Method for in-situ lithiation of lithium ion battery with intrinsic lithium-free positive and negative electrodes

Abstract

The invention relates to an in-situ lithiation method of a lithium ion battery with intrinsic lithium-free positive and negative electrodes, which comprises the following steps of: in the assembly process of the lithium ion battery, directly placing a lithium supplement agent on the surface of an electrode to be subjected to lithium supplement, and injecting lithiation liquid, so that the electrode to be subjected to lithium supplement and the lithium supplement agent are subjected to short-circuit reaction to realize in-situ lithiation and interface regulation and control. Compared with the prior art, the in-situ lithiation speed and the lithiation degree of the lithium ion battery with the positive electrode and the negative electrode not containing lithium are regulated and controlled, temperature rise in the in-situ lithiation process is inhibited, and the safety of the in-situ lithiation process is improved; and meanwhile, a compact interface film with high ionic conductivity is formed in the lithiation process by utilizing the film-forming additive, so that the composition and structure of the interface film of the negative electrode or the positive electrode or the positive and negative electrodes are regulated and controlled, and important practical value is achieved.

Description

Technical Field

[0001] This invention pertains to lithium secondary battery materials and relates to a method for in-situ lithiation and interface control of lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries are widely used in electric vehicles, energy storage, and 3C (computer, communication, and consumer electronics) due to their high energy density, long cycle life, and low self-discharge. However, because lithium-ion batteries have a wide operating voltage range while most solvents have a narrow voltage window, electrolyte decomposition occurs during the first charge-discharge cycle, forming a solid electrolyte interface film on the electrode surface. This results in the loss of active lithium, leading to a lower initial coulombic efficiency and affecting capacity utilization. Therefore, lithium replenishment is necessary for the entire battery system to compensate for lithium loss during battery cycling.

[0003] Electrode lithium replenishment technology is broadly categorized into negative electrode lithium replenishment and positive electrode lithium replenishment. Negative electrode lithium replenishment has been more extensively researched and its technology is more mature, encompassing both chemical and electrochemical lithium replenishment. However, certain technological shortcomings and gaps remain in the lithium replenishment field. First, electrode lithium replenishment and battery assembly are two independent processes. After lithium replenishment, the electrode becomes highly reactive and should not be stored for extended periods, even in dry environments with extremely low water content. Failure to immediately assemble a full battery can easily lead to lithium replenishment failure and safety accidents. Second, current lithium replenishment technologies all require the development of additional equipment. For example, contact roller pre-lithiation requires rolling equipment, electrochemical pre-lithiation requires an electrolytic cell, and wet chemical pre-lithiation requires expensive and unstable pre-lithiation reagents and associated electrode cleaning processes, further increasing battery manufacturing costs. For currently mature full-cell systems, positive electrode materials such as lithium iron phosphate (manganese), lithium cobalt oxide, binary materials, and ternary materials contain abundant lithium sources. To achieve better cycle performance, a certain amount of lithium is replenished on both the positive and negative electrode sides, but generally not exceeding 10%. For full battery systems where neither the positive nor negative electrode contains lithium, such as low-cost sulfur-based lithium-ion batteries, the development of full lithium replenishment technology (i.e., 100% lithium replenishment) is still in its infancy, and common lithium replenishment technologies cannot meet the needs of such batteries. Summary of the Invention

[0004] The purpose of this invention is to provide a method for in-situ lithiation of lithium-ion batteries with intrinsically lithium-free positive and negative electrodes, which combines in-situ lithiation with battery assembly processes, thereby saving equipment and operating costs and improving the safety of the in-situ lithiation process.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a method for in-situ lithiation of a lithium-ion battery where the positive and negative electrodes are intrinsically lithium-free. During the assembly of the lithium-ion battery, a lithium replenishing agent is directly placed on the surface of the electrode to be replenished with lithium, and a lithiation solution is injected, causing a short-circuit reaction between the electrode to be replenished with lithium and the lithium replenishing agent, thereby achieving in-situ lithiation and interface control. Furthermore, after in-situ lithiation, depending on the characteristics of different lithiation solutions, the battery can be charged and discharged or not charged and discharged, forming a stable interface film at the negative electrode, positive electrode, or both electrodes.

[0007] Furthermore, the lithium replenishing agent is one or a combination of several of the following: lithium metal powder, lithium-rich alloy powder, lithium-rich oxide powder, lithium or lithium alloy foil, lithium or lithium alloy strip, and lithium or lithium alloy mesh. The amount of lithium replenishing agent added is 50-100% of the mass of the active material, and the actual amount is based on meeting the lithium requirements for stable battery operation (i.e., fully replenishing).

[0008] Furthermore, the lithium-ionizing solution includes lithium salt, organic solvent, and film-forming additive. In the lithium-ionizing solution, the lithium salt concentration is 0.001 mol / L to 10 mol / L, preferably 0.01 mol / L to 5 mol / L, and more preferably 0.01 mol / L to 1 mol / L. The concentration of the film-forming additive is 0.01 to 20 wt%, preferably 0.1 wt% to 10 wt%.

[0009] Furthermore, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(oxalato)borate, lithium difluorosulfonate imide, lithium bis(trifluoromethyl)sulfonylimide, lithium perchlorate, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, and lithium nitrate.

[0010] The organic solvent is selected from one or more combinations of carbonate solvents, ether solvents, carboxylic acid ester solvents, nitrile solvents, phosphate ester solvents, sulfonate solvents, siloxane solvents, fluorinated ether solvents, and hydrocarbon solvents;

[0011] The film-forming additive is selected from one or a combination of several of the following: fluorine-containing additives, boron-containing additives, organophosphorus additives, carbonate additives, sulfur-containing additives, and lithium salt additives.

[0012] More preferably, the carbonate solvent is selected from one or a combination of several of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), di(trifluoroethyl) carbonate (DTFEC), trifluoroethyl methyl carbonate (TFEMC), and ethylene ethylene carbonate (VEC);

[0013] The ether solvent is selected from one or a combination of several of the following: diethyl ether (EE), diisopropyl ether (DisoPE), dibutyl ether (DBE), dimethyl ethylene glycol (DME), diethyl ethylene glycol (DEE), dibutyl ethylene glycol (EGDBE), methyl tert-butyl ether (MTBE), dimethyl ethylene glycol (DEGDME), triethylene glycol (TGM), dimethyl tetraethylene glycol (TEGME), 1,3-dioxolane (DOL), tetrahydrofuran (THF), and 2-methyltetrahydrofuran (MeTHF).

[0014] The carboxylic acid ester solvent is selected from one or a combination of several of methyl formate (MF), ethyl acetate (EA), ethyl formate (ME), methyl acetate (MA), butyl acetate (EB), butyl formate (MB), butyl butyrate (n-BB), ethyl fluoroacetate (FEA), ethyl difluoroacetate (DFEA), and ethyl trifluoroacetate (TFEA);

[0015] The nitrile solvent is selected from one or a combination of several of acetonitrile (AN), succinic anion (SN), and adiponitrile (ADN);

[0016] The phosphate ester solvent is selected from one or a combination of several of trimethyl phosphate (TMP), triethyl phosphate (TEP), tripropyl phosphate (TPP), tributyl phosphate (TBP), and triethyl fluorophosphate (TTFP).

[0017] The sulfonate solvent is selected from one or a combination of two of dimethyl sulfoxide (DMSO) and sulfolane (SL);

[0018] The siloxane solvent is selected from one or a combination of several of tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), methyltriethoxysilane (MTEOS), and diethoxydimethylsilane (DMDES);

[0019] The fluorinated ether solvent is selected from one or a combination of several of the following: 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE), 2,2,2-trifluoroethyl ether (BTFE), 2,2,3,3,3-pentafluoropropyl-1,1,2,2-tetrafluoroethyl ether, 1,1,2,3,3,3-hexafluoropropyl-2,2,2-trifluoroethyl ether, 1,1,2,3,3,3-hexafluoropropyl-2,2,3,3-tetrafluoropropyl ether, and trifluoromethoxybenzene (TFMB).

[0020] Furthermore, the fluorinated additive is selected from one or a combination of several of the following: fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), fluoroacetonitrile (FAN), p-toluenesulfonyl fluoride (pTSF), ethoxy-pentafluorocyclotriphosphazene (PFN), and 2,4,6-tris(trifluoromethyl)-1,3,5-triazine (TTFMT).

[0021] The boron-containing additive is selected from one or a combination of several of the following: tri(trimethyl)silaneborate (TMSB), trimethyl borate (TMB), triethyl borate (TEB), tripropyl borate (TPB), tri(2-acrylonitrile ethyl)borate (TCEB), tri(2,2,2-trifluoroethyl)borate (TTFEB), pyridine-boron trifluoride (PBF), and pyridine-boron trifluoride (PBF).

[0022] The organophosphorus additive is selected from one or a combination of several of trimethyl phosphate (TMP), triethyl phosphate (TEP), tris(trimethylsilyl) phosphite (TTSPi), and tris(trimethylsilyl) phosphate (TTSP);

[0023] The carbonate additives are selected from one or a combination of several of the following: vinylene carbonate (VC), ethylene ethylene carbonate (VEC), propylene trifluorocarbonate (TFPC), ethylene carbonate ether, and glyceryl carbonate trimethylsilyl ether.

[0024] The sulfur-containing additive is selected from one or a combination of several of the following: ethylene sulfite (ES), ethylene sulfate (DTD), propylene sulfite (PS), propylene sulfate, 1,4-butanesulfonate lactone (1,4-BS), 1,3-propanesulfonate lactone (1,3-PS), and 4-methylethylene sulfite.

[0025] The lithium salt additive is selected from one or a combination of several of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(oxalato)borate, lithium difluorosulfonylimide, lithium bis(trifluoromethyl)sulfonylimide, lithium perchlorate, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, and lithium nitrate.

[0026] Furthermore, the injection volume of the lithium-ionized liquid is 0.5g / Ah-10g / Ah, preferably 1g / Ah-5g / Ah.

[0027] Furthermore, the in-situ lithiation temperature is -40 to 100°C, preferably 0 to 80°C, more preferably 20 to 60°C, and the time is 1 min to 120 h, preferably 1 h to 60 h, and more preferably 4 h to 24 h.

[0028] Furthermore, the electrode is a lithium-free positive electrode or a lithium-free negative electrode, wherein the lithium-free positive electrode is one or a combination of several of the following: sulfurized polyacrylonitrile positive electrode, elemental sulfur positive electrode, sulfur / carbon composite positive electrode, metal sulfide positive electrode, metal fluoride positive electrode, and organic positive electrode.

[0029] The lithium-free anode is one or a combination of several of the following: carbon anode, silicon anode, silicon suboxide anode, silicon / carbon composite anode, tin anode, and metal oxide anode.

[0030] Furthermore, the lithium-free cathode is prepared by the following method:

[0031] The positive electrode material, binder, and conductive agent are uniformly dispersed in water at a mass ratio of (60-80):(2-20):(4-40), then coated onto a current collector, dried, and pressed into a sheet to obtain the positive electrode of the lithium-sulfur secondary battery. The positive electrode material includes sulfurized polyacrylonitrile (SPAN), elemental sulfur, sulfur / carbon composites, metal sulfides, metal fluorides, organic positive electrodes, etc.; the conductive agent is acetylene black or conductive graphite. The current collector is aluminum foil, aluminum mesh, carbon-coated aluminum foil, carbon-coated aluminum mesh, nickel mesh, or nickel foam; the binder is carbonyl-β-cyclodextrin, polyvinylidene fluoride (PVDF), sodium alginate, carboxymethyl cellulose (CMC), carboxylated styrene-butadiene rubber (SCR), guar gum (GG), or polyacrylic acid (PAA).

[0032] Furthermore, the lithium-free anode is prepared by the following method: Anode material, binder, and conductive agent are uniformly dispersed in water at a mass ratio of (60-80):(2-20):(4-40), then coated onto a current collector, dried, and pressed into a sheet to obtain the sulfur-based lithium-ion battery anode. The anode material includes: graphite, silicon, silicon-oxygen composites, silicon-carbon composites, hard carbon, soft carbon, silicon / graphite composites, silicon-oxygen / graphite composites, tin, metal oxides, etc. The conductive agent is acetylene black or conductive carbon black. The current collector is copper foil, copper mesh, carbon cloth, carbon paper, etc. The binder is carboxymethyl cellulose (CMC), carboxylated styrene-butadiene rubber (SCR), carbonyl-β-cyclodextrin, polyvinylidene fluoride (PVDF), sodium alginate, guar gum (GG), or polyacrylic acid (PAA).

[0033] On the other hand, the present invention provides a method for assembling a lithium secondary battery. After in-situ lithiation according to any of the above-described methods for in-situ lithiation of lithium-ion batteries whose positive and negative electrodes are intrinsically lithium-free, the injected lithiation solution is removed or not removed by vacuuming, and then an electrolyte is injected, packaged, left to stand, and activated to obtain a lithium secondary battery.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) By adjusting the composition, amount added, and in-situ lithiation time of the lithiation solution, in-situ safe and controllable full lithiation of the sulfur-based full battery system can be achieved. At the same time, by adjusting the composition and solvation structure of each component of the lithiation solution, and by using different lithium salts, solvents and adding a certain proportion of additives, the composition and dynamic performance of the electrode interface protective film can be precisely controlled.

[0036] (2) Combining in-situ lithiation with battery assembly processes saves equipment and operating costs and improves the safety of the in-situ lithiation process. By adjusting the composition of the lithiation solution and the lithium salt concentration, not only can the in-situ lithiation time be precisely controlled, but the composition of the solid electrolyte film on the electrode surface can also be adjusted to meet the different application scenarios and power requirements of the subsequent battery. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the internal structure of a lithium-ion battery after assembly.

[0038] Figure 2 In Example 1, lithium strip was used as a lithium replenishing agent, 0.1M LiPF6 EC / DMC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with graphite anode and lithium metal after in-situ lithiation at 20°C for 1h was measured.

[0039] Figure 3 In Example 2, lithium powder was used as a lithium replenishing agent, 0.1M LiPF6 EC / DMC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with graphite anode and lithium metal after in-situ lithiation at 20°C for 1h was measured.

[0040] Figure 4 In Example 3, lithium strip was used as a lithium replenishing agent, 0.1M LiPF6 EC / DMC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled by the graphite anode and lithium metal after in-situ lithiation at 20°C for 24h was measured.

[0041] Figure 5 In Example 4, lithium strip was used as a lithium replenishing agent, 0.1M LiPF6 EC / DMC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with graphite anode and lithium metal after in-situ lithiation at 60°C for 3h was measured.

[0042] Figure 6 In Example 6, lithium strip was used as a lithium replenishing agent, 0.1M LiPF6 EC / DMC was used as the lithiation solution, and the injection volume was controlled at 10g / Ah. The first charge specific capacity of the half-cell assembled with graphite anode and lithium metal after in-situ lithiation at 20°C for 24h was obtained.

[0043] Figure 7 In Example 7, lithium strip was used as a lithium replenishing agent, 0.01M LiPF6 EC / DMC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with graphite anode and lithium metal after in-situ lithiation at 20°C for 24h was measured.

[0044] Figure 8 In Example 8, lithium strip was used as a lithium replenishing agent, 1M LiPF6 EC / DMC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled from the graphite anode and lithium metal after in-situ lithiation at 20°C for 24h was measured.

[0045] Figure 9 In Example 9, lithium strip was used as a lithium replenishing agent, 0.1M LiPF6 EC / DEC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with graphite anode and lithium metal after in-situ lithiation at 20°C for 24h was measured.

[0046] Figure 10 In Example 11, lithium strip was used as a lithium replenishing agent, 0.1M LiFSIDBE was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with graphite anode and lithium metal after in-situ lithiation at 20°C for 24h was measured.

[0047] Figure 11 In Example 13, lithium strip was used as a lithium replenishing agent, and 0.1M LiPF6 EC / DMC+10% FEC was used as the lithiation solution. The injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with graphite anode and lithium metal after in-situ lithiation at 20°C for 24h was measured.

[0048] Figure 12 In Example 14, lithium strip was used as a lithium replenishing agent, and 0.05M LiFSI+0.05M LiClO4EC / DEC was used as the lithiation solution. The injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with graphite anode and lithium metal after in-situ lithiation at 20°C for 24h was measured.

[0049] Figure 13 In Example 16, lithium strip was used as a lithium replenishing agent, 0.1M LiPF6 EC / DEC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with silicon-carbon anode and lithium metal after in-situ lithiation at 20°C for 24h was obtained.

[0050] Figure 14These are photographs of silicon-carbon anodes after in-situ lithiation for different times at 20°C, using lithium strip as a lithium replenishing agent, 0.1M LiPF6 EC / DEC as the lithiation solution, and controlling the injection volume at 0.5 g / Ah.

[0051] Figure 15 In Example 19, lithium strip was used as a lithium replenishing agent, 0.1M LiPF6 EC / DEC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with SPAN cathode and lithium metal after in-situ lithiation at 20°C for 1h was measured.

[0052] Figure 16 In Example 20, lithium strip was used as a lithium replenishing agent, 0.1M LiPF6 EC / DEC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with SPAN cathode and lithium metal after in-situ lithiation at 20°C for 24h was obtained.

[0053] Figure 17 In Example 21, lithium powder was used as a lithium replenishing agent, 0.1M LiPF6 EC / DEC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The first charge specific capacity of the half-cell assembled with SPAN cathode and lithium metal after in-situ lithiation at 20°C for 24h was obtained.

[0054] Figure 18 In Example 24, lithium strips were used as lithium replenishing agents, 0.1M LiPF6 EC / DMC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The lithium strips were placed directly on the graphite anode surface and Gr(Li)||SPAN full cells were assembled in sequence. After in-situ lithiation at 20°C for 24h, the lithiation solution was completely removed by vacuuming, and then conventional electrolyte was injected for formation and cycle performance testing to obtain the cycle data.

[0055] Figure 19 In Example 25, lithium strips were used as lithium replenishing agents, 0.1M LiPF6 EC / DMC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The lithium strips were placed directly on the surface of the SPAN positive electrode and the Gr||SPAN(Li) full cell was assembled in sequence. After in-situ lithiation at 20°C for 24h, the lithiation solution was completely removed by vacuuming, and then conventional electrolyte was injected for formation and cycle performance testing to obtain the cycle data.

[0056] Figure 20In Example 26, lithium strips were used as lithium replenishing agents, and 0.1M LiPF6 EC / DMC was used as the lithiation solution. The injection volume was controlled at 0.5g / Ah. The lithium strips were placed on the surfaces of the graphite anode and the SPAN cathode and the Gr(Li)||SPAN(Li) full cell was assembled in sequence. After in-situ lithiation at 20°C for 24h, the lithiation solution was completely removed by vacuuming, and then conventional electrolyte was injected for formation and cycle performance testing to obtain the cycle data.

[0057] Figure 21 In Example 27, lithium strips were used as lithium replenishing agents, 0.1M LiPF6 EC / DMC was used as the lithiation solution, and the injection volume was controlled at 0.5g / Ah. The lithium strips were placed directly on the SiC electrode surface and SiC(Li)||SPAN full cells were assembled in sequence. After in-situ lithiation at 20°C for 24h, the lithiation solution was completely removed by vacuuming, and then conventional electrolyte was injected for formation and cycle performance testing to obtain the cycle data.

[0058] Figure 22 In Example 29, lithium strips were used as lithium replenishing agents, and 0.1M LiPF6 EC / DMC was used as the lithiation solution. The injection volume was controlled at 0.5g / Ah. The lithium strips were placed directly on the graphite electrode surface and Gr(Li)||SPAN full cells were assembled in sequence. After in-situ lithiation at 20°C for 24h, the lithiation solution was used to form the battery. Then, the lithiation solution was completely removed by vacuuming, and conventional electrolyte was injected to obtain the cycle performance test data.

[0059] Figure 23 This is a comparison of the impedance of symmetrical cells assembled from graphite anodes after in-situ lithiation for 24 hours using different lithiation solutions in Examples 3, 9, and 11.

[0060] Figure 24 These are XPS spectra of the graphite anode surface after in-situ lithiation for 24 hours using different lithiation solutions in Examples 9 and 11.

[0061] Figure 25 The following are Raman spectra of different lithium-ion solutions: (a) 0.1M LiPF6 DBE, (b) 0.1M LiFSI EC / DEC.

[0062] Explanation of each mark in the diagram:

[0063] 1-Positive electrode, 2-Negative electrode, 3-Separator, 4-Internal electrolyte, 5-Aluminum-plastic outer packaging, 6-Taper, 7-Lithium replenisher. Detailed Implementation

[0064] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0065] In some embodiments, the present invention provides an in-situ lithiation method for lithium-ion batteries, combining in-situ lithiation with battery assembly processes, such as... Figure 1 As shown, during the battery assembly process following conventional assembly procedures, the tabs 6, aluminum-plastic outer packaging 5, positive electrode 1, negative electrode 2, and separator 3 are directly placed on the surface of the negative electrode, positive electrode, or both electrodes (the amount of lithium replenishing agent added is determined by meeting the lithium requirements for stable battery operation). Then, a lithium-ionizing solution is injected, causing a short-circuit reaction between the lithium replenishing agent and the corresponding electrode, thereby achieving in-situ lithiation and interface control. After in-situ lithiation, the lithium-ionizing solution is removed by vacuuming, and then the internal electrolyte 4 is injected before subsequent processes such as encapsulation, settling, and activation are performed to obtain a lithium secondary battery.

[0066] Based on the above embodiments, the present invention will further explain the above process by combining more specific embodiments and experimental data.

[0067] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0068] Example 1

[0069] The lithium-ion additive was placed directly on the graphite anode surface. A 0.1M LiPF6EC / DMC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the mixture was left at 20°C for 1 hour. The lithium-ion additive underwent a short-circuit reaction with the anode, achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion wafers in a conventional sequence for charging testing.

[0070] Example 2

[0071] Lithium powder, acting as a lithium supplement, was directly placed on the surface of the graphite anode. A 0.1M LiPF6EC / DMC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the mixture was left at 20°C for 1 hour. The lithium supplement reacted with the anode via a short circuit, achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium wafers in a conventional sequence, followed by charging tests.

[0072] Example 3

[0073] The lithium-ion additive was directly placed on the surface of the graphite anode. A 0.1M LiPF6EC / DMC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the mixture was left at 20°C for 24 hours. The lithium-ion additive underwent a short-circuit reaction with the anode, thus achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion wafers in a conventional sequence, followed by charging tests.

[0074] Example 4

[0075] The lithium-ion additive was directly placed on the surface of the graphite anode. A 0.1M LiPF6EC / DMC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the mixture was placed at 60°C for 3 hours. The lithium-ion additive underwent a short-circuit reaction with the anode, thus achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion wafers in a conventional sequence, followed by charging tests.

[0076] Example 5

[0077] The lithium-ion additive was directly placed on the surface of the graphite anode. A 0.1M LiPF6EC / DMC (1:1, vol.-%) lithiation solution was injected at a rate of 5 g / Ah. After being placed at 20°C for 24 hours, the lithium-ion additive underwent a short-circuit reaction with the anode, thus achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion wafers in a conventional sequence for charging testing.

[0078] Example 6

[0079] The lithium-ion additive was directly placed on the surface of the graphite anode. A 0.1M LiPF6EC / DMC (1:1, vol.-%) lithiation solution was injected at a rate of 10 g / Ah, and the mixture was left at 20°C for 24 hours. The lithium-ion additive underwent a short-circuit reaction with the anode, thus achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion wafers in a conventional sequence, followed by charging tests.

[0080] Example 7

[0081] The lithium-ion additive was directly placed on the surface of the graphite anode. A 0.01M LiPF6EC / DMC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the mixture was left at 20°C for 24 hours. The lithium-ion additive underwent a short-circuit reaction with the anode, thus achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion sheets in a conventional sequence for charging testing.

[0082] Example 8

[0083] The lithium-ion additive was directly placed on the surface of the graphite anode. A 1M LiPF6EC / DMC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the mixture was left at 20°C for 24 hours. During this time, the lithium-ion additive underwent a short-circuit reaction with the anode, achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion wafers in a conventional sequence for charging testing.

[0084] Example 9

[0085] The lithium-ion additive was placed directly on the graphite anode surface, and 0.1M LiPF6EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah. After being placed at 20°C for 24 h, the lithium-ion additive underwent a short-circuit reaction with the anode, thereby achieving in-situ lithiation and interface control. Subsequently, the battery was disassembled and assembled into a half-cell with lithium sheets in a conventional sequence, and charging tests were performed.

[0086] Example 10

[0087] The lithium-ion additive was directly placed on the surface of the graphite anode. A 0.1M LiPF6EC / DMC / DEC (1:1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah. After being placed at 20°C for 24 hours, the lithium-ion additive underwent a short-circuit reaction with the anode, thus achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion wafers in a conventional sequence for charging testing.

[0088] Example 11

[0089] The lithium-ion additive was placed directly on the graphite anode surface, and 0.1M LiFSIDBE lithiation solution was injected at a rate of 0.5 g / Ah. After being placed at 20°C for 24 hours, the lithium-ion additive underwent a short-circuit reaction with the anode, thereby achieving in-situ lithiation and interface control. Subsequently, the battery was disassembled and assembled into a half-cell with lithium sheets in a conventional sequence, and charging tests were conducted.

[0090] Example 12

[0091] The lithium-ion packing agent was directly placed on the graphite anode surface. A 0.1M LiPF6EC / DMC (1:1, vol.-%) + 0.1% FEC (film-forming agent) lithiation solution was injected at a rate of 0.5 g / Ah. After being placed at 20°C for 24 hours, the lithium-ion packing agent underwent a short-circuit reaction with the anode, thus achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium wafers in a conventional sequence for charging testing.

[0092] Example 13

[0093] The lithium-ion additive was directly placed on the graphite anode surface. A 0.1M LiPF6EC / DMC (1:1, vol.-%) + 10% FEC (film-forming agent) lithiation solution was injected at a rate of 0.5 g / Ah. After being placed at 20°C for 24 hours, the lithium-ion additive underwent a short-circuit reaction with the anode, achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium wafers in a conventional sequence for charging testing.

[0094] Example 14

[0095] The lithium-ion additive was directly placed on the graphite anode surface. A 0.05M LiFSI + 0.05M LiClO4 EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah. After being placed at 20°C for 24 hours, the lithium-ion additive underwent a short-circuit reaction with the anode, achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium wafers in a conventional sequence for charging testing.

[0096] Example 15

[0097] The lithium-ion additive was directly placed on the surface of the silicon-carbon anode. A 0.1M LiPF6EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the mixture was left at 20°C for 1 hour. The lithium-ion additive underwent a short-circuit reaction with the anode, thus achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion cells in a conventional sequence, followed by charging tests.

[0098] Example 16

[0099] The lithium-ion additive was directly placed on the surface of the silicon-carbon anode. A 0.1M LiPF6EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the mixture was left at 20°C for 24 hours. During this time, the lithium-ion additive underwent a short-circuit reaction with the anode, achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion cells in a conventional sequence for charging testing.

[0100] Example 17

[0101] The lithium-ion additive was placed directly on the surface of the silicon anode. A 0.1M LiPF6EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the mixture was left at 20°C for 24 hours. During this time, the lithium-ion additive underwent a short-circuit reaction with the anode, achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion cells in a conventional sequence for charging testing.

[0102] Example 18

[0103] The lithium-ion additive was placed directly on the surface of the tin anode. Then, 0.1 M LiPF6EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah. After being placed at 20°C for 24 h, the lithium-ion additive underwent a short-circuit reaction with the anode, thus achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium wafers in a conventional sequence for charging testing.

[0104] Example 19

[0105] The lithium-ion packing agent was placed directly on the surface of the SPAN positive electrode. Then, 0.1M LiPF6EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah. After being placed at 20°C for 1 hour, the lithium-ion packing agent underwent a short-circuit reaction with the positive electrode, thus achieving in-situ lithiation and interface control. Subsequently, the battery was disassembled and assembled into a half-cell with lithium sheets in a conventional sequence, followed by charging tests.

[0106] Example 20

[0107] The lithium-ion additive was placed directly on the surface of the SPAN positive electrode. A 0.1M LiPF6EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the battery was left at 20°C for 24 hours. During this time, the lithium-ion additive underwent a short-circuit reaction with the positive electrode, achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium-ion cells in a conventional sequence, followed by charging tests.

[0108] Example 21

[0109] Lithium powder, the lithium replenishing agent, was directly placed on the surface of the SPAN positive electrode. A 0.1M LiPF6EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the mixture was left at 20°C for 24 hours. The lithium replenishing agent underwent a short-circuit reaction with the positive electrode, thus achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium sheets in a conventional sequence, followed by charging tests.

[0110] Example 22

[0111] Lithium powder, acting as a lithium supplement, was directly placed on the surface of the iron disulfide cathode. Then, 0.1 M LiPF6EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah. After being placed at 20°C for 24 h, the lithium supplement reacted with the cathode via a short circuit, achieving in-situ lithiation and interface control. The battery was then disassembled and assembled into a half-cell with lithium sheets in a conventional sequence for charging testing.

[0112] Example 23

[0113] The lithium-ion additive was simultaneously placed on the surfaces of the graphite anode and the SPAN cathode. After injecting 0.1 M LiPF6 EC / DEC (1:1, vol.-%) lithiation solution at a rate of 0.5 g / Ah, the mixture was placed at 20°C for 24 h. The lithium-ion additive simultaneously underwent a short-circuit reaction with both the anode and cathode, thus achieving in-situ lithiation and interface control. Subsequently, the battery was disassembled and assembled into half-cells with lithium-ion sheets in a conventional sequence, followed by charging tests.

[0114] Example 24

[0115] The lithium-ion packing agent was directly placed on the graphite anode surface and assembled into a Gr(Li)||SPAN full cell in sequence. A 0.1M LiPF6 EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the cell was placed at 20°C for 24 h. The lithium-ion packing agent underwent a short-circuit reaction with the anode, thus achieving in-situ lithiation and interface control. Subsequently, the lithiation solution was completely removed by vacuuming, and then conventional electrolyte was injected for formation and cycle performance testing.

[0116] Example 25

[0117] The lithium-stripping agent was directly placed on the surface of the SPAN cathode and assembled into a Gr||SPAN(Li) full cell in sequence. A 0.1M LiPF6 EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the cell was placed at 20°C for 24 h. The lithium-stripping agent underwent a short-circuit reaction with the cathode, achieving in-situ lithiation and interface control. Subsequently, the lithiation solution was completely removed by vacuuming, and then conventional electrolyte was injected for formation and cycle performance testing.

[0118] Example 26

[0119] Lithium-containing additives were placed on the surfaces of graphite anodes and SPAN cathodes, respectively, and Gr(Li)||SPAN(Li) full cells were assembled in sequence. A 0.1M LiPF6 EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the cells were placed at 20°C for 24 h. The lithium additives underwent a short-circuit reaction with both the anode and cathode, achieving in-situ lithiation and interface control. Subsequently, the lithiation solution was completely removed by vacuuming, and then conventional electrolyte was injected for formation and cycle performance testing.

[0120] Example 27

[0121] The lithium-ion packing agent was directly placed on the surface of the silicon-carbon anode and assembled into a SiC(Li)||SPAN full cell in sequence. A 0.1M LiPF6 EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the cell was placed at 20°C for 24 h. The lithium-ion packing agent underwent a short-circuit reaction with the anode, thus achieving in-situ lithiation and interface control. Subsequently, the lithiation solution was completely removed by vacuuming, and then conventional electrolyte was injected for formation and cycle performance testing.

[0122] Example 28

[0123] Lithium-containing additives were directly placed on the surface of the graphite anode and Gr(Li)||SPAN full cells were assembled sequentially. A 0.1M LiPF6 EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah, and the cells were placed at 20°C for 24 h. The lithium additives underwent a short-circuit reaction with the anode, achieving in-situ lithiation and interface control. Subsequently, a portion of the lithiation solution was removed by vacuuming, and conventional electrolyte was injected for formation and cycle performance testing.

[0124] Example 29

[0125] The lithium-ion packing agent was directly placed on the graphite anode surface and assembled into a Gr(Li)||SPAN full cell in sequence. A 0.1M LiPF6 EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah. After standing at 20°C for 24 h, the lithium-ion packing agent underwent a short-circuit reaction with the anode and formed using the lithiation solution, thus achieving in-situ lithiation and interface control. Subsequently, the lithiation solution was completely removed by vacuuming, and then conventional electrolyte was injected for cycle performance testing.

[0126] Example 30

[0127] The lithium-ion packing agent was directly placed on the graphite anode surface and assembled into a Gr(Li)||SPAN full cell in sequence. A 0.1M LiPF6 EC / DEC (1:1, vol.-%) lithiation solution was injected at a rate of 0.5 g / Ah. After being placed at 20°C for 24 h, the lithium-ion packing agent underwent a short-circuit reaction with the anode and formed using the lithiation solution, thus achieving in-situ lithiation and interface control. Subsequently, 60-100% (e.g., around 80%) of the lithiation solution was removed by vacuuming, and then conventional electrolyte was added for cycle performance testing.

[0128] Test Plan

[0129] The lithium replenishment method provided by this invention for intrinsically lithium-free positive and negative electrodes was applied to lithium-free electrode materials such as graphite and SPAN to verify the practicality of the lithium replenishment method.

[0130] The lithium replenishment methods described in Examples 1-18 were used to conduct lithium replenishment experiments on the negative electrode material. Conventional electrolyte was added, and charge-discharge analysis was performed at 25°C and a current density of 0.5C. The resulting charging curves are shown in the attached figures.

[0131] As attached Figure 2-13 It can be seen that the graphite anode after lithium replenishment treatment can extract a large amount of lithium ions, indicating that a large amount of lithium is obtained in the anode material during the lithium replenishment process.

[0132] The surface of the negative electrode during the lithium replenishment process of the usage example was observed, and the surface changes under macroscopic conditions are shown in the attached figure.

[0133] As attached Figure 14 As the lithium replenishment time increases, the color of the electrode surface gradually changes from black to golden yellow, showing a good lithium replenishment effect.

[0134] The lithium replenishment methods described in Examples 19-30 were used to conduct lithium replenishment experiments on the cathode material. Conventional electrolyte was added, and charge-discharge analysis was performed at 25°C and a current density of 0.5C. The resulting charging curves are shown in the attached figures.

[0135] As attached Figure 15-17 It can be seen that the SPAN cathode after lithium replenishment treatment can extract a large amount of lithium ions, indicating that a large amount of lithium is obtained in the cathode material during the lithium replenishment process.

[0136] Lithium replenishment experiments were conducted on the positive and negative electrode materials using the lithium replenishment methods described in Examples 1-30. The lithium-replenished positive and negative electrodes were assembled into a full cell, and conventional electrolyte was added. Charge-discharge analysis was performed at 25°C and a current density of 0.5C. The resulting cycle curves are shown in the attached figure.

[0137] As attached Figure 18-22 It can be seen that the battery after lithium replenishment treatment can cycle stably, indicating that the lithium replenishment process provides a sufficient lithium source for the entire battery.

[0138] Lithium replenishment experiments were conducted on the negative electrode materials using the lithium replenishment methods described in Examples 9, 12, and 15. The lithium-replenished negative electrodes were then assembled into symmetrical cells for impedance testing and elemental state analysis of the electrode surface. The test results are shown in the attached figures.

[0139] As attached Figure 23 It can be seen that the interfacial transfer resistance of the electrode sheet after lithium supplementation treatment is significantly reduced, indicating that the lithium supplementation method can effectively promote the entry of lithium into the negative electrode material and form a low-resistance SEI film. (See attached image) Figure 24 It can be observed that the lithium replenishment method improves the elemental distribution and state on the electrode surface, which is beneficial for building a stable cycling system.

[0140] In summary, the lithium replenishment method for intrinsically lithium-free positive and negative electrodes provided by this invention includes: lithium salt, organic solvent, lithium replenishing agent, assembly method, and the addition and removal of lithium replenishing solution. Through the in-situ action of the lithium replenishing agent and lithium replenishing solution on the intrinsically lithium-free electrode material, the lithium content of the electrode material can be effectively increased. It can serve as a highly efficient lithium replenishment method for intrinsically lithium-free positive and negative electrode materials. The lithium replenishing solution used in this method is easy to prepare, low in cost, and uses standardized materials. The positive and negative electrodes obtained by combining this in-situ lithium replenishment method can meet the lithium requirements for stable cycling and exhibit good stability during long-term cycling, demonstrating the high practical application value of this invention.

[0141] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for in-situ lithiation of lithium-ion batteries with intrinsically lithium-free positive and negative electrodes, characterized in that, In the process of assembling lithium-ion batteries, the lithium replenishing agent is placed directly on the surface of the electrode to be replenished with lithium, and the lithium-ion liquid is injected, so that the electrode to be replenished with lithium and the lithium replenishing agent undergo a short-circuit reaction, thereby achieving in-situ lithiation and interface control.

2. The method for in-situ lithiation of an intrinsically lithium-free lithium-ion battery according to claim 1, characterized in that, The lithium replenishing agent is one or a combination of several of the following: lithium metal powder, lithium-rich alloy powder, lithium-rich oxide powder, lithium or lithium alloy foil, lithium or lithium alloy strip, and lithium or lithium alloy mesh.

3. The method for in-situ lithiation of an intrinsically lithium-free lithium-ion battery according to claim 1, characterized in that, The lithium-ionizing solution includes lithium salt, organic solvent and film-forming additive. In the lithium-ionizing solution, the concentration of lithium salt is 0.001 mol / L to 10 mol / L, and the concentration of film-forming additive is 0.01 to 20 wt%.

4. The method for in-situ lithiation of an intrinsically lithium-free lithium-ion battery according to claim 3, characterized in that, The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(oxalate)borate, lithium difluorosulfonate imide, lithium bis(trifluoromethyl)sulfonylimide, lithium perchlorate, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, and lithium nitrate. The organic solvent is selected from one or more combinations of carbonate solvents, ether solvents, carboxylic acid ester solvents, nitrile solvents, phosphate ester solvents, sulfonate solvents, siloxane solvents, fluorinated ether solvents, and hydrocarbon solvents; The film-forming additive is selected from one or a combination of several of the following: fluorine-containing additives, boron-containing additives, organophosphorus additives, carbonate additives, sulfur-containing additives, and lithium salt additives.

5. The method for in-situ lithiation of an intrinsically lithium-free lithium-ion battery according to claim 4, characterized in that, The carbonate solvent is selected from one or a combination of several of the following: dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, fluoroethylene carbonate, vinylene carbonate, di(trifluoroethyl) carbonate, trifluoroethyl methyl carbonate, and ethyleneene carbonate. The ether solvent is selected from one or a combination of several of the following: diethyl ether, diisopropyl ether, dibutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, methyl tert-butyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, and 2-methyltetrahydrofuran. The carboxylic acid ester solvent is selected from one or a combination of several of methyl formate, ethyl acetate, ethyl formate, methyl acetate, butyl acetate, butyl formate, butyl butyrate, ethyl fluoroacetate, ethyl difluoroacetate, and ethyl trifluoroacetate. The nitrile solvent is selected from one or a combination of acetonitrile, butadiene nitrile, and adiponitrile; The phosphate ester solvent is selected from one or a combination of several of trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, and triethyl fluorophosphate. The sulfonate solvent is selected from one or a combination of two of dimethyl sulfoxide and sulfolane. The siloxane solvent is selected from one or a combination of several of tetraethoxysilane, tetramethoxysilane, methyltriethoxysilane, and diethoxydimethylsilane; The fluorinated ether solvent is selected from one or a combination of several of the following: 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, 2,2,2-trifluoroethyl ether, 2,2,3,3,3-pentafluoropropyl-1,1,2,2-tetrafluoroethyl ether, 1,1,2,3,3,3-hexafluoropropyl-2,2,2-trifluoroethyl ether, 1,1,2,3,3,3-hexafluoropropyl-2,2,3,3-tetrafluoropropyl ether, and trifluoromethoxybenzene.

6. The method for in-situ lithiation of an intrinsically lithium-free lithium-ion battery according to claim 4, characterized in that, The fluorinated additive is selected from one or a combination of several of the following: fluoroethylene carbonate, difluoroethylene carbonate, fluoroacetonitrile, p-toluenesulfonyl fluoride, ethoxy-pentafluorocyclotriphosphazene, and 2,4,6-tris(trifluoromethyl)-1,3,5-triazine. The boron-containing additive is selected from one or a combination of several of the following: tri(trimethyl)silane boronic acid ester, trimethyl borate, triethyl borate, tripropyl borate, tri(2-acrylonitrile ethyl) boronic acid ester, tri(2,2,2-trifluoroethyl) boronic acid ester, pyridine-boron trifluoride, and pyridine-boron trifluoride. The organophosphorus additive is selected from one or a combination of several of trimethyl phosphate, triethyl phosphate, tris(trimethylsilyl)phosphite, and tris(trimethylsilyl)phosphate; The carbonate additives are selected from one or a combination of several of the following: vinylene carbonate, ethylene ethylene carbonate, propylene trifluorocarbonate, ethylene carbonate ether, and glyceryl carbonate trimethylsilyl ether. The sulfur-containing additive is selected from one or a combination of several of the following: ethylene sulfite, ethylene sulfate, propylene sulfite, propylene sulfate, 1,4-butanesulfonate lactone, 1,3-propanesulfonate lactone, and 4-methylethylene sulfite. The lithium salt additive is selected from one or a combination of several of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(oxalato)borate, lithium difluorosulfonylimide, lithium bis(trifluoromethyl)sulfonylimide, lithium perchlorate, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, and lithium nitrate.

7. The method for in-situ lithiation of an intrinsically lithium-free lithium-ion battery according to claim 4, characterized in that, The amount of lithium-ionized liquid injected is 0.5 g / Ah to 10 g / Ah.

8. The method for in-situ lithiation of an intrinsically lithium-free lithium-ion battery according to claim 1, characterized in that, The in-situ lithiation temperature is -40 to 100℃, and the time is 1 min to 120 h.

9. The method for in-situ lithiation of an intrinsically lithium-free lithium-ion battery according to claim 1, characterized in that, The electrode is a lithium-free positive electrode or a lithium-free negative electrode, wherein the lithium-free positive electrode is one or a combination of several of the following: sulfurized polyacrylonitrile positive electrode, elemental sulfur positive electrode, sulfur / carbon composite positive electrode, metal sulfide positive electrode, metal fluoride positive electrode, and organic positive electrode. The lithium-free anode is one or a combination of several of the following: carbon anode, silicon anode, silicon suboxide anode, silicon / carbon composite anode, tin anode, and metal oxide anode.

10. A method for assembling a lithium secondary battery, characterized in that, After in-situ lithiation according to the method of in-situ lithiation of lithium-ion batteries with intrinsically lithium-free positive and negative electrodes as described in any one of claims 1-9, the injected lithiation solution is removed or not removed by vacuuming, electrolyte is injected, packaged, left to stand, and activated to obtain a lithium secondary battery.

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