Lithium supplement compound, lithium ion battery positive electrode and solid-state lithium ion battery

Abstract

The invention provides a lithium supplement compound, a lithium ion battery positive electrode and a solid-state lithium ion battery, the lithium supplement compound comprises a mixture of a first lithium supplement agent and a second lithium supplement agent, the molecular formula of the first lithium supplement agent is Li5FeO4, and the molecular formula of the second lithium supplement agent is Li2NiO2; the mass ratio of the first lithium supplement agent to the second lithium supplement agent is (1-4): 1. The lithium supplementing compound provided by the invention not only effectively improves the cycle performance and the first efficiency of the battery, but also reduces the gas production rate in the lithium supplementing process.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a lithium supplementing compound and a lithium ion battery positive electrode and a solid lithium ion battery containing the lithium supplementing compound. Background Art

[0002] With the vigorous development of new energy technologies in recent years, lithium-ion secondary batteries are widely used in portable electronic devices, hybrid electric vehicles and renewable energy storage systems. Usually, lithium-ion batteries are usually composed of transition metal oxide positive electrodes and graphite negative electrodes. Spinel lithium manganese oxide has attracted widespread attention for its excellent performance and low cost. The applicant has found through research that the overall operating trend of spinel lithium manganese oxide shows a trend of first decreasing and then flattening. Therefore, the applicant has developed a lithium replenishment system with dual lithium replenishers to achieve improved cycle performance during the entire operation of the battery.

[0003] However, the commonly used positive electrode lithium replenishers all have the problem of gas production, which is particularly obvious in the formation stage. The applicant has developed a special positive electrode lithium replenishment composite to better solve the gas production problem of spinel lithium manganese oxide during the lithium replenishment process. Summary of the invention

[0004] In order to solve the above problems, the present application provides a lithium supplementation complex in a first aspect, wherein the lithium supplementation complex comprises a mixture of a first lithium supplementation agent and a second lithium supplementation agent, wherein the molecular formula of the first lithium supplementation agent is as follows:

[0005] Li5FeO4;

[0006] The molecular formula of the second lithium supplement is as follows:

[0007] Li2NiO2;

[0008] The mass ratio of the first lithium supplement agent to the second lithium supplement agent is (1-4):1;

[0009] Furthermore, the mass ratio of the first lithium supplement agent to the second lithium supplement agent is (1.3-2.5):1.

[0010] The second aspect of the present application provides a positive electrode for a lithium-ion battery, wherein the positive electrode active material comprises spinel lithium manganese oxide, and the molecular structure of the spinel lithium manganese oxide is as follows:

[0011] Li (1+b) Mn 2-b-c MO 4-a Q a ,

[0012] Wherein, 0≤a≤1, 0≤b≤0.3; and 0≤c≤1, M is one or more elements selected from Mg, Al, Ni, Co, Fe, Cr, Cu, B, Ca, Nb, Mo, Sr, Sb, W, B, Ti, V, Zr and Zn, and Q is one or more elements selected from N, F, S, and Cl.

[0013] Further preferably, the lithium supplementing compound is added in an amount of 0.5-5 wt % in the positive electrode.

[0014] Further preferably, the amount of the lithium supplementing composite added to the positive electrode is 1.5-2.5 wt %.

[0015] Further preferably, the positive electrode further comprises a third lithium replenisher, and the third lithium replenisher is not completely consumed in the first three cycles.

[0016] The third invention of the present application provides a solid-state lithium-ion battery, comprising the positive electrode, negative electrode and solid electrolyte layer described in the second aspect above, wherein the solid electrolyte layer is located between the positive electrode and the negative electrode.

[0017] The lithium supplementation complex composed of the first lithium supplementation agent and the second lithium supplementation agent involved in the present application unexpectedly solves the gas production problem during the lithium supplementation process. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In the description of the specific implementation methods of the present invention, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0021] Reference to "embodiments" in the present invention means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present invention may be combined with other embodiments.

[0022] In the description of the embodiments of the present invention, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects before and after are in an "or" relationship.

[0023] Throughout the present invention, numerical values ​​represent approximate measures or limits of ranges to cover minor deviations from given values ​​as well as embodiments with about the values ​​mentioned and embodiments with the exact values ​​mentioned. Except for the working examples provided at the end of the detailed description, all numerical values ​​of parameters (e.g., amounts or conditions) in this specification (including the appended claims) should be understood as modified by the term "about" in all cases, regardless of whether "about" actually appears before the numerical value. "About" indicates that the stated numerical value allows some minor imprecision (close to the exact value of the value to some extent; approximately or reasonably close to the value; almost). If the imprecision provided by "about" is not otherwise understood in this ordinary sense in the art, "about" as used in the present invention at least indicates the variation that can be produced by the ordinary methods of measuring and using such parameters. For example, "about" may include a variation of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in some aspects, optionally less than or equal to 0.1%.

[0024] Additionally, disclosure of ranges includes disclosure of all values ​​within the entire range and further divided ranges, including endpoints and sub-ranges given for such ranges.

[0025] This embodiment provides a lithium supplementation complex, wherein the lithium supplementation complex comprises a mixture of a first lithium supplementation agent and a second lithium supplementation agent, wherein the molecular formula of the first lithium supplementation agent is as follows:

[0026] Li5FeO4;

[0027] The molecular formula of the second lithium supplement is as follows:

[0028] Li2NiO2;

[0029] The mass ratio of the first lithium supplement agent to the second lithium supplement agent is (1-4):1;

[0030] Furthermore, the mass ratio of the first lithium supplement agent to the second lithium supplement agent is (1.3-2.5):1.

[0031] This embodiment further provides a positive electrode for a lithium-ion battery, wherein the positive electrode active material includes spinel lithium manganese oxide, and the molecular structure of the spinel lithium manganese oxide is as follows:

[0032] Li (1+b) Mn 2-b-c MO 4-a Q a ,

[0033] Wherein, 0≤a≤1, 0≤b≤0.3; and 0≤c≤1, M is one or more elements selected from Mg, Al, Ni, Co, Fe, Cr, Cu, B, Ca, Nb, Mo, Sr, Sb, W, B, Ti, V, Zr and Zn, and Q is one or more elements selected from N, F, S, and Cl.

[0034] Further preferably, the lithium supplementing compound is added in an amount of 0.5-5 wt % in the positive electrode.

[0035] Further preferably, the amount of the lithium supplementing composite added to the positive electrode is 1.5-2.5 wt %.

[0036] Further preferably, the positive electrode further comprises a third lithium replenisher, and the third lithium replenisher is not completely consumed in the first three cycles.

[0037] Further preferably, the third lithium supplement agent is selected from layered lithium manganese oxide, and the molecular structure of the layered lithium manganese oxide is as follows:

[0038] xLi2MnO 3-(1-a) LiMO2;

[0039] M is selected from any one of Al, Mg, Mn, Ni, Co, Cr, V, Fe, Cu, Zn, Ti and B, or two or more of the above elements used simultaneously.

[0040] In one embodiment, one or more lithium-based positive electrode electroactive materials may optionally be coated (e.g., by LiNbO3 and / or Al2O3) and / or may be doped (e.g., by magnesium (Mg)). In addition, in certain embodiments, one or more lithium-based positive electrode active materials may optionally be mixed with one or more conductive agents that provide an electron conduction path and / or at least one polymer binder that improves the structural integrity of the positive electrode. For example, the positive electrode active material layer may include greater than or equal to about 30 wt% to less than or equal to about 98 wt% of one or more lithium-based positive electrode active materials; greater than or equal to 0 wt% to less than or equal to about 30 wt% of a positive electrode conductive agent; and greater than or equal to about 0 wt% to less than or equal to about 20 wt% of a positive electrode binder, and in some aspects, optionally greater than or equal to about 1 wt% to less than or equal to about 20 wt% of a positive electrode binder.

[0041] The present application has no particular restrictions on the types of positive electrode binders and positive electrode conductors. Without violating the inventive concept of the present application, any known binder or conductive agent type can be used in the present application as a positive electrode binder and a positive electrode conductor. It is only used as an illustrative example, not a limitation on the scope of protection. The positive electrode binder can be selected from polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butylene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, one or a combination of lithium alginate. The positive electrode conductor can be selected from carbon-based materials, powdered nickel or other metal particles, or conductive polymers. Carbon-based materials can include particles such as carbon black, graphite, acetylene black (such as KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of the conductive polymer include polyaniline, polythiophene, polyacetylene, polypyrrole, and the like.

[0042] The positive electrode current collector can facilitate the flow of electrons between the positive electrode and the external circuit. The positive electrode current collector may include a metal, such as a metal foil, a metal grid or screen, or a metal mesh. For example, the positive electrode current collector may be formed of aluminum, stainless steel and / or nickel, or any other suitable conductive material known to those skilled in the art.

[0043] The third invention of this embodiment provides a solid-state lithium-ion battery, comprising the positive electrode, the negative electrode and the solid electrolyte layer described in the second aspect above, wherein the solid electrolyte layer is located between the positive electrode and the negative electrode.

[0044] The lithium supplementation complex composed of the first lithium supplementation agent and the second lithium supplementation agent involved in the present application unexpectedly solves the gas production problem during the lithium supplementation process.

[0045] The negative electrode is formed of a lithium-based material that can be used as a negative active material for a lithium-ion battery. For example, the negative electrode may include a lithium-based material that can be used as a negative active material for a battery. In various aspects, the negative electrode may be defined by a plurality of negative active material particles. Such negative active material particles may be arranged in one or more layers to define a three-dimensional structure of the negative electrode. In certain variations, the negative electrode may also include an electrolyte having lithium ion transport properties, such as oxide electrolyte particles.

[0046] The negative electrode may include a lithium-based negative electrode active material, which includes, for example, lithium metal and / or a lithium alloy. In other embodiments, the negative electrode is a silicon-based negative electrode active material, which includes silicon, such as a silicon alloy, silicon oxide, or a combination thereof, which may also be mixed with graphite in some cases. In other embodiments, the negative electrode may include a carbonaceous-based negative electrode active material, which includes one or more of graphite, graphene, carbon nanotubes (CNTs), and combinations thereof. In yet another embodiment, the negative electrode includes one or more negative electrode active materials that accept lithium, such as lithium titanium oxide (Li4Ti5O12), one or more transition metals (e.g., tin (Sn)), one or more metal oxides (e.g., vanadium oxide (V2O5), tin oxide (SnO), titanium dioxide (TiO2)), titanium niobium oxide (TixNbyOz, where 0≤x≤2, 0≤y≤24, and 0≤z≤64), a metal alloy (e.g., copper-tin alloy (Cu6Sn5)) and one or more metal sulfides (e.g., iron sulfide (FeS)).

[0047] Alternatively, the negative electrode active material in the negative electrode can be mixed with one or more conductive agents providing an electronic conduction path and / or at least one polymer binder that improves the structural integrity of the negative electrode. For example, alternatively, the negative electrode active material can be doped with a binder such as poly (tetrafluoroethylene) (PTFE), sodium carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene ethylene butylene styrene copolymer (SEBS), styrene butadiene styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate and combinations thereof. The conductive agent may include carbon-based materials, powdered nickel or other metal particles or conductive polymers. Carbon-based materials may include particles such as carbon black, graphite, superP, acetylene black (such as, KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, and the like. Examples of the conductive polymer include polyaniline, polythiophene, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, and the like.

[0048] The negative electrode may include greater than or equal to about 50 weight % to less than or equal to about 97 weight % of a negative electrode active material, optionally greater than or equal to about 0 weight % to less than or equal to about 60 weight % of a solid electrolyte, optionally greater than or equal to about 0 weight % to less than or equal to about 15 weight % of a conductive agent, and optionally greater than or equal to about 0 weight % to less than or equal to about 10 weight % of a binder.

[0049] It is understood that the present application has no special requirements for the type of solid electrolyte. Without violating the inventive concept of the present application, any known type of solid electrolyte can be used in the present application. As an embodiment, the solid electrolyte may include one or more solid electrolyte particles. Preferably, solid electrolyte particles may also be added to the negative electrode. The solid electrolyte particles may include one or more components of polymer solid electrolytes, particles of oxide solid electrolytes, particles of sulfide solid electrolytes, particles of halide solid electrolytes, particles of borate solid electrolytes, particles of nitride solid electrolytes, or particles of hydrides. When polymer particles are used, lithium salts may be used for compounding. As an embodiment, the polymer-based component may include one or more polymer materials selected from the group including the following: polyethylene glycol, polyethylene oxide (PEO), poly (p-phenylene oxide) (PPO), poly (methyl methacrylate) (PMMA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinylidene fluoride co-hexafluoropropylene (PVDF-HFP), polyvinyl chloride (PVC) and combinations thereof. In one variation, one or more polymer materials may have a relative molecular mass equal to about 10 -4 S / cm ionic conductivity.

[0050] Suitable lithium salts generally have inert anions, such as lithium hexafluorophosphate (LiPF6); lithium perchlorate (LiClO4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium difluorooxalatoborate (LiBF2(C2O4))(LiODFB), lithium tetraphenylborate (LiB(C6H5)4), lithium bis(oxalato)borate (LiB(C2O4)2)(LiBOB), lithium tetrafluorooxalatophosphate (LiPF4(C2O4))(LiFOP), lithium nitrate (LiNO3), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonyl imide) (LITFSI)(LiN(CF3SO2)2), lithium bis(fluorosulfonyl imide) (LiN(FSO2)2)(LIFSI), and combinations thereof. In certain variations, the lithium salt is selected from lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl imide) (LiTFSI)(LiN(CF3SO2)2), lithium bis(fluorosulfonyl imide) (LiN(FSO2)2)(LiFSI), lithium fluoroalkyl phosphonate (LiFAP), lithium phosphate (Li3PO4), and combinations thereof.

[0051] As one implementation, the oxide particles may include one or more garnet ceramics, LISICON-type oxides, NASICON-type oxides, and perovskite ceramics. For example, one or more garnet ceramics may be selected from the group consisting of: Li 6.5 La3Zr 1.75 Te 0.25 O 12 、Li7La3Zr2O 12 、Li 6.2 Ga 0.3 La 2.95 Rb 0.05 Zr2O 12 、Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 、Li 6.25 Al 0.25 La3Zr2O 12 、Li 6.75 La3Zr 1.75 Nb 0.25 O 12 、Li 6.75 La3Zr 1.75 Nb 0.25 O 12 and combinations thereof. One or more LISICON-type oxides may be selected from the group consisting of: Li 14 Zn(GeO4)4、Li 3+x (P 1-x Si x )O4(where 0 < x < 1)、Li 3+x Ge x V 1-x O4(where 0 < x < 1) and combinations thereof. One or more NASICON-type oxides may be defined by LiMM′(PO4)3, where M and M′ are independently selected from Al, Ge, Ti, Sn, Hf, Zr, and La. For example, in certain variations, one or more NASICON-type oxides may be selected from the group consisting of: Li 1+x Al x Ge 2-x (PO4)3(LAGP)(where 0 ≤ x ≤ 2)、Li 1+x Al x Ti 2-x (PO4)3(LATP)(where 0 ≤ x ≤ 2)、Li 1+x Y x Zr 2-x (PO4)3(LYZP)(where 0 ≤ x ≤ 2)、Li1.3 Al 0.3 Ti 1.7 (PO4)3, LiTi2(PO4)3, LiGeTi(PO4)3, LiGe2(PO4)3, LiHf2(PO4)3, and combinations thereof. One or more perovskite-type ceramics may be selected from the group consisting of: Li 3.3 La 0.53 TiO3, LiSr 1.65 Zr 1.3 Ta 1.7 O9, Li 2x-y Sr 1-x Ta y Zr 1-y O3 (where x = 0.75y and 0.60 < y < 0.75), Li 3 / 8 Sr 7 / 16 Nb 3 / 4 Zr 1 / 4 O3, Li 3x La (2 / 3-x) TiO3 (where 0 < x < 0.25), and combinations thereof. In one variant, one or more oxide-based materials may have an ionic conductivity greater than or equal to about 10 -5 S / cm to less than or equal to about 10 -1 S / cm.

[0052] In various aspects, the sulfide-based particles may include one or more sulfide-based materials selected from the group consisting of: Li2S-P2S5, Li2S-P2S5-MS x (where M is Si, Ge, and Sn and 0 ≤ x ≤ 2), Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.3 、Li 9.6 P3S 12 、Li7P3S 11 、Li9P3S9O3、Li 10.35 Si 1.35 P 1.65 S 12 、Li 9.81 Sn 0.81 P 2.19 S 12 、Li 10 (Si 0.5 Ge 0.5 )P2S 12 、Li(Ge 0.5 Sn 0.5 )P2S12 , Li(Si 0.5 Sn 0.5 )PsS 12 , Li 10 GeP2S 12 (LGPS), Li6PS5X (where X is Cl, Br, or I), Li7P2S8I, Li 10.35 Ge 1.35 P 1.65 S 12 , Li 3.25 Ge 0.25 P 0.75 S4, Li 10 SnP2S 12 , Li 10 SiP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 C l0.3 , (1-x) P2S 5-x Li2S (where 0.5 ≤ x ≤ 0.7) and combinations thereof. In one variant, one or more sulfide-based materials may have an ionic conductivity greater than or equal to about 10 -7 S / cm to less than or equal to about 1 S / cm.

[0053] In various aspects, the halide-based particles may include one or more halide-based materials selected from the group consisting of: Li2CdC l4 , Li2MgC l4 , Li2Cd I4 , Li2ZnI4, Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1) and combinations thereof. In one variant, one or more halide-based materials may have an ionic conductivity greater than or equal to about 10 -8 S / cm to less than or equal to about 10 -1 S / cm.

[0054] In various aspects, the borate-based particles may include one or more borate-based materials selected from the group consisting of: Li2B4O7, Li2O-(B2O3)-(P2O5), and combinations thereof. In one variant, one or more borate-based materials may have an ionic conductivity greater than or equal to about 10 -7 S / cm to less than or equal to about 10 -2 S / cm.

[0055] In various aspects, the nitride-based particles may include one or more nitride-based materials selected from the group consisting of Li3N, Li7PN4, LiSi2N3, LiPON, and combinations thereof. In one variation, the one or more nitride-based materials may have a carbon content greater than or equal to about 10 -9 S / cm to an ionic conductivity of less than or equal to about 1 S / cm.

[0056] In various aspects, the hydride-based particles may include one or more hydride-based materials selected from the group consisting of Li3AlH6, LiBH4, LiBH4-LiX (wherein X is one of Cl, Br and I), LiNH2, Li2NH, LiBH4-LiNH2, and combinations thereof. In one variation, the one or more hydride-based materials may have a carbon content greater than or equal to about 10 -7 S / cm to less than or equal to about 10 -2 S / cm ionic conductivity.

[0057] In yet another variation, the solid electrolyte particles may be a quasi-solid electrolyte comprising a mixture of a non-aqueous electrolyte solution and a solid electrolyte system; the present application has no particular requirements for the non-aqueous electrolyte solution, which may include a solvent and a lithium salt. The present application has no particular requirements for the non-aqueous electrolyte solution system, and the lithium salt may be selected from the same lithium salt in the polymer solid electrolyte system. The organic solvent includes but is not limited to various alkyl carbonates, such as cyclic carbonates (e.g., ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (F In some embodiments, the non-aqueous electrolyte solution may include a concentration of greater than or equal to 1 M to less than or equal to about 2 M of the one or more lithium salts. In some embodiments, the non-aqueous electrolyte solution may include a concentration of greater than or equal to 1 M to less than or equal to about 2 M of the one or more lithium salts. In some embodiments, the non-aqueous electrolyte solution may include a concentration of greater than or equal to 1 M to less than or equal to about 2 M of the one or more lithium salts. In some embodiments, the electrolyte may include one or more diluents, such as fluoroethylene carbonate (FEC) and / or hydrofluoroether (HFE), for example, when the non-aqueous electrolyte solution has a lithium concentration greater than about 2 M or has an ionic liquid.

[0058] Hereinafter, this application further illustrates the present invention only through specific implementation modes.

[0059] Embodiment 1:

[0060] Preparation of positive electrode:

[0061] The positive electrode active material LiMn2O4, the binder PVDF, the conductive agent super-P, the first lithium supplement Li5FeO4, and the second lithium supplement Li2NiO2 are mixed in a ratio of 90:2:2:1.6:0.4, dissolved in a solvent N,N-dimethylpyrrolidone, and stirred evenly to obtain a positive electrode slurry;

[0062] The positive electrode slurry is coated on the current collector, and after drying, the positive electrode sheet is obtained by rolling.

[0063] Preparation of negative electrode:

[0064] The negative electrode active material graphite, the binder SBR+CMC, and the conductive agent super-P were mixed in a ratio of 95:2:3, dissolved in a solvent N,N-dimethylpyrrolidone, and stirred evenly to obtain a negative electrode slurry;

[0065] The negative electrode slurry is coated on the negative electrode current collector, and after drying, the negative electrode is rolled to obtain a negative electrode sheet. Preparation of the battery: The positive electrode, the negative electrode, and the LLZO solid electrolyte membrane are stacked to obtain a solid-state battery.

[0066] Formation process: Perform the formation process at room temperature according to the following steps: ① Charge to 3V at 0.05C; ② Charge to 3.9V at 0.025C; ③ Charge to 4.2V at 0.05C;

[0067] Examples 1-5

[0068]

[0069] Test method:

[0070] 1. Cycle performance:

[0071] Test temperature: 25℃±2℃

[0072] ① Charge at 1C or specified current to the end voltage, cut-off current 0.05C, and let stand for 30 minutes;

[0073] ②Discharge at 1C to the final discharge voltage, record the discharge capacity, and let stand for 30 minutes;

[0074] Cycle ①~②

[0075] 500th cycle capacity retention rate = (500th cycle discharge capacity / initial discharge capacity) × 100%

[0076] 2. Gas production: measured by drainage method

[0077] ① Fill a container that can hold a soft-pack battery completely with water, put the unactivated battery into the container, and the battery is completely submerged in water. The volume of the overflowed water is recorded as V0;

[0078] ② Fill the container with water again, put the unvented battery back into the container, and immerse it completely in water. The volume of overflowed water is recorded as V1;

[0079] ③Gas production = V1-V0

[0080] 3. Initial efficiency ε=C1 / C0*100%

[0081] The specific process is

[0082] ①0.05C charge to 3V;

[0083] ②0.025C charge to 3.9V;

[0084] ③0.05C charge to 4.2V;

[0085] ④Let stand for 15 minutes;

[0086] ⑤0.1C discharge to 3.0V.

[0087] The total charge capacity of ①②③ is C0, and the discharge capacity of ④ is C 1。

[0088] It can be seen from the examples that the lithium-replenishing composite of the present application can effectively reduce the gas production of the battery and effectively improve the cycle performance and initial efficiency of the battery, indicating that the lithium-replenishing composite of the present application has achieved unexpected technical effects.

Claims

1. A lithium supplementation complex, characterized in that: The lithium supplementation complex comprises a mixture of a first lithium supplementation agent and a second lithium supplementation agent, wherein the molecular formula of the first lithium supplementation agent is as follows: Li5FeO4; The molecular formula of the second lithium supplement is as follows: Li2NiO2; The mass ratio of the first lithium supplement agent to the second lithium supplement agent is (1-4):

1.

2. The lithium supplementation complex according to claim 1, characterized in that The mass ratio of the first lithium supplement agent to the second lithium supplement agent is (1.3-2.5):

1.

3. A lithium ion battery positive electrode, characterized in that: The invention comprises a positive electrode active material and a lithium supplementing composite according to any one of claims 1 to 2; the positive electrode active material comprises spinel lithium manganese oxide, and the molecular structure of the spinel lithium manganese oxide is as follows: Li (1+b) Mn 2-b-c MO 4-a Q a , Wherein, 0≤a≤1, 0≤b≤0.3; and 0≤c≤1, M is one or more elements selected from Mg, Al, Ni, Co, Fe, Cr, Cu, B, Ca, Nb, Mo, Sr, Sb, W, B, Ti, V, Zr and Zn, and Q is one or more elements selected from N, F, S, and Cl.

4. The lithium ion battery positive electrode according to claim 3, characterized in that The lithium supplementing compound is added in an amount of 1-2 wt % in the positive electrode.

5. The lithium ion battery positive electrode according to claim 4, characterized in that The lithium supplementing compound is added in an amount of 1.5-2.5 wt % in the positive electrode.

6. The lithium ion battery positive electrode according to claim 5, characterized in that The positive electrode further includes a third lithium replenisher, and the third lithium replenisher is not completely consumed in the first three cycles.

7. A solid-state lithium-ion battery, characterized in that: The invention comprises the positive electrode, the negative electrode and the solid electrolyte layer according to any one of claims 3 to 6, wherein the solid electrolyte layer is located between the positive electrode and the negative electrode.

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