Multifunctional lithium battery additive containing fluorine and boron element and application thereof

Abstract

The present application relates to a kind of multifunctional lithium battery additives containing fluorine and boron element substance and its application, the multifunctional lithium battery additives include: fluoroborate B a F b Or BF c X d , the complex of the fluoroborate, fluoroboric acid HBF4, inorganic fluoroborate M n (BF4) m , organic fluoroborate R-BF3M, polyfluoroaromatic boride F-R-BH y , fluorinated organoborane R-BF3, fluoroboric acid nitro BF4NO or BF4NO2 One or several kinds;Wherein, X includes one or several elements of Cl, Br, I;M includes one or several elements of aluminum, copper, lead, tin, nickel, zinc, cadmium, beryllium, magnesium, calcium, strontium, barium, cesium, rubidium, manganese, iron, cobalt, silver, indium, thallium;R includes one or several organic groups of hydrocarbon, alcohol, ether, ester, ketone, carboxylic acid, phenol;0.5≤a≤2, 1.5≤b≤3;0.5≤c≤3, 0.5≤d≤3;0.2≤n≤5, 0.2≤m≤8;0.5≤y≤3.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials, in particular to a multifunctional lithium battery additive containing fluorine and boron elements and application thereof. BACKGROUND

[0002] Lithium batteries have the highest energy density among all commercial batteries at present, and are widely used in consumer electronics, electric vehicles, large-scale energy storage, medical electronics, unmanned aerial vehicles and other fields. In recent years, the development of various industries has put forward higher requirements for the battery life, energy density, rate performance and safety.

[0003] The electrolyte in lithium batteries plays a crucial role and is the carrier of ion transmission in the battery, which guarantees the advantages of high safety, high voltage, high rate, high specific energy, low cost and the like of lithium ion batteries. However, it is difficult for traditional non-aqueous liquid electrolytes and solid-state electrolytes to simultaneously achieve the construction of a good solid-state electrolyte interface (SEI), high stability, high ionic conductivity and good wettability, and therefore the use of electrolyte additives is considered to be the most feasible, economical and effective method to assist in improving the comprehensive performance of the electrolyte.

[0004] In order to improve the cycle life of the battery, Huang Ling et al. developed a kind of polymer as an electrolyte additive added to the ester electrolyte to avoid the occurrence of continuous side reactions, make the lithium deposition more uniform, slow down the generation of lithium dendrites, and realize the long-term stable cycle of the battery with lithium metal as the negative electrode. Lai Dingkun et al. developed a kind of bispyridine sulfonate as an electrolyte additive for non-aqueous lithium ion batteries. This additive acts on the negative electrode to form a SEI film with better performance, and at the same time inhibits the decomposition of the organic solvent of the electrolyte on the electrode, effectively protecting the electrode material, thus improving the cycle performance and high-temperature performance of the battery. In order to improve the rate performance and power density of the battery, Wan Guangcong et al. developed a kind of ethylene sulfate cyclic carbonate as an electrolyte additive. This additive has a multi-carbonate structure, so the SEI structure formed is more uniform and has smaller impedance than that of vinyl carbonate (VC), which can effectively reduce the direct current resistance of the battery and improve the working performance of the battery under large current conditions.

[0005] Although the above research ideas can improve some performance of lithium batteries under certain specific conditions, they cannot comprehensively improve the energy efficiency, cycle life and rate performance of the battery, and some additives are expensive. Therefore, it is necessary to continuously explore and research, and develop electrolyte additives that can comprehensively improve the performance of the battery, are inexpensive and can be applied to large-scale production. SUMMARY

[0006] The embodiment of the present application provides a multifunctional lithium battery additive containing fluorine and boron elements and application thereof, and the multifunctional lithium battery additive can effectively improve the cycle life, power density, rate performance and energy efficiency of the lithium battery.

[0007] In the first aspect, the embodiment of the present application provides a multifunctional lithium battery additive containing fluorine and boron elements, which comprises: fluoroborate B a F b Or BF c X d , a complex of the fluoroborate, fluoroboric acid HBF4, inorganic fluoroborate M n (BF4) m , organic fluoroborate R-BF3M, polyfluoroarene borate F-R-BH y , fluorinated organoborane R-BF3, fluoroboric acid nitrate BF4NO or BF4NO2.

[0008] Wherein, X comprises one or more elements of Cl, Br and I; M comprises one or more elements of aluminum, copper, lead, tin, nickel, zinc, cadmium, beryllium, magnesium, calcium, strontium, barium, cesium, rubidium, manganese, iron, cobalt, silver, indium and thallium; R comprises one or more organic groups of hydrocarbon, alcohol, ether, ester, ketone, carboxylic acid and phenol; 0.5≤a≤2, 1.5≤b≤3; 0.5≤c≤3, 0.5≤d≤3; 0.2≤n≤5, 0.2≤m≤8; 0.5≤y≤3.

[0009] Preferably, the complex of the fluoroborate is specifically a complex of the fluoroborate with any one of water, ammonia, argon, alcohol, carboxylic acid, amine, nitrile, ester, aldehyde, ketone, ether, phenol and sulfone.

[0010] Further preferably, the fluoroborate complex specifically comprises one or more of boron trifluoride dihydrate, boron trifluoride methanol, boron trifluoride ethanol, boron trifluoride acetic acid, boron trifluoride propionic acid, boron trifluoride phosphoric acid, boron trifluoride dimethyl carbonate, boron trifluoride ethyl acetate, boron trifluoride butyl acetate, boron trifluoride ethyl chloroacetate, boron trifluoride acetonitrile, boron trifluoride tetrahydrofuran, boron trifluoride methyl ether, boron trifluoride ethyl ether, boron trifluoride butyl ether, boron trifluoride butyrolactone, boron trifluoride monoethylamine, boron trifluoride ethylamine, boron trifluoride benzylamine, boron trifluoride phenol, phenol formaldehyde resin boron trifluoride phenol and boron trifluoride dimethyl ether.

[0011] Preferably, the inorganic fluoroborate salt comprises one or more of rubidium tetrafluoroborate, cesium tetrafluoroborate, ammonium tetrafluoroborate, copper tetrafluoroborate, tin tetrafluoroborate, zinc tetrafluoroborate, nickel tetrafluoroborate, iron tetrafluoroborate, cobalt tetrafluoroborate, manganese tetrafluoroborate, silver tetrafluoroborate, cadmium tetrafluoroborate, aluminum tetrafluoroborate, magnesium tetrafluoroborate, calcium tetrafluoroborate, strontium tetrafluoroborate, barium tetrafluoroborate;

[0012] The organic fluoroborate salt comprises one or more of organic cesium trifluoroborate, organic rubidium trifluoroborate, organic potassium trifluoroborate, organic sodium trifluoroborate, organic lithium trifluoroborate, organic ammonium trifluoroborate, organic copper trifluoroborate, organic tin trifluoroborate, organic zinc trifluoroborate, organic nickel trifluoroborate, organic iron trifluoroborate, organic cobalt trifluoroborate, organic manganese trifluoroborate, organic silver trifluoroborate, organic cadmium trifluoroborate, organic aluminum trifluoroborate, organic magnesium trifluoroborate, organic calcium trifluoroborate, organic strontium trifluoroborate, organic barium trifluoroborate.

[0013] Preferably, the multifunctional lithium battery additive containing fluorine element and boron element is used in a lithium battery electrolyte, and the total concentration of the multifunctional lithium battery additive in the electrolyte ranges from 0.0001 mol / L to 1 mol / L.

[0014] Preferably, the lithium battery electrolyte further comprises a solvent and a salt.

[0015] one or more of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), ethylene sulfite (ES), dimethyl sulfite (DMS), diethyl sulfite (DES), dibutyl carbonate (DBC), butyl glycol carbonate (GBL), butyl methyl carbonate (BMC), dipropyl carbonate (DPC), methyl acrylate (PA), propylene sulfite (PS), γ-butyrolactone (γ-BL), γ-valerolactone (γ-VL), vinyl ethylene carbonate (VEC), vinyl sulfone (VS), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), fluoroethylene carbonate (FEC), dimethyl pyrocarbonate (DMPC), dioxolane (DOL), ethylene glycol dimethyl ether (DME), dimethoxy methane (DMM), ethylene glycol diethyl ether (DEE), tetraethylene glycol dimethyl ether (TEGDME), 3'-formyl-4',6'-dihydroxy-2'-methoxy-5'-methyl chalcone (FMC), methyl propyl carbonate (MPC), methyl isopropyl carbonate (MiPC), methyl formate (MF), ethyl formate (EF), methyl acetate (MA), ethyl acetate (EA), methyl propionate (MP), ethyl propionate (EP), ethyl butyrate (EB), fluorobenzene (FB), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2Me-THF), tetrahydropyran (THP), diglyme (DG), acetonitrile (AN), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), sulfolane (SL), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), 3,3,3-trifluoropropyl methyl sulfone (FPMS), 1,3 dioxolane (1,3-DL), 4-methyl-1,3-dioxolane (4-Me-1,3-DL), 2-methyl-1,3-dioxolane (2Me-1,3-DL), acetone;

[0016] The salt includes: lithium fluoride (LiF), lithium carbonate (Li2CO3), lithium nitrate (LiNO3), potassium perchlorate (KClO4), sodium perchlorate (NaClO4), lithium sulfide (Li2S), lithium sulfite (Li2SO3), lithium sulfate (Li2SO4), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluorotantalate (LiTaF6), lithium hexafluorotin (LiSnF6), lithium hexafluorogermanate (LiGeF6), lithium sulfate (Li2SO4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium nitrate (LiNO3), lithium tetrahalogen aluminate (LiAlX4, X is halogen), lithium tris (o-phenol) phosphate (LTBP), Li (C2O4) 3P (LiTOP), Li (CO2) 2PF4 (LiTFOP), Li (C3F7) PF3, lithium bis (trimethylsilyl) amide (LiHMDS), lithium bis (trifluoromethyl sulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiFSI), lithium trifluoromethyl sulfonate (LiCF3SO3), lithium tris (trifluoromethyl sulfonyl) methyl (LiC (SO2CF3) 3), lithium bis (perfluoroethyl sulfonyl) imide (LiBETI), (trifluoromethyl sulfonyl) (n- perfluorobutyl sulfonyl) imide lithium (LiTNFSI), (trifluoromethyl sulfonyl) (fluorosulfonyl) imide lithium (LiFTFSI), LiC2F6 (SO2) N (LiFPFSI), (sulfonamide) (n- perfluorobutyl sulfonyl) imide lithium (LiFNFSI), lithium sulfocyanate (LiSCN), LiC8F 18 (SO2) 2N (LiFHFSI), LiBF3 (CF2CF3) 3 (LiFAB), lithium tris (pentafluoroethyl) trifluorophosphate (LiPF3 (CF2CF3) 3, LiFAP), lithium bisoxalate borate (LiBOB), lithium difluoro oxalate borate (LiDFOB), lithium bis (malonate) borate (LiBMB), lithium bis (o-phenol) borate (LBBB), lithium bis (3- fluorophenol) borate (3-FLBBB), lithium bis (2, 3, 4, 5- tetrafluorophenol) borate (TFLBBB), lithium bis (salicylate) borate (LBSB), lithium bis (2, 3-naphthalene diol) borate (LBNB), lithium bis (2, 2'-biphenol) borate (LBBPB), lithium bis (2, 3-pyridine dioxy) borate (LBPB), Li (C6F 12 O2) 2B (LBPFPB).

[0017] In a second aspect, the embodiments of the present application provide a solid-state electrolyte, comprising the multifunctional lithium battery additive containing fluorine and boron elements in the first aspect; wherein the solid-state electrolyte comprises any one of: a polymer solid-state electrolyte, an oxide solid-state electrolyte, and a sulfide solid-state electrolyte.

[0018] In a third aspect, the embodiments of the present application provide a solid-liquid mixed electrolyte, which comprises the multifunctional lithium battery additive containing fluorine and boron elements according to any one of claims 1-4.

[0019] In a fourth aspect, the embodiments of the present application provide a solid-state lithium battery, which comprises the solid-state electrolyte according to the second aspect or the solid-liquid mixed electrolyte according to the third aspect.

[0020] In a fifth aspect, the embodiments of the present application provide a liquid-state lithium battery, which comprises the multifunctional lithium battery additive containing fluorine and boron elements according to any one of the first aspect.

[0021] The multifunctional lithium battery additive containing fluorine and boron elements provided by the embodiments of the present application has the effects of passivating aluminum foil as a current collector and removing trace water, and can also increase electrode wettability, improve lithium salt solubility, and improve electrode kinetics and other excellent comprehensive performances. The multifunctional lithium battery additive containing fluorine and boron elements is applied in liquid electrolyte, solid-liquid mixed electrolyte, or solid-state electrolyte, and can effectively improve the cycle life, power density, rate performance, and energy efficiency of lithium batteries by matching different positive and negative electrode materials. BRIEF DESCRIPTION OF DRAWINGS

[0022] The technical solutions of the embodiments of the present application are described in further detail below with reference to the drawings and examples.

[0023] Figure 1 The comparison of the cycle performance curves of the battery with the multifunctional additive containing fluorine and boron compounds added and the battery without the additive added for the embodiment 1 of the present application;

[0024] Figure 2A The discharge curves of the battery without the additive added for the comparison of the embodiment 2 of the present application at different rates;

[0025] Figure 2B The discharge curves of the battery with the multifunctional additive containing fluorine and boron compounds added for the embodiment 2 of the present application at different rates. DETAILED DESCRIPTION

[0026] The present application is further described below with reference to the drawings and specific examples, but it should be understood that these examples are only used for more detailed description and should not be understood as limiting the present application in any form, i.e., the protection scope of the present application is not intended to be limited.

[0027] The multifunctional lithium battery additive containing fluorine and boron elements of the present application comprises:

[0028] Fluoroborate B a F b or BFc X d , complex of fluoroborate, HBF4, inorganic fluoroborate M n (BF4) m , organic fluoroborate R-BF3M, polyfluoroarene borate F-R-BH y , one or several of fluorinated organoborane R-BF3, nitro BF4NO or BF4NO2;

[0029] Wherein, BF c X d X in the X includes one or several elements of Cl, Br, I; M includes one or several elements of aluminum, copper, lead, tin, nickel, zinc, cadmium, beryllium, magnesium, calcium, strontium, barium, cesium, rubidium, manganese, iron, cobalt, silver, indium, thallium; R includes one or several organic groups of hydrocarbon, alcohol, ether, ester, ketone, carboxylic acid, phenol; 0.5≤a≤2, 1.5≤b≤3; 0.5≤c≤3, 0.5≤d≤3; 0.2≤n≤5, 0.2≤m≤8; 0.5≤y≤3.

[0030] The complex of fluoroborate is specifically the complex of fluoroborate with any one of water, ammonia, argon, alcohol, carboxylic acid, amine, nitrile, ester, aldehyde, ketone, ether, phenol, sulfone, and can specifically include one or several of boron trifluoride dihydrate, boron trifluoride methanol, boron trifluoride ethanol, boron trifluoride acetic acid, boron trifluoride propionic acid, boron trifluoride phosphoric acid, boron trifluoride dimethyl carbonate, boron trifluoride ethyl acetate, boron trifluoride butyl acetate, boron trifluoride ethyl chloroacetate, boron trifluoride acetonitrile, boron trifluoride tetrahydrofuran, boron trifluoride methyl ether, boron trifluoride ethyl ether, boron trifluoride butyl ether, boron trifluoride butyrolactone, boron trifluoride monoethylamine, boron trifluoride ethylamine, boron trifluoride benzylamine, boron trifluoride phenol, phenol formaldehyde resin boron trifluoride phenol, boron trifluoride dimethyl ether.

[0031] The inorganic fluoroborate includes one or several of rubidium tetrafluoroborate, cesium tetrafluoroborate, ammonium tetrafluoroborate, copper tetrafluoroborate, tin tetrafluoroborate, zinc tetrafluoroborate, nickel tetrafluoroborate, iron tetrafluoroborate, cobalt tetrafluoroborate, manganese tetrafluoroborate, silver tetrafluoroborate, cadmium tetrafluoroborate, aluminum tetrafluoroborate, magnesium tetrafluoroborate, calcium tetrafluoroborate, strontium tetrafluoroborate, barium tetrafluoroborate.

[0032] The organic fluoroborate includes one or several of organic cesium trifluoroborate, organic rubidium trifluoroborate, organic potassium trifluoroborate, organic sodium trifluoroborate, organic lithium trifluoroborate, organic ammonium trifluoroborate, organic copper trifluoroborate, organic tin trifluoroborate, organic zinc trifluoroborate, organic nickel trifluoroborate, organic iron trifluoroborate, organic cobalt trifluoroborate, organic manganese trifluoroborate, organic silver trifluoroborate, organic cadmium trifluoroborate, organic aluminum trifluoroborate, organic magnesium trifluoroborate, organic calcium trifluoroborate, organic strontium trifluoroborate, organic barium trifluoroborate.

[0033] The multifunctional lithium battery additive containing fluorine element and boron element described above can be used as an additive in a solid-liquid mixed electrolyte or a solid electrolyte of a solid-state lithium battery.

[0034] The solid electrolyte can specifically include any one of a polymer solid electrolyte, an oxide solid electrolyte, and a sulfide solid electrolyte.

[0035] The polymer solid electrolyte can include, but is not limited to, any one of polyethylene oxide (PEO), polyphenyl ether (PPO), polyacrylonitrile (PAN), polyvinyl chloride (PVC), polystyrene (PS), polyvinyl acetate (PVAC), polymethyl methacrylate (PMMA), polyimide (PI), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylpyrrolidone (PVP), polyvinylsulfonic acid sodium (PVS), and polyethylene glycol (diol) diacrylate (PEGDA); the oxide solid electrolyte / sulfide solid electrolyte can include, but is not limited to, any one of Li5La3Ta2O12, Li5La3Nb2O12, Li7La3Sn2O12, Li10GeP2S12, Li3PO4, LiAlO2, Li4 / 3Ge1-xAlx(PO4)3, Li3La2 / 3TiO3, LiZr2(PO4)3, Li4 / 3Ti5 / 3(PO4)3, Li3Al2(PO4)3, Li3Ge2(PO4)3, Li3P, Li3PS4, LiPON, Li3SiP2O7, Li7La3Zr2O7, Li3La3Zr2O7, Li2O-P2O5, Li2S-P2S5, and Li2S-P2S5-LiI. 12 12 12 1+x x 2-x 3y 2 / 3- y 2-z z 1+m m 2-m 4-n 1-n n 3+p p p 12 7-q 2-q q 12

[0036] ​​​​​​​​​​​​​​​​​​​​​​​​The multifunctional lithium battery additive containing fluorine element and boron element of the present application can also be used in the lithium battery electrolyte of liquid lithium battery, the total concentration of the multifunctional lithium battery additive in the electrolyte ranges from 0.0001 mol / L to 1 mol / L, preferably, the concentration ranges from 0.001 mol / L to 0.1 mol / L; more preferably, the concentration ranges from 0.001 mol / L to 0.05 mol / L.

[0037] The lithium battery electrolyte further comprises a solvent and a salt; wherein the solvent comprises one or more of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), ethylene sulfite (ES), dimethyl sulfite (DMS), diethyl sulfite (DES), dibutyl carbonate (DBC), butyl diglyme (GBL), butyl methyl carbonate (BMC), dipropyl carbonate (DPC), methyl acetate (PA), propylene sulfite (PS), gamma-butyrolactone (gamma-BL), gamma-valerolactone (gamma-VL), vinyl ethylene carbonate (VEC), vinyl sulfone (VS), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), fluoroethylene carbonate (FEC), dimethyl pyruvate (DMPC), dioxolane (DOL), ethylene glycol dimethyl ether (DME), dimethoxy methane (DMM), ethylene glycol diethyl ether (DEE), tetraethylene glycol dimethyl ether (TEGDME), 3'-formyl-4',6'-dihydroxy-2'-methoxy-5'-methyl chalcone (FMC), methyl propyl carbonate (MPC), methyl isopropyl carbonate (MiPC), methyl formate (MF), ethyl formate (EF), methyl acetate (MA), ethyl acetate (EA), methyl propionate (MP), ethyl propionate (EP), ethyl butyrate (EB), fluorobenzene (FB), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2Me-THF), tetrahydropyran (THP), diglyme (DG), acetonitrile (AN), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), sulfolane (SL), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), 3,3,3-trifluoropropyl methyl sulfone (FPMS), 1,3 dioxolane (1,3-DL), 4-methyl-1,3-dioxolane (4-Me-1,3-DL), 2-methyl-1,3-dioxolane (2Me-1,3-DL), and acetone;LiF, Li2CO3, LiNO3, KClO4, NaClO4, Li2S, Li2SO3, Li2SO4, LiPF6, LiBF4, LiTaF6, LiSnF6, LiGeF6, Li2SO4, LiClO4, LiAsF6, LiNO3, LiAlX4 (X is halogen), LiTBP, Li(TOP), Li(TFOP), Li(C3F7)PF3, LiHMDS, LiTFSI, LiFSI, LiCF3SO3, LiC(SO2CF3)3, LiBETI, Li(TNFSI), Li(FTFSI), Li(C2F6(SO2)N) (LiFPFSI), Li(FNFSI), LiSCN, LiC8F; 18 Li(SO2)2N (LiFHFSI), LiBF3(CF2CF3)3 (LiFAB), LiPF3(CF2CF3)3 (LiFAP), LiBOB, LiDFOB, LiBMB, LiBBB, Li(3-FLBBB), Li(TFLBBB), LiBSB, Li(BNB), Li(BPB), Li(BPB), Li(C6F 12 O2)2B (LBPFPB).

[0038] In the above lithium battery, the positive electrode can include, but is not limited to, one of lithium iron phosphate, lithium cobaltate, lithium manganate, lithium nickel cobalt manganate, lithium nickel cobalt aluminum, lithium-rich layered oxide, lithium nickel manganate, lithium titanate, fluorinated graphite, iodine, MnO2, FeS2, FeF3, S, H2O, CO2, O2. The negative electrode can include, but is not limited to, one of high-phase graphite, artificial graphite, natural graphite, graphitized carbon fiber, graphitized mesophase carbon microbeads, hard carbon, soft carbon, carbon nanotubes, graphene and graphene composite negative electrode, silicon negative electrode, silicon monoxide, silicon-carbon composite negative electrode, lithium metal negative electrode, lithium alloy, composite lithium metal negative electrode, tin-based negative electrode, tin oxide negative electrode, and MoS2. The separator can include, but is not limited to, a single-layer polyethylene (PE) separator, a single-layer polypropylene (PP) separator, a polyethylene-polypropylene-polyethylene (PE-PP-PE) three-layer separator, a polyimide (PI) separator, a polyaramid separator, a cellulose separator, and a polyetherimide separator.

[0039] The multifunctional lithium battery additive containing fluorine and boron elements provided by the embodiments of the present application has the effects of passivating the aluminum foil current collector and removing trace water, and can also increase electrode wettability, improve lithium salt solubility, and improve electrode kinetics and other excellent comprehensive performance. The multifunctional lithium battery additive is applied in a liquid electrolyte, a solid-liquid mixed electrolyte, or a solid electrolyte, and can effectively improve the cycle life, power density, rate performance, and energy efficiency of a lithium battery by matching different positive electrode and negative electrode materials.

[0040] In order to better understand the technical solutions provided by the present application, the following specific examples are described.

[0041] Embodiment 1

[0042] In this embodiment, fluoroborate BF3 is used as an ester electrolyte additive to improve battery performance.

[0043] 1. First, configure the electrolyte in an argon-protected glove box: 1M LiPF6 / EC-DMC (the volume ratio of EC and DMC is 1:1). Then, weigh a certain amount of fluoroborate BF3 and add it to the prepared electrolyte to obtain 1M LiPF6 / EC-DMC electrolyte containing 0.005 mol / L fluoroborate additive. At the same time, the same electrolyte without fluoroborate additive is used as a comparative electrolyte.

[0044] 2. The battery is assembled in an argon-protected glove box. The specific battery uses a CR2032 button cell structure, in which lithium sheet is used as the negative electrode, lithium cobaltate is used as the positive electrode, and the electrolyte containing 0.005 mol / L fluoroborate additive and the electrolyte without fluoroborate additive prepared in step 1 are used to complete the assembly of the battery.

[0045] 3. Assembled batteries were tested on the blue electric test system, and the comparison of the cycle coulombic efficiency showed that the battery containing 0.005 mol / L fluoroborate additive had higher coulombic efficiency and longer cycle life, thus it can be seen that the fluoroborate additive increased the stability of the interface layer.

[0046] 4. After the battery was disassembled, the positive and negative electrode surfaces were observed by Hitachi S8600 scanning electron microscope, and it was found that the stability of the electrode active material of the battery containing fluoroborate additive was obviously improved after cycling. The test results are shown in Figure 1 , which shows that the cycle efficiency of the battery containing 0.005 mol / L fluoroborate BF3 is stable at more than 99.5%, and can be cycled for more than 600 times, while the battery without fluoroborate BF3 can only be maintained for 80 times.

[0047] And the positive aluminum current collector in the electrolyte system containing fluoroborate additive was studied by X-ray photoelectron spectroscopy, and it was found that the electrolyte with fluoroborate additive formed a passivation film on the surface of the aluminum foil, which proved that the additive had the effect of passivating the aluminum foil, thereby improving the stability of the current collector during the cycling process, reducing the contact resistance, and thus significantly improving the battery performance.

[0048] Example 2

[0049] In this embodiment, fluoroborate complex is used as an additive for ester electrolyte to improve battery performance.

[0050] 1. First, configure the electrolyte in the argon glove box: 1M LiBF4 / EC-DMC (the volume ratio of EC and DMC is 1:1). Then weigh a certain amount of fluoroborate complex (the complex of BF3 and dimethyl carbonate), and add it to the prepared electrolyte to obtain 1M LiBF4 / EC-DMC electrolyte containing 0.01 mol / L fluoroborate complex. At the same time, the electrolyte without fluoroborate complex is used as a comparative electrolyte.

[0051] 2. The battery was assembled in the argon glove box, and the specific battery used CR2032 button cell structure, in which lithium sheet was used as negative electrode, and fluorinated graphite was used as positive electrode, and the electrolyte containing 0.01 mol / L fluoroborate complex and the electrolyte without fluoroborate complex prepared in step 1 were used to complete the assembly of the battery.

[0052] 3. The assembled battery was tested on the blue electric test system, and the battery was cycled at 0.05C-15C rate, and the test temperature was 25 degrees Celsius. As shown in Figure 2A , 2B , the cycle test of the example and the comparative battery was carried out at different rates, and the test temperature was 25 degrees Celsius, and the results are shown in Figure 2A ,2B The discharge curves of the batteries without additive at different rates are shown in the figure. Among them, Figure 2A The discharge curves of the batteries with the multifunctional additive containing fluorine boride provided in Example 2 of the present application at different rates are shown in the figure. The test results show that the battery containing 0.01 mol / L fluorine boride complex has higher coulombic efficiency, longer cycle life, and releases higher specific capacity at high rate, showing excellent rate performance. Figure 2B The discharge curves of the batteries without additive at different rates are shown in the figure. Among them,

[0053] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope. It is found by comparison that the battery containing fluorine boride complex additive has significantly improved stability of the electrode active material after cycling, and the corrosion of the current collector is inhibited, thereby significantly improving the battery performance.

[0054] Example 3

[0055] In this example, fluorine boride BF3 is used as an additive for ester electrolyte to improve battery performance.

[0056] 1. First, configure the electrolyte in an argon glove box: 1M LiBF4 / EC-DMC (the volume ratio of EC and DMC is 1:1). Then weigh a certain amount of fluorine boride BF3 and add it to the prepared electrolyte to obtain 1M LiBF4 / EC-DMC electrolyte containing 0.001 mol / L fluorine boride additive. At the same time, the electrolyte without fluorine boride additive is used as a comparative electrolyte. Trace water test is performed on the prepared electrolyte, and it is found that the trace water content in the electrolyte containing fluorine boride additive is significantly reduced, thereby being beneficial to the improvement of battery performance.

[0057] 2. The battery is assembled in an argon glove box. Specifically, CR2032 button cell structure is used for the battery, in which lithium sheet is used as negative electrode and lithium iron phosphate is used as positive electrode, and the electrolyte containing 0.001 mol / L fluorine boride additive and the electrolyte without fluorine boride additive prepared in step 1 are used to complete the assembly of the battery.

[0058] 3. The assembled battery is tested on a blue light test system. The battery is cycled at 0.2C-20C rate, and the test temperature is 25 degrees Celsius. The test results show that the battery containing 0.001 mol / L fluorine boride additive has higher coulombic efficiency, longer cycle life, and releases higher specific capacity at high rate, showing excellent rate performance.

[0059] 4. After the battery was disassembled, the positive and negative electrode surfaces were observed by Hitachi S8600 scanning electron microscope. It was found that the stability of the electrode active material of the battery containing fluoroborate additive was significantly improved after cycling, and the corrosion of the current collector was inhibited.

[0060] Example 4

[0061] In this example, inorganic fluoroborate was used as an additive for ester electrolyte to improve the performance of the battery.

[0062] 1. First, configure the electrolyte in the argon glove box: 1M LiPF6 / EC-DMC (the volume ratio of EC and DMC is 1:1). Then weigh a certain amount of inorganic fluoroborate Cu(BF4)2 and add it to the prepared electrolyte to obtain 1M LiPF6 / EC-DMC electrolyte containing 0.005 mol / L inorganic fluoroborate Cu(BF4)2. At the same time, the electrolyte without inorganic fluoroborate Cu(BF4)2 was used as a comparative electrolyte.

[0063] 2. The battery was assembled in the argon glove box. The specific battery used CR2032 button cell structure, in which lithium sheet was used as negative electrode and lithium manganate was used as positive electrode. The electrolyte containing 0.02 mol / L inorganic fluoroborate Cu(BF4)2 prepared in step 1 and the electrolyte without inorganic fluoroborate Cu(BF4)2 were used to complete the assembly of the battery.

[0064] 3. The assembled battery was tested on the blue electric test system. The battery was tested at 0.01C-20C rate, and the test temperature was 25 degrees Celsius. The test results showed that the battery containing 0.02 mol / L inorganic fluoroborate Cu(BF4)2 had higher coulombic efficiency and longer cycle life, which indicated that inorganic fluoroborate Cu(BF4)2 increased the stability of the interface layer.

[0065] 4. After the battery was disassembled, the positive and negative electrode surfaces were observed by Hitachi S8600 scanning electron microscope. It was found that the stability of the electrode active material of the battery containing inorganic fluoroborate Cu(BF4)2 was significantly improved after cycling. And the positive aluminum current collector in the electrolyte system of inorganic fluoroborate Cu(BF4)2 showed less corrosion behavior. It was found through X-ray photoelectron spectroscopy that a passivation film could be formed on the surface of the aluminum foil by using inorganic fluoroborate Cu(BF4)2 electrolyte, so the additive had the function of passivating aluminum foil. And it was found that the additive could complex and remove the water in the electrolyte, weakening the acid corrosion of the positive electrode and aluminum foil due to the decomposition of water in the electrolyte, thereby improving the stability during the cycle process, reducing the contact resistance, and thus significantly improving the performance of the battery.

[0066] Example 5

[0067] In this embodiment, inorganic fluoroborate salt is used as an additive of ester-based electrolyte to improve battery performance.

[0068] 1. First, prepare electrolyte in an argon-protected glove box: 1M LiPF6 / EC-DMC (volume ratio of EC and DMC is 1:1), then weigh a certain amount of inorganic fluoroborate salt Co(BF4)2, and add it to the prepared electrolyte to obtain 1M LiPF6 / EC-DMC electrolyte containing 0.01 mol / L fluoroborate additive. At the same time, electrolyte without fluoroborate additive is used as a comparative electrolyte.

[0069] 2. Assemble the battery in an argon-protected glove box, and use CR2032 button cell structure for the battery, in which lithium sheet is used as the negative electrode, and fluorinated graphite is used as the positive electrode. The battery is assembled with the electrolyte prepared in step 1 containing 0.01 mol / L fluoroborate additive and without fluoroborate additive.

[0070] 3. The assembled battery is tested on a blue light test system, and the battery is tested at 0.5C-20C rate, and the test temperature is 25 degrees Celsius. The test results show that the rate performance and power density of the battery have been significantly improved, indicating that the addition of fluoroborate additive improves the electrode kinetics.

[0071] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope, and it is found that the battery containing fluoroborate additive inorganic fluoroborate salt Co(BF4)2 has smaller electrode particle size, thereby reducing polarization, increasing the migration rate of lithium ions, and further improving the electrode kinetics. At the same time, the fluoroborate additive further passivates the aluminum current collector, reduces the contact resistance, and thus significantly improves the battery performance.

[0072] 5. The composition of the positive electrode is characterized by X-ray photoelectron spectroscopy (XPS), and the results show that the fluorine content in the film layer is significantly increased, indicating that the capacity of the electrode active material is fully released, and the energy efficiency of the battery is improved.

[0073] Example 6

[0074] In this embodiment, inorganic fluoroborate salt is used as an additive of ester-based electrolyte to improve battery performance.

[0075] 1. First, configure the electrolyte in the glove box under argon protection: 1M LiTFSI / DME-DOL (the volume ratio of DME and DOL is 1:1). Then weigh a certain mass of inorganic fluoroborate Ni(BF4)2, add it to the configured electrolyte, and obtain 1M LiTFSI / DME-DOL electrolyte containing 0.05 mol / L of inorganic fluoroborate Ni(BF4)2. At the same time, the electrolyte without inorganic fluoroborate Ni(BF4)2 is used as a comparative electrolyte.

[0076] 2. The assembly of the battery is carried out in the glove box under argon protection. The specific battery uses a CR2032 button cell structure, in which lithium sheet is used as the negative electrode, lithium nickel manganese cobalt oxide is used as the positive electrode, and the electrolyte containing 0.05 mol / L of inorganic fluoroborate Ni(BF4)2 prepared in step 1 and the electrolyte without inorganic fluoroborate Ni(BF4)2 are used to complete the assembly of the battery.

[0077] 3. The assembled battery is tested on a blue light test system. The battery is tested at a 1C rate, and the test temperature is 25 degrees Celsius. The test results show that the battery containing 0.05 mol / L of inorganic fluoroborate Ni(BF4)2 has a stable cycle efficiency of more than 99.5%, and can be cycled for more than 600 times, while the battery without inorganic fluoroborate Ni(BF4)2 can only be maintained for 280 times.

[0078] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope. It is found by comparison that the stability of the electrode active material of the battery containing inorganic fluoroborate Ni(BF4)2 is obviously improved after cycling. It can be known that inorganic fluoroborate Ni(BF4)2 increases the stability of the interface layer. At the same time, inorganic fluoroborate Ni(BF4)2 further passivates the aluminum current collector, reduces the contact resistance, and thus significantly improves the battery performance.

[0079] Example 7

[0080] In this embodiment, fluoroboric acid HBF4 is used as an ether-based electrolyte additive to improve the battery performance.

[0081] 1. First, configure the electrolyte in the glove box under argon protection: 1M LiTFSI / DME-DOL (the volume ratio of DME and DOL is 1:1). Then weigh a certain mass of fluoroboric acid HBF4, add it to the configured electrolyte, and obtain 1M LiTFSI / DME-DOL electrolyte containing 0.1 mol / L of fluoroboric acid HBF4. At the same time, the electrolyte without fluoroboric acid HBF4 is used as a comparative electrolyte.

[0082] 2. The battery was assembled in an argon-filled glove box. Specifically, the battery used a CR2032 button cell structure, in which lithium was used as the negative electrode, nickel-cobalt-aluminum lithium was used as the positive electrode, and the electrolyte prepared in step 1 containing 0.1 mol / L fluoroboric acid HBF4 and not containing fluoroboric acid HBF4 was used to complete the assembly of the battery.

[0083] 3. The assembled battery was tested on a blue light test system. The battery was tested at a rate of 0.5C, and the test temperature was 25 degrees Celsius. The test results showed that the cycle efficiency of the battery containing 0.1 mol / L fluoroboric acid HBF4 was significantly improved, and the capacity retention rate of 80% could reach more than 1000 cycles, and the polarization was reduced from 0.12V to 0.06V.

[0084] 4. After the battery was disassembled, the positive and negative electrode surfaces were observed by Hitachi S8600 scanning electron microscope. It was found that the battery containing fluoroboric acid HBF4 had significantly improved stability of the electrode active material after cycling. Therefore, the fluoroboric acid HBF4 additive increased the stability of the interface layer. At the same time, the fluoroboric acid HBF4 additive further passivated the aluminum current collector, reduced the contact resistance, and thus significantly improved the battery performance.

[0085] Example 8

[0086] In this example, nitrofluoroboric acid BF4NO was used as an ether-based electrolyte additive to improve battery performance.

[0087] 1. First, the electrolyte was prepared in an argon-filled glove box: 1M LiTFSI / DME-DOL (the volume ratio of DME and DOL was 1:1). Then a certain amount of nitrofluoroboric acid BF4NO was added to the prepared electrolyte to obtain 1M LiTFSI / DME-DOL electrolyte containing 0.5mol / L nitrofluoroboric acid BF4NO. At the same time, the electrolyte without nitrofluoroboric acid BF4NO additive was used as a comparative electrolyte.

[0088] 2. The battery was assembled in an argon-filled glove box. Specifically, the battery used a CR2032 button cell structure, in which lithium was used as the negative electrode, lithium nickel manganese oxide was used as the positive electrode, and the electrolyte prepared in step 1 containing 0.5mol / L nitrofluoroboric acid BF4NO and not containing nitrofluoroboric acid BF4NO additive was used to complete the assembly of the battery.

[0089] 3. The assembled battery was tested on a blue light test system. The battery was tested at a rate of 5C, and the test temperature was 25 degrees Celsius. The test results showed that the cycle performance, rate performance and power density of the battery were significantly improved.

[0090] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope. It is found that the battery containing fluoroboric acid nitrate BF4NO2 additive increases the electrode wettability, improves the solubility of lithium salt, and further improves the electrode kinetics. At the same time, the fluoroboric acid nitrate BF4NO2 additive further passivates the aluminum current collector, reduces the contact resistance, and further significantly improves the battery performance.

[0091] 5. The composition of the positive electrode is characterized by X-ray photoelectron spectroscopy (XPS). The results show that the content of LiF in the film layer is significantly increased, indicating that the stability of the electrode interface is enhanced, and the performance of the battery is improved.

[0092] Example 9

[0093] In this example, fluoroboric acid nitrate BF4NO2 is used as an ether-based electrolyte additive to improve battery performance.

[0094] 1. First, configure the electrolyte in an argon glove box: 1M LiTFSI / DME-DOL (the volume ratio of DME and DOL is 1:1). Then weigh a certain amount of fluoroboric acid nitrate BF4NO2 and add it to the prepared electrolyte to obtain 1M LiTFSI / DME-DOL electrolyte containing 1 mol / L fluoroboric acid nitrate BF4NO2. At the same time, the electrolyte without fluoroboric acid nitrate BF4NO2 additive is used as a comparative electrolyte.

[0095] 2. The battery is assembled in an argon glove box. Specifically, CR2032 button cell structure is used, in which lithium sheet is used as negative electrode and MnO2 is used as positive electrode. The electrolyte containing 1 mol / L fluoroboric acid nitrate BF4NO2 additive prepared in step 1 and the electrolyte without fluoroboric acid nitrate BF4NO2 additive are used to complete the assembly of the battery.

[0096] 3. The assembled battery is tested on a blue light test system. The battery is tested at 0.01C-15C rate, and the test temperature is 25 degrees Celsius. The test results show that the rate performance and power density of the battery have been significantly improved.

[0097] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope. It is found that the battery containing fluoroboric acid nitrate BF4NO2 additive increases the electrode wettability, improves the solubility of lithium salt, and further improves the electrode kinetics. At the same time, the fluoroboric acid nitrate BF4NO2 additive further passivates the aluminum current collector, reduces the contact resistance, and further significantly improves the battery performance.

[0098] 5. The composition of the positive electrode is characterized by X-ray photoelectron spectroscopy (XPS). The results show that the content of LiF in the film layer is significantly increased, indicating that the stability of the electrode interface is enhanced, and the performance of the battery is improved.

[0099] Example 10

[0100] This example uses BF3OH as an ether-based electrolyte additive to improve battery performance.

[0101] 1. First, configure the electrolyte in an argon-protected glove box: 1M LiTFSI / DME-DOL (volume ratio of DME and DOL is 1:1). Then measure a certain volume of BF3OH and add it to the prepared electrolyte to obtain 1M LiTFSI / DME-DOL electrolyte containing 0.02 mol / L BF3OH additive. At the same time, the electrolyte without BF3OH additive is used as a comparative electrolyte.

[0102] 2. The assembly of the battery was carried out in an argon-protected glove box. The specific battery uses CR2032 button cell structure, in which lithium sheet is used as negative electrode and S is used as positive electrode, and the electrolyte containing 0.02 mol / L BF3OH additive and the electrolyte without BF3OH additive prepared in step 1 are used to complete the assembly of the battery.

[0103] 3. The assembled battery was tested on a blue light test system. The battery was tested at 0.5C rate, and the test temperature was 25 degrees Celsius. The test results show that the cycle performance and energy efficiency of the battery have been significantly improved.

[0104] 4. After the battery was disassembled, the positive and negative electrode surfaces were observed by Hitachi S8600 scanning electron microscope. It was found that the battery containing BF3OH additive had obvious improvement in the stability of electrode active material after cycling. And the positive aluminum current collector in the electrolyte system containing BF3OH additive showed less corrosion behavior, indicating that the BF3OH additive has the effect of passivating aluminum foil, thereby improving the stability of the current collector during the cycling process, reducing the contact resistance, and thus significantly improving the battery performance.

[0105] Example 11

[0106] This example uses fluoroborate compound BF2Cl as a polyethylene oxide solid-state electrolyte additive to improve battery performance.

[0107] 1. First, 0.5 grams of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), a certain amount of fluoroborate, and 5 milliliters of acetonitrile solvent were placed in the same container and ultrasonically dispersed for at least 15 minutes. Then, 10 grams of polyimide (PI) purchased from Sigma were dissolved in the dispersed solution and stirred for 6 hours, wherein the oxygen-to-lithium ratio of the PI polymer and lithium salt was maintained at 20:1. The uniformly stirred solution was coated on the surface of a silicon substrate, dried at 50°C, and prepared into a suitable size, and then peeled off to obtain a polyimide solid-state electrolyte sheet containing 0.05M fluoroborate BF2Cl additive with a thickness of 60μm and a porosity of 10%.

[0108] 2. The assembly of the battery was carried out in an argon glove box, and the specific battery used a CR2032 button cell structure, wherein lithium was used as the negative electrode, lithium cobaltate was used as the positive electrode, and the electrolyte containing 0.05M fluoroborate BF2Cl additive and the electrolyte without fluoroborate additive prepared in step 1 were used to complete the assembly of the battery.

[0109] 3. The assembled battery was tested on a blue light test system, and the battery was tested at a 1C rate, and the test temperature was 60°C. The test results showed that the cycle performance and energy efficiency of the battery were significantly improved.

[0110] 4. After the battery was disassembled, the positive and negative electrode surfaces were observed by Hitachi S8600 scanning electron microscope, and it was found that the battery containing fluoroborate BF2Cl additive had significantly improved the stability of the electrode active material after cycling. The electrode wettability and lithium salt solubility were also improved, which improved the electrode kinetics. At the same time, the fluoroborate BF2Cl additive further passivated the aluminum current collector, reduced the contact resistance, and thus significantly improved the battery performance.

[0111] Example 12

[0112] In this example, fluoroborate BF3 was used as a polyethylene oxide solid-state electrolyte additive to improve battery performance.

[0113] 1. First, 0.5 grams of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), a certain amount of fluoroborate, and 5 milliliters of acetonitrile solvent were placed in the same container and ultrasonically dispersed for at least 15 minutes. Then, 10 grams of polyimide (PI) purchased from Sigma were dissolved in the dispersed solution and stirred for 6 hours, wherein the oxygen-to-lithium ratio of the PI polymer and lithium salt was maintained at 20:1. The uniformly stirred solution was coated on the surface of a silicon substrate, dried at 50°C, and prepared into a suitable size, and then peeled off to obtain a polyimide solid-state electrolyte sheet containing 0.05M fluoroborate BF3 additive with a thickness of 60μm and a porosity of 10%.

[0114] 2. The battery assembly was carried out in an argon glove box. The CR2032 button cell structure was used, in which lithium sheet was used as the negative electrode, lithium iron phosphate was used as the positive electrode, and the electrolyte prepared in step 1 containing 0.07M fluoroborate BF3 additive and not containing fluoroborate BF3 additive was used to complete the battery assembly.

[0115] 3. The assembled battery was tested on the Blue Electric test system. The battery was tested at 3C rate, and the test temperature was 60 degrees Celsius. The test results showed that the cycle performance and energy efficiency of the battery were significantly improved.

[0116] 4. After the battery was disassembled, the positive and negative electrode surfaces were observed by Hitachi S8600 scanning electron microscope. It was found that the battery containing fluoroborate BF3 additive had significantly improved the stability of the electrode active material after cycling. The electrode wettability and lithium salt solubility were also improved, which improved the electrode kinetics. At the same time, the fluoroborate BF3 additive further passivated the aluminum current collector, reduced the contact resistance, and significantly improved the battery performance.

[0117] Example 13

[0118] In this example, fluoroboric acid nitrate BF4NO2 was used as a polyethylene oxide solid electrolyte additive to improve battery performance.

[0119] 1. First, 0.5 grams of lithium bis(trifluoromethanesulfonimide) (LiTFSI), a certain amount of fluoroborate, and 5 milliliters of acetonitrile solvent were weighed into the same container and ultrasonicated for at least 15 minutes until completely dispersed. Then 10 grams of polyimide (PI) purchased from Sigma was dissolved in the dispersed solution, and stirred for 6 hours, wherein the oxygen lithium ratio of PI polymer and lithium salt was maintained at 20:1. The uniformly stirred solution was coated on the surface of a silicon substrate, dried at 50°C, and prepared into a suitable size. The fluoroboric acid nitrate BF4NO2 additive-containing polyimide solid electrolyte sheet with a thickness of 60μm and a porosity of 10% was peeled off.

[0120] 2. The battery assembly was carried out in an argon glove box. The CR2032 button cell structure was used, in which lithium sheet was used as the negative electrode, lithium iron phosphate was used as the positive electrode, and the solid electrolyte prepared in step 1 containing fluoroboric acid nitrate BF4NO2 additive and not containing fluoroboric acid nitrate BF4NO2 additive was used to complete the battery assembly.

[0121] 3. The assembled battery was tested on the Blue Electric test system. The battery was tested at 3C rate, and the test temperature was 60 degrees Celsius. The test results showed that the cycle performance and energy efficiency of the battery were significantly improved.

[0122] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope. It is found that the stability of the electrode active material of the battery containing fluoroboric acid nitrate BF4NO2 additive is significantly improved after cycling. The electrode wettability and lithium salt solubility are also improved, which improves the electrode kinetics. At the same time, the fluoroboric acid nitrate BF4NO2 additive further passivates the aluminum current collector, reduces the contact resistance, and thus significantly improves the battery performance.

[0123] Example 14

[0124] In this example, fluoroborate BF3 complex is added to Li 1.5 Al 0.5 Ge 1.5 (PO4)3(LAGP) and polyimide composite solid electrolyte to improve battery performance.

[0125] The inorganic solid electrolyte LAGP powder and fluoroborate are dispersed into the polyimide solid electrolyte, dried at 50°C, and prepared into a suitable size. The fluoroborate BF3 complex additive-containing LAGP, polyimide composite solid electrolyte sheet with a thickness of 60 μm and a porosity of 10% is obtained by peeling.

[0126] 2. The symmetric battery system of Li-Li is used to characterize its cycle performance, rate performance and polarization properties. The battery is assembled in an argon glove box. Specifically, CR2032 button cell structure is used, and lithium sheet is used as the negative electrode and the counter electrode. The fluoroborate BF3 complex additive-containing electrolyte sheet prepared in step 1 and the electrolyte sheet without fluoroborate BF3 complex additive are used respectively.

[0127] 3. The assembled battery is tested on a blue light test system. The battery is cycled at a rate of 0.2C, and the test temperature is 60°C. The results show that compared with the battery without fluoroborate BF3 complex additive, the polarization of the battery with fluoroborate BF3 complex additive is greatly reduced, and the cycle life is greatly improved.

[0128] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope. It is found that the stability of the electrode active material of the battery containing fluoroborate BF3 complex additive is significantly improved after cycling.

[0129] Example 15

[0130] In this example, inorganic fluoroborate Co(BF4)2 is added to inorganic solid electrolyte Li 1.5 Al 0.5 Ge 1.5 (PO4)3(LAGP) to improve battery performance.

[0131] 1. Inorganic solid electrolyte LAGP and a certain amount of inorganic fluoroborate Co(BF4)2 powder are pressed into tablets, sintered at 1100°C for 8 hours to make the conductivity optimal, and LAGP electrolyte tablets with inorganic fluoroborate Co(BF4)2 additives are obtained.

[0132] 2. The assembly of the battery is carried out in an argon glove box. Specifically, the battery uses a CR2032 button cell structure, in which lithium sheet is used as the negative electrode, lithium iron phosphate is used as the positive electrode, and the electrolyte prepared in step 1 containing inorganic fluoroborate Co(BF4)2 additives and the electrolyte without inorganic fluoroborate Co(BF4)2 additives are used to complete the assembly of the battery.

[0133] 3. The assembled battery is tested on a blue light test system, and the battery is tested at a rate of 0.2C, and the test temperature is 60 degrees Celsius. The results show that the battery containing inorganic fluoroborate additives has a stable cycle efficiency of more than 99%, and can be cycled for more than 500 times, while the battery without inorganic fluoroborate Co(BF4)2 additives can only maintain for 200 times. Compared with the battery without inorganic fluoroborate Co(BF4)2 additives, the polarization of the battery containing inorganic fluoroborate Co(BF4)2 additives is greatly reduced.

[0134] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope, and it is found that the stability of the electrode active material of the battery containing inorganic fluoroborate Co(BF4)2 additives has been significantly improved after cycling.

[0135] Example 16

[0136] In this example, HBF4 is used to add to Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP) and polyimide composite solid electrolyte to improve battery performance.

[0137] 1. Inorganic solid electrolyte LATP powder and fluoroborate HBF4 are dispersed into polyimide solid electrolyte, dried at 50°C, and prepared into a suitable size, peeled off to obtain LATP, polyimide composite solid electrolyte tablets containing fluoroborate additives with a thickness of 60μm and a porosity of 10%.

[0138] 2. The assembly of the battery is carried out in an argon glove box. Specifically, the battery uses a CR2032 button cell structure, in which lithium sheet is used as the negative electrode, lithium manganate is used as the positive electrode, and the electrolyte prepared in step 1 containing fluoroboric acid HBF4 additives and the electrolyte without fluoroboric acid HBF4 are used to complete the assembly of the battery.

[0139] 3. Assembled batteries were tested on the Blue Electric test system, and the batteries were cycled at 0.1C rate, and the test temperature was 60 degrees Celsius. The results showed that the polarization of the battery containing HBF4 was greatly reduced, and the cycle life was greatly improved compared with the battery without HBF4.

[0140] 4. After the battery was disassembled, the positive and negative electrode surfaces were observed by Hitachi S8600 scanning electron microscope. It was found that the stability of the electrode active material of the battery containing HBF4 was obviously improved after cycling.

[0141] 5. The impedance spectrum of the battery containing HBF4 and the battery without HBF4 was tested by Zahner IM6 impedance spectrum tester. The results showed that the impedance of the battery with the additive was significantly lower than that of the battery without the additive.

[0142] Example 17

[0143] In this example, nitro BF4NO was added to Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP) and polyimide composite solid electrolyte to improve battery performance.

[0144] 1. Inorganic solid electrolyte LATP powder and nitro BF4NO were dispersed into polyimide solid electrolyte and dried at 50°C to prepare LATP, polyimide composite solid electrolyte sheet containing nitro BF4NO additive with a thickness of 60 μm and a porosity of 10%.

[0145] 2. The battery was assembled in an argon glove box. The specific battery used CR2032 button cell structure, in which lithium sheet was used as negative electrode, lithium nickel manganese cobalt oxide as positive electrode, and electrolyte containing and not containing nitro BF4NO additive prepared in step 1 was used to complete the assembly of the battery.

[0146] 3. Assembled batteries were tested on the Blue Electric test system, and the batteries were cycled at 0.05-3C rate, and the test temperature was 60 degrees Celsius. The results showed that the rate performance and power density of the battery were also significantly improved, and the cycle efficiency of the battery containing nitro BF4NO was stable at more than 95%, and could be cycled more than 200 times, while the battery without nitro BF4NO could only maintain 50 cycles.

[0147] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope. It is found that the stability of the electrode active material of the battery containing fluoroboric acid nitrate BF4NO is significantly improved after cycling. At the same time, the fluoroboric acid nitrate BF4NO further passivates the aluminum current collector, reduces the contact resistance, and thus significantly improves the battery performance.

[0148] 5. The impedance spectrum of the battery containing fluoroboric acid nitrate BF4NO and the battery not containing fluoroboric acid nitrate BF4NO is tested by Zahner IM6 impedance spectrum tester. The results show that the impedance of the battery with the additive is significantly lower than that of the battery without the additive.

[0149] Example 18

[0150] In this embodiment, fluoroboric BF3 is used as an additive for polyacrylonitrile solid-state electrolyte to improve battery performance.

[0151] 1. First, 1 gram of lithium bis-trifluoromethanesulfonimide (LiTFSI) and a certain amount of BF3 powder, 0.2 grams of aluminum oxide nanoparticles with a particle size of 50 nm, and 20 milliliters of acetonitrile solvent are placed in the same container and ultrasonically dispersed for at least 15 minutes. Then, 10 grams of polyacrylonitrile (PAN) purchased from Sigma are dissolved in the dispersed solution, and stirred for 6 hours, wherein the oxygen-lithium ratio of the PAN polymer and lithium salt is maintained at 20:1. The uniformly stirred solution is coated on the surface of a silicon substrate, dried at 50°C, and prepared into a suitable size. The BF3-containing polyacrylonitrile solid-state electrolyte sheet with a thickness of 60 μm and a porosity of 10% is peeled off.

[0152] 2. The Li-Li symmetric battery system is used to characterize its cycle performance, rate performance, and polarization properties. The battery is assembled in an argon glove box. Specifically, a CR2032 button cell structure is used, and lithium foil is used as the negative electrode and the counter electrode. The BF3-containing electrolyte sheet and the electrolyte sheet without BF3 additive prepared in step 1 are used respectively.

[0153] 3. The assembled battery is tested on a blue light test system. The battery is cycled at a rate of 0.5C, and the test temperature is 55°C. The results show that compared with the battery without fluoroboric BF3 additive, the polarization of the battery with fluoroboric BF3 additive is greatly reduced, and the cycle life is improved by 2 times.

[0154] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope. It is found that the stability of the electrode active material of the battery containing fluoroborate BF3 additive is significantly improved after cycling. At the same time, the fluoroborate BF3 additive further passivates the aluminum current collector, reduces the contact resistance, and thus significantly improves the battery performance.

[0155] 5. The batteries containing fluoroborate BF3 additive and the batteries not containing fluoroborate BF3 additive are tested by impedance spectrum test instrument Zahner IM6. The results show that the impedance of the battery with additive is significantly lower than that of the battery without additive.

[0156] Example 19

[0157] In this example, inorganic fluoroborate Cu(BF4)2 is used as a polyimide solid-state electrolyte additive to improve battery performance.

[0158] 1. First, 0.5 grams of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), a certain amount of inorganic fluoroborate Cu(BF4)2 powder and 5 milliliters of acetonitrile solvent are weighed into the same container and ultrasonically dispersed for at least 15 minutes. Then 10 grams of polyimide (PI) purchased from Sigma is dissolved in the dispersed solution, and stirred for 6 hours, wherein the oxygen-lithium ratio of the PI polymer and lithium salt is maintained at 20:1. The uniformly stirred solution is coated on the surface of a silicon substrate, dried at 50°C, and prepared into a polyimide solid-state electrolyte sheet containing inorganic fluoroborate Cu(BF4)2 additive with a thickness of 60 μm and a porosity of 10%.

[0159] 2. The Li-Li symmetric battery system is used to characterize its cycle performance, rate performance and polarization properties. The battery is assembled in an argon glove box. Specifically, a CR2032 button cell structure is used, and lithium sheet is used as the negative electrode and the counter electrode. The electrolyte sheet containing inorganic fluoroborate Cu(BF4)2 additive prepared in step 1 and the electrolyte sheet not containing inorganic fluoroborate Cu(BF4)2 additive are used respectively to assemble the battery.

[0160] 3. The assembled battery is tested on a blue electric test system. The battery is cycled at a rate of 0.1C, and the test temperature is 50°C. The results show that the battery containing inorganic fluoroborate Cu(BF4)2 additive has higher coulombic efficiency and longer cycle life.

[0161] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope. It is found that the aluminum current collector of the battery containing inorganic fluoroborate Cu(BF4)2 additive is further passivated, the contact resistance is reduced, and the battery performance is significantly improved.

[0162] 5. The battery containing inorganic fluoroborate Cu(BF4)2 additive and the battery not containing inorganic fluoroborate Cu(BF4)2 additive are tested by Zahner IM6 impedance spectrum tester. The results show that the impedance of the battery with the additive is significantly lower than that of the battery without the additive. It is indicated that the wettability of the electrode and the solubility of lithium salt are improved, thereby improving the electrode kinetics.

[0163] Example 20

[0164] In this embodiment, fluoroborate BF3 is used as a polyimide solid-state electrolyte additive to improve battery performance.

[0165] 1. First, 0.5 grams of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), a certain amount of fluoroborate BF3 powder and 5 milliliters of acetonitrile solvent are weighed into the same container and ultrasonically dispersed for at least 15 minutes. Then 10 grams of polyimide (PI) purchased from Sigma is dissolved in the dispersed solution, and stirred for 6 hours, wherein the oxygen-lithium ratio of the PI polymer and lithium salt is maintained at 20:1. The uniformly stirred solution is coated on the surface of a silicon substrate, dried at 50°C, and prepared into a fluoroborate BF3 additive-containing polyimide solid-state electrolyte sheet with a thickness of 60 μm and a porosity of 10%.

[0166] 2. The battery is assembled in an argon glove box. The specific battery uses a CR2032 button cell structure, in which lithium sheet is used as the negative electrode, lithium cobaltate is used as the positive electrode, and the fluoroborate BF3 additive-containing and non-fluoroborate BF3 additive-containing solid-state electrolyte prepared in step 1 is used to complete the assembly of the battery.

[0167] 3. The assembled battery is tested on a blue light test system. The battery is cycled at a rate of 0.5C, and the test temperature is 50°C. The results show that the battery with fluoroborate BF3 additive has a stable cycle efficiency of more than 90% and can be cycled for more than 150 weeks, while the battery without fluoroborate BF3 additive can only be maintained for 10 weeks.

[0168] 4. After the battery is disassembled, the positive and negative electrode surfaces are observed by Hitachi S8600 scanning electron microscope. It is found that the aluminum current collector of the battery containing inorganic fluoroborate Cu(BF4)2 additive is further passivated, the contact resistance is reduced, and the stability of the electrode active material after cycling is also significantly improved.

[0169] 5. The impedance spectrum of the battery containing fluorine boride BF3 additive and the battery without fluorine boride BF3 additive is tested by using the impedance spectrum tester of Zahner IM6 type, and the result shows that the impedance of the battery with the additive is obviously lower than that of the battery without the additive. It is illustrated that the wettability of the electrode and the solubility of the lithium salt are improved, thereby improving the electrode kinetics.

[0170] The above detailed description of the specific embodiments has further illustrated the purposes, technical solutions and beneficial effects of the present application, and it should be understood that the above description is only the specific embodiments of the present application and is not used to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. The application of a multifunctional lithium battery additive containing fluorine and boron elements, characterized in that, The multifunctional lithium battery additive, used as an additive for solid electrolytes, includes: boron fluoride (BF). c X d , fluoroboronic acid HBF4, inorganic fluoroborate M n (BF4) m Organic fluoroborate R-BF3M, polyfluoroaromatic borate FR-BH y One or more of the following: fluoroorganoboranes R-BF3, fluoroborate nitrate BF4NO or BF4NO2; Wherein, X includes one or more elements selected from Cl, Br, and I; M includes one or more elements selected from aluminum, copper, lead, tin, nickel, zinc, cadmium, beryllium, magnesium, calcium, strontium, barium, cesium, rubidium, manganese, iron, cobalt, silver, indium, and thallium; R includes one or more organic groups selected from hydrocarbons, alcohols, ethers, esters, ketones, carboxylic acids, and phenols; 0.5≤a≤2, 1.5≤b≤3; 0.5≤c≤3, 0.5≤d≤3; 0.2≤n≤5, 0.2≤m≤8; 0.5≤y≤3.

2. The application of the multifunctional lithium battery additive according to claim 1, characterized in that, The inorganic fluoroborates include one or more of the following: rubidium tetrafluoroborate, cesium tetrafluoroborate, copper tetrafluoroborate, tin tetrafluoroborate, zinc tetrafluoroborate, nickel tetrafluoroborate, iron tetrafluoroborate, cobalt tetrafluoroborate, manganese tetrafluoroborate, silver tetrafluoroborate, cadmium tetrafluoroborate, aluminum tetrafluoroborate, magnesium tetrafluoroborate, calcium tetrafluoroborate, strontium tetrafluoroborate, and barium tetrafluoroborate. The organofluoroborates include one or more of the following: cesium trifluoroborate, rubidium trifluoroborate, copper trifluoroborate, tin trifluoroborate, zinc trifluoroborate, nickel trifluoroborate, iron trifluoroborate, cobalt trifluoroborate, manganese trifluoroborate, silver trifluoroborate, cadmium trifluoroborate, aluminum trifluoroborate, magnesium trifluoroborate, calcium trifluoroborate, strontium trifluoroborate, and barium trifluoroborate.

3. A solid electrolyte, characterized in that, The solid electrolyte comprises the multifunctional lithium battery additive containing fluorine and boron elements as described in any one of claims 1-2; wherein the solid electrolyte comprises any one of polymer solid electrolyte, oxide solid electrolyte, and sulfide solid electrolyte.

4. A solid-liquid mixed electrolyte, characterized in that, The solid phase of the solid-liquid hybrid electrolyte includes the multifunctional lithium battery additive containing fluorine and boron elements as described in any one of claims 1-2.

5. A solid-state lithium battery, characterized in that, The solid-state lithium battery includes the solid electrolyte as described in claim 3 or the solid-liquid hybrid electrolyte as described in claim 4.

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