrochemical impedance, and the coating is easily damaged during delithiation, thus reducing its cycle life; although the plastic adhesive can limit the volume expansion of silicon to a certain extent, the plastic adhesive also has the problems that part of the adhesive breaks during the expansion process and the active material particles are in poor contact, thereby influencing the subsequent cycle performance.

Disclosure of Invention

The electrochemical device and the electronic equipment can improve the problems of low first efficiency and low lithium supplementing efficiency of the silicon-based material, improve the problem of cycle performance deterioration caused by volume expansion in the cycle process of the silicon-based material, improve the problem of poor conductivity of the silicon-based material, improve electron transfer impedance, reduce polarization and improve capacity, and simultaneously facilitate the improvement of ion transmission in the silicon-based electrode and further improve rate capability.

In a first aspect, the present application provides an electrochemical device comprising a negative electrode tab; the negative electrode plate comprises a carbon nano tube array, and a first negative electrode active material is arranged in the carbon nano tube array.

In some of these embodiments, the negative electrode tab further comprises a current collector; the carbon nanotube array is positioned on the current collector; the carbon nanotube array comprises carbon nanotubes; the first negative electrode active material is positioned between the carbon nanotubes; further, an outer tube wall of the carbon nanotube is in contact with the first negative electrode active material.

By arranging the carbon nanotube array on the current collector, carbon nanotubes in the carbon nanotube array have high conductivity, uniform gaps are formed among the carbon nanotubes arranged in the array, so that the rapid and uniform infiltration of electrolyte can be ensured, high-concentration lithium ions can be rapidly transferred into the cathode pole piece along the uniform gaps after the lithium ions on the anode side pass through the diaphragm, the uniform and rapid ion conduction in the electrochemical reaction process is accelerated, and the problem of lithium precipitation caused by the non-uniform concentration of local lithium ions is avoided; and the first anode active material is loaded on the surface of the outer tube wall of the carbon nano tube with the array structure, so that the contact area of the current collector and the anode active material is increased, the electronic resistance is reduced, and the conductivity is increased.

In some of these embodiments, the first negative electrode active material is a silicon-containing material; the silicon-containing material includes at least one of a silicon-carbon material, a silicon oxygen material, or a pure silicon material. In this patent, a silicon content of greater than 80% can be considered as a pure silicon material. The silicon-containing material is attached to the surface of the outer tube wall of the carbon nanotube, so that silicon particles (including silicon carbon particles, silicon oxygen particles or pure silicon particles) can be fully contacted with the carbon nanotube, and an effective electronic path is ensured.

In some of these embodiments, the silicon-containing material further includes a lithium element therein. The lithium element is formed by depositing a lithium supplementing material after the lithium supplementing material contacts with the uniformly distributed carbon nanotubes; specifically, the lithium supplementing material can be uniformly and rapidly absorbed and deposited into the interior of the silicon-containing material after being contacted with the uniformly distributed carbon nanotubes. In the lithium supplementing process, uniformly distributed carbon nanotubes are arranged on one side of a current collector, and the surfaces of the carbon nanotubes are loaded with silicon-containing materials; when lithium is supplemented, firstly, the lithium supplementing material is contacted with the uniformly distributed carbon nano tubes, so that potential safety hazards caused by local overheating phenomenon caused by nonuniform deposition can be avoided, secondly, the lithium supplementing material is uniformly absorbed and deposited into the silicon-containing material, at the moment, the problem of lithium precipitation caused by nonuniform lithium supplementing can be avoided, and meanwhile, the carbon nano tubes with the array structure can play a role in uniform heat conduction and can well reduce lithium supplementing temperature rise. Therefore, after the lithium supplementing is combined with the carbon nano tube array structure containing the first negative electrode active material, the problems of low lithium supplementing efficiency, high heating and potential safety hazard can be improved, and the first effect is further improved.

In some of these embodiments, the mass ratio of the lithium element to the silicon element is 5% to 30%. On one hand, the mass ratio of the lithium element to the silicon element is controlled in a proper range, so that lithium loss caused by the formation of an SEI film on the negative electrode can be compensated, and the first effect and the cycle performance are improved; on the other hand, by selecting a proper lithium supplementing amount, the balance among lithium supplementing cost, lithium supplementing efficiency/temperature rise and electrical performance can be realized, and the large-scale production is facilitated.

In some of these embodiments, at least a portion of the surface of the silicon-containing material is provided with a conductive material; the conductive material includes at least one of a carbon material, a metal material, or other material having conductivity. And introducing a proper conductive material on the surface of the silicon-containing material for coating so as to further improve the conductivity of the silicon-containing material.

In some of these embodiments, the carbon nanotube array is patterned on the current collector; or, the carbon nanotube array is distributed on the current collector in a full coverage mode. In this patent, the full-coverage distribution means that at least one side surface of the current collector is provided with the carbon nanotube array entirely; the patterning distribution means that at least one side surface of the current collector is at least partially provided with the carbon nanotube array.

In some of these embodiments, the carbon nanotube array is patterned on the current collector;

the negative electrode plate comprises two or more carbon nanotube arrays arranged at intervals, the average distance between the carbon nanotube arrays is M, and the following conditions are satisfied: d < M.ltoreq.500. Mu.m, preferably d < M.ltoreq.50. Mu.m.

In some of these embodiments, the negative electrode tab satisfies at least one of the following conditions:

(I) Viewed along the direction perpendicular to the plane of the current collector, the projection area surrounded by the upper top surface of the carbon nanotube array is S ₁ The projection area surrounded by the lower bottom surface is S ₂ The method comprises the following steps: s is more than or equal to 90 percent ₁ /S ₂ ≤110％；

Projection area S enclosed by upper top surface of the carbon nanotube array ₁ The area obtained by horizontally extending the surface (i.e. the upper top surface) surrounding the top of the carbon nanotube array to a horizontal plane in the direction perpendicular to the plane of the current collector is the projection area S ₁ The method comprises the steps of carrying out a first treatment on the surface of the Projection area S enclosed by lower bottom surface ₂ The area obtained by horizontally extending the surface (namely the lower bottom surface) surrounded by the bottom of the carbon nano tube array to the same horizontal plane in the direction perpendicular to the plane of the current collector is the projection area S ₂ 。

(II) on a longitudinal section vertical to the surface of the current collector, selecting any area where the carbon nanotube array is located for EDS energy spectrum analysis, wherein the mass content of silicon element in the selected area is w, and the mass content is as follows: w is more than or equal to 60% and less than or equal to 95%; and for two regions selected at will, the difference of the mass contents of silicon elements is Deltaw, which satisfies the following conditions: deltaw is less than or equal to 20 percent;

The longitudinal section is obtained by carrying out section treatment on a film layer arranged on one side of the current collector along the direction vertical to the surface of the current collector, wherein the treatment mode can be ion polishing to obtain a section, and the film layer comprises the carbon nanotube array; the region generally refers to a region containing at least one carbon nanotube; the two arbitrarily selected regions refer to at least one different carbon nanotube between the two regions.

(III) selecting an area where any carbon nanotube array is located, and observing along a direction perpendicular to a plane where a current collector is located, wherein the ratio of the projection area enclosed by the carbon nanotube array to the projection area of the current collector in the selected area is S, and the requirements are satisfied: s is more than or equal to 50% and less than or equal to 100%.

The projection area enclosed by the carbon nanotube array is an area obtained by horizontally extending a surface enclosed by the surrounding carbon nanotube array to a horizontal plane, namely the projection area enclosed by the carbon nanotube array; wherein, the surface formed around may refer to a surface formed around any position of the carbon nanotube array, and the carbon nanotube array is in contact with the current collector; the selected area collector area means that the selected area corresponds to the area on the collector.

(i) Viewed along the direction perpendicular to the plane of the current collector, the projection area surrounded by the upper top surface of the carbon nanotube array is S ₁ The projection area surrounded by the lower bottom surface is S ₂ The method comprises the following steps: s is 95 percent or less ₁ /S ₂ ≤105％；

(ii) On a longitudinal section vertical to the surface of the current collector, selecting an area where any carbon nanotube array is located for EDS energy spectrum analysis, wherein the mass content of silicon element in the selected area is w, and the mass content is as follows: w is more than or equal to 80% and less than or equal to 95%; and for two regions selected at will, the difference of the mass contents of silicon elements is Deltaw, which satisfies the following conditions: deltaw is less than or equal to 10 percent;

(iii) Selecting an area where any carbon nanotube array is located, observing along a direction perpendicular to a plane where a current collector is located, wherein the ratio of the projection area enclosed by the carbon nanotube array to the projection area of the current collector in the selected area is S, and the requirements are satisfied: s is more than or equal to 70% and less than or equal to 100%.

At the moment, on one hand, the electrolyte infiltration can be further improved, the ion conduction is accelerated, and the concentration polarization is reduced; on the other hand, the volume expansion can be further buffered, the integrity of the pole piece shape is ensured, and the problems of wrinkling, falling of active substances and the like in the charge and discharge process are solved.

In some of these embodiments, the negative electrode tab satisfies: (A) The average particle diameter of the negative electrode active material is D, and the following conditions are satisfied: d is more than or equal to 5nm and less than or equal to 2 mu m; (B) The distance between adjacent carbon nanotubes is d, which satisfies the following conditions: d is more than or equal to 20nm and less than or equal to 5 mu m; the pipe diameter of the carbon nano-tube is p, and the following conditions are satisfied: p is more than or equal to 5nm and less than or equal to 100nm; (D) the length of the carbon nanotube is H, satisfying: h is more than or equal to 5 mu m and less than or equal to 80 mu m.

The adjacent carbon nanotubes may be adjacent in the longitudinal direction of the current collector or adjacent in the width direction of the current collector; for example, in the length direction of the current collector, the distance d between adjacent carbon nanotubes refers to the distance between two carbon nanotubes arranged laterally along the length direction of the current collector; in the width direction of the current collector, the distance d between adjacent carbon nanotubes refers to the distance between two carbon nanotubes longitudinally arranged along the width direction of the current collector, and the distance between two carbon nanotubes generally refers to the average distance between two carbon nanotubes.

The length direction of the carbon nanotubes is perpendicular to the surface of the current collector, the length direction of the carbon nanotubes refers to the extending direction of the bottom ends of the carbon nanotubes towards the top ends of the carbon nanotubes, and it is required to be noted that the included angle between the extension line of the length direction of the carbon nanotubes and the surface of the current collector is in the range of 60-90 degrees, and the extension line of the length direction of the carbon nanotubes and the surface of the current collector can be regarded as being perpendicular to the surface of the current collector.

(a) The average particle diameter of the negative electrode active material is D, and the following conditions are satisfied: d is more than or equal to 5nm and less than or equal to 500nm;

(b) The distance between adjacent carbon nanotubes is d, which satisfies the following conditions: d is more than or equal to 20nm and less than or equal to 1 mu m;

(c) The length of the carbon nano tube is H, and the following conditions are satisfied: h is more than or equal to 5 mu m and less than or equal to 40 mu m

(d) The ratio of the spacing D between adjacent carbon nanotubes to the average particle diameter D of the negative electrode active material satisfies: 2 < D/D < 10;

(e) The ratio of the distance d between the adjacent carbon nanotubes to the pipe diameter p of the carbon nanotubes satisfies the following conditions: d/p is less than or equal to 0.2nm and less than or equal to 500nm.

By adjusting the average particle size of the anode active material, the distance between adjacent carbon nanotubes and the length and the pipe diameter of the carbon tubes, on one hand, the lithium supplementing performance of the silicon-containing material can be improved, and further, the first effect can be improved, and on the other hand, the cycle performance can be improved.

In some of these embodiments, the ratio of the spacing D between adjacent carbon nanotubes to the average particle diameter D of the anode active material satisfies: D/D is more than or equal to 2 and less than or equal to 5. At this time, the lithium supplementing performance of the silicon material can be improved, and the first effect and the cyclic electrical performance can be improved.

In some of these embodiments, the ratio of the spacing d between adjacent carbon nanotubes to the tube diameter p of the carbon nanotubes satisfies: d/p is less than or equal to 1nm and less than or equal to 250nm. The method is used for further improving the lithium supplementing performance of the silicon material and improving the first effect and the cycle electrical performance.

In a second aspect, the present application provides an electronic device comprising an electrochemical apparatus as described in any one of the above.

The beneficial effects that this technical scheme brought include at least:

(1) According to the method, the carbon nanotube array is arranged on the current collector, and the silicon-containing material is arranged on the outer tube wall surface of the carbon nanotubes in the carbon nanotube array in a contact manner, so that the contact area of the current collector and the silicon-containing material is increased, the electronic resistance is reduced, the conductivity is increased, and an effective electronic path is ensured; and lithium element is deposited in the silicon-containing material to improve the first effect; the surface of the silicon-containing material is introduced with a proper conductive material for coating so as to improve the conductivity of the silicon-containing material;

(2) The carbon nano tube structure which is uniformly distributed in the method can play a role in uniform heat conduction, well reduce lithium supplementing temperature rise, and ensure rapid and uniform infiltration of electrolyte; after the lithium ions on the positive electrode side pass through the diaphragm, the high-concentration lithium ions can be quickly transferred into the negative electrode plate along the uniform gap, so that the uniform and quick ion conduction in the electrochemical reaction process is accelerated, the problem of lithium precipitation caused by the non-uniform local lithium ion concentration is avoided, and the first efficiency, the multiplying power performance and the cycle performance of the battery are further improved;

(3) The silicon-containing material is bound between the carbon nanotube arrays, and the carbon nanotube arrays have high mechanical strength, so that the deformation of the pole piece and even the deformation of the battery caused by the volume expansion of the silicon-containing material in the circulation process can be limited, and poor interface contact can be effectively prevented; the problems of falling of active materials from a current collector, poor contact among active material particles, SEI thickening caused by particle breakage and the like can be avoided, so that effective electronic and ionic conduction in a circulation process is ensured, side reaction exacerbation is avoided, and the circulation performance is improved;

(4) The carbon nano tube in the carbon nano tube array can rapidly lead out the heat inside the battery, is favorable for reducing the temperature rise, avoids the accumulation of the heat inside the battery, and therefore improves the safety performance of the battery.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a partial enlarged view of a fully covered distributed carbon nanotube array according to an embodiment of the present application;

FIG. 2 is a partial enlarged view of a patterned array of carbon nanotubes according to an embodiment of the present application;

fig. 3 is a top view of a patterned carbon nanotube array according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.

The silicon-based negative electrode material has gram capacity of up to 1500-4200 mAh/g, and is regarded as the next generation lithium ion negative electrode material with the highest application prospect for realizing a high-energy density lithium battery, but the low conductivity of silicon (> 108 Ω. Cm) and the excessive volume expansion (with about 300% volume expansion) during the charge and discharge process prevent the further application to a certain extent; in addition, during initial charging, lithium is consumed to form the SEI and results in low initial efficiency of the material. At present, the first effect of a silicon-based material is mainly improved by a lithium supplementing technology, lithium band lithium supplementing is the most common and low-cost lithium supplementing technology, but the lithium band lithium supplementing has the problems of low lithium supplementing efficiency and high lithium supplementing heating and has potential safety hazards; the method mainly comprises the following steps of: designing a porous silicon-based material, reducing the size of the silicon material, adopting oxide/polymer coating, adopting plastic adhesive and the like; the design of the porous silicon-based material and the reduction of the size of the silicon material can improve the rate performance to a certain extent, but the occurrence of side reactions and the growth of an uncontrollable SEI film further limit the cycling stability of the silicon material along with the cycling; coating with oxides and polymers can avoid coating with electrolyte and electrode materials, but due to their poor conductivity (> 105 Ω.cm) can increase electrochemical impedance, and the coating is easily damaged during delithiation, thus reducing its cycle life; although the plastic adhesive can limit the volume expansion of silicon to a certain extent, the plastic adhesive also has the problems that part of the adhesive breaks during the expansion process and the active material particles are in poor contact, thereby influencing the subsequent cycle performance.

In order to solve the above technical problems, the present application proposes an electrochemical device and an electronic apparatus.

Electrochemical device

The electrochemical device comprises a negative electrode plate, wherein the negative electrode plate comprises a current collector and a carbon nano tube array arranged on at least one side of the current collector, and a first negative electrode active material is arranged in the carbon nano tube array; the carbon nanotube array comprises carbon nanotubes, the first negative electrode active material is positioned between the carbon nanotubes, and the outer tube wall of the carbon nanotubes is in contact with the first negative electrode active material.

Referring to fig. 1 and fig. 2, the carbon nanotube array is disposed on one side of the current collector, and the carbon nanotube array has at least two arrangements, for example, the carbon nanotube array in full coverage distribution shown in fig. 1, that is, at least one side of the current collector is fully paved with carbon nanotubes having an array structure; the carbon nanotube arrays may be patterned and arranged as shown in fig. 2 or fig. 3, that is, at least one side of the current collector is provided with a plurality of carbon nanotube arrays, and a plurality of carbon nanotube arrays are patterned and arranged at a certain interval; further, the average distance between different carbon nanotube arrays is M (as shown in fig. 3), where M satisfies: d < M.ltoreq.500. Mu.m, preferably d < M.ltoreq.50. Mu.m, where d is the spacing between adjacent carbon nanotubes. As is apparent from the combination of fig. 1 or fig. 2, the surface of the outer tube wall of the carbon nanotube having the array arrangement structure is provided with the first negative electrode active material in contact, that is, the first negative electrode active material is in contact with the surface of the outer tube wall of the carbon nanotube; by arranging the carbon nanotubes with the array structure on the current collector, the carbon nanotubes have high conductivity, uniform gaps are formed among the carbon nanotubes with the array structure, so that the rapid and uniform infiltration of electrolyte can be ensured, high-concentration lithium ions can be rapidly transferred into the cathode pole piece along uniform gaps after lithium ions on the anode side pass through the diaphragm, the uniform and rapid ion conduction in the electrochemical reaction process is accelerated, and the problem of lithium precipitation caused by the non-uniform local lithium ion concentration is avoided; meanwhile, the first anode active material is loaded on the surface of the outer tube wall of the carbon nano tube with the array structure, so that the contact area of the current collector and the anode active material is increased, the electronic resistance is reduced, and the conductivity is increased.

In some embodiments, the first negative active material is a silicon-containing material; the silicon-containing material includes at least one of a silicon-carbon material, a silicon oxygen material, or a pure silicon material. Attaching the silicon-containing material to the surface of the outer tube wall of the carbon nanotubes helps silicon particles (including silicon carbon particles, silicon oxygen particles, or pure silicon particles) in the silicon-containing material to fully contact the carbon nanotubes for ensuring an efficient electronic pathway.

In some embodiments, the silicon-containing material further comprises elemental lithium; the lithium element is formed by depositing a lithium supplementing material after the lithium supplementing material contacts with the uniformly distributed carbon nanotubes; specifically, the lithium supplementing material can be uniformly and rapidly absorbed and deposited into the interior of the silicon-containing material after being contacted with the uniformly distributed carbon nanotubes. In the lithium supplementing process, uniformly distributed carbon nanotubes are arranged on one side of a current collector, and the surfaces of the carbon nanotubes are loaded with silicon-containing materials; when lithium is supplemented, firstly, the lithium supplementing material is contacted with the uniformly distributed carbon nano tubes, so that potential safety hazards caused by local overheating phenomenon caused by nonuniform deposition can be avoided, secondly, the lithium supplementing material is uniformly absorbed and deposited into the silicon-containing material, at the moment, the problem of lithium precipitation caused by nonuniform lithium supplementing can be avoided, and meanwhile, the carbon nano tubes with the array structure can play a role in uniform heat conduction and can well reduce lithium supplementing temperature rise. Therefore, after the lithium supplementing is combined with the carbon nano tube array structure containing the first negative electrode active material, the problems of low lithium supplementing efficiency, high heating and potential safety hazard can be improved, and the first effect is further improved.

In some embodiments, the mass ratio of the lithium element to the silicon element is 5% to 30%. On one hand, the mass ratio of the lithium element to the silicon element is controlled in a proper range, so that lithium loss caused by the formation of an SEI film on the negative electrode can be compensated, and the first effect and the cycle performance are improved; on the other hand, by selecting a proper lithium supplementing amount, the balance among lithium supplementing cost, lithium supplementing efficiency/temperature rise and electrical performance can be realized, and the large-scale production is facilitated.

Illustratively, the mass ratio of lithium element to silicon element is 5%, 8%, 10%, 14%, 16%, 18%, 20%, 24%, 26%, 28%, 30% or a range of any two values recited above.

As shown in connection with fig. 1 or 2, at least part of the surface of the silicon-containing material is provided with a conductive material; the conductive material is wrapped around or doped on at least part of the surface or even the whole surface of the silicon-containing material, and the conductive material comprises at least one of a carbon material, a metal material or other materials with conductivity. And introducing a proper conductive material on the surface of the silicon-containing material for coating so as to further improve the conductivity of the silicon-containing material.

In some embodiments, the negative electrode tab satisfies at least one of the following conditions:

the longitudinal section is obtained by carrying out section treatment on a film layer arranged on one side of the current collector along the direction vertical to the surface of the current collector, wherein the treatment mode can be ion polishing to obtain a section; the region generally refers to a region containing at least one carbon nanotube; the two arbitrarily selected regions are at least one different carbon nanotube between the two regions.

Illustratively, the projected area S enclosed by the top of the carbon nanotube array ₁ Projection area S enclosed by the bottom of the lens ₂ Ratio S ₁ /S ₂ 90%, 92%, 95%, 98%, 100%, 105%, 108%, 110% or a range of any two of the above values.

Illustratively, the mass content w of elemental silicon in the selected region is 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or a range of any two of the foregoing values.

Illustratively, the difference Δw in mass content of the silicon element in the plurality of regions is 0%, 1%, 5%, 8%, 10%, 15%, 20% or a range of any two of the above values.

Illustratively, the ratio S of the projected area enclosed by the carbon nanotube array to the area of the selected region current collector is 50%, 60%, 70%, 80%, 90%, 100% or a range of any two of the above values.

Illustratively, the projected area S enclosed by the top of the carbon nanotube array ₁ Projection area S enclosed by the bottom of the lens ₂ Ratio S ₁ /S ₂ 95%, 97%, 98%, 100%, 102%, 104%, 105% or a range of any two of the above values.

Illustratively, the mass content w of elemental silicon in the selected region is 80%, 83%, 85%, 88%, 90%, 93%, 95% or a range of any two of the foregoing values.

Illustratively, the difference Δw in mass content of the silicon element in the plurality of regions is 0%, 1%, 3%, 5%, 7%, 9%, 10% or a range of any two of the above values.

Illustratively, the ratio S of the projected area enclosed by the carbon nanotube array to the selected area current collector area is 70%, 75%, 80%, 85%, 90%, 95%, 100% or a range of any two of the above values.

In some embodiments, the negative electrode tab satisfies: (A) The average particle diameter of the negative electrode active material is D, and the following conditions are satisfied: d is more than or equal to 5nm and less than or equal to 2 mu m; (B) The distance between adjacent carbon nanotubes is d, which satisfies the following conditions: d is more than or equal to 20nm and less than or equal to 5 mu m; the pipe diameter of the carbon nano-tube is p, and the following conditions are satisfied: p is more than or equal to 5nm and less than or equal to 100nm; (D) the length of the carbon nanotube is H, satisfying: h is more than or equal to 5 mu m and less than or equal to 80 mu m.

The adjacent carbon nanotubes may be adjacent in the longitudinal direction of the current collector or adjacent in the width direction of the current collector; for example, in the length direction of the current collector, the distance d between adjacent carbon nanotubes refers to the distance between two carbon nanotubes arranged laterally along the length direction of the current collector (for example, as shown in fig. 3); in the width direction of the current collector, the distance d between adjacent carbon nanotubes refers to the distance between two carbon nanotubes longitudinally arranged along the width direction of the current collector, and the distance between two carbon nanotubes generally refers to the distance between the corresponding positions of the middle positions of the two carbon nanotubes. The length H of the carbon nanotubes refers to the distance between the bottom end of the carbon nanotubes and the top end thereof (e.g., as shown in fig. 1).

Illustratively, the average particle diameter D of the negative electrode active material is 5nm, 50nm, 100nm, 500nm, 1000nm, 1500nm, 2000nm, or a range of any two of the above values.

Illustratively, the spacing d between adjacent carbon nanotubes is 20nm, 40nm, 60nm, 80nm, 100nm, 400nm, 600nm, 800nm, 1000nm, 1500nm, 2000nm, 2500nm, 3000nm, 3500nm, 4000nm, 4500nm, 5000nm, or a range of any two of the foregoing values.

Illustratively, the carbon nanotubes have a tube diameter p of 5nm, 10nm, 15nm, 20nm, 35nm, 50nm, 70nm, 85nm, 90nm, 100nm or a range of any two values recited above.

Illustratively, the carbon nanotubes have a length H of 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 60 μm, 80 μm or a range of any two values described above.

Illustratively, the average particle diameter D of the negative electrode active material is 5nm, 50nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, or a range of any two values of the above.

Illustratively, the spacing d between adjacent carbon nanotubes is 20nm, 40nm, 60nm, 80nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm or a range of any two of the above values.

Illustratively, the carbon nanotubes have a length H of 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm or a range of any two values described above.

Illustratively, the ratio D/D of the spacing D between adjacent carbon nanotubes to the average particle diameter D of the anode active material is 2.1, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 9.9 or a range of any two of the above values.

Illustratively, the ratio d/p of the spacing d between adjacent carbon nanotubes to the tube diameter p of the carbon nanotubes is 0.2nm, 1nm, 5nm, 10nm, 20nm, 40nm, 80nm, 100nm, 160nm, 180nm, 200nm, 250nm, 300nm, 400nm, 500nm or a range of any two of the above values.

In some embodiments, the ratio of the spacing D between adjacent carbon nanotubes to the average particle diameter D of the anode active material satisfies: D/D is more than or equal to 2 and less than or equal to 5. The method is used for improving the lithium supplementing performance of the silicon material and improving the first effect and the cycle electrical performance.

Illustratively, the ratio D/D of the spacing D between adjacent carbon nanotubes to the average particle diameter D of the anode active material is 2, 2.5, 3, 3.5, 4, 4.5, 5 or a range of any two of the above values.

In some embodiments, the ratio of the spacing d between adjacent carbon nanotubes to the tube diameter p of the carbon nanotubes satisfies: d/p is less than or equal to 1nm and less than or equal to 250nm. Further improves the lithium supplementing performance of the silicon material and improves the first effect and the cycle electrical performance.

Illustratively, the ratio d/p of the spacing d between adjacent carbon nanotubes to the tube diameter p of the carbon nanotubes is 1nm, 5nm, 10nm, 30nm, 60nm, 80nm, 100nm, 150nm, 200nm, 250nm or a range of any two of the above values.

The embodiment of the application also provides electronic equipment comprising any electrochemical device. The electronic device of the present application may be used for, but is not limited to, notebook computers, pen-input computers, mobile computers, electronic book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, video recorders, liquid crystal televisions, portable cleaners, portable CD players, mini-compact discs, transceivers, electronic notepads, calculators, memory cards, portable audio recorders, radios, backup power supplies, motors, automobiles, motorcycles, mopeds, bicycles, lighting fixtures, toys, game consoles, clocks, electric tools, flashlights, cameras, home-use large-sized batteries, lithium ion capacitors, and the like.

The present application will be described in further detail with reference to specific examples.

The two-dimensional plane conductive substrate (namely, the current collector) comprises an aluminum foil, a copper foil, a stainless steel foil, a nickel film, an iron film, a gold film, a silver film, a platinum film, a titanium film, a zinc film, a manganese film, a carbon film, other composite metal films, a conductive polymer film or a composite polymer-metal film.

The positive electrode active material includes: at least one of NCM811, NCM622, NCM523, NCM111, NCA, lithium iron phosphate, lithium cobaltate, lithium manganate, lithium manganese iron phosphate, or lithium titanate.

The negative electrode active material includes: at least one of graphite, pure silicon, silicon carbon or silicon oxide, tin oxide, lithium metal and the like, preferably pure silicon material.

The electrolyte of the lithium ion battery is not particularly limited, and any electrolyte known in the art, which may be any of gel state, solid state, and liquid state, may be used. For example, the liquid electrolyte includes a lithium salt and a nonaqueous solvent.

The lithium salt is not particularly limited, and any lithium salt known in the art may be used as long as the object of the present application can be achieved. For example, the lithium salt may include LiPF ₆ 、LiBF ₄ 、LiAsF ₆ 、LiClO ₄ 、LiB(C ₆ H ₅ ) ₄ 、LiCH ₃ SO ₃ 、LiCF ₃ SO ₃ 、LiN(SO ₂ CF ₃ ) ₂ 、LiC(SO ₂ CF ₃ ) ₃ Or LiPO ₂ F ₂ At least one of the following. For example, the lithium salt may be LiPF ₆ 。

The nonaqueous solvent is not particularly limited as long as the object of the present application can be achieved. For example, the nonaqueous solvent may include at least one of a carbonate compound, a carboxylate compound, an ether compound, a nitrile compound, or other organic solvent, or the like.

For example, the carbonate compound may include at least one of diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylene Propylene Carbonate (EPC), methylethyl carbonate (MEC), ethylene Carbonate (EC), propylene Carbonate (PC), butylene Carbonate (BC), vinyl Ethylene Carbonate (VEC), fluoroethylene carbonate (FEC), 1, 2-difluoroethylene carbonate, 1, 2-trifluoroethylene carbonate, 1, 2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1, 2-difluoro-1-methylethylene carbonate, 1, 2-trifluoro-2-methylethylene carbonate, or trifluoromethyl ethylene carbonate, etc.

Comparative example 1

Pure silicon pole piece without carbon nano tube array

Preparation of positive electrode plate

Lithium cobalt oxide (LiCoO) as a positive electrode active material ₂ ) Mixing conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5, adding N-methyl pyrrolidone (NMP) as a solvent, preparing into slurry with solid content of 0.75, and uniformly stirring. And uniformly coating the slurry on an aluminum foil of the positive electrode current collector, and drying at 90 ℃ to obtain the positive electrode plate. After coating, the pole piece was cut to size (980 mm. Times.58 mm) for use.

After the steps are finished, the single-sided coating of the positive electrode plate is finished. And then, completing the steps on the back of the pole piece by a completely consistent method, and obtaining the positive pole piece with the double-sided coating.

Preparation of negative electrode plate

Mixing silicon as a cathode active material, conductive carbon black (Super P) and a binder according to a weight ratio of 90:5:5, and adding deionized water (H) ₂ O) was used as a solvent, and the slurry was prepared to have a solid content of 0.7, and stirred uniformly. And uniformly coating the slurry on a negative current collector copper foil, and drying at 110 ℃ to obtain a negative electrode plate. After the coating is completed, the pole piece is cut into (1000 mm x 60 mm) specifications for use.

After the steps are finished, the single-sided coating of the negative electrode plate is finished. And then, completing the steps on the back of the pole piece by a completely consistent method, and obtaining the double-sided coated negative pole piece. The thickness of the membrane was 10. Mu.m. And supplementing lithium to the negative electrode plate by using a lithium belt. The specific parameters are shown in tables 1 to 3.

Preparation of electrolyte

In a dry argon atmosphere, the organic solvents Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio EC: EMC: dec=30:50:20, and then adding lithium hexafluorophosphate (LiPF ₆ ) Dissolving and mixing uniformly to obtain the electrolyte with the concentration of lithium salt of 1.15M.

Preparation of a separator film

The base material of the isolating film is Polyethylene (PE) with the thickness of 8 mu m, two sides of the base material of the isolating film are respectively coated with 2 mu m alumina ceramic layers, and finally two sides coated with the ceramic layers are respectively coated with 2.5mg of adhesive polyvinylidene fluoride (PVDF) and dried.

Preparation of electrode assemblies

The positive electrode tab and the negative electrode tab are welded in a laser welding mode respectively, and the positive electrode Al switching tab and the negative electrode Ni switching tab are welded in the same direction. And placing the isolating film between the positive pole piece and the negative pole piece and then winding to obtain the coiled electrode assembly.

Preparation of a Battery

And (5) packaging, injecting liquid and forming the wound electrode assembly.

Comparative example 2

Preparation of positive electrode plate

Preparation of negative electrode plate

And growing carbon nano tube clusters (S1/S2=30%) with cone array structures on the surface of a current collector by chemical vapor deposition, attaching a silicon-containing material on the surface of the cone carbon nano tube clusters by vapor deposition, and wrapping a layer of conductive material outside the silicon-containing material by vapor deposition to complete the electrode preparation. After completion, the pole piece was cut to (1000 mm. Times.60 mm) gauge for use. The thickness of the membrane is 10 μm, and specific parameters are shown in tables 1 to 3.

After the steps are finished, the single-sided coating of the negative electrode plate is finished. And then, completing the steps on the back of the pole piece by a completely consistent method, and obtaining the double-sided coated negative pole piece.

Preparation of electrolyte

In a dry argon atmosphere, the organic solvents Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in mass ratio EC: EMC: dec=30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF) was added to the organic solvent ₆ ) Dissolving and mixing uniformly to obtain the electrolyte with the concentration of lithium salt of 1.15M.

Preparation of a separator film

Preparation of electrode assemblies

Preparation of a Battery

And (5) packaging, injecting liquid and forming the wound electrode assembly.

[ comparative example 3 ]

Conical CNT cluster + pure silicon pole piece

Preparation of positive electrode plate

Lithium cobalt oxide (LiCoO) as a positive electrode active material ₂ ) Mixing conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) according to a weight ratio of 97.5:1.0:1.5, adding N-methylpyrrolidone (NMP) as a solvent, preparing into slurry with solid content of 0.75, and uniformly stirring. And uniformly coating the slurry on an aluminum foil of the positive electrode current collector, and drying at 90 ℃ to obtain the positive electrode plate. After coating, the pole piece was cut to size (980 mm. Times.58 mm) for use.

Preparation of negative electrode plate

And growing carbon tubes with an array structure on the surface of the current collector by chemical vapor deposition, and then bombarding the carbon tubes with inert atoms to form an array-shaped conical carbon nanotube cluster. And then attaching a silicon-containing material on the surface of the tapered carbon nanotube by a vapor deposition mode, and then coating a layer of conductive material on the outer side of the silicon material by vapor deposition to complete the preparation of the electrode. After the completion, the pole piece is cut into the specification of (1000 mm multiplied by 60 mm) for standby, and lithium is supplemented to the pole piece. The thickness of the membrane is 10 μm, and specific parameters are shown in tables 1 to 3.

Preparation of electrolyte

Preparation of a separator film

Preparation of electrode assemblies

The positive electrode tab and the negative electrode tab are welded in a laser welding mode respectively, and the positive electrode Al switching tab and the negative electrode Ni switching tab are welded in the same direction. The separator is placed between the positive electrode sheet and the negative electrode sheet and then wound into a rolled electrode assembly.

Preparation of a Battery

And packaging, injecting liquid and forming the wound battery.

[ example 1 ]

Preparation of positive electrode plate

Preparation of negative electrode plate

And growing carbon tubes with an array structure on the surface of a current collector by chemical vapor deposition, attaching a silicon-containing material on the surface of uniformly distributed carbon nanotubes by vapor deposition, and wrapping a layer of conductive material on the outer side of the silicon material by vapor deposition to complete the preparation of the electrode. After the completion, the pole piece is cut into the specification of (1000 mm multiplied by 60 mm) for standby, and lithium is supplemented to the pole piece. The film thickness was 10 μm and the parameters involved are shown in tables 1 to 3.

Preparation of electrolyte

In a dry argon atmosphere, the organic solvents Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) anddiethyl carbonate (DEC) was mixed in mass ratio EC: EMC: dec=30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF) was added to the organic solvent ₆ ) Dissolving and mixing uniformly to obtain the electrolyte with the concentration of lithium salt of 1.15M.

Preparation of a separator film

Preparation of electrode assemblies

The positive electrode tab and the negative electrode tab are welded in a laser welding mode respectively, and the positive electrode Al switching tab and the negative electrode Ni switching tab are welded in the same direction. And placing the isolating film between the positive pole piece and the negative pole piece and then winding the isolating film into a winding type electrode assembly structure.

Preparation of a Battery

And (5) packaging, injecting liquid and forming the wound electrode assembly.

[ example 2 ] to [ example 27 ]

Examples 2 to 27 include most of the operation steps in example 1, except that each parameter in the preparation process of the negative electrode sheet was controlled to be changed within a certain range, specifically, see tables 1 to 3.

Test part

(1) Mass ratio test of lithium element and silicon element in silicon-containing material

a. Sampling: and discharging the battery to 3.0V, disassembling the battery, and taking out the pole piece. And (3) flushing the surface of the pole piece by DMC, cleaning the electrolyte on the surface of the pole piece, and drying. Punching the pole piece into a regular small disc, wherein the total mass of the pole piece is more than 0.5g;

b. sample pretreatment-acid removal digestion: taking a proper amount of sample in a digestion tank, adding a digestion reagent (3 ml of pure water+3 ml of nitric acid+5 ml of HF), shaking the digestion tank, placing the digestion tank in an acid-dispelling instrument, heating and evaporating to a proper volume (120 min at 180 ℃), taking out the digestion tank, and flushing the edge of the digestion tank with ultrapure water;

c. and (3) testing: (1) starting up and preheating: switching on a stabilized voltage power supply, regulating argon to 0.6MPa, switching on an instrument and switching on software; (2) the establishment method comprises the following steps: testing by adopting a calibration curve method, and selecting the test elements as Li and silicon; (3) igniting; (4) and (3) testing: a) using 1mg/L Mn Shan Biao as a torch tube for collimation, cleaning a sample injection system, b) carrying out optical initialization, wherein an initialization value is less than 50step, c) drawing a working curve by using the prepared standard liquid in sequence; d) Checking whether the linearity of the curve is R2 > 0.999, e) testing a quality control sample, confirming the accuracy of the curve, f) inputting sample information, and testing the sample; (5) shutting down; (6) processing the data; (7) and (5) cleaning the container.

(2) Lithium replenishment temperature rise and lithium absorption rate test

And placing the lithium strip on the surface of the pole piece, pressing and standing for 12 hours. The temperature change during the whole standing process was recorded with a temperature sensor, and the lithium-compensating temperature rise=maximum temperature-room temperature. Recording the weight increment of the unit area before and after 12 hours, and obtaining the lithium supplementing quantity, wherein the lithium absorption rate=the lithium supplementing quantity/time, and the unit mg/(cm) ² h)。

(3) First-effect test

The electrochemical device was charged from 3.0 to 4.45V at a charge rate of 0.2C under 25 ℃ environment, the capacity was recorded as the first charge capacity, and then discharged to 3.0V at a discharge rate of 0.2C, the capacity was recorded as the first discharge capacity, and the first efficiency= (first discharge capacity/first charge capacity) ×100%.

(4) Cycle performance test

The electrochemical device was charged to 4.45V from 3.0 at a charge rate of 0.5C and then discharged to 3.0V at a discharge rate of 0.2C in an environment of 25C, the discharge capacity at this time was determined as the first discharge capacity, the above charge-discharge cycle was repeated 200 times, and the discharge capacity at 200 th discharge was measured, with 200-turn capacity retention=200 th discharge capacity/100% of the first discharge capacity.

(5) Rate capability test

The electrochemical device was charged from 3.0 to 4.45V at a charge rate of 0.1C and then discharged to 3.0V at a discharge rate of 0.1C in an environment of 25C, and the above steps were repeated twice. Then, the battery was charged from 3.0 to 4.45V at a charge rate of 0.2C, and discharged to 3.0V at a discharge rate of 0.2C, and the discharge capacity at this time was recorded as Q1. Charging from 3.0 to 4.45V at a charge rate of 0.2C, discharging to 3.0V at a discharge rate of 2C, and recording the discharge capacity at this time as Q2. The discharge capacity retention rate of 2C/0.2 c=q2/q1×100%.

(6) Diaphragm adhesion test after cycling

And (3) after the battery is circulated for 200 circles according to the test method in the step (3), full discharge treatment is carried out, namely, the battery is discharged to 3.0V at 0.2C, then the battery is disassembled, and the pole piece is taken out. And cutting the pole piece to be tested by a blade to obtain a sample with the width of 30mm and the length of 100 mm. The special double-sided adhesive tape is adhered to a steel plate, and the width of the adhesive tape is 20mm and the length is 90mm. The pole piece test piece was attached to a double sided tape with the test face down. And (3) inserting paper tape with the width equal to the width of the pole piece and the length greater than the length of the sample by 80-200mm under the pole piece, and fixing the paper tape by using crepe adhesive. And fixing one end of the steel plate, which is not attached with the pole piece, by using a lower clamp of a pulling machine. The paper tape is turned upwards and fixed by an upper clamp of a pulling machine, and the position of the upper clamp is adjusted by an 'up' button and a 'down' button on a manual controller attached to the pulling machine. And starting a testing program of the tension machine, and testing.

The test results of comparative examples 1 to 3 and examples 1 to 27 are shown in tables 1 to 3.

TABLE 1

Examples 1 to 7 can improve the utilization ratio of lithium and further improve the initial efficiency by combining lithium replenishment with the carbon nanotube array structure, as compared with comparative example 1; and the carbon nano tube array structure can accelerate the absorption of lithium and improve the lithium absorption rate through capillary force among the carbon nano tubes. Meanwhile, the carbon nano tube has high thermal conductivity, so that heat generated in the lithium supplementing process can be quickly exported to the external environment, and the lithium supplementing temperature rise is greatly reduced. Examples 1 to 7 can compensate for lithium loss caused by formation of an SEI film at the negative electrode by means of lithium supplementation, thereby improving initial efficiency and cycle performance, as compared with comparative example 2. Examples 1-4 achieve a balance between lithium supplementation cost, lithium supplementation efficiency/temperature rise, and electrical performance by optimizing the different lithium supplementation amounts. Example 5 by changing the lithium supplementing material, the lithium supplementing temperature rise and the absorption rate can be further reduced, but the lithium slurry cost is slightly higher. Example 6 demonstrates that similar technical effects can be achieved by combining carbon nanotube arrays with lithium supplementation for different anode active materials. Example 7 demonstrates the possibility of coating with different conductive layers, as can be seen from table 1, with similar technical effects, but the metallic conductive layer presents a risk of internal self-discharge caused by metallic particles, resulting in a slight decrease in the cycling performance.

TABLE 2

Examples 8 to 17 have improved utilization of lithium supplementation compared with comparative example 1, and have improved initial efficiency, and it can be seen that the carbon nanotube array structure can improve lithium absorption rate and reduce lithium supplementation temperature rise. Under the condition of no carbon nanotube array, in the cyclic process, the silicon and lithium are alloyed to cause volume expansion, so that the bonding force between the active substance and the membrane is weakened; the carbon nano tube has high mechanical strength, and can tie up the volume expansion of silicon in the expansion process, so that the bonding force of the recycled diaphragm is improved, the powder dropping problem is avoided, the reliable electronic and ionic conductive network structure is ensured, and the better recycling performance is ensured.

Examples 8 to 17 compared with comparative example 3, examples 8 to 17 had a uniformly distributed carbon nanotube structure, and comparative example 3 had a tapered carbon nanotube cluster structure in which since CNTs were present in the form of tapered carbon clusters, silicon was attached to the periphery of the tapered carbon clusters by physical deposition, the conductive effect of the carbon tubes was reduced, the conductive path length of silicon deposited on the outermost side of the tapered carbon clusters was long, the conductivity was poor, and in addition, the active load amount in this manner was lower than in the present applicationIn the embodiment, the capacity of unit area is low, meanwhile, as the carbon cluster is conical, the process of entering the carbon tube by the electrolyte is a narrow-mouth path, and the electrolyte is rapidly transported in the unit area to a certain extent, so that active substance particles near the lower end of the current collector are difficult to rapidly obtain ions, and dynamics are influenced. Compared with the conical carbon nano tube cluster structure, the uniform carbon nano tube distribution (90 percent is less than or equal to S) ₁ /S ₂ And less than or equal to 110 percent) is favorable for the uniform absorption of lithium supplementing substances and the uniform heating and heat conducting functions, so that the temperature rise of the lithium supplementing is greatly reduced, in addition, as silicon is coated between the carbon tubes, compared with the gaps of the conical carbon nanotube clusters, each silicon can be fully contacted with the carbon nanotubes, so that a conductive network is ensured, and meanwhile, the silicon can be slightly/independently bound between the carbon tubes, but not a large amount of silicon is deposited in the conical carbon nanotube cluster array, so that the volume expansion can be relieved, and the bonding force of the membrane is improved.

Adjustment of S in examples 8 to 10 ₁ /S ₂ The positive effect of uniformly arranging the carbon tubes is proved. Examples 11-13 tailor w, with lower w having better performance than higher w, but lower ED, with a balance of electrical properties and ED, preferably w values. In examples 14 to 15, the adjustment of Deltaw, the uniform deposition of silicon, contributes to the improvement of the overall performance. Examples 16-17, in which the carbon nanotubes were distributed in a patterned structure, help to further improve electrical properties and reduce temperature rise, but there was some loss in ED.

TABLE 3 Table 3

Examples 18 to 27 are optimized compared with comparative example 1 by adjusting various parameters of the particle size D of the anode active material, the interval D between adjacent carbon nanotubes, the tube diameter p of the carbon nanotubes, and the length H of the carbon nanotubes, thereby improving the lithium supplementing performance of the silicon-containing material and enhancing the initial efficiency and the cycle electrical performance. Compared with comparative example 3, the uniform carbon nanotube distribution can further improve the cycle performance, in particular, the constraint of the carbon nanotubes on silicon expansion is improved, and further, the adhesion of the membrane is improved.

The foregoing description of the preferred embodiments of the present application is not intended to be limiting, but is intended to cover any and all modifications, equivalents, and alternatives falling within the spirit and principles of the present application.

Claims

1. An electrochemical device, characterized by comprising a negative electrode piece; the negative electrode piece comprises a carbon nano tube array; the carbon nanotube array is provided with a first negative electrode active material.

2. The electrochemical device of claim 1, wherein the negative electrode tab further comprises a current collector;

the carbon nanotube array is positioned on the current collector;

the carbon nanotube array comprises carbon nanotubes;

the first negative electrode active material is located between the carbon nanotubes.

3. The electrochemical device of claim 1, wherein the first negative active material is a silicon-containing material.

4. The electrochemical device of claim 3, wherein the silicon-containing material comprises at least one of a silicon-carbon material, a silicon oxygen material, or a pure silicon material.

5. The electrochemical device of claim 3 wherein said silicon-containing material further comprises a lithium element therein;

The mass ratio of the lithium element to the silicon element is 5 to 30%.

6. The electrochemical device of claim 3, wherein at least a portion of a surface of the silicon-containing material is provided with a conductive material;

the conductive material includes at least one of a carbon material, a metal material, or other material having conductivity.

7. The electrochemical device of claim 2, wherein the array of carbon nanotubes is patterned on the current collector; or alternatively, the first and second heat exchangers may be,

the carbon nanotube arrays are distributed on the current collector in a full-coverage mode.

8. The electrochemical device of claim 7, wherein the array of carbon nanotubes is patterned on the current collector;

the negative electrode plate comprises two or more carbon nanotube arrays which are arranged at intervals, and the average distance between the carbon nanotube arrays is M; in one of the carbon nanotube arrays, a distance between adjacent carbon nanotubes is d, which satisfies: d < M.ltoreq.500. Mu.m, preferably d < M.ltoreq.50. Mu.m.

9. The electrochemical device according to any one of claims 1 to 8, wherein at least one of the following conditions is satisfied:

10. The electrochemical device of claim 9, wherein at least one of the following conditions is satisfied:

11. The electrochemical device according to claim 1, wherein:

(A) The average particle diameter of the negative electrode active material is D, and the following conditions are satisfied: d is more than or equal to 5nm and less than or equal to 2 mu m;

(B) The distance between adjacent carbon nanotubes is d, which satisfies the following conditions: d is more than or equal to 20nm and less than or equal to 5 mu m;

(C) The pipe diameter of the carbon nano-tube is p, and the following conditions are satisfied: p is more than or equal to 5nm and less than or equal to 100nm;

(D) The length of the carbon nano tube is H, and the following conditions are satisfied: h is more than or equal to 5 mu m and less than or equal to 80 mu m.

12. The electrochemical device of claim 11, wherein at least one of the following conditions is satisfied:

13. The electrochemical device according to claim 12, wherein a ratio of a spacing D between adjacent carbon nanotubes to an average particle diameter D of the anode active material satisfies: D/D is more than or equal to 2 and less than or equal to 5.

14. The electrochemical device of claim 12, wherein a ratio of a spacing d between adjacent carbon nanotubes to a tube diameter p of the carbon nanotubes satisfies: d/p is less than or equal to 1nm and less than or equal to 250nm.

15. An electronic device comprising the electrochemical apparatus of any one of claims 1 to 14.