CN110867559A

CN110867559A - Porous lithium metal anode, preparation and application thereof in lithium metal battery

Info

Publication number: CN110867559A
Application number: CN201810978735.XA
Authority: CN
Inventors: 赖延清; 洪波; 范海林; 段柏禹; 张治安; 张凯
Original assignee: Central South University
Current assignee: Guangdong Mic Power New Energy Co Ltd
Priority date: 2018-08-27
Filing date: 2018-08-27
Publication date: 2020-03-06
Anticipated expiration: 2038-08-27
Also published as: CN110867559B

Abstract

The invention belongs to the technical field of lithium metal batteries, and particularly discloses a porous lithium metal anode which comprises a porous metal current collector, a metal lithium layer compounded on a framework of the porous metal current collector, and a lithium oxide layer covering the surface of the metal lithium layer. The invention also discloses a preparation method of the porous lithium metal anode, which comprises the steps of carrying out surface oxidation on the porous metal current collector, then filling metal lithium into the porous metal current collector after the surface oxidation, and carrying out a replacement reaction to obtain the porous lithium metal anode. The invention also discloses application of the porous lithium metal anode and a prepared lithium metal battery. In the invention, the existence of the lithium oxide layer formed in situ reduces the direct contact of the lithium metal and the electrolyte, effectively avoids the occurrence of interface reaction, and simultaneously maintains the advantage of high specific surface area of the porous metal current collector. Meanwhile, the good lithium affinity of the oxide layer is beneficial to stabilizing the transmission of lithium ions, and finally the long cycle life of the lithium metal battery is realized.

Description

Porous lithium metal anode, preparation and application thereof in lithium metal battery

Technical Field

The invention belongs to the field of energy storage, and particularly relates to preparation and application of a porous lithium metal anode.

Background

The mechanism of action of metallic lithium anodes in batteries is the deposition and dissolution of metallic lithium, which is essentially reflected by the formula:

charging: li⁺+ e ═ Li; discharging: li-e ═ Li⁺. What occurs with the negative electrode unlike conventional lithium ion batteries is the intercalation and deintercalation of lithium ions in the graphite negative electrode.

By virtue of the ultrahigh theoretical specific capacity (3860mAh/g) and the lowest electrode potential (-3.04V), the metallic lithium is considered as the most promising anode material for the next generation of lithium batteries by more and more researchers. Against this background, lithium sulfur batteries and lithium air batteries using metallic lithium as an anode have been developed in recent years. However, the large volume effect of lithium dendrites and lithium metal battery cycling limits their practical applications. To cope with these problems, a number of strategies, such as optimizing lithium salts, solvents, functional additives in the electrolyte and even ionic liquids, have been widely developed and studied. Such as Miao Wang et al [ P.Zhuang, J.Zhu, M.Wang, N.Imanishi, O.Yamamoto, Lithium dentures prediction and cycling efficacy of Lithium anode, electrochemistry communications 87(2018)27-30 ] use 2.5M Lithium salt to change the physicochemical properties of the electrolyte, thereby inhibiting the growth of Lithium dendrites. Ji-Guang Zhang et al [ J.Qian, W.Xu, P.Bhattacharya, M.Engelhard, W.A.Henderson, Y.Zhang, J. -G.Zhang, Dendrie-free Li disposition using trace-around of water as an electrolyte additive, Nano Energy15(2015) 135-. After these studies, researchers have achieved a very favorable performance with a large number of lithium dendrites being successfully suppressed. However, the problem of the large volume effect in the cycling process of lithium metal batteries, especially at high area capacity, remains to be solved.

In recent years, researchers have found that loading metallic lithium in a 3D porous current collector can effectively mitigate volume changes during the deposition/dissolution of metallic lithium. Meanwhile, the ultra-high specific surface area of the 3D porous current collector can sufficiently reduce the current density on the surface of the electrode, so that the lithium metal can be deposited without dendrites at a lower current density, such as Quan-Hong Yang et al [ Q.Yun, Y. -B.He, W.Lv, Y.ZHao, B.Li, F.kang, Q. -H.Yang, Chemical dealloying derivative 3D porous current collector for Li metal alloys, Advanced Materials 28(32 (2016) 6932-.]The porous copper current collector is prepared by dealloying Cu-Zn alloy and is used as a working electrode, and the content of the porous copper current collector is 1mA/cm²A current density of 150 cycles is achieved. Similarly, Yu-Guo Guo et al [ S. -H.Wang, Y. -X.yin, T. -T.Zuo, W.Dong, J. -Y.Li, J. -L.Shi, C. -H.Zhang, N. -W.Li, C. -J.Li, Y. -G.Guo, Stable Li metal alloys a regulating lithium plating/linear inverting additive microchannels, Advanced Materials 29(40 (2017) 1703729-1703736).]The porous copper is prepared by the laser technology and is realized at 1mA/cm²At a current density of 200 cycles. However, the ultra-high specific surface area of the 3D porous current collector as a pair of double-edged swords reduces the current density on the surface of the electrode and also causes the contact area between the lithium metal and the electrolyte to be greatly increased. The large contact area results in a large number of interfacial side reactions, resulting in a large loss of active lithium. Therefore, the conventional metallic lithium supported 3D porous current collector is difficult to be actually used industrially as an anode material of a lithium metal battery.

Disclosure of Invention

In view of the problems common to 3D lithium metal anodes, a first object of the present invention is to provide a porous lithium metal anode coated with a lithium oxide layer in situ.

The second objective of the present invention is to provide a method for preparing the porous lithium metal anode, which aims to deposit lithium on the framework of the 3D current collector in situ and cover the lithium oxide layer in situ, thereby significantly improving the electrical properties of the anode.

The third purpose of the invention is to provide the application of the porous lithium metal anode.

A porous lithium metal anode comprises a porous metal current collector, a metal lithium layer compounded on the skeleton of the porous metal current collector, and a lithium oxide layer covering the surface of the metal lithium layer.

The lithium metal anode is characterized in that a metal lithium layer is innovatively and compositely deposited on a framework of pores of a 3D porous metal current collector, and the surface of the metal lithium layer is coated with a lithium oxide layer; the structure is matched with the material components, so that the apparent current density of the surface of the lithium metal can be obviously reduced, the stable circulation of the lithium metal under high current density is realized, and the (2-5 mA/cm) current density under high current density is effectively improved²) The cycle performance of (c). Meanwhile, due to the existence of the uniform and compact lithium oxide layer, the direct contact between the electrolyte and the metal lithium is effectively avoided, and the occurrence of the interface reaction of the conventional 3D lithium metal anode and the loss of the continuous metal lithium are inhibited.

Preferably, the material of the 3D porous metal current collector is at least one of titanium, chromium, manganese, iron, cobalt, nickel, and copper.

Preferably, the porous metal current collector is any one of porous titanium, porous chromium, porous manganese, porous iron, porous cobalt, porous nickel, porous copper and the like, and binary and ternary porous alloy current collectors thereof.

Preferably, the 3D porous binary alloy current collector is any one of porous nickel-copper, porous nickel-titanium, porous nickel-chromium, porous nickel-iron, porous nickel-cobalt, porous nickel-manganese, porous iron-titanium, porous iron-chromium, porous iron-copper, porous iron-cobalt, porous iron-manganese, porous cobalt-titanium, porous cobalt-copper, and porous cobalt-manganese alloy. The component proportion of the 3D porous binary alloy is arbitrary.

Preferably, the 3D porous ternary alloy current collector is any one of porous nickel-copper-titanium, porous nickel-copper-iron, porous nickel-copper-cobalt, porous nickel-copper-manganese, porous iron-cobalt-nickel, porous iron-chromium-nickel and porous nickel-copper-chromium alloy. The component proportion of the 3D porous ternary alloy is arbitrary.

Further preferably, the material of the 3D porous metal current collector is porous nickel, porous copper, porous nickel-chromium, porous nickel-iron, porous nickel-copper, porous iron-copper, porous cobalt-copper, porous nickel-copper-titanium, porous nickel-copper-iron, porous nickel-copper-cobalt, porous nickel-copper-manganese. The preferred metallic current collector has superior performance.

Most preferably, the material of the 3D porous metal current collector is porous nickel (also called nickel foam).

The thickness of the 3D porous current collector is 10-1200 mu m; preferably 30 to 500 μm; more preferably 40 to 70 μm.

The porosity of the 3D porous current collector is 20-99%; preferably 30-90%; more preferably 40 to 90%. The inventors have found that the use of a higher porosity current collector helps to improve the electrical properties of the resulting anode, particularly the cycling performance at high current densities.

The porosity of the 3D porous current collector is most preferably 40-60%.

The pore spacing of the 3D porous current collector is 1-400 mu m; preferably 5 to 300 μm; more preferably 40 to 120 μm. The larger pore size helps to further enhance the electrical performance of the resulting anode.

Preferably, the content of metallic lithium in the porous lithium metal anode is in the range of 10-90 wt.%.

Preferably, the thickness of the lithium oxide is in the range of 10 to 700 nm.

Preferably, the content of the metal lithium is 2-12 mAh/cm 2; further preferably 5 to 8mAh/cm 2.

The metal lithium layer and the lithium oxide layer are formed in situ by the replacement reaction of the metal oxide material and the metal lithium compounded on the surface of the 3D porous current collector. The metal element of the metal oxide material is the same as that of the 3D porous current collector.

Preferably, the metal oxide material is obtained by oxidizing and roasting the 3D porous current collector.

The oxidizing roasting atmosphere is, for example, an oxygen-containing atmosphere, wherein the volume content of oxygen is 5-90%; preferably 15-70%; more preferably 25 to 55%.

The temperature of oxidizing roasting is 500-800 ℃.

The invention also provides a preparation method of the porous lithium metal anode, which comprises the steps of carrying out surface oxidation (oxidation pretreatment) on a porous metal current collector, then filling metal lithium into the porous metal current collector after the surface oxidation, carrying out a replacement reaction, forming the metal lithium layer on the surface of the framework in situ, and covering the lithium oxide layer on the surface of the metal lithium layer to prepare the porous lithium metal anode.

The invention innovatively carries out oxidation pretreatment on the porous metal current collector in advance to ensure that the framework is subjected to micro-oxidation, and then uses the oxidation product formed in situ as an induced lithium deposition material to ensure that lithium preferentially enters the framework to carry out a displacement reaction with the framework, thereby achieving the purpose of inducing the in-situ deposition of the lithium in the framework. The preparation method provided by the invention realizes the induced in-situ deposition of lithium and the in-situ one-step formation of the SEI protective film, so that the uniformity of lithium deposition and a lithium oxide layer can be fully ensured, the effective specific surface area of the 3D metal current collector can be fully utilized, the problem of lithium dendrite is solved, the cycle life of the anode is remarkably prolonged, and particularly the cycle performance under high current density is improved.

Preferably, the surface oxidation is: and roasting the porous metal current collector in an oxygen-containing atmosphere. Researches show that the treatment mode is convenient, and the subsequent one-step in-situ deposition of the metal lithium layer and the lithium oxide layer is facilitated.

The inventor researches and discovers that for the innovative porous metal lithium anode, the control of the oxidation degree of the surface of the 3D metal current collector framework has great influence on the performance of the subsequent anode; further research shows that the in-situ deposition effect of the metal lithium layer and the lithium oxide layer can be further improved by regulating and controlling parameters such as oxidizing atmosphere, roasting temperature, time and the like, and the electrical performance of the prepared porous metal lithium anode can be further improved.

The oxygen volume content of the oxygen-containing atmosphere is 5-90%.

Preferably, the oxygen-containing atmosphere has an oxygen volume content of 15 to 70%.

Further preferably, the oxygen volume content of the oxygen-containing atmosphere is 25 to 55%. In this preferred atmosphere, the electrical properties of subsequently produced anodes can be surprisingly improved.

The oxygen-containing atmosphere comprises oxygen and also comprises a protective gas. The protective gas is, for example, nitrogen or an inert gas.

Preferably, the oxygen-containing atmosphere is a mixed atmosphere of oxygen and nitrogen.

The roasting temperature is 100-1000 ℃; preferably 500-800 ℃; further preferably 500 to 700 ℃.

The inventor researches and discovers that for the lithium metal anode, the electrical performance, particularly the cycle performance at high current density, of the prepared lithium metal anode can be unexpectedly improved by controlling the oxidizing and roasting temperature to be 500-800 ℃, particularly 500-700 ℃.

Preferably, the time of oxidizing roasting is 0.2-10 h.

Preferably, the oxidizing roasting time is 0.5-5 h. The calcination results are more excellent at the above-mentioned atmosphere and calcination temperature for the preferred calcination time.

Preferably, the method for filling the metallic lithium is electrodeposition or melting; electrodeposition is preferred. It was found that lithium filling was performed using an electrodeposition method, utilizing in-situ formation of the lithium metal layer and the lithium oxide layer.

Preferably, the electrodeposition step is: and taking the porous metal current collector after the oxidation treatment as a working electrode and a lithium sheet as a counter electrode, and carrying out electrodeposition in an organic solvent containing lithium salt.

Preferably, the amount of the electrodeposited lithium metal is 2-12 mAh/cm 2; further preferably 5 to 8mAh/cm 2. At a preferred amount of deposited lithium, the resulting anode material is excellent in electrical properties, particularly cycle performance.

The invention also provides an application of the porous lithium metal anode, and the porous lithium metal anode is used as an anode of a lithium metal battery.

The invention also provides a lithium metal battery using the porous lithium metal anode as an electrode.

Preferably, the lithium metal battery is a lithium sulfur battery, a lithium iodine battery, a lithium selenium battery, a lithium tellurium battery, a lithium oxygen battery or a lithium carbon dioxide battery.

Has the advantages that:

according to the provided porous lithium metal anode, the apparent current density of the surface of lithium metal can be obviously reduced due to the high specific surface area of the porous lithium metal anode, and stable circulation of metal lithium under high current density is realized. Meanwhile, due to the existence of the uniform and compact lithium oxide layer, the direct contact between the electrolyte and the metal lithium is effectively avoided, and the occurrence of the interface reaction of the conventional 3D lithium anode and the loss of the continuous metal lithium are inhibited. The actual specific capacity of the 3D lithium anode prepared by the method can reach 3500mAh/g, which is 3-10 times of that of the cathode material of the conventional lithium ion battery. In addition, the simple preparation process is beneficial to promoting the practical application of 3D metal lithium industrialization.

Drawings

FIG. 1 is an SEM photograph of copper foam of example 1.

FIG. 2 is an SEM image of oxidized copper foam of example 1.

FIG. 3 is the EDS of the oxidized copper foam of example 1.

FIG. 4 is a graph of the cycle performance of the copper foam of example 1 and the copper foam after oxidation.

Detailed Description

The following is a detailed description of the preferred embodiments of the invention and is not intended to limit the invention in any way, i.e., the invention is not intended to be limited to the embodiments described above, and modifications and alternative compounds that are conventional in the art are intended to be included within the scope of the invention as defined in the claims.

Example 1

A commercial copper foam current collector (FIG. 1) having a thickness of 40 μm, a porosity of 60% and a pore spacing of 80 μm was placed in an oxygen-containing nitrogen atmosphere (oxygen content 20%) at 500 deg.CAnd sintering for 1h to obtain the copper oxide modified foam copper (figure 2). The electrode was used as a working electrode, a lithium metal sheet was used as a counter electrode, and 1 wt.% LiNO was contained in a volume ratio of 1M LiTFSI/DOL: DME (volume ratio: 1)₃And (5) assembling the button cell for the electrolyte, and carrying out charge-discharge cycle test. Meanwhile, pure copper foam is used as a comparison sample to carry out corresponding charge-discharge cycle test.

Tests show that the surface of the copper foam is uniformly covered with a layer of compact copper oxide (figure 3), so that uniform dendrite-free lithium deposition is realized, and lithium dendrites and interface reactions are effectively avoided. In particular at 2mA/cm²The cycle life of the oxidized copper foam electrode was 6 times or more the cycle life of the pure copper foam electrode at the current density of (2) (fig. 4).

Example 2

The thickness of a commercial porous ferronickel current collector is 70 mu m, the porosity is 40 percent, and the pore spacing is 120 mu m, the porous ferronickel is placed in an oxygen-containing argon atmosphere (oxygen content is 30 percent), and sintered for 2h at 700 ℃ to obtain the porous ferronickel with an oxide layer modified. The electrode was used as a working electrode, a lithium metal sheet was used as a counter electrode, and 1 wt.% LiNO was contained in a volume ratio of 1M LiTFSI/DOL: DME (volume ratio: 1)₃And (5) assembling the button cell for the electrolyte, and carrying out charge-discharge cycle test. Meanwhile, corresponding charge-discharge cycle test is carried out by taking pure porous ferronickel as a comparison sample.

Tests show that the surface of the porous ferronickel is uniformly covered with a compact oxide layer. In particular at 5mA/cm²The cycle life of the oxidized porous nickel-iron electrode is more than 5 times of that of the pure porous nickel-iron electrode under the current density of (1).

Example 3

Full cell case:

the copper oxide modified copper foam prepared in example 1 was used as a working electrode and then at 0.5mA/cm²At a current density of 5mAh/cm²Metallic lithium is coated on the electrode to prepare a composite anode material, and then the composite anode material and a carbon nano tube anode rich in S simple substance form a lithium sulfur battery, wherein the lithium sulfur battery contains 1 wt.% LiNO in a volume ratio of 1M LiTFSI/DOL: DME (1: 1)₃In the electrolyte, at 1C, the charge-discharge cycle test is carried out。

Comparative example 1

Using foam copper as working electrode, then at 0.5mA/cm²At a current density of 5mAh/cm²Lithium metal is added into the copper foam, and then the lithium metal and the carbon nano tube anode rich in the S simple substance form a lithium sulfur battery, and the lithium sulfur battery contains 1 wt.% LiNO in a volume ratio of 1M LiTFSI/DOL to DME (volume ratio is 1: 1)₃The charge-discharge cycle test was carried out in the electrolyte solution of (1).

The results of the tests on the obtained batteries are shown in the attached table 1.

TABLE 1

The comparison between example 3 and comparative example 1 shows that the coulombic efficiency and the cycle performance of the porous lithium metal anode are obviously improved.

Example 4

The thicknesses of commercial foam nickel and foam iron current collectors are 50 micrometers, the porosity is 50%, and the pore spacing is 90 micrometers, the foam nickel and the foam iron are placed in an oxygen-containing nitrogen atmosphere (with the oxygen content of 30%), and sintering is carried out for 1.5 hours at the temperature of 600 ℃ to respectively obtain nickel oxide modified foam nickel and iron oxide modified foam iron. The two types of electrodes are respectively used as working electrodes, a metal lithium sheet is used as a counter electrode, and 1M LiTFSI/DOL: DME (volume ratio is 1: 1) contains 1 wt.% LiNO₃Assembling the button cell for the electrolyte at 2mA/cm²The charge-discharge cycle test was carried out at the current density of (1).

The results of the tests on the obtained batteries are shown in the attached table 2.

Example 5

The thickness of each of the two commercial foam nickel current collectors is 50 μm, the pore spacing is 90 μm, and the porosity is 30% and 90%, respectively, the two foam nickel are placed in an oxygen-containing nitrogen atmosphere (oxygen content is 30%) and sintered for 1.5h at 600 ℃ to obtain nickel oxide modified foam nickel. The two electrodes were used as working electrodes, a metallic lithium plate was used as a counter electrode, and 1 wt.% LiNO was contained in a volume ratio of 1 MLiTFSI/DOL: DME (volume ratio: 1)₃Button cell assembly for electrolyte, 2mA/cm²The charge-discharge cycle test was carried out at the current density of (1).

Example 6

The commercial foam nickel current collector has a thickness of 50 μm and a porosity of 50% and a pore spacing of 5 μm and 300 μm, respectively, and the two types of foam nickel are placed in an oxygen-containing nitrogen atmosphere (oxygen content of 30%) and sintered at 600 ℃ for 1.5h to obtain nickel oxide modified foam nickel. Two electrodes are used as working electrodes, a metal lithium sheet is used as a counter electrode, and 1M LiTFSI/DOL/DME (volume ratio is 1: 1) contains 1 wt.% LiNO₃Assembling the button cell for the electrolyte at 2mA/cm²The charge-discharge cycle test was carried out at the current density of (1).

TABLE 2

Example 4 shows that the current collector material has a certain influence on the electrical properties, and it is found through example 4 that when the nickel foam is used as the porous metal current collector, the electrical properties can be further improved unexpectedly.

Example 5 shows that the porosity is large, which is helpful for improving the performance, and particularly, the electrical performance, particularly the cycle performance, of the obtained anode is excellent under the porosity of 40-60%.

Example 6 shows that in the preferred range, the large pore spacing contributes to the performance enhancement, and the electrical properties, especially the cycle performance, of the anode obtained at the preferred 40-300 μm are excellent.

Example 7

The commercial porous iron-copper current collector has the thickness of 60 mu m, the porosity of 60 percent and the pore spacing of 45 mu m, and is respectively placed in nitrogen and argon atmosphere with the oxygen content of 40 percent and sintered for 2 hours at 700 ℃ to obtain the porous iron-copper jointly modified by two types of iron oxide and copper oxide. The two obtained electrodes are used as working electrodes, a metal lithium sheet is used as a counter electrode, and 1M LiTFSI/D is usedAssembling button cell with OL: DME (volume ratio of 1: 1) containing 1 wt.% LiNO3 as electrolyte at 3 mA/cm²The charge-discharge cycle test was carried out at the current density of (1).

The results of the tests on the batteries obtained are shown in the attached Table 3.

Example 8

The commercial porous iron-copper current collector has the thickness of 60 mu m, the porosity of 60 percent and the pore spacing of 45 mu m, and is respectively placed in a nitrogen atmosphere with the oxygen content of 5 percent, 15 percent, 25 percent, 55 percent, 70 percent and 90 percent and sintered for 2 hours at 700 ℃ to obtain the porous iron-copper jointly modified by two types of iron oxide and copper oxide. The obtained electrodes were used as working electrodes, a metal lithium sheet was used as a counter electrode, and a button cell was assembled using 1M LiTFSI/DOL: DME (volume ratio 1: 1) containing 1 wt.% of LiNO3 as an electrolyte at 3 mA/cm²The charge-discharge cycle test was carried out at the current density of (1).

Example 9

The commercial porous iron-copper current collector has the thickness of 60 mu m, the porosity of 60 percent and the pore spacing of 45 mu m, and is sintered for 0.2, 0.5, 3, 5 and 10 hours at 700 ℃ in a nitrogen atmosphere with the oxygen content of 40 percent to obtain the porous iron-copper jointly modified by two types of iron oxide and copper oxide. The obtained electrodes were used as working electrodes, a metal lithium sheet was used as a counter electrode, and a button cell was assembled using 1M LiTFSI/DOL: DME (volume ratio 1: 1) containing 1 wt.% of LiNO3 as an electrolyte at 3 mA/cm²The charge-discharge cycle test was carried out at the current density of (1).

TABLE 3

Example 7 shows that the current collector obtained in a nitrogen atmosphere has good performance, examples 8 and 9 show that the performance of the prepared material is better when the oxygen content is 25-55%, and in addition, the electrical performance of the subsequently prepared anode is better after roasting for 0.5-5 h.

Example 10

The commercial porous nickel-copper-iron current collector has the thickness of 150 mu m, the porosity of 75 percent and the pore spacing of 100 mu m, and is sintered for 3.5 hours at 650 ℃ respectively in a nitrogen atmosphere with the oxygen content of 35 percent to obtain the oxide modified porous nickel-copper-iron. The obtained electrode was used as a working electrode, a metal lithium sheet was used as a counter electrode, and a button cell was assembled using 1M LiTFSI/DOL: DME (volume ratio 1: 1) containing 1 wt.% LiNO3 as an electrolyte, followed by 1mA/cm²Depositing 0.5, 2, 5, 8, 12mAh/cm2 of metal lithium on the working electrode under the current density to obtain a composite 3D lithium anode, forming a lithium sulfur battery with the graphene anode rich in the S simple substance, and carrying out a charge-discharge cycle test at 1C.

The results of the tests on the batteries obtained are shown in the attached Table 4.

TABLE 4

The result shows that the 3D lithium anode obtained when the deposited lithium amount is within 5-8 mAh/cm2 has good performance.

Example 11

The copper oxide modified copper foam prepared in example 1 was used as an electrode, and was contacted with molten lithium metal at 220 ℃ in an argon atmosphere to prepare a composite lithium anode material, which was then combined with a carbon nanotube positive electrode rich in elemental S to form a lithium sulfur battery, and a charge-discharge cycle test was performed at 1C in an electrolyte containing 1 wt.% of LiNO3 in a volume ratio of 1 MLiTFSI/DOL: DME (1: 1).

As can be seen from Table 1, the effect of filling lithium with molten material is slightly inferior to that of filling lithium by electrodeposition.

Comparative example 2

The present comparative example discusses the use of a planar current collector, as follows:

the commercial copper foil was placed in an oxygen-containing nitrogen atmosphere (oxygen content: 20%) and sintered at 500 ℃ for 1 hour to obtain a copper oxide-modified copper foil. The electrode was used as a working electrode, a lithium metal sheet was used as a counter electrode, and 1 wt.% LiNO was contained in a volume ratio of 1M LiTFSI/DOL: DME (volume ratio: 1)₃Assembling the button cell for the electrolyte at 2mA/cm²At the current density of (3), a charge-discharge cycle test was performed. Meanwhile, the copper foil is used as a comparison sample to carry out corresponding charge-discharge cycle test.

The results of the tests on the batteries obtained are shown in the attached Table 5.

Comparative example 3

The commercial copper foam current collector has a thickness of 40 μm, a porosity of 10% and a pore spacing of 80 μm, and is sintered at 500 ℃ for 1 hour in an oxygen-containing nitrogen atmosphere (oxygen content of 20%) to obtain copper oxide-modified copper foam. The electrode was used as a working electrode, a lithium metal sheet was used as a counter electrode, and 1 wt.% LiNO was contained in a volume ratio of 1M LiTFSI/DOL: DME (volume ratio: 1)₃Assembling the button cell for the electrolyte at 2mA/cm²At the current density of (3), a charge-discharge cycle test was performed.

Comparative example 4

The commercial copper foam current collector has the thickness of 40 mu m, the porosity of 60 percent and the pore spacing of 500 mu m, and the copper foam is placed in an oxygen-containing nitrogen atmosphere (the oxygen content is 20 percent) and sintered for 1h at 500 ℃ to obtain the copper oxide modified copper foam. The electrode was used as a working electrode, a lithium metal sheet was used as a counter electrode, and 1 wt.% LiNO was contained in a volume ratio of 1M LiTFSI/DOL: DME (volume ratio: 1)₃Assembling the button cell for the electrolyte at 2mA/cm²At the current density of (3), a charge-discharge cycle test was performed.

Comparative example 5

This comparative example discusses the calcination temperature as follows:

the commercial copper foam current collector has the thickness of 40 mu m, the porosity of 60 percent and the pore spacing of 80 mu m, and the copper foam is placed in an oxygen-containing nitrogen atmosphere (the oxygen content is 20 percent) and sintered for 1h at 50 and 1200 ℃ respectively to obtain two kinds of copper oxide modified copper foams. The two electrodes were used as working electrodes, a lithium metal sheet was used as a counter electrode, and 1M LiTFSI/DOL: DME (volume ratio: 1) containing 1 wt.% LiNO₃Assembling the button cell for the electrolyte at 2mA/cm²At the current density of (3), a charge-discharge cycle test was performed.

Comparative example 6

This comparative example discusses the oxygen content as follows:

the commercial copper foam current collector has the thickness of 40 mu m, the porosity of 60 percent and the pore spacing of 80 mu m, and is respectively placed in a pure oxygen atmosphere, a nitrogen atmosphere with the oxygen content of 2 percent and an argon atmosphere with the oxygen content of 2 percent, and sintered for 1h at 500 ℃ to obtain three kinds of copper oxide modified copper foam. The three electrodes were used as working electrodes, lithium metal sheets as counter electrodes, and 1M LiTFSI/DOL: DME (volume ratio 1: 1) containing 1 wt.% LiNO₃Assembling the button cell for the electrolyte at 2mA/cm²At the current density of (3), a charge-discharge cycle test was performed.

TABLE 5

Comparative examples 2-6 show that poor performance is obtained with planar current collectors or without being in the preferred range.

Claims

1. A porous lithium metal anode characterized by: the lithium ion battery comprises a porous metal current collector, a metal lithium layer compounded on a porous metal current collector framework and a lithium oxide layer covering the surface of the metal lithium layer.

2. The porous lithium metal anode of claim 1, wherein: the material of the 3D porous metal current collector is at least one of titanium, chromium, manganese, iron, cobalt, nickel and copper;

preferably, the thickness of the 3D porous current collector is 10-1200 μm; more preferably 30 to 500 μm;

preferably, the porosity of the 3D porous current collector is 20-99%; further preferably 30-90%;

preferably, the pore space of the 3D porous current collector is 1-400 μm; more preferably 5 to 300 μm.

3. The porous lithium metal anode of claim 1, wherein: the content of the metal lithium ranges from 10 to 90 wt.%; the thickness of the lithium oxide ranges from 10 nm to 700 nm.

4. The porous lithium metal anode of any one of claims 1 to 3, wherein: the metal lithium layer and the lithium oxide layer are formed in situ by the replacement reaction of a metal oxide material and metal lithium compounded on the surface of the 3D porous current collector;

preferably, the metal element of the metal oxide material is the same as the metal element of the 3D porous current collector;

5. A method for preparing a porous lithium metal anode according to any one of claims 1 to 4, characterized in that: carrying out surface oxidation on the porous metal current collector, then filling metal lithium into the porous metal current collector after the surface oxidation, and carrying out a displacement reaction to obtain the porous lithium metal anode;

preferably, the surface oxidation is: and roasting the porous metal current collector in an oxygen-containing atmosphere.

6. The method of preparing a porous lithium metal anode of claim 5, wherein: the oxygen volume content of the oxygen-containing atmosphere is 5-90%; preferably 15 to 70%.

7. The method of preparing a porous lithium metal anode of claim 5, wherein: the roasting temperature is 100-1000 ℃; preferably 500-800 ℃; further preferably 500-700 ℃;

preferably, the roasting time is 0.2-10 h; further preferably 0.5 to 5 hours.

8. The method of preparing a porous lithium metal anode according to any one of claims 5 to 7, wherein: the method for filling the metallic lithium is electrodeposition or melting;

preferably, the electrodeposition step is: taking the oxidized porous metal current collector as a working electrode and a lithium sheet as a counter electrode, and carrying out electrodeposition in an organic solvent containing lithium salt;

the amount of the electrodeposited metal lithium is 2-12 mAh/cm 2; further preferably 5 to 8mAh/cm 2.

9. Use of a porous lithium metal anode according to any one of claims 1 to 4 or a porous lithium metal anode prepared by the preparation method according to any one of claims 5 to 8, wherein: the anode is used as the anode of the lithium metal battery;

10. A lithium metal battery using the porous lithium metal anode according to any one of claims 1 to 4 or the porous lithium metal anode prepared by the preparation method according to any one of claims 5 to 8 as an electrode.