CN111799445B

CN111799445B - A kind of lithium metal anode and its preparation and application

Info

Publication number: CN111799445B
Application number: CN202010857142.5A
Authority: CN
Inventors: 洪波; 赖延清; 高春晖; 董庆元; 张凯; 张治安
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2020-08-24
Filing date: 2020-08-24
Publication date: 2022-03-04
Anticipated expiration: 2040-08-24
Also published as: CN111799445A

Abstract

本发明属于锂金属电池领域，具体公开了一种锂金属阳极的制备方法，包括以下步骤：步骤(1)：第一段电处理：采用集流体作为工作电极，金属锂作为对电极，在电解液A中以0.01～10mA/cm²的电流密度循环1‑100圈；所述的电解液A包含基础电解液和添加剂A；步骤(2)：第二段电处理：将步骤(1)处理后的集流体继续作为工作电极，金属锂作为对电极，在电解液B中以0.01～20mA/cm²的电流密度下进行第二段电处理，处理后的工作电极即为所述的锂金属阳极；所述的电解液B包含基础电解液和添加剂B。本发明经过所述的二段电处理配合处理过程的添加剂以及电流密度等条件的协同控制，能够制得具有优异电化学稳定性和高容量、高循环稳定性的金属锂阳极。The invention belongs to the field of lithium metal batteries, and specifically discloses a preparation method of a lithium metal anode. Circulate 1-100 circles with the current density of 0.01～10mA/cm in solution ^A ; Described electrolyte solution A comprises basic electrolyte solution and additive A; After the current collector continues to be used as the working electrode, the metal lithium is used as the counter electrode, and the second stage electric treatment is performed in the electrolyte B at a current density of 0.01 to 20 mA/cm ² , and the treated working electrode is the lithium metal. Anode; the electrolyte B contains basic electrolyte and additive B. Through the synergistic control of the two-stage electric treatment and the additives in the treatment process, the current density and other conditions, the present invention can prepare a metal lithium anode with excellent electrochemical stability, high capacity and high cycle stability.

Description

Lithium metal anode and preparation and application thereof

Technical Field

The invention relates to the technical field of lithium metal batteries, in particular to a preparation method of a metal lithium anode of a lithium metal battery.

Background

The lithium secondary battery is mainly a lithium metal battery and a lithium ion battery. The anode material of the lithium ion battery is mainly carbon material, and Li is mainly generated in the charge and discharge process⁺Intercalation and deintercalation in the carbon material structure. However, the anode of the metal lithium battery is usually elemental metal lithium, and the action mechanism in the battery is deposition and dissolution of the metal lithium, and the charge and discharge mechanism is as follows: charging of Li⁺+e＝Li(ii) a Discharge Li-e ═ Li⁺. The lithium metal battery and the lithium ion battery have different material requirements, different charging and discharging mechanisms and similar surfaces, and are actually completely different battery systems.

The lithium metal anode is already in the 70 th 20 th century, and an industrialized lithium metal battery is already known, but the safety problem caused by dendritic crystal growth is not solved all the time, and the lithium metal battery is rapidly replaced right after the lithium ion battery is known in the 90 th 20 th century, so that the long-term development of more than thirty years is started. Although lithium anodes are favored by researchers again, the problems of low coulombic efficiency and short cycle life caused by dendritic crystal growth are still not solved, and therefore, in order to realize practical development of metal lithium anodes, clear understanding must be provided for the problems of lithium anodes.

In response to these problems of metallic lithium anodes, various strategies have been employed in the literature to improve lithium anode performance, such as artificial SEI films, electrolyte additives, solid-state electrolytes, three-dimensional lithium anodes, and the like. However, a single method cannot solve all the problems of the lithium anode, such as an artificial SEI film, which can improve coulombic efficiency and improve mechanical, physical and chemical properties of the SEI film, but the lithium anode still has a volume effect problem, such as adopting a three-dimensional lithium anode, which can greatly relieve the volume effect in a lithium deposition/dissolution process, but the three-dimensional current collector also has a problem of poor quality of the SEI film, and the coulombic efficiency of the battery is deteriorated due to the large specific surface area of the three-dimensional current collector and the generation of a large amount of SEI films.

Disclosure of Invention

The invention aims to overcome the defects of the current lithium metal anode application technology, and provides a method for preparing a lithium metal anode (also called lithium metal anode in the invention) aiming at improving the electrochemical performance of the prepared lithium metal anode.

The second purpose of the invention is to provide the lithium metal anode prepared by the preparation method.

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

A fourth object of the present invention is to provide a lithium metal battery comprising the lithium metal anode.

A method of making a lithium metal anode comprising the steps of:

step (1): first stage of electric treatment

Adopting a current collector as a working electrode, metal lithium as a counter electrode and 0.01-10mA/cm in electrolyte A²Current density cycle of 1-100 cycles;

the electrolyte A comprises a base electrolyte and an additive A;

step (2): second stage of electrical treatment

Continuously taking the current collector treated in the step (1) as a working electrode, taking metal lithium as a counter electrode, and adding 0.01-20 mA/cm of metal lithium into electrolyte B²Performing second-stage electrical treatment at the current density of the lithium metal anode, wherein the treated working electrode is the lithium metal anode;

the electrolyte B comprises a base electrolyte and an additive B;

the additive A and the additive B independently select at least one of Acetic Anhydride (AA), Vinyl Acetate (VA), tris (trimethylsilane) phosphate (TMSP), Allyl Ethyl Carbonate (AEC), methyl Propinyl Methanesulfonate (PMS), tetrachloroethylene, fluoroethylene carbonate (FEC), Vinylene Carbonate (VC), vinylene carbonate (VEC), 1, 3-Propane Sultone (PS), vinyl sulfate (DTD), N-Methyl Pyrrole (MPL), 2-Phenylimidazole (PID), Maleimide (MI), vinyl sulfite (ES), pyrocatechol carbonate (BO), polyhydric phenol, tannin, flavone and phenolic acid.

In order to solve the technical problems of large volume effect, poor SEI stability, non-ideal electrochemical performance and the like of the lithium metal anode, the invention innovatively provides a preparation idea for constructing the lithium metal anode through two-stage electrical treatment, and under the innovative two-stage electrical treatment idea, the system, the current density and the cycle number of the first-stage electrical treatment process are further combined to be controlled, and the system, the current density of the second-stage electrical treatment process are controlled, so that the form and the structural stability of the prepared lithium metal anode can be further improved, and the electrochemical performance of the prepared lithium metal anode can be improved.

In the invention, the two-stage current density electrical treatment idea and the cooperative control of the conditions of each stage of electrical treatment process are the key points for improving the good electrochemical performance of the prepared lithium metal anode. Researches show that in the first stage of electric treatment process, based on the combined control of the electrolyte A and the current density and the cycle number, the electrochemical performance of the lithium metal anode can be unexpectedly improved by further matching with the coordinated control of the electrolyte B and the current density of the second stage of electric treatment.

The research of the invention finds that the system of the first stage electric treatment process and the cooperative control of the current density and the cycle number of the cycle process are one of the keys for improving the electrochemical performance of the prepared lithium metal anode.

In the present invention, the electrolyte a of the first stage of the electrical treatment contains a base electrolyte and an additive a.

Preferably, the additive a is at least one of tetrachloroethylene, fluoroethylene carbonate (FEC), Vinylene Carbonate (VC), vinylene carbonate (VEC), 1, 3 Propane Sultone (PS), vinyl sulfate (DTD), nitromethyl pyrrole (MPL), 2-Phenylimidazole (PID), Maleimide (MI), vinyl sulfite (ES), and pyrocatechol carbonate (BO).

The research also finds that the control of the additive content in the system of different electric stages helps to further exert the synergy of the additives of different stages and further improve the electrochemical performance.

Preferably, the additive a is added in the electrolyte a in an amount of 0.01-20 wt.%; preferably 0.1-10 wt.%; further preferably 2-8 wt.%; even more preferably 2-5 wt.%. The preferred types of additives, in combination with the two-stage electroprocessing described, contribute to further improving the electrochemical performance of the resulting lithium metal anode.

In the present invention, the base electrolyte may be an electrolyte well known in the field of lithium metal batteries, for example, the base electrolyte includes a solvent and a lithium salt;

the lithium salt comprises one or more of lithium bis (trifluoromethanesulfonyl) imide, lithium bis (fluorosulfonyl) imide, lithium trifluoromethanesulfonate, lithium difluorooxalato borate, lithium difluorobis (oxalato) phosphate, lithium dioxalate borate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium nitrate and lithium perchlorate;

the organic solvent is an ester solvent, an ether solvent and/or a sulfone solvent:

the ester solvent is one or more of ethylene carbonate (VEC), 1, 3-Propane Sultone (PS), Vinylene Carbonate (VC), Propyl Acetate (PA), fluoroethylene carbonate (FEC), methylpropyl carbonate (MPC), Ethyl Acetate (EA), Methyl Acetate (MA), methylethyl carbonate (EMC), Propylene Carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC) and Ethylene Carbonate (EC);

the ether solvent is one or more of tetraethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dimethyl ether, Tetrahydrofuran (THF), 1, 3 Dioxolane (DOL), 1, 4 Dioxane (DX), ethylene glycol dimethyl ether (DME), glycoside glycol dimethyl ether, 2-methyl tetrahydrofuran, 2, 5-diethyl tetrahydrofuran and dimethoxypropane;

the sulfone solvent is one or more of dimethyl sulfone, dimethyl sulfoxide (DMSO), Sulfolane (SUL), ethyl methyl sulfone, diethyl sulfone, methyl isopropyl sulfone, ethyl methoxyethyl sulfone, methoxyethyl methyl sulfone, ethyl isopropyl sulfone and ethyl n-butyl sulfone;

preferably, the concentration of lithium salt in the basic electrolyte of the electrolyte A is 0.1-10 mol/L; preferably 1 to 5 mol/L.

In the step (1): the current collector is at least one of copper foil, aluminum foil, nickel foil, cobalt foil, titanium foil, stainless steel foil, copper foam, nickel foam, aluminum foam, cobalt foam, titanium foam, iron foam, hard carbon, graphite, graphene, carbon fiber, carbon nanotube and porous carbon.

The research of the invention also finds that on the basis of the system control of the first stage of electrical treatment, the combined control of the electrical treatment conditions, particularly the current density and the cycle number, is beneficial to further exerting the synergistic effect of the two-stage electrical treatment and further improving the electrochemical effect of the prepared metal lithium anode.

Preferably, in the first stage of electric treatment, the current density is 0.1-5mAh/cm 2; further preferably 0.1 to 1mAh/cm 2. At the preferred current densities, it helps to further improve the electrochemical renewal capacity, capacity and cycling stability of the resulting lithium metal anode.

In the invention, the first section of electrical treatment is electrical cycle treatment, and one charging and discharging period is one electrical cycle, wherein the number of cycles is 1-100, preferably 10-60; more preferably 10 to 50 turns. It was found that further control of the number of cycles with additive a and current density further improved the electrochemical performance of the resulting lithium metal anode.

Research also finds that under the combined control of a circulation system, current density and the number of circulation cycles of the first-stage electric treatment process, the temperature and the circulation capacity of the circulation process are further controlled, and the electrochemical performance of the metal lithium anode obtained by the two-stage electric treatment process is further improved.

Preferably, the temperature of the circulating process is-10-90 ℃; preferably 20 to 50 ℃.

Preferably, the circulating electric quantity is 0.5-5mAh/cm²(ii) a Preferably 0.5-2mAh/cm²。

In the invention, the working electrode obtained by the first-stage electrical treatment is continuously used as the working electrode of the second-stage electrical treatment, and the metal lithium is also used as a counter electrode and is placed in the electrolyte B for the second-stage treatment. The research finds that the working electrode treated in the first stage is continuously subjected to second stage treatment in an electric treatment system of the additive B, and the control of the current density is further matched, so that the cooperativity with the first stage electric treatment process is further improved, the form and the structure of the prepared metallic lithium anode are improved, and the electrochemical performance of the obtained lithium metallic anode is improved.

Preferably, the additives A and B are selected from the same or different components; preferably of different compositions.

The research of the invention finds that different additives preferably selected from the electrolyte A and the electrolyte B are beneficial to improving the morphological construction of the two-stage metal lithium anode and improving the electrochemical performance.

Preferably, the additive B is at least one of Acetic Anhydride (AA), Vinyl Acetate (VA), tris (trimethylsilane) phosphate (TMSP), Allyl Ethyl Carbonate (AEC), Propynyl Methane Sulfonate (PMS), tetrachloroethylene, fluoroethylene carbonate (FEC), Vinylene Carbonate (VC), polyhydric phenol, tannin, flavone, phenolic acid, pyrocatechol carbonate (BO).

The research of the invention finds that the content of the additive for the second-stage electric treatment is further controlled, which is beneficial to further exerting the advantages of the two-stage electric treatment, further improving the shape of the prepared lithium metal anode and further improving the electrochemical performance.

Preferably, the additive B is added in the electrolyte B in an amount of 0.01-20 wt.%; preferably 1-15 wt.%; further preferably 5-10 wt.%.

The selection range of the base electrolyte in the electrolyte B is the same as that of the electrolyte a, but the types and concentrations of the base electrolytes in the electrolyte B and the electrolyte a may be the same or different, and are preferably the same.

For example, the concentration of the lithium salt in the base electrolyte in the electrolyte B is 0.1 to 10 mol/L; preferably 1 to 5 mol/L.

In the invention, the second-stage electric treatment is an electrodeposition process, and researches show that under the control of the second-stage electric treatment system, the electrochemical performance is further improved by further matching with the control of the current density.

Preferably, in step (2): the current density is 0.1-10 mA/cm²(ii) a Further preferably 1 to 5mA/cm²。

Preferably, the current density in the step (2) is 2 to 10 times that in the step (1). Researches find that the two-stage gradient electric treatment process is beneficial to further improving the capacity and the cycling stability of the prepared lithium metal anode.

Preferably, in step (2): the temperature of the treatment process is 40-70 ℃.

Preferably, in step (2): the electric treatment time is preferably 10-1000 min.

Preferably, after the treatment in step (2)The lithium carrying capacity of the material is 5-30 mAh/cm²。

The invention also provides a lithium metal anode prepared by the preparation method. The lithium metal anode comprises a current collector, and a metal lithium active layer and an SEI protective layer which are compounded on the surface of the current collector in sequence. The thickness of the SEI protective layer is 50-500 nm.

The invention also provides an application of the lithium metal anode, and the lithium metal anode is used as a lithium metal anode for assembling a lithium metal battery. According to the application of the invention, the lithium metal anode prepared by the invention can replace the lithium foil of the existing lithium metal battery and be used for assembling to obtain a brand-new lithium metal battery. In the lithium metal battery, except for adopting the lithium metal anode as the anode, other part structures and materials can be known by technicians in the industry, and the lithium metal battery can be assembled by adopting the existing equipment and method.

The invention also provides a lithium metal battery comprising the lithium metal anode.

The lithium metal battery is a lithium-ternary, lithium-sulfur or lithium-air battery.

Advantageous effects

The invention provides a means for constructing a lithium metal anode based on electric treatment, and finds that the combined control of a system based on a two-stage treatment process and the electric treatment condition is beneficial to generating a synergistic effect, further improving the form and the structural stability of the lithium metal anode and further improving the electrochemical performance of the prepared lithium metal anode.

The method has the advantages of high technical operation flexibility, simple method in industrial production, feasible operation and hopeful large-scale popularization.

Detailed Description

The following examples are intended to illustrate the invention in further detail; and the scope of the claims of the present invention is not limited by the examples.

The additive is used based on the weight of the electrolyte.

Example 1

First stageElectric treatment: in an argon atmosphere glove box, porous carbon material (particle size 500nm, wall thickness 30nm, specific surface area 259 cm)³(g, porosity of 78%) as active material, using the current collector as working electrode, pole piece thickness of 100 μ M, lithium piece as counter electrode, and 1M LiPF₆in VEC/PC/EMC (volume ratio 1: 1: 1) with 5 wt.% VC as electrolyte at 25 deg.C at 1mA/cm²Current density of 1mAh/cm²The electric quantity of (2) is circulated for 30 circles;

and (3) second-stage electric treatment: removing the current collector of the first section of electric treatment as a working electrode, taking a lithium sheet as a counter electrode, taking 1M LiTFSI in DME/DOL (volume ratio of 1: 1) with 10 wt.% FEC as an electrolyte, and taking 2mA/cm at 45 DEG C²The current density is deposited for 5 hours, and the working electrode after the second section of electric treatment is taken out, namely the metal lithium anode.

Assembling and testing the battery: lithium iron phosphate is taken as a cathode (the active matter amount is 4 mg/cm)²) The anode was a lithium metal anode prepared in the previous step with 1M LiPF₆Assembling a 2025 button cell by taking in EC/DEC/EMC (volume ratio of 1: 1: 1) as electrolyte, standing the prepared cell in a thermostatic chamber at 25 ℃ for 12h, and performing charge-discharge test circulation on a blue charge-discharge tester under the test condition of 1C. The results obtained are shown in table 1.

Comparative example 1

The difference compared to example 1 is mainly that only the first stage of electrical treatment is carried out: in an argon atmosphere glove box, porous carbon material (particle size 500nm, wall thickness 30nm, specific surface area 259 cm)³The porosity of the active material is 78 percent) is taken as a working electrode, the thickness of a pole piece is 100 mu M, a lithium piece is taken as a counter electrode, and 1M LiPF is adopted₆in VEC/PC/EMC (volume ratio 1: 1: 1) with 10 wt.% VC as electrolyte at 25 deg.C at 1mA/cm²Current density of 1mAh/cm²The electric quantity of the power supply is circulated for 30 circles and then is 2mA/cm²The current density is deposited for 5h, and the detached working electrode is the lithium anode.

Assembling and testing the battery: lithium iron phosphate is taken as a cathode (the active matter amount is 4 mg/cm)²) The anode was a lithium metal anode prepared in the previous step with 1M LiPF₆in EC/DEC/EMC (body)Product ratio of 1: 1: 1) and (3) assembling the 2025 button cell for the electrolyte, standing the prepared cell in a thermostatic chamber at 25 ℃ for 12h, and performing charge and discharge test circulation on a blue test charge and discharge tester under the test condition of 1C. The results obtained are shown in table 1.

Comparative example 2

The difference compared to example 1 is mainly that only the second stage of the electrical treatment is carried out: in an argon atmosphere glove box, porous carbon material (particle size 500nm, wall thickness 30nm, specific surface area 259 cm)³G, porosity 78%) as active material as working electrode, pole piece thickness of 100 μ M, lithium piece as counter electrode, 1M LiTFSI in DME/DOL (volume ratio 1: 1) with 10 wt.% FEC as electrolyte at 45 ℃ at 2mA/cm²The current density is deposited for 5 hours, and the working electrode is taken out to be the metal lithium anode.

Assembling and testing the battery: lithium iron phosphate is taken as a cathode (the active matter amount is 4 mg/cm)²) The anode was a lithium metal anode prepared in the previous step with 1M LiPF₆Assembling a 2025 button cell by taking in EC/DEC/EMC (volume ratio of 1: 1: 1) as electrolyte, standing the prepared cell in a thermostatic chamber at 25 ℃ for 12h, and performing charge and discharge test circulation on a blue test charge and discharge tester under the test condition of 1C. The results obtained are shown in table 1.

Comparative example 3

The only difference compared to example 1 is that the second stage of the electrical treatment is additive-free (no FEC added). Other procedures and parameters were the same as in example 1: the results obtained are shown in table 1.

Comparative example 4

Lithium iron phosphate is taken as a cathode (the active matter amount is 4 mg/cm)²) Lithium sheet (equivalent to 10 mAh/cm) 50 μm thick²Lithium metal of (2) as an anode with 1M LiPF₆Assembling a 2025 button cell by taking in EC/DEC/EMC (volume ratio of 1: 1: 1) as electrolyte, standing the prepared cell in a thermostatic chamber at 25 ℃ for 12h, and performing charge and discharge test circulation on a blue test charge and discharge tester under the test condition of 1C. The results obtained are shown in table 1.

Example 2

The main difference from example 1 is that the current and the amount of electricity for the first stage of electrical treatment are too large and the current and the amount of electricity for the second stage of electrical treatment are too small, which are not the most suitable process parameters.

The first stage of electric treatment: in an argon atmosphere glove box, porous carbon material (particle size 500nm, wall thickness 30nm, specific surface area 259 cm)³(g, porosity of 78%) as active material, using the current collector as working electrode, the thickness of pole piece is 100 μ M, using lithium piece as counter electrode, using 1M LiPF₆in VEC/PC/EMC (volume ratio 1: 1: 1) with 10 wt.% VC as electrolyte at 25 ℃ at 5mA/cm²Current density of 5mAh/cm²The electric quantity of (2) is circulated for 30 circles;

and (3) second-stage electric treatment: removing the current collector of the first section of electric treatment as a working electrode, taking a lithium sheet as a counter electrode, taking 1M LiTFSI in DME/DOL (volume ratio of 1: 1) with 5 wt.% FEC as an electrolyte, and taking 0.2mA/cm at 45 DEG C²The current density is deposited for 50 hours, and the working electrode after the second section of electric treatment is taken out, namely the metallic lithium anode.

TABLE 1 Battery Performance test results

Sample (I)	First turn coulombic efficiency	First circle capacity	Capacity retention rate of 80% of turns
				Example 1	98.9％	150.4mAh/g	245
Comparative example 1	91.4％	120.4mAh/g	78
				Comparative example 2	95.2％	128.5mAh/g	59
Comparative example 3	54.6％	98.4mAh/g	28
				Comparative example 4	60％	100.8mAh/g	32
Example 2	97.1％	147.8mAh/g	195

Comparing example 1 with comparative examples 1, 2, 3 and 4, the lithium anodes obtained by two-stage electrical treatment have better performance; comparing example 1 with example 2, the parameters of the two-stage electric treatment process are cooperated to obtain better effect.

Example 3

The first stage of electric treatment: in an argon atmosphere glove box, copper foil (thickness 10 μ M) is used as a working electrode, the thickness of a pole piece is 20 μ M, a lithium piece is used as a counter electrode, and 1M LiBF is used₄in EC/DE/EMC (volume ratio 1: 1: 1) with 0.01, 1, 2, 5, 8, 10 wt.% tetrachloroethylene (different addition amounts) as electrolyte, at 25 deg.C, 1mA/cm²Current density of 1mAh/cm²The electric quantity of (2) is circulated for 30 circles;

and (3) second-stage electric treatment: the current collector detached in the first stage of electrical treatment is used as a working electrode, a lithium sheet is used as a counter electrode, 1M LiFSI in THF/DOL (volume ratio of 1: 1) with 10 wt.% of pyrocatechol carbonate is used as electrolyte, and 0.5mA/cm is adopted at 25 DEG C²The current density is deposited for 5 hours, and the working electrode is taken out to be the metal lithium anode.

Assembling and testing the battery: ternary (NCM811) is used as a cathode (the active material amount is 4 mg/cm)²) The anode was a lithium metal anode prepared in the previous step with 1M LiPF₆Assembling a 2025 button cell by using in PA/DEC/MPC (volume ratio of 1: 1: 1) as electrolyte, standing the prepared cell in a thermostatic chamber at 25 ℃ for 12h, and performing charge and discharge test circulation on a blue charge and discharge tester under the test condition of 1C. The results obtained are shown in Table 2.

TABLE 2

Example 3	First turn coulombic efficiency	100 cycles average coulombic efficiency	Number of turns with coulombic efficiency lower than 80%
				0.01wt.％	96.1％	98.1％	219
1wt.％	96.4％	98.7％	226
				2wt.％	98.7％	99.1％	231
5wt.％	98.4％	99.2％	236
				8wt.％	97.4％	98.5％	221
10wt.％	95.9％	98.6％	217

As can be seen by comparison of example 3, the first stage electrical treatment additive content is in the range of 2 to 8 wt.%; preferably 2 to 5 wt.% of the total weight of the composition.

Example 4

The first stage of electric treatment: in an argon atmosphere glove box, carbon nanotubes (diameter 150nm, wall thickness 10nm, length 1.5 μm) are used as active materialsThe smear is used as a working electrode, the thickness of the pole piece is 300 mu M, the lithium piece is used as a counter electrode, and 1M LiPF is used₆in VEC/PC/MA (volume ratio 1: 1: 1) with 5 wt.% VA as electrolyte at 25 deg.C and 0.01, 0.1, 1, 5, 10mA/cm²Current density of 1mAh/cm²The electric quantity of (2) is circulated for 25 circles;

and (3) second-stage electric treatment: the current collector after the first section of electric treatment is taken as a working electrode, a lithium sheet is taken as a counter electrode, and 1M LiClO₄in DMSO/DOL (volume ratio 1: 1) with 5 wt.% DTD as electrolyte at 55 deg.C and 1mA/cm²The current density is deposited for 5 hours, and the working electrode is taken out to be the metal lithium anode.

Assembling and testing the battery: ternary (NCM811) was used as a cathode (active material amount 3.6 mg/cm)²) The anode was a lithium metal anode prepared in the previous step with 1M LiPF₆Assembling a 2025 button cell by taking in EC/DEC/EMC (volume ratio of 1: 1: 1) as electrolyte, standing the prepared cell in a thermostatic chamber at 25 ℃ for 12h, and performing charge-discharge test circulation on a blue charge-discharge tester under the test condition of 1C. The results obtained are shown in Table 3.

TABLE 3

Compared with the first stage of electric treatment process, the electric treatment process adopts circulation with different current density, preferably 0.1-5mA/cm²(ii) a More preferably 0.1 to 1mA/cm²The optimum performance is obtained.

Example 5

The first stage of electric treatment: in an argon atmosphere glove box, a smear with graphene as an active material is used as a working electrode, the thickness of the pole piece is 150 mu M, a lithium piece is used as a counter electrode, and 1M LiPF is used₆in VEC/PC/EMC (volume ratio 1: 1: 1) with 1 wt.% TMSP as electrolyte at 25 ℃ at 1mA/cm²Current density of 1mAh/cm²Under the electricity of 1, 10, 30, 50, 70, 100 circles;

and (3) second-stage electric treatment: the current collector disassembled by the first section of electrical treatment is taken as a working electrode, and a lithium sheet is taken as a counter electrode1M LiTFSI in DME/DOL (volume ratio 1: 1) with 6 wt.% MI as electrolyte at 45 ℃ at 3mA/cm²The current density is deposited for 5 hours, and the working electrode is taken out to be the metal lithium anode.

Assembling and testing the battery: sulfur/carbon as cathode (active substance amount 3 mg/cm)²) The anode was a lithium metal anode prepared in the previous step with 1M LiCF₃SO₃Assembling a 2025 button cell by using in DX/DME (volume ratio of 1: 1) as electrolyte, standing the prepared cell in a thermostatic chamber at 25 ℃ for 12h, and performing charge and discharge test circulation on a blue charge and discharge tester under the test condition of 0.5C. The results obtained are shown in Table 4.

TABLE 4

The best performance is obtained at preferably 10-50 turns compared to the different turns of the first stage of electrical treatment.

Example 6

The first stage of electric treatment: in an argon atmosphere glove box, foam nickel (thickness 300 μ M) is used as a working electrode, the thickness of a pole piece is 50 μ M, a lithium piece is used as a counter electrode, and 1M LiPF is used₆in VEC/PC/EMC (volume ratio 1: 1: 1) with 4 wt.% AEC as electrolyte at 25 deg.C and 0.5mA/cm²Current density of 1mAh/cm²Cycling for 50 cycles;

and (3) second-stage electric treatment: the current collector disassembled in the first stage of electrical treatment is taken as a working electrode, a lithium sheet is taken as a counter electrode, 1M LiFSI in DME/DOL (volume ratio of 1: 1) with 1 wt.% PID is taken as electrolyte, and 0.01, 0.1, 1, 5, 10, 20mA/cm are taken at 45 DEG C²Current density of up to 20mAh/cm²And detaching the working electrode to obtain the metal lithium anode.

Assembling and testing the battery: lithium iron phosphate is taken as a cathode (the active material mass is 5 mg/cm)²) The anode is a metallic lithium anode prepared in the previous step and is prepared by LiC₂BF₂O₄in DME/DOL (1: 1 by volume) with 2 wt.% LiNO₃Assembling 2025 button cell for electrolyteThe prepared battery is placed in a thermostatic chamber at 25 ℃ and is kept still for 12 hours, and then a charging and discharging test cycle is carried out on a blue charging and discharging tester, wherein the test condition is 1C. The results obtained are shown in Table 5.

TABLE 5

Compared with the second electric treatment process, the second electric treatment process adopts deposition with different current density, preferably 1-5mA/cm²With the best performance.

Example 7

The first stage of electric treatment: in an argon atmosphere glove box, titanium foil (thickness 20 μ M) is used as a working electrode, the thickness of a pole piece is 8 μ M, a lithium piece is used as a counter electrode, and 1M LiPF is used₆in VEC/PC/EMC (volume ratio 1: 1: 1) with 5 wt.% PMS as electrolyte at 15 deg.C and 1mA/cm²Current density of 1mAh/cm²The electric quantity of (2) is circulated for 10 circles;

and (3) second-stage electric treatment: the current collector detached in the first section of electric treatment is used as a working electrode, a lithium sheet is used as a counter electrode, 1M LiTFSI in DME/DOL (volume ratio of 1: 1) with 4 wt.% of tetrachloroethylene is used as electrolyte, and 5mA/cm is used at 65 DEG C²The current density is deposited for 4 hours, and the working electrode is taken out to be the metal lithium anode.

Assembling and testing the battery: ternary (NCA) is taken as a cathode (the active matter amount is 4 mg/cm)²) The anode was a lithium metal anode prepared in the previous step with 1M LiPF₆Assembling a 2025 button cell by using in MA/DEC (volume ratio of 1: 1) as electrolyte, standing the prepared cell in a thermostatic chamber at 25 ℃ for 12h, and performing charge and discharge test circulation on a blue charge and discharge tester under the test condition of 1C. The results obtained are shown in Table 6.

Example 8

The first stage of electric treatment: in an argon atmosphere glove box, a carbon fiber (diameter 200nm and length 900nm) smear is taken as an active material smear and taken as a working electrode, the thickness of the pole piece is 240 mu M, a lithium piece is taken as a counter electrode, and 1M LiPF is taken₆in VEC/PC/EMC (volume ratio 1: 1: 1) with 2 wt.% tetrachloroethylene as electrolyte,at 25 ℃ at 2mA/cm²Current density of 1mAh/cm²Cycling for 50 cycles;

and (3) second-stage electric treatment: the current collector detached in the first section of electric treatment is used as a working electrode, a lithium sheet is used as a counter electrode, 1M LiTFSI in DME/DOL (volume ratio of 1: 1) with 8 wt.% tannic acid is used as electrolyte, and 5mA/cm is adopted at 45 DEG C²The current density is deposited for 5 hours, and the working electrode is taken out to be the metal lithium anode.

Assembling and testing the battery: lithium iron phosphate is taken as a cathode (the active matter amount is 4 mg/cm)²) The anode was a lithium metal anode prepared in the previous step with 1M LiPF₆The in EC/DEC/EMC (volume ratio 1: 1: 1) electrolyte is used for assembling the 2025 button cell, the prepared cell is placed in a thermostatic chamber at 25 ℃ for standing for 12h, and then a charging and discharging test cycle is carried out on a blue charging and discharging tester under the test condition of 1C, and the obtained results are shown in Table 6.

Example 9

The first stage of electric treatment: in an argon atmosphere glove box, a smear with graphene as an active material is used as a working electrode, the thickness of the pole piece is 180 mu M, a lithium piece is used as a counter electrode, and 1M LiPF is used₆in VEC/PC/EMC (volume ratio 1: 1: 1) with 10 wt.% vinyl sulfate as electrolyte at 55 deg.C and 0.6mA/cm²Current density of 0.8mAh/cm²Cycling for 45 cycles;

and (3) second-stage electric treatment: the current collector detached in the first section of electrical treatment is used as a working electrode, a lithium sheet is used as a counter electrode, 1M LiTFSI in DME/DOL (volume ratio of 1: 1) with 5 wt.% acetic anhydride is used as electrolyte, and 8mA/cm is used at 45 DEG C²The current density is deposited for 4 hours, and the working electrode is taken out to be the metal lithium anode.

Assembling and testing the battery: lithium iron phosphate is taken as a cathode (the active matter amount is 4 mg/cm)²) The anode was a lithium metal anode prepared in the previous step with 1M LiPF₆Assembling a 2025 button cell by taking in EC/DEC/EMC (volume ratio of 1: 1: 1) as electrolyte, standing the prepared cell in a thermostatic chamber at 25 ℃ for 12h, and performing charge and discharge test circulation on a blue charge and discharge tester under the test condition of 5C. The results obtained are shown in Table 6.

Example 10

The first stage of electric treatment: in an argon atmosphere glove box, foam copper (thickness 250 μ M) is used as a working electrode, the thickness of a pole piece is 200 μ M, a lithium piece is used as a counter electrode, and 1M LiPF is used₆in VEC/PC/EMC (volume ratio 1: 1: 1) with 10 wt.% DTD as electrolyte at 25 deg.C at 1.5mA/cm²Current density of 0.5mAh/cm²Cycling for 20 cycles;

and (3) second-stage electric treatment: the current collector detached in the first section of electrical treatment is used as a working electrode, a lithium sheet is used as a counter electrode, 1M LiTFSI in DME/DOL (volume ratio of 1: 1) with 7 wt.% of vinyl acetate is used as electrolyte, and 10mA/cm is used at 45 DEG C²The current density is deposited for 3 hours, and the working electrode is taken out to be the metal lithium anode.

Assembling and testing the battery: lithium iron phosphate is taken as a cathode (the active matter amount is 4 mg/cm)²) The anode was a lithium metal anode prepared in the previous step with 1M LiPF₆Assembling a 2025 button cell by taking in EC/DEC/EMC (volume ratio of 1: 1: 1) as electrolyte, standing the prepared cell in a thermostatic chamber at 25 ℃ for 12h, and performing charge-discharge test circulation on a blue charge-discharge tester under the test condition of 1C. The results obtained are shown in Table 6.

Example 11

The first stage of electric treatment: in an argon atmosphere glove box, cobalt foil (thickness 30 μ M) is used as a working electrode, the thickness of a pole piece is 10 μ M, a lithium piece is used as a counter electrode, and 1M LiPF is used₆InVEC/PC/EMC (volume ratio 1: 1: 1) with 10 wt.% catechol carbonate as electrolyte at 25 deg.C and 2mA/cm²Current density of 2mAh/cm²Cycling for 50 cycles;

and (3) second-stage electric treatment: taking a current collector detached in the first section of electric treatment as a working electrode, a lithium sheet as a counter electrode, 1M LiTFSI in DME/DOL (volume ratio of 1: 1) with 3 wt.% of fluoroethylene carbonate as electrolyte, and taking 15mA/cm at 45 DEG C²The current density is deposited for 2 hours, and the working electrode is taken out to be the metal lithium anode.

Assembling and testing the battery: lithium iron phosphate is taken as a cathode (the active matter amount is 4 mg/cm)²) The anode isThe lithium metal anode prepared in the previous step is 1M LiPF₆Assembling a 2025 button cell by taking in EC/DEC/EMC (volume ratio of 1: 1: 1) as electrolyte, standing the prepared cell in a thermostatic chamber at 25 ℃ for 12h, and performing charge and discharge test circulation on a blue charge and discharge tester under the test condition of 2C. The results obtained are shown in Table 6.

Example 12

The first stage of electric treatment: in an argon atmosphere glove box, a smear with hard carbon (the particle size is 900nm) as an active material is taken as a working electrode, the thickness of the pole piece is 60 mu M, a lithium piece is taken as a counter electrode, and 1M LiPF is taken₆in VEC/PC/EMC (volume ratio 1: 1: 1) with 10 wt.% 2-phenylimidazole as electrolyte at 55 ℃ and 0.1mA/cm²Current density of 0.1mAh/cm²Cycling for 40 cycles;

and (3) second-stage electric treatment: the current collector detached in the first section of electric treatment is used as a working electrode, a lithium sheet is used as a counter electrode, 1M LiTFSI in DME/DOL (volume ratio of 1: 1) with 4 wt.% of ethylene carbonate is used as electrolyte, and 6mA/cm is used as electrolyte at 45 DEG C²The current density is deposited for 5 hours, and the working electrode is taken out to be the metal lithium anode.

TABLE 6

In conclusion, by adopting the technical scheme of the invention, the lithium metal anode with better electrochemical performance can be obtained.

Claims

1. a preparation method of lithium metal anode, is characterized in that, comprises the following steps:

Step (1): The first stage of electrical treatment

The current collector is used as the working electrode, and the metal lithium is used as the counter electrode, and the current density is 0.01-10 mA/cm ² in the electrolyte A for 1-100 cycles; the current collector is copper foil, aluminum foil, nickel foil, cobalt foil at least one of foil, titanium foil, stainless steel foil, copper foam, nickel foam, aluminum foam, cobalt foam, titanium foam, iron foam, hard carbon, graphite, graphene, carbon fiber, and carbon nanotubes;

Described electrolyte A comprises basic electrolyte and additive A;

Step (2): Second stage electrodeposition treatment

The current collector treated in step (1) is used as the working electrode, the metal lithium is used as the counter electrode, and the second stage electrodeposition treatment is performed in the electrolyte B at a current density of 0.01-20 mA/cm ² . The treated working electrode is the lithium metal anode;

Described electrolyte B comprises basic electrolyte and additive B;

Additive A is vinylene carbonate, tetrachloroethylene, vinyl acetate, tris(trimethylsilane) phosphate, allyl ethyl carbonate, propynyl mesylate, vinyl sulfate, catechol carbonate , at least one in 2-phenylimidazole;

Additive B is fluoroethylene carbonate, catechol carbonate, vinyl sulfate, maleimide, 2-phenylimidazole, tetrachloroethylene, tannic acid, acetic anhydride, vinyl acetate, subcarbonate at least one of vinyl esters;

The additives A and B are selected from different components;

The addition amount of additive A and additive B in respective electrolytes is 0.01-20 wt.%;

The current density of step (2) is 2-10 times the current density of step (1).

2. the preparation method of lithium metal anode as claimed in claim 1, is characterized in that,

Described additive A is vinylene carbonate, additive B is fluorinated ethylene carbonate;

Or, described additive A is tetrachloroethylene, and additive B is catechol carbonate;

Or, described additive A is vinyl acetate, and additive B is vinyl sulfate;

Or, the additive A is tris(trimethylsilane) phosphate, and the additive B is maleimide;

Or, the additive A is allyl ethyl carbonate, and the additive B is 2-phenylimidazole;

Or, described additive A is propynyl methanesulfonate, and additive B is tetrachloroethylene;

Or, described additive A is tetrachloroethylene, and additive B is tannic acid;

Or, described additive A is vinyl sulfate, additive B is acetic anhydride;

Or, described additive A is vinyl sulfate, additive B is vinyl acetate;

Or, the additive A is catechol carbonate, and the additive B is fluoroethylene carbonate;

Or, the additive A is 2-phenylimidazole, and the additive B is vinylene carbonate.

3. The method for preparing a lithium metal anode according to claim 1, wherein, in the electrolyte A, the additive amount of the additive A is 0.1-10 wt.%.

4. The method for preparing a lithium metal anode according to claim 1, wherein, in the electrolyte A, the additive amount of the additive A is 2-8 wt.%.

5. The preparation method of lithium metal anode according to claim 1, wherein, in the electrolyte A, the addition amount of the additive A is 2-5 wt.%.

6. The method for preparing a lithium metal anode according to claim 1, wherein, in the electrolyte B, the addition amount of the additive B is 1-15 wt.%.

7. the preparation method of lithium metal anode as claimed in claim 1, is characterized in that, basic electrolyte comprises organic solvent and lithium salt;

The lithium salts include lithium bis(trifluoromethanesulfonyl)imide, lithium bisfluorosulfonimide, lithium trifluoromethanesulfonate, lithium difluorooxalate borate, lithium difluorobis(oxalate) phosphate , one or more of lithium dioxalate borate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium nitrate, and lithium perchlorate;

Described organic solvent is ester solvent, ether solvent and/or sulfone solvent:

The ester solvents are ethylene ethylene carbonate (VEC), 1,3-propane sultone (PS), vinylene carbonate (VC), propyl acetate (PA), fluoroethylene carbonate ( FEC), methyl propyl carbonate (MPC), ethyl acetate (EA), methyl acetate (MA), ethyl methyl carbonate (EMC), propylene carbonate (PC), diethyl carbonate (DEC), dicarbonate One or more of methyl ester (DMC) and ethylene carbonate (EC);

The ether solvents are tetraethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran (THF), 1,3 dioxolane (DOL), 1,4 One of dioxane (DX), ethylene glycol dimethyl ether (DME), glycoside glycol dimethyl ether, 2-methyltetrahydrofuran, 2,5-diethyltetrahydrofuran, dimethoxypropane or several;

The sulfone solvents are dimethyl sulfone, dimethyl sulfoxide (DMSO), sulfolane (SUL), ethyl methyl sulfone, diethyl sulfone, methyl isopropyl sulfone, and ethyl methoxy ethyl sulfone. One or more of sulfone, methoxyethyl methyl sulfone, ethyl isopropyl sulfone, and ethyl n-butyl sulfone;

In the basic electrolyte of electrolyte A, the concentration of lithium salt is 1-5mol/L;

In the base electrolyte of electrolyte B, the concentration of lithium salt is 1-5 mol/L.

8. the preparation method of lithium metal anode as claimed in claim 1, is characterized in that, in step (1):

The current density is 0.1-5 mA/cm ² .

9. the preparation method of lithium metal anode as claimed in claim 1, is characterized in that, in step (1):

The current density is 0.1~1 mA/cm2.

10 . The method for preparing a lithium metal anode according to claim 1 , wherein, in step (1): the number of cycles is 10 to 60 cycles. 11 .

11 . The method for preparing a lithium metal anode according to claim 1 , wherein in step (1): the temperature of the cycle process is -10-90° C. 11 .

12 . The method for preparing a lithium metal anode according to claim 1 , wherein, in step (1): the cycle power is 0.5-5 mAh/cm ² . 13 .

13 . The method for preparing a lithium metal anode according to claim 1 , wherein in step (2): the current density is 0.1-10 mA/cm ² . 14 .

14. The method for preparing a lithium metal anode according to claim 1, wherein in step (2): the current density is 1-5 mA/cm ² .

15 . The method for preparing a lithium metal anode according to claim 1 , wherein in step (2): the electric treatment time is 10-1000 min. 16 .

16. A lithium metal anode prepared by the preparation method according to any one of claims 1 to 15.

17. An application of the lithium metal anode according to claim 16, characterized in that it is used as a lithium metal anode for assembling into a lithium metal battery.

18. A lithium metal battery comprising the lithium metal anode of claim 16.

19. The lithium metal battery of claim 18, wherein the lithium metal battery is a lithium-ternary, lithium-sulfur or lithium-air battery.