CN110611088A - A kind of negative electrode of lithium ion battery based on organic electrode material and preparation method thereof - Google Patents

Abstract

The invention relates to a lithium ion battery negative electrode material based on quinone organic matter, belonging to the field of secondary batteries. Electrochemically active 1,5-dihydroxynaphthalene is attached to the surface of porous activated carbon by electrochemical polymerization and deposition to prepare a battery positive electrode. The organic matter plays a decisive role in its energy storage capacity, voltage window, and electrochemical behavior. The composite positive electrode in the present invention has been tested by a half-cell, and shows a relatively high charge-discharge specific capacity and excellent rate and cycle performance. The capacity can maintain 320mAh/g after constant current charge and discharge 250 times. An organic lithium-ion battery with high energy density and long cycle life can be prepared by using the poly(1,5-dihydroxynaphthalene)/porous activated carbon composite positive electrode proposed by the present invention.

Description

A kind of negative electrode of lithium ion battery based on organic electrode material and preparation method thereof

technical field

The invention relates to the selection and preparation of an organic lithium ion battery negative electrode material, which belongs to the field of secondary batteries. The main content is a polymer attached to porous activated carbon, which is prepared by polymerizing and depositing 1,5-dihydroxynaphthalene. It is used in the negative electrode of lithium-ion batteries, which can highlight the high-quality loading of negative active materials. Reversible chemical reactions between polymers and ions in organic electrolytes play a key role in energy storage. The negative electrode is combined with a lithium sheet, and the voltage window of the composed half-cell can reach 3V. The technical method for preparing the negative electrode of the organic lithium ion battery proposed by the present invention has four significant advantages: (1) the porous activated carbon and the organic electrode material are combined to prepare the negative electrode, which has low cost and high specific capacity; (2) good cycle performance; ( 3) Good rate performance; (4) Wide voltage window. The method has the advantages of novel material, simple operation and good repeatability, and is suitable for preparing lithium-ion batteries with long life and high power characteristics.

Background technique

Secondary batteries, also known as rechargeable batteries or storage batteries, refer to batteries that can be activated by charging the active material after the battery is discharged and continue to be used. There are four main types of rechargeable batteries today: sealed lead-acid batteries; nickel-cadmium (NiCd) batteries; nickel-metal hydride (NiMH) batteries, and lithium-ion batteries. Lithium-ion batteries dominate the current battery market. For a long time, the research focus of lithium-ion battery anode materials has been on inorganic materials, such as graphite, hard carbon, silicon-carbon composites, and so on.

Organic electrode materials are a new type of energy storage materials proposed in recent years, which have the advantages of excellent processability, multi-electron reaction, redox stability, and structural diversity. Organic electrode materials are generally classified according to functional groups, including conductive polymers, sulfur-containing compounds, free radical compounds, and carbonyl compounds. Carbonyl composite electrodes can be divided into three categories. The first category is the reduction of the adjacent carbonyl group to form a stable enolate; the second category is the aromatic carbonyl derivative; the third category is the quinone compound, which can form an additional aromatic compound through reduction. system, most quinone electrode materials can be used as negative electrodes for organic secondary batteries. At present, the research on organic anode materials for lithium-ion batteries is still in the initial stage. Compared with other organic compounds, quinone compounds show superior performance in terms of capacity, discharge potential, and reaction reversibility.

The invention proposes an organic negative electrode material and a preparation method thereof for an organic lithium ion battery. Using this electrode material can improve the overall energy storage performance of lithium-ion batteries.

Contents of the invention

The invention provides a preparation method of an organic lithium ion battery negative electrode material. The main technical point lies in the selection and preparation of negative electrode materials. Coat the slurry containing porous activated carbon with high specific surface area (specific surface area>2000m ² /g) on the conductive carbon paper or carbon cloth, and use it as a working electrode after drying, and dip it into the 1,5-dihydroxynaphthalene small molecule in acid electrolyte. 1,5-Dihydroxynaphthalene was electrochemically polymerized and deposited on the inner and outer surfaces of the nanopores of porous activated carbon in a three-electrode electrolytic cell. A lithium-ion half-battery assembled from a negative electrode based on poly(1,5-dihydroxynaphthalene)/porous activated carbon composite and a lithium sheet was used for performance testing. The significant advantages of the negative electrode are high capacity per unit area, good cycle performance and low price.

In order to achieve the above object, the technical scheme of the present invention is as follows:

First, a substrate based on porous nanocarbon powder is prepared.

(1) Disperse the purchased porous activated carbon powder, polyvinylidene fluoride, and acetylene black in N-methylpyrrolidone (NMP) at a mass ratio of 8:1:1, and then stir magnetically for 24 hours to obtain a concentration of ~110 mg/mL Toner paste.

(2) Coat the carbon powder slurry evenly on the carbon fiber paper, and then place it in an oven at 100° C. for 12 hours to dry. The mass loading of carbon powder can be controlled between 2–10 mg/cm ² . Here commercial carbon fiber paper is used as current collector.

This is followed by electrochemical deposition of polymers.

(3) Dissolve 1,5-dihydroxynaphthalene in a certain concentration of sulfuric acid aqueous solution to prepare an electrolyte solution.

(4) Immerse the conductive carbon paper coated with porous activated carbon in the electrolyte described in (3) as the working electrode, the platinum mesh is used as the counter electrode, adopt Ag/AgCl reference electrode, utilize cyclic voltammetry, at a certain Electrochemical deposition was carried out at a voltage scanning speed (20mV/s), so that the 1,5-dihydroxynaphthalene molecules in the electrolyte were polymerized and uniformly deposited on the porous activated carbon substrate, as shown in Figure 1. Voltammetric cycle 200–400 cycles. In this way, on the basis of the original electric double layer capacitance of activated carbon, the pseudocapacitance and ion deintercalation reaction of the polymer can be introduced, which can increase the energy storage capacity by about 4 times. At the same time, the voltage window can also be widened.

Finally, assemble the lithium-ion half-cell, the specific steps are as follows:

(6) The poly(1,5-dihydroxynaphthalene)/activated carbon composite is used as the positive electrode, and the lithium sheet is used as the negative electrode, and the lithium-ion half-cell is assembled in the order of the negative electrode shell, shrapnel, gasket, lithium sheet, separator, and positive electrode sheet, Drop in the electrolyte and package. The active ingredient of the electrolyte is lithium hexafluorophosphate.

The organic lithium ion battery negative electrode material of the present invention is characterized in the following aspects:

(1) Select porous activated carbon powder with high specific surface area as the carrier of the polymer. During the electrodeposition process, the polymer not only filled the nanopores, but also attached to the surface of the carbon particles. Since there is no polymer structure with a thicker block, the ions in the electrolyte can be easily intercalated in the polymer and undergo reversible redox reactions with the molecular chains, effectively utilizing the polymer molecules for energy storage.

(2) Using poly(1,5-dihydroxynaphthalene)/porous activated carbon composite as the positive electrode to construct a lithium-ion half-cell, the voltage window is 0–3V, and when the current density is 0.1A/g, the first discharge ratio of the battery is The capacity exceeds 1200mAh/g. Under the current density of 0.5A/g, the capacity can maintain 320mAh/g after 250 times of constant current charge and discharge.

(3) Organic anode materials for lithium-ion batteries are safe and environmentally friendly, have a wide range of sources, high specific capacity, good cycle performance, and low price.

The invention proposes a method for preparing the negative electrode material of the organic lithium ion battery, which abandons the traditional inorganic negative electrode material and is conducive to improving the mass loading capacity of the active material on the electrode. The whole preparation process is simple, good in repeatability, low in cost, easy in preparation and large-scale production, and meets the needs of practical applications.

Description of drawings

Accompanying drawing 1 is the scanning electron microscope picture after electrochemical polymerization deposition poly(1,5-dihydroxynaphthalene) on the surface of porous activated carbon coating. (a) Low magnification image; (b) High magnification image of the surface of a single activated carbon particle.

Accompanying drawing 2 adopts the poly(1,5-dihydroxynaphthalene)/activated carbon composite material as positive electrode, the galvanostatic charge and discharge curve of the lithium-ion half-cell battery constructed.

Accompanying drawing 3 adopts the poly(1,5-dihydroxynaphthalene)/activated carbon composite material as the positive electrode, the linear cyclic voltammetry curve of the lithium-ion half-cell battery constructed.

Detailed ways

The present invention is described further below in conjunction with example, but the present invention is not limited to specific embodiment.

(1) Dry the conductive carbon fiber paper in an oven at 60°C for 24 hours, and set it aside.

(2) Disperse porous activated carbon powder with a specific surface area of 2230m ² /g, polyvinylidene fluoride, and conductive acetylene black in N-methylpyrrolidone (NMP) at a mass ratio of 8:1:1, and then make a magnetic stirrer for 24 Hours to obtain a uniform carbon powder slurry (120mg/mL).

(3) The carbon powder slurry was uniformly coated on the carbon paper, and then dried in an oven at 100° C. for 12 hours, and the area loading of the obtained carbon powder coating was 3 mg/cm ² .

(4) Weigh 1,5-dihydroxynaphthalene powder and add it into 1M sulfuric acid aqueous solution to form a solution containing 1,5-dihydroxynaphthalene with a concentration of 0.03M, which is used as a mother liquor for electrochemical polymerization.

(5) Immerse the conductive carbon paper coated with porous activated carbon as the working electrode in the acidic electrolyte dissolved in 1,5-dihydroxynaphthalene, the platinum mesh as the counter electrode, and the Ag/AgCl as the reference electrode. Anfa performs electrochemical polymerization on carbon powder flexible electrodes. Under the voltage scanning rate of 20mV/s, the voltage range of -0.3-1.0V, the cyclic voltammetry curve is 200 times, and the electrode composited with poly(1,5-dihydroxynaphthalene) and porous activated carbon is obtained as the positive electrode of lithium ion battery .

(6) Assemble the lithium-ion half-battery in the order of the negative electrode shell, shrapnel, gasket, lithium sheet, diaphragm, poly(1,5-dihydroxynaphthalene)/activated carbon composite material, and conduct electrochemical tests. The active ingredient of the electrolyte is lithium hexafluorophosphate .

The above is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process conversion made by using the content of the description of the present invention, or directly or indirectly used in other related technical fields, All are included in the scope of patent protection of the present invention in the same way.

Claims (5)

1. a kind of lithium-ion battery negative pole based on organic electrode material and preparation method thereof of the present invention is characterized in that the selection and preparation method of negative electrode material: (1), porous activated carbon, PVDF and conductive carbon black are uniformly mixed according to the ratio of 8:1:1 in mass ratio, and dispersed in NMP organic solvent to obtain slurry; (2), the slurry obtained in step (1) is evenly coated on the surface of carbon fiber paper, and dried to obtain sample 1; (3), dissolving 1,5-dihydroxynaphthalene in an acid electrolyte to obtain a solution 2; (4), the sample 1 that obtains in step (2) is used as working electrode, platinum mesh is as counter electrode, and Ag/AgCl is reference electrode, and solution 2 is obtained as electrolyte in step (3), in three-electrode electrolytic cell Electrochemical polymerization deposition is carried out by cyclic voltammetry at a rate of 20-80mV/s, and the number of cycles is 200, and the polymerized 1,5-dihydroxynaphthalene can be attached to the porous activated carbon particles. During the electrodeposition process, 1,5-dihydroxynaphthalene can not only be filled into the nanopores of porous activated carbon, but also attached to the surface of carbon particles in the form of particles; (5) Using 1,5-dihydroxynaphthalene/porous activated carbon composite positive electrode, metal lithium negative electrode, separator, and lithium hexafluorophosphate electrolyte to form a lithium-ion half-cell for testing. 2. a kind of lithium-ion battery negative pole based on organic electrode material and preparation method thereof according to claim 1, is characterized in that the selection of the porous activated carbon of the high specific surface area described in step (1). 3. a kind of lithium-ion battery negative pole based on organic electrode material and preparation method thereof according to claim 1, is characterized in that the selection of carbon fiber paper described in step (2). 4. a kind of lithium-ion battery negative pole based on organic electrode material and preparation method thereof according to claim 1, it is characterized in that described in step (3) selects 1,5-dihydroxynaphthalene for use, and the setting of concentration thereof Certainly. 5. A kind of negative electrode of lithium ion battery based on organic electrode material and preparation method thereof according to claim 1, it is characterized in that the voltammetric cycle method described in step (4) electrochemically polymerizes and deposits polymer.