Lithium ion battery non-aqueous electrolyte and application thereof

Abstract

The invention relates to a lithium ion battery non-aqueous electrolyte and application thereof. The lithium ion battery non-aqueous electrolyte comprises the following components: a lithium salt, an organic solvent, a boron-containing additive and a compound A, the compound A comprises a compound as shown in a formula I; wherein R1, R2, R3 and R4 are respectively and independently selected from any one of hydrogen, halogen and substituted or unsubstituted C1-C4 alkyl; the substituted C1-C4 alkyl group comprises any one of C1-C4 alkyl groups substituted by halogen atoms, C1-C4 alkyl groups substituted by oxygen atoms, C1-C4 alkyl groups substituted by silicon atoms or C1-C4 alkyl groups substituted by cyano groups. The electrolyte of the lithium ion battery is designed, so that the high-temperature cycle performance of the battery is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a non-aqueous electrolyte for lithium-ion batteries and its application. Background Technology

[0002] Lithium manganese iron phosphate (LMFP) is an upgraded material of lithium iron phosphate (LFP) by introducing manganese (Mn) to improve the voltage platform (~4.1 V vs. Li). + / Li, LFP is 3.4 V), thus increasing the energy density (~20%). LMFP performs excellently in room temperature cycling (cycle lifetime >3000 cycles).

[0003] For example, CN116914087A discloses a lithium manganese iron phosphate battery, including a positive electrode, a negative electrode, and a separator. The positive electrode includes a positive electrode active material, which in turn includes a lithium manganese iron phosphate active material. The particle size D50 of the positive electrode active material is 1.6-5 μm. This lithium manganese iron phosphate battery exhibits good structural stability and lithium-ion kinetic transport characteristics during charge and discharge. CN120237208A discloses a hybrid lithium iron phosphate and lithium manganese iron phosphate positive electrode material, achieving good cycle stability, safety, and processing performance, and improving the battery's energy density. CN120165016A discloses a lithium manganese iron phosphate battery, which, through composition optimization of the lithium-ion battery, improves the battery's low-temperature discharge performance while maintaining high-temperature cycle performance.

[0004] However, existing lithium iron phosphate (LFP) lithium-ion batteries still suffer from a significant deterioration in high-temperature cycle performance. This is mainly due to the fact that Mn2+ phosphate degrades significantly at high temperatures. 2+ It is easy to dissolve from the crystal lattice, migrate to the negative electrode to destroy the SEI film, and catalyze the decomposition of the electrolyte, thus accelerating capacity decay.

[0005] Therefore, how to further improve the high-temperature cycle performance of lithium-ion batteries has become an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a non-aqueous electrolyte for lithium-ion batteries and its applications. By designing the electrolyte for lithium-ion batteries, the high-temperature cycle performance of the batteries is effectively improved.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a non-aqueous electrolyte for lithium-ion batteries, wherein the components of the non-aqueous electrolyte include lithium salt, organic solvent, boron-containing additive, and compound A; wherein compound A includes compounds as shown in Formula I:

[0009]

[0010] Formula I;

[0011] R1, R2, R3, and R4 are each independently selected from any one of hydrogen, halogen, and substituted or unsubstituted C1-C4 alkyl groups; the substituted C1-C4 alkyl groups include any one of halogen-substituted C1-C4 alkyl groups, oxygen-substituted C1-C4 alkyl groups, silicon-substituted C1-C4 alkyl groups, or cyano-substituted C1-C4 alkyl groups.

[0012] The C1-C4 alkyl group can be, for example, methyl, ethyl, propyl or butyl.

[0013] In this invention, by using boron-containing additives and compound A, the high-temperature cycle performance and rate performance of lithium manganese iron phosphate battery systems can be effectively improved, achieving the goal of long-term high-temperature cycling. The principle is that the boron-containing additives are preferentially oxidized compared to the organic solvents in the electrolyte during cycling, forming a protective film that covers the positive electrode surface. This film has good ionic conductivity, inhibiting the oxidative decomposition of the electrolyte in subsequent cycles and the complexation of transition metal ions in the positive electrode material, thus suppressing the destruction of the positive electrode material structure and stabilizing the electrode / electrolyte interface. Compound A, lacking α-H, has a high boiling point and low reactivity, inhibiting the continuous decomposition of the electrolyte and the growth of lithium dendrites, suppressing gas production, and reducing impedance. Furthermore, compound A can reduce the coordination capacity of the organic solvents in the electrolyte, promoting lithium ion desolvation and improving ion migration efficiency, thereby improving low-temperature rate performance and high-temperature cycle performance. In other words, the electrolyte provided by this invention simultaneously contains boron-containing additives and compound A. These two substances work synergistically to inhibit the dissolution of transition metal ions from the positive electrode material, improving its high-temperature cycle performance and meeting the application requirements of high-temperature, long-life lithium manganese iron phosphate batteries.

[0014] Preferably, the boron-containing additives include any one or a combination of at least two of the following: lithium bis(oxalato)borate, lithium difluorooxalato)borate, lithium tetrafluoroborate, tris(trimethylsilane)borate, spirocyclic quaternary ammonium tetrafluoroborate, tris(2,2,2-trifluoroethyl) borate, tris(hexafluoroisopropyl) borate, trimethyl borate, tris(trimethylsilane)borate, tetramethylborate, or 1,3-propanediol pyridine-3-boron.

[0015] Preferably, R4 is selected from C1-C4 alkyl groups, and more preferably methyl groups.

[0016] Preferably, R1 is selected from fluorine or methyl.

[0017] Preferably, compound A comprises any one or a combination of at least two of the following compounds:

[0018] ;

[0019] Further preferred options are: .

[0020] In this invention, when R4 is a C1-C4 alkyl group, the degree of dissociation of compound A for lithium salt can be increased, thereby improving the performance of the lithium-ion battery. Further limiting compound A to the structures shown in A-1 to A-4 further reduces the viscosity of the electrolyte and improves the performance of the lithium-ion battery.

[0021] Preferably, based on the mass percentage of the non-aqueous electrolyte of the lithium-ion battery being 100%, the mass percentage of boron-containing additives is 0.1%-10%, for example, it can be 1%, 1.5%, 2%, 3%, 5%, or 9%, etc.

[0022] Preferably, based on the mass percentage of the non-aqueous electrolyte of the lithium-ion battery being 100%, the mass percentage of compound A is 1%-90%, for example, it can be 5%, 10%, 30%, 50%, 60% or 70%, more preferably 30%-90%, and even more preferably 50%-70%.

[0023] In this invention, compound A has poor dissociation ability for lithium salt due to the lack of α-H. Too much compound A will result in poor electrolyte conductivity and affect battery performance; too little compound A cannot prevent solvent decomposition during cycling.

[0024] Preferably, the components of the non-aqueous electrolyte of the lithium-ion battery further include lithium salt additives.

[0025] Preferably, the lithium salt additive includes any one or a combination of at least two of lithium difluorophosphate, lithium tetrafluorooxalate phosphate, or lithium difluorobis(oxalate) phosphate.

[0026] Preferably, based on the mass percentage of the non-aqueous electrolyte of the lithium-ion battery being 100%, the mass percentage of the lithium salt additive is 0.1%-5%, for example, it can be 0.5%, 1%, 2%, 3% or 4%, etc.

[0027] Preferably, the components of the non-aqueous electrolyte for the lithium-ion battery further include film-forming additives.

[0028] Preferably, the film-forming additive comprises any one or a combination of at least two of the following: vinylene carbonate, 1,3-propanesulfonate lactone, fluoroethylene carbonate, ethylene ethylene sulfate, ethylene sulfate, methane disulfonate, ethylene ethylene carbonate, or tris(trimethylsilane) phosphate.

[0029] Preferably, based on the mass percentage of the non-aqueous electrolyte of the lithium-ion battery being 100%, the mass percentage of the film-forming additive is 0.5%-11%, for example, it can be 1%, 2%, 4%, 6%, 8% or 10%, etc.

[0030] Preferably, the lithium salt comprises any one or a combination of at least two of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, or lithium difluorosulfonateimide.

[0031] Preferably, based on the mass of the non-aqueous electrolyte as 100%, the mass percentage of the lithium salt is 0.5%-22%, for example, it can be 1%, 5%, 10%, 15% or 20%, etc.

[0032] Preferably, the organic solvent includes carbonate organic solvents and / or carboxylic acid ester organic solvents.

[0033] Preferably, the carbonate organic solvent includes cyclic carbonates and / or chain carbonates.

[0034] Preferably, the cyclic carbonate includes any one or a combination of at least two of ethylene carbonate (EC), propylene carbonate, or butene carbonate.

[0035] Preferably, the chain carbonate includes any one or a combination of at least two of diethyl carbonate, ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), or methyl propyl carbonate.

[0036] Preferably, the carboxylic acid ester organic solvent includes any one or a combination of at least two of ethyl propionate, propyl propionate, ethyl acetate, ethyl butyrate, methyl acetate, propyl acetate, methyl propionate, or γ-butyrolactone.

[0037] Preferably, with the non-aqueous electrolyte of the lithium-ion battery comprising 100% by mass, the organic solvent comprises 10%-80% by mass, for example, 20%, 40%, 50%, 60% or 70%, etc.

[0038] In a second aspect, the present invention provides a lithium-ion battery, the lithium-ion battery comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte for lithium-ion batteries as described in the first aspect.

[0039] Preferably, the positive electrode comprises a positive electrode active material, a conductive agent, and a binder.

[0040] Preferably, the positive electrode active material includes LiNi. x Co y Mn z L (1-x-y-z) O2, LiNix' L' y' Mn (2-x'-y') O4 or LiMn 1-x” Fe x” Any one or at least two of PO4, more preferably LiMn 1-x” Fe x” PO4;

[0041] Wherein, L is any one or at least two combinations of Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe, 0.05≤x≤1 (e.g., it can be 0.2, 0.4, 0.5, 0.6 or 0.8, etc.), 0≤y<1 (e.g., it can be 0.2, 0.4, 0.5, 0.6 or 0.8, etc.), 0≤z≤1 (e.g., it can be 0.2, 0.4, 0.5, 0.6 or 0.8, etc.), and 0<x+y+z≤1 (e.g., it can be 0.2, 0.4, 0.5, 0.6 or 0.8, etc.).

[0042] 0 < x' ≤ 1 (e.g., it can be 0.2, 0.4, 0.5, 0.6 or 0.8, etc.), 0.01 ≤ y' ≤ 0.2 (e.g., it can be 0.05, 0.08, 0.1, 0.15 or 0.18, etc.), and L' is any one or a combination of at least two of Co, Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe.

[0043] 0.05≤x”≤1 (for example, it can be 0.2, 0.4, 0.5, 0.6 or 0.8, etc.).

[0044] Preferably, the negative electrode comprises a negative electrode active material.

[0045] Preferably, the negative electrode active material includes any one or a combination of at least two of the following: natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microspheres, graphene, graphynylene, lithium metal, nano-carbon, carbon nanotubes, elemental silicon, silicon oxide, silicon / copper oxide composite, AG composite, silicon alloy, elemental tin, tin oxide, tin-carbon composite, tin alloy, or lithium titanate.

[0046] Preferably, the negative electrode active material includes graphite and silicon-based materials, wherein the silicon-based material includes any one or a combination of at least two of elemental silicon, silicon oxide compounds, silicon / copper oxide composites, or silicon alloys; and the graphite includes natural graphite and / or artificial graphite.

[0047] Preferably, with the negative electrode active material having a mass percentage of 100%, the silicon-based material has a mass percentage of 10%-20%, for example, it can be 12%, 14%, 15%, 16% or 18%, etc.

[0048] Preferably, the membrane material includes any one or a combination of at least two of polyethylene, polypropylene, or composite ceramic membrane.

[0049] Compared with the prior art, the present invention has at least the following beneficial effects:

[0050] The electrolyte provided by this invention improves the high-temperature cycle performance of the battery by using a combination of boron-containing additives and compound A. Detailed Implementation

[0051] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0052] Some of the raw materials used in the following examples.

[0053] Compound A-1 was purchased from Aladdin, CAS number 598-98-1;

[0054] Compound A-2 was purchased from Aladdin, CAS number 431-47-0;

[0055] Compound A-3 was purchased from Aladdin, CAS number 38650-84-9;

[0056] Compound A-4 was purchased from Aladdin, CAS number 338-76-1;

[0057] Compound A-5 was purchased from Aladdin, CAS number 57392-43-5, and its structure is as follows: .

[0058] Examples 1-11, Comparative Examples 1-4

[0059] Examples 1-11 and Comparative Examples 1-4 each provide a non-aqueous electrolyte for lithium-ion batteries. The components of the non-aqueous electrolyte are shown in Table 1. The percentages in Table 1 are the mass percentages of each component in the non-aqueous electrolyte for lithium-ion batteries. The sum of the mass percentages of all components in Table 1 is 1.

[0060] The preparation method of the non-aqueous electrolyte includes the following steps:

[0061] The electrolyte was prepared in a Mikelona glove box (filled with argon gas, with less than 10 ppm of gaseous water). First, the organic solvent and compound A were mixed evenly in proportion. Then, boron-containing additives and film-forming additives were added to the evenly mixed solvent package in sequence, and finally lithium salt was added. The mixture was stirred until there was no lithium salt residue at the bottom and the electrolyte was clear and free of turbidity, thus obtaining the non-aqueous electrolyte, which was stored in a -10°C refrigerator.

[0062] Table 1

[0063]

[0064] Application Example 1-11, Comparative Application Example 1-4

[0065] Examples 1-11 and Comparative Examples 1-4 each provide a lithium-ion battery, the lithium-ion battery comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte for lithium-ion batteries as described in Examples 1-11 and Comparative Examples 1-4, respectively.

[0066] The method for preparing the lithium-ion battery includes the following steps:

[0067] (1) Preparation of positive electrode: Polyvinylidene fluoride (PVDF) is uniformly dissolved in N-methylpyrrolidone (NMP), then the conductive agent Super P is added and mixed thoroughly. Then the positive electrode active material lithium iron phosphate powder is gradually added (the mass ratio of lithium iron phosphate powder, PVDF and conductive agent Super P is 97.4:1.3:1.3) to obtain positive electrode slurry (the solid content of the positive electrode slurry is 63.1%). The positive electrode slurry is coated on the current collector and then dried, rolled and slit to obtain a positive electrode that can be directly stacked.

[0068] (2) Preparation of negative electrode: Artificial graphite, conductive carbon, silicon oxide powder and sodium carboxymethyl cellulose in a mass ratio of 80.9:2.9:15:1.2 are fed and premixed. The mixture is stirred at 250 rpm for 140 min to obtain negative electrode slurry. The negative electrode slurry is then transferred to deionized water for dispersion. After being mixed evenly, the negative electrode slurry is sieved (180 mesh). Finally, the sieved negative electrode slurry is coated onto the negative electrode current collector. After drying, rolling and slitting, a negative electrode that can be directly stacked is obtained.

[0069] (3) Cell manufacturing: The slit positive and negative electrodes are stacked on a stacking machine, and the separator is made of PP / PE / PP three-layer material to obtain a soft-pack cell;

[0070] (4) Electrolyte injection, formation and aging: After the cell is dried at high temperature, the non-aqueous electrolyte of Examples 1-11 and Comparative Examples 1-4 is injected into the soft-pack cell. After injection, the lithium-ion battery undergoes initial packaging, surface cleaning and other processes to complete the preliminary work, and is placed at room temperature for one day. Formation is carried out by step formation method. The first step formation current is 0.05 C, and constant current is charged for 2 hours. The second step formation current is 0.1 C, and constant current is charged until the voltage reaches 3.85 V. After formation, it is aged at 45°C for one day, cooled to room temperature and finally sealed to obtain the lithium-ion battery.

[0071] Test methods

[0072] After the battery is assembled, it is left at room temperature for 10 hours to allow the electrolyte to fully wet the battery electrodes before being tested as follows.

[0073] (1) 45℃ high temperature cycle test: constant current charge and discharge is performed in a high temperature oven at a constant temperature of 45℃ with a current density of 1 C at the rated capacity. The cycle number is 1000 cycles, the test voltage range is 3 V-4.2 V, the charging cut-off current is 0.05 C, and after the test, the capacity retention rate of the 1000th cycle is calculated based on the discharge capacity of the first cycle.

[0074] The formula for calculating the capacity retention rate after 1000 cycles of cryogenic cycling is as follows:

[0075] Capacity retention rate after 1000 cycles (%) = (Discharge capacity after 1000 cryogenic cycles / Initial discharge capacity) × 100%.

[0076] After cycling to 1000 cycles, charge to 50% SOC, let stand for 1 hour, and then perform a short-term high-rate discharge of 3C and 10S to obtain DCIR.

[0077] (2) Low-temperature rate performance test of lithium-ion battery: constant current charging was performed in a high-low temperature oven at -10℃ with current densities of 2C, 3C, 4C and 5C at the rated capacity of 1C, and then constant voltage charging was performed at 4.2V until the current was 0.05C. The constant current ratio was recorded and the charge retention rate was calculated. Constant current discharge was performed with current densities of 2C, 3C, 4C and 5C at the rated capacity of 1C, and the discharge retention rate was calculated.

[0078] Constant current ratio = constant current charging capacity / total constant current and constant voltage charging capacity × 100%;

[0079] Charge retention rate = (2, 3, 4, or 5)C constant current charging capacity / 1C constant current charging capacity × 100%;

[0080] Discharge retention rate = (2 or 3 or 4 or 5)C discharge capacity / 1C discharge capacity × 100%.

[0081] The test results are shown in Table 2.

[0082] Table 2

[0083]

[0084] The test results show that:

[0085] (1) As can be seen from Examples 1-11, by adding boron-containing additives and compound A to the electrolyte, the present invention enables the lithium-ion battery to have good high-temperature cycling performance and low-temperature high-rate capacity retention, and can greatly suppress the DCIR growth of the battery during high-temperature cycling. This is because the addition of inert compound A reduces solvent side reactions, and compound A accelerates the desolventization of Li ions at low temperatures.

[0086] (2) By comparing Examples 3, 7, 9, 10 and 11, it can be seen that the present invention improves the performance of lithium-ion batteries by further defining the structure of compound A.

[0087] (3) As can be seen from the comparison of Examples 2-4, the present invention improves the high-temperature cycle performance and low-temperature rate performance of lithium-ion batteries by further limiting the amount of compound A.

[0088] (4) As can be seen from the comparison between Example 3 and Comparative Examples 3-4, the present invention achieves a synergistic effect by using boron-containing additives and compound A in combination, so that the lithium-ion battery has both good high-temperature cycle performance and low-temperature rate performance. Without either one, the technical effect of this application cannot be obtained.

[0089] In summary, this invention improves the high-temperature cycle performance of batteries by using a combination of boron-containing additives and compound A.

[0090] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A non-aqueous electrolyte for lithium-ion batteries, characterized in that, The components of the non-aqueous electrolyte for the lithium-ion battery include lithium salt, organic solvent, boron-containing additives, and compound A; compound A includes compounds as shown in Formula I: Formula I; R1, R2, R3, and R4 are each independently selected from any one of hydrogen, halogen, and substituted or unsubstituted C1-C4 alkyl groups; the substituted C1-C4 alkyl groups include any one of halogen-substituted C1-C4 alkyl groups, oxygen-substituted C1-C4 alkyl groups, silicon-substituted C1-C4 alkyl groups, or cyano-substituted C1-C4 alkyl groups.

2. The non-aqueous electrolyte for lithium-ion batteries according to claim 1, characterized in that, The boron-containing additives include any one or a combination of at least two of the following: lithium bis(oxalato)borate, lithium difluorooxalato)borate, lithium tetrafluoroborate, tris(trimethylsilane)borate, spirocyclic quaternary ammonium tetrafluoroborate, tris(2,2,2-trifluoroethyl) borate, tris(hexafluoroisopropyl) borate, trimethyl borate, tris(trimethylsilane)borate, tetramethylborate, or 1,3-propanediol pyridine-3-boron.

3. The non-aqueous electrolyte for lithium-ion batteries according to claim 1 or 2, characterized in that, R4 is selected from C1-C4 alkyl groups, and is more preferably methyl. Preferably, R1 is selected from fluorine or methyl; Preferably, compound A comprises any one or a combination of at least two of the following compounds: ； Further preferred options are: .

4. The non-aqueous electrolyte for lithium-ion batteries according to any one of claims 1-3, characterized in that, Based on the non-aqueous electrolyte of the lithium-ion battery being 100% by mass, the boron-containing additives comprise 0.1%-10% by mass. Preferably, with the non-aqueous electrolyte of the lithium-ion battery having a mass percentage content of 100%, the mass percentage content of compound A is 1%-90%.

5. The non-aqueous electrolyte for lithium-ion batteries according to any one of claims 1-4, characterized in that, The components of the non-aqueous electrolyte for the lithium-ion battery also include lithium salt additives; Preferably, the lithium salt additive includes any one or a combination of at least two of lithium difluorophosphate, lithium tetrafluorooxalate phosphate, or lithium difluorobis(oxalate) phosphate. Preferably, based on the non-aqueous electrolyte of the lithium-ion battery having a mass percentage content of 100%, the lithium salt additive has a mass percentage content of 0.1%-5%. Preferably, the components of the non-aqueous electrolyte for the lithium-ion battery further include film-forming additives; Preferably, the film-forming additive includes any one or a combination of at least two of the following: vinylene carbonate, 1,3-propanesulfonate lactone, fluoroethylene carbonate, ethylene ethylene sulfate, ethylene sulfate, methane disulfonate, ethylene ethylene carbonate, or tris(trimethylsilane) phosphate. Preferably, based on the mass percentage of the non-aqueous electrolyte in the lithium-ion battery being 100%, the mass percentage of the film-forming additive is 0.5%-11%. Preferably, the lithium salt comprises any one or a combination of at least two of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, or lithium difluorosulfonateimide. Preferably, the lithium salt has a mass percentage content of 0.5%-22% based on the mass of the non-aqueous electrolyte (100%).

6. The non-aqueous electrolyte for lithium-ion batteries according to any one of claims 1-5, characterized in that, The organic solvents mentioned include carbonate organic solvents and / or carboxylic acid ester organic solvents; Preferably, the carbonate organic solvent includes cyclic carbonates and / or chain carbonates; Preferably, the cyclic carbonate includes any one or a combination of at least two of ethylene carbonate, propylene carbonate, or butene carbonate; Preferably, the chain carbonate includes any one or a combination of at least two of diethyl carbonate, methyl ethyl carbonate, dimethyl carbonate, or methyl propyl carbonate. Preferably, the carboxylic acid ester organic solvent includes any one or a combination of at least two of ethyl propionate, propyl propionate, ethyl acetate, ethyl butyrate, methyl acetate, propyl acetate, methyl propionate, or γ-butyrolactone. Preferably, the organic solvent has a mass percentage content of 10%-80%, based on the mass percentage content of the non-aqueous electrolyte of the lithium-ion battery being 100%.

7. A lithium-ion battery, characterized in that, The lithium-ion battery includes a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte for lithium-ion batteries as described in any one of claims 1-6.

8. The lithium-ion battery according to claim 7, characterized in that, The positive electrode includes a positive electrode active material, a conductive agent, and a binder; Preferably, the positive electrode active material includes LiNi. x Co y Mn z L (1-x-y-z) O2, LiNi x' L' y' Mn (2-x'-y') O4 or LiMn 1-x” Fe x” Any one or at least two of PO4, more preferably LiMn 1-x” Fe x” PO4; Where L is any one or at least two of Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe, and 0.05≤x≤1, 0≤y<1, 0≤z≤1, 0<x+y+z≤1; 0 < x' ≤ 1, 0.01 ≤ y' ≤ 0.2, and L' is any one or at least two of Co, Al, Sr, Mg, Ti, Ca, Zr, Zn, Si, or Fe; 0.05≤x”≤1。 9. The lithium-ion battery according to claim 7 or 8, characterized in that, The negative electrode includes a negative electrode active material; Preferably, the negative electrode active material includes any one or a combination of at least two of the following: natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microspheres, graphene, graphynylene, lithium metal, nano-carbon, carbon nanotubes, elemental silicon, silicon oxide, silicon / copper oxide composite, AG composite, silicon alloy, elemental tin, tin oxide, tin-carbon composite, tin alloy, or lithium titanate. Preferably, the negative electrode active material comprises graphite and silicon-based materials, wherein the silicon-based material comprises any one or a combination of at least two of elemental silicon, silicon oxide compounds, silicon / copper oxide composites, or silicon alloys; and the graphite comprises natural graphite and / or artificial graphite. Preferably, with the negative electrode active material having a mass percentage content of 100%, the silicon-based material has a mass percentage content of 10%-20%.

10. The lithium-ion battery according to any one of claims 7-9, characterized in that, The membrane material includes any one or a combination of at least two of polyethylene, polypropylene, or composite ceramic membranes.

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