Secondary battery

Abstract

The present disclosure relates to the technical field of lithium-ion batteries, and specifically relates to a secondary battery. In the secondary battery of the present disclosure, in a covalent molecule formed by sp2 hybridization of a B atom in a functional additive of a battery electrolyte, the remaining empty orbit can be used as a Lewis acid to accept external lone-pair electrons, thereby forming an sp3-hybridized tetrahedron-configuration complex; and a fluorine atom in alkali metal variscite has relatively high electronegativity and can interact with a B atom via electron clouds, thereby forming a complex F-B. A cyano group in the functional additive can be complexed with a metal ion to form a complex; and the functional additive contains a cyano group and a B atom, and can be combined with both a fluorine ion and a metal ion of the alkali metal variscite, thereby improving the solubility of the alkali metal variscite. When the alkali metal variscite is dissolved in an electrolyte, a porous structure is formed in an electrode sheet, and the dissolved alkali metal variscite forms AlF, Li3PO4 and Na3PO4 at a positive electrode and forms LiF and NaF at a negative electrode under the action of an electric field, thereby improving the initial efficiency, rate capacity and cycle performance of a battery.

Description

A secondary battery

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 2023115126694, entitled “A Secondary Battery,” filed with the Patent Office of China on November 14, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the technical field of lithium-ion batteries, and in particular to a secondary battery. Background Art

[0004] As battery energy density continues to increase, the range of mainstream models has exceeded 400km, and high-end models are greater than 700km, which can basically solve the range anxiety of electric vehicles. However, compared with the refueling time of fuel vehicles, fast charging of electric vehicles is a bottleneck.

[0005] During the first cycle of charge and discharge, the battery consumes active metals such as lithium and sodium due to the formation of the interface film. Especially when silicon and amorphous carbon are used as the negative electrode, more active metals will be consumed, resulting in the actual capacity of the battery being lower than the designed capacity.

[0006] During battery cycling, the positive electrode experiences significant changes in unit cell volume, easy breakage of material powder particles, migration and dissolution of transition metal ions, and continuous electrolyte consumption, increased SEI film thickness, increased internal resistance, and active metal depletion on the negative electrode side. This results in poor battery cyclability and rapid decay in specific capacity and energy density. This results in decreased battery capacity, shortened cycle life, and significant safety hazards.

[0007] Application Contents

[0008] An object of the present disclosure is to provide a secondary battery having high first efficiency, high rate, high voltage, and long cycle performance.

[0009] In order to achieve the above-mentioned purpose of the present disclosure, the following technical solutions are adopted:

[0010] The present disclosure provides a secondary battery comprising a positive electrode, a negative electrode, a separator and an electrolyte, wherein the positive electrode and / or the negative electrode comprises alkali metal aluminum phosphate MAlPO4(OH) x F 1-x , wherein 0≤x<1; M is an alkali metal Li or Na, and the electrolyte includes a functional additive, and the functional additive is selected from any one of the compounds having the structures shown in Formula I, II, and III;

[0011] Wherein, R1, R2, and R3 are independently selected from a hydrocarbon group, a hydrocarbon group substituted by B, N, F, Si, P, S, Cl, Br, or I, an alkoxy group, an aryl group, or a heteroaryl group.

[0012] The hydrocarbon group is C a H 2a+1 、C b H 2b-1 、C c H 2c-3 , where 0<a≤6, 0<b≤6, 0<c≤6;

[0013] The alkoxy group is C a H 2a+1 O, C b H 2b-1 O, C c H 2c-3 O, where 0<a≤6, 0<b≤6, 0<c≤6;

[0014] The aryl group includes any one of phenyl, anthracenyl, naphthyl or biphenyl;

[0015] The heteroaryl group has 1 to 20 carbon atoms, including 1 to 3 heteroatoms selected from O, S, P, and N.

[0016] Further, the heteroaryl group includes any one of pyridyl, indolyl, pyrrolyl, imidazolyl, thienyl, furyl, 1,2-thiazolyl, 1,3-thiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, thiadiazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, pyridyl, pyrazinyl, pyrimidinyl, 1,3,5-triazinyl, 1,2,4-triazinyl, 1,2,3-triazinyl, isoindolyl, benzimidazolyl, naphthioimidazolyl, phenanthroimidazolyl, benzotriazolyl, benzoxazolyl, naphthioxazolyl, phenanthroxazolyl, benzothiadiazolyl, benzotriazolyl, quinolyl, isoquinolyl, benzopyrazinyl, benzothienyl, benzofuranyl, benzopyrrolyl, carbazolyl, and naphthiodiazolyl.

[0017] Furthermore, the functional additive is selected from one or more of the following compounds:

[0018] Furthermore, the electrolyte comprises:

[0019] 0.1 wt% to 20 wt% of an electrolyte salt;

[0020] 0.1wt% to 10wt% of functional additives;

[0021] 0.1 wt% to 10 wt% of auxiliary additives;

[0022] 60 wt% to 90 wt% of solvent.

[0023] Further, the electrolyte salt includes: one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate, lithium bisoxalatoborate, lithium difluorooxalatoborate, bis(trifluoromethylsulfonylimide)lithium and bis(fluorosulfonylimide)lithium, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium difluorophosphate, sodium bisoxalatoborate, sodium difluorooxalatoborate, bis(trifluoromethylsulfonylimide)sodium and bis(fluorosulfonylimide)sodium;

[0024] The solvent includes: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methylpropyl carbonate, 1,4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, ethyl butyrate, and a mixture of one or more of their halogenated derivatives;

[0025] The auxiliary additives include: any one or more of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, 1,3-(1-propylene) sultone, methylene disulfonate, succinonitrile, adiponitrile, lithium bis(fluorosulfonyl)imide, vinyl sulfate, tris(trimethylsilane)borate, tris(trimethylsilane)phosphite or tris(trimethylsilane)phosphate.

[0026] Furthermore, the alkali metal phosphate is selected from LiAlPO4F, LiAlPO4(OH) 0.9 F 0.1 、LiAlPO4(OH) 0.5 F 0.5 、NaAlPO4F、NaAlPO4(OH) 0.9 F 0.1 、NaAlPO4(OH) 0.5 F 0.5 ;

[0027] Furthermore, the positive electrode includes a current collector and a positive electrode membrane. The positive electrode membrane is prepared from a positive electrode active material, a conductive agent, a binder and alkali metal phosphate. The mass percentage of the alkali metal phosphate in the positive electrode membrane is 0.1% to 5%.

[0028] Furthermore, the negative electrode includes a current collector and a negative electrode membrane, the negative electrode membrane is prepared from a negative electrode active material, a conductive agent, a binder and alkali metal phosphate, and the alkali metal phosphate accounts for 0.1% to 5% by mass of the negative electrode membrane;

[0029] Furthermore, the secondary battery is a lithium ion battery or a sodium ion battery. DETAILED DESCRIPTION

[0030] In some embodiments of the present disclosure, a secondary battery is provided, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode and / or the negative electrode comprises alkali metal aluminum phosphate MAlPO4(OH) x F 1-x , wherein 0≤x<1; M is an alkali metal Li or Na, and the electrolyte includes a functional additive selected from compounds having structures shown in Formulas I, II, and III;

[0031] Wherein, R1, R2, and R3 are independently selected from a hydrocarbon group, a hydrocarbon group substituted by B, N, F, Si, P, S, Cl, Br, or I, an alkoxy group, an aryl group, or a heteroaryl group.

[0032] In some embodiments of the present disclosure, the hydrocarbon group is C a H 2a+1 、C b H 2b-1 、C c H 2c-3 , where 0<a≤6, 0<b≤6, 0<c≤6;

[0033] The alkoxy group is C a H 2a+1 O, C b H 2b-1 O, C c H 2c-3 O, where 0<a≤6, 0<b≤6, 0<c≤6;

[0034] The aryl group includes any one of phenyl, anthracenyl, naphthyl or biphenyl;

[0035] The heteroaryl group has 1 to 20 carbon atoms, including 1 to 3 heteroatoms among O, S, and N.

[0036] In some embodiments of the present disclosure, the heteroaryl group specifically includes pyridyl, indolyl, pyrrolyl, imidazolyl, thienyl, furyl, 1,2-thiazolyl, 1,3-thiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, thiadiazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, pyridyl, pyrazinyl, pyrimidinyl, 1,3,5-triazinyl , 1,2,4-triazinyl, 1,2,3-triazinyl, isoindolyl, benzimidazolyl, naphthioimidazolyl, phenanthroimidazolyl, benzotriazolyl, benzoxazolyl, naphthioxazolyl, phenanthroxazolyl, benzothiadiazolyl, benzotriazolyl, quinolyl, isoquinolyl, benzopyrazinyl, benzothiophenyl, benzofuranyl, benzopyrrolyl, carbazolyl, naphthiodiazolyl.

[0037] In some embodiments of the present disclosure, the functional additive is selected from the following specific compounds:

[0038] In some embodiments of the present disclosure, the electrolyte comprises:

[0039] 0.1 wt% to 20 wt% of an electrolyte salt;

[0040] 0.1wt% to 10wt% of functional additives;

[0041] 0.1 wt% to 10 wt% of auxiliary additives;

[0042] 60 wt% to 90 wt% of solvent.

[0043] In some embodiments of the present disclosure, the electrolyte includes 0.1 wt% to 20 wt% of electrolyte salt, which can be 0.1 wt%, 0.5 wt%, 1 wt%, 3 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, or any value between 0.1 wt% and 20 wt%.

[0044] In some embodiments of the present disclosure, the electrolyte salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate, lithium bisoxalatoborate, lithium difluorooxalatoborate, lithium bis(trifluoromethylsulfonylimide)lithium and lithium bis(fluorosulfonylimide), sodium hexafluorophosphate, sodium tetrafluoroborate, sodium difluorophosphate, sodium bisoxalatoborate, sodium difluorooxalatoborate, sodium bis(trifluoromethylsulfonylimide)sodium and sodium bis(fluorosulfonylimide).

[0045] In some embodiments of the present disclosure, the electrolyte further comprises 0.1 wt% to 10 wt% of a functional additive, which may be 0.1 wt%, 0.5 wt%, 1 wt%, 3 wt%, 5 wt%, 10 wt%, or any value between 0.1 wt% and 10 wt%. The functional additive is selected from the above functional additives.

[0046] In some embodiments of the present disclosure, the electrolyte further includes 0.1 wt% to 10 wt% of an auxiliary additive, preferably 0.1 wt%, 0.5 wt%, 1 wt%, 3 wt%, 5 wt%, 10 wt%, or any value between 0.1 wt% and 10 wt%.

[0047] In some embodiments of the present disclosure, the auxiliary additive includes: any one or more of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, 1,3-(1-propylene) sultone, methylene disulfonate, succinonitrile, adiponitrile, lithium bis(trimethylsilyl)imide, vinyl sulfate, tris(trimethylsilane) borate, tris(trimethylsilane) phosphite or tris(trimethylsilane) phosphate. The auxiliary additive can form a film on the positive and negative electrodes and inhibit the continuous decomposition of the electrolyte.

[0048] In some embodiments of the present disclosure, the electrolyte further includes 60 wt% to 90 wt% of a solvent, which may be 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, or any value between 60 wt% and 90 wt%.

[0049] In some embodiments of the present disclosure, the solvent includes: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methylpropyl carbonate, 1,4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, ethyl butyrate, and a mixture of one or more of their halogenated derivatives.

[0050] In some embodiments of the present disclosure, the secondary battery further includes a positive electrode and a negative electrode, and the positive electrode and / or the negative electrode include alkali metal aluminum phosphate.

[0051] The general formula of the alkali metal aluminum phosphate is: MAlPO4(OH) x F 1-x ;

[0052] Wherein, 0≤x<1; M is an alkali metal Li or Na.

[0053] In some embodiments of the present disclosure, the alkali metal phosphate is selected from LiAlPO4F, LiAlPO4(OH) 0.9 F 0.1 、LiAlPO4(OH) 0.5 F 0.5 、NaAlPO4F、NaAlPO4(OH) 0.9 F 0.1 、NaAlPO4(OH) 0.5 F 0.5 .

[0054] In some embodiments of the present disclosure, the positive electrode includes a current collector and a positive electrode membrane, and the positive electrode membrane is prepared from a positive electrode active material, a conductive agent, a binder and alkali metal phosphate. The mass percentage of the alkali metal phosphate in the positive electrode membrane is 0.1% to 5%, which can be 0.1%, 0.3%, 0.5%, 1.0%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any value between 0.1% and 5%.

[0055] The negative electrode includes a current collector and a negative electrode membrane, and the negative electrode membrane is prepared from a negative electrode active material, a conductive agent, a binder and alkali metal phosphate aluminum stone. The mass percentage of the alkali metal phosphate aluminum stone in the negative electrode membrane is 0.1% to 5%, and can be 0.1%, 0.3%, 0.5%, 1.0%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any value between 0.1% and 5%.

[0056] The present disclosure has no particular limitation on the preparation methods of the positive electrode and the negative electrode, and any preparation method known to those skilled in the art may be used.

[0057] In the present disclosure, alkali metal phosphate is added to the slurry of the positive and negative electrodes in the form of solid or slurry. The positive electrode uses a solid or non-aqueous slurry, and the negative electrode uses a solid or water slurry. After the electrode is dried, the alkali metal phosphate is evenly distributed in the electrode.

[0058] The secondary battery provided in the present disclosure further includes a separator. The present disclosure does not particularly limit the type of the separator, and any separator known to those skilled in the art may be used.

[0059] In some embodiments of the present disclosure, the secondary battery may be a lithium ion battery or a sodium ion battery.

[0060] The secondary battery provided by the present disclosure uses functional additives containing -CN and B in the electrolyte to dissolve alkali metal aluminum phosphate from the positive and negative electrodes, leaving gaps to form porous electrodes, thereby improving the battery's rate performance; the alkali metal aluminum phosphate dissolved from the positive electrode forms AlF, Li3PO4, and Na3PO4 at the positive electrode, stabilizing the electrode structure, inhibiting the dissolution of transition metal ions, and preventing continuous side reactions of the electrolyte; the metal oxide coating on the surface of the positive electrode material can serve as a physical barrier, inhibit side reactions, remove HF, prevent chemical corrosion of the electrolyte, reduce transition metal dissolution, improve electronic and ionic conductivity, chemically modify the surface, promote interfacial ion charge transfer, stabilize the structure, and reduce phase change stress.

[0061] The alkali metal phosphate dissolved from the negative electrode forms LiF and NaF at the negative electrode, which reduces the consumption of active metals, improves the initial efficiency, inhibits dendrites, and prevents the continuous side reactions of the electrolyte. Among them, LiF has lower electronic conductivity, larger band gap, higher negative electrode electrochemical stability, low Li + Diffusion energy barrier, high interfacial energy, and Li + The weaker binding force, the SEI rich in lithium fluoride (LiF) can inhibit the growth of dendrites on the negative electrode.

[0062] The following is further explained with reference to specific embodiments and comparative examples.

[0063] Example 1

[0064] Synthesis of additives:

[0065] (1) Raw material pretreatment: Tetrahydrofuran is heated and distilled, and simultaneously dried and dehydrated with metallic sodium to make the tetrahydrofuran purity greater than 99.9% and the water content less than 50 ppm; triethylamine is heated and fractionated to obtain a colorless and transparent triethylamine solution, and then activated 4A molecular sieves are added to make the water content of triethylamine (Et3N) less than 50 ppm; 2-thiopheneboric acid and chloroacetonitrile are added to activated 4A molecular sieves respectively to make the water content of 2-thiopheneboric acid and chloroacetonitrile less than 50 ppm.

[0066] (2) The preparation reaction of the additive of this embodiment was carried out under nitrogen. After the reactor was filled with nitrogen, 50 mL of tetrahydrofuran was added;

[0067] (3) 0.2 mol of chloroacetonitrile and 0.2 mol of triethylamine were added to the reactor in sequence;

[0068] (4) Maintaining the reaction system temperature at 0°C-5°C, slowly add 0.1 mol of 2-thiopheneboronic acid while stirring continuously, and continue stirring at room temperature for 12 hours;

[0069] (5) Filter and remove the white precipitate of triethylamine hydrochloride;

[0070] (6) The low-boiling-point triethylamine, 2-thiopheneboric acid, and tetrahydrofuran in the filtrate are removed by repeated reduced-pressure distillation, and the additive A is obtained after washing.

[0071] The washed product was dissolved in dimethyl sulfoxide (DMSO) and subjected to H NMR analysis and structural characterization. The results were: GC-MS (m / z): calcd. for C8H7BN2O2S[M+1]+, 206.03, found 206.01.

[0072] Battery production:

[0073] Select LiNi 0.6 Co 0.2 Mn 0.2 O2 positive electrode material, the positive electrode material LiNi 0.6 Co 0.2 Mn 0.2 O2, LiAlPO4F, carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 95.4:2:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to produce the required positive electrode sheet.

[0074] Artificial graphite was selected as the negative electrode material. Graphite, CMC, carbon nanotubes (CNTs), and binder styrene-butadiene rubber (SBR) were evenly mixed in a mass ratio of 95.3:1.3:1.4:2.0, coated on a copper foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0075] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0076] Electrolyte preparation:

[0077] In a glove box filled with argon with a moisture content of less than 0.1 ppm and an oxygen content of less than 0.1 ppm, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1, and 0.5 wt% of a functional additive was added. LiPF6 concentration is 1 mol·L -1 , and then 0.5 wt% of fluoroethylene carbonate (FEC) was added.

[0078] Example 2

[0079] Synthesis of additives:

[0080] (1) Raw material pretreatment: Tetrahydrofuran is heated and distilled, and simultaneously dried and dehydrated with metallic sodium to make the purity of tetrahydrofuran greater than 99.9% and the water content less than 50 ppm; triethylamine is heated and fractionated to obtain a colorless and transparent triethylamine solution, and then activated 4A molecular sieves are added to make the water content of triethylamine (Et3N) less than 50 ppm; cyclohexene-1-ylboronic acid and chloroacetonitrile are added to activated 4A molecular sieves respectively to make the water content of cyclohexene-1-ylboronic acid and chloroacetonitrile less than 50 ppm.

[0081] (2) The preparation reaction of the additive of this example was carried out in nitrogen. After the reactor was filled with nitrogen, 50 mL of tetrahydrofuran was added;

[0082] (3) 0.2 mol of chloroacetonitrile and 0.2 mol of triethylamine were added to the reactor in sequence;

[0083] (4) Maintaining the reaction system temperature at 0°C-5°C, slowly add 0.1 mol of cyclohexene-1-ylboronic acid while stirring continuously, and continue stirring at room temperature for 12 hours;

[0084] (5) Filter and remove the white precipitate of triethylamine hydrochloride;

[0085] (6) The low-boiling-point triethylamine, cyclohexene-1-ylboronic acid, and tetrahydrofuran in the filtrate are removed by repeated reduced-pressure distillation, and the additive B is obtained after washing.

[0086] The washed product was dissolved in dimethyl sulfoxide (DMSO) and then subjected to H NMR analysis and structural characterization. The results were as follows: GC-MS (m / z): calcd.for C 10 H 13 BN2O2[M+1]+,204.11, found 204.14.

[0087] Battery production:

[0088] Select LiNi 0.6 Co 0.2 Mn 0.2 O2 positive electrode material, the positive electrode material LiNi 0.6 Co 0.2 Mn 0.2 O2, LiAlPO4(OH) 0.9 F 0.1 , carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 96.4:1:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to obtain the required positive electrode sheet.

[0089] Artificial graphite was selected as the negative electrode material. Graphite, CMC, carbon nanotubes (CNTs), and binder styrene-butadiene rubber (SBR) were evenly mixed in a mass ratio of 95.3:1.3:1.4:2.0, coated on a copper foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0090] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0091] Electrolyte preparation:

[0092] In a glove box filled with argon with a moisture content of less than 0.1 ppm and an oxygen content of less than 0.1 ppm, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1, and 0.5 wt% of a functional additive was added. LiPF6 concentration is 1 mol·L -1 , and then 0.5 wt% of lithium bis(fluorosulfonyl)imide (LiFSI) was added.

[0093] Example 3

[0094] Synthesis of additives:

[0095] (1) Raw material pretreatment: Tetrahydrofuran is heated and distilled, and simultaneously dried and dehydrated with metallic sodium to make the purity of tetrahydrofuran greater than 99.9% and the water content less than 50 ppm; triethylamine is heated and fractionated to obtain a colorless and transparent triethylamine solution, and then activated 4A molecular sieves are added to make the water content of triethylamine (Et3N) less than 50 ppm; phenylboric acid and chloroacetonitrile are added to activated 4A molecular sieves respectively to make the water content of phenylboric acid and chloroacetonitrile less than 50 ppm.

[0096] (2) The preparation reaction of the additive of this embodiment was carried out in nitrogen. After the reactor was filled with nitrogen, 50 mL of tetrahydrofuran was added;

[0097] (3) 0.2 mol of chloroacetonitrile and 0.2 mol of triethylamine were added to the reactor in sequence;

[0098] (4) Maintaining the reaction system temperature at 0°C-5°C, slowly add 0.1 mol of phenylboric acid while stirring continuously, and continue stirring at room temperature for 12 hours;

[0099] (5) Filter and remove the white precipitate of triethylamine hydrochloride;

[0100] (6) The low-boiling-point triethylamine, phenylboric acid, and tetrahydrofuran in the filtrate are removed by repeated reduced-pressure distillation, and the additive C is obtained after washing.

[0101] The washed product was dissolved in dimethyl sulfoxide (DMSO) and then subjected to H NMR analysis and structural characterization. The results were as follows: GC-MS (m / z): calcd.for C 10 H9BN2O2[M+1]+,200.08,found 200.12.

[0102] Battery production:

[0103] Select LiNi 0.6 Co 0.2 Mn 0.2 O2 positive electrode material, the positive electrode material LiNi 0.6 Co 0.2 Mn 0.2 O2, LiAlPO4(OH) 0.5 F 0.5 , carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 96.9:0.5:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to obtain the required positive electrode sheet.

[0104] Artificial graphite was selected as the negative electrode material. Graphite, CMC, carbon nanotubes (CNTs), and binder styrene-butadiene rubber (SBR) were evenly mixed in a mass ratio of 95.3:1.3:1.4:2.0, coated on a copper foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0105] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0106] Electrolyte preparation:

[0107] In a glove box filled with argon with a moisture content of less than 0.1 ppm and an oxygen content of less than 0.1 ppm, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1, and 0.5 wt% of a functional additive was added. LiPF6 concentration is 1 mol·L -1 , and then 0.5 wt% of diethyl sulfate (DTD) was added.

[0108] Example 4

[0109] Synthesis of additives:

[0110] (1) Raw material pretreatment: Tetrahydrofuran is heated and distilled, and simultaneously dried and dehydrated with metallic sodium to make the purity of tetrahydrofuran greater than 99.9% and the water content less than 50 ppm; triethylamine is heated and fractionated to obtain a colorless and transparent triethylamine solution, and then activated 4A molecular sieves are added to make the water content of triethylamine (Et3N) less than 50 ppm; n-propylboric acid and chloroacetonitrile are added to activated 4A molecular sieves respectively to make the water content of n-propylboric acid and chloroacetonitrile less than 50 ppm.

[0111] (2) The preparation reaction of the additive of this example was carried out in nitrogen. After the reactor was filled with nitrogen, 50 mL of tetrahydrofuran was added;

[0112] (3) 0.2 mol of chloroacetonitrile and 0.2 mol of triethylamine were added to the reactor in sequence;

[0113] (4) Maintaining the reaction system temperature at 0°C-5°C, slowly add 0.1 mol of n-propylboric acid while stirring continuously, and continue stirring at room temperature for 12 hours;

[0114] (5) Filter and remove the white precipitate of triethylamine hydrochloride;

[0115] (6) The low-boiling-point triethylamine, n-propylboric acid, and tetrahydrofuran in the filtrate are removed by repeated reduced-pressure distillation, and the additive D is obtained after washing.

[0116] The washed product was dissolved in dimethyl sulfoxide (DMSO) and then subjected to H NMR spectrum analysis and structural characterization. The results were as follows: GC-MS (m / z): calcd.for C7H 11 BN2O2[M+1]+,166.09,found 166.11.

[0117] The positive electrode of sodium ion battery: choose Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2 is the positive electrode material, and the positive electrode material Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2, NaAlPO4F, carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 97.2:0.2:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to produce the required positive electrode sheet.

[0118] Negative electrode of sodium ion battery: hard carbon is selected as the negative electrode material, and hard carbon, sodium carboxymethyl cellulose (CMC), carbon nanotubes (CNTs), and styrene-butadiene rubber (SBR) are evenly mixed in a ratio of 95.8:1.4:0.8:2.0, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0119] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0120] Electrolyte preparation:

[0121] In a glove box filled with argon with a moisture content of less than 0.1 ppm and an oxygen content of less than 0.1 ppm, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1, and 0.5 wt% of a functional additive was added. LiPF6 concentration is 1 mol·L -1 , and then 0.5 wt% of 1,3-(1-propylene)sultone (PS) was added.

[0122] Example 5

[0123] Synthesis of additives:

[0124] (1) Raw material pretreatment: Tetrahydrofuran is heated and distilled, and simultaneously dried and dehydrated with metallic sodium to make the purity of tetrahydrofuran greater than 99.9% and the water content less than 50 ppm; triethylamine is heated and fractionated to obtain a colorless and transparent triethylamine solution, and then activated 4A molecular sieves are added to make the water content of triethylamine (Et3N) less than 50 ppm; 1-methylpyrimidine-4-boric acid and chloroacetonitrile are added to activated 4A molecular sieves respectively to make the water content of 1-methylpyrimidine-4-boric acid and chloroacetonitrile less than 50 ppm.

[0125] (2) The preparation reaction of the additive of this example was carried out in an inert atmosphere. After the reactor was filled with inert gas, 50 mL of tetrahydrofuran was added;

[0126] (3) 0.2 mol of chloroacetonitrile and 0.2 mol of triethylamine were added to the reactor in sequence;

[0127] (4) Maintaining the reaction system temperature at 0°C-5°C, slowly add 0.1 mol of 1-methylpyrimidine-4-boronic acid while stirring continuously, and continue stirring at room temperature for 12 hours;

[0128] (5) Filter and remove the white precipitate of triethylamine hydrochloride;

[0129] (6) The low-boiling-point triethylamine, 1-methylpyrimidine-4-boric acid, and tetrahydrofuran in the filtrate were removed by repeated reduced-pressure distillation, and the additive E was obtained after washing.

[0130] The washed product was dissolved in dimethyl sulfoxide (DMSO) and then subjected to H NMR analysis and structural characterization. The results were as follows: GC-MS (m / z): calcd.for C 10 H 16 BN3O2[M+1]+,221.13, found 221.08.

[0131] Battery production:

[0132] The positive electrode of sodium ion battery: choose Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2 is the positive electrode material, and the positive electrode material Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2, NaAlPO4(OH) 0.9 F 0.1, carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 97.2:0.2:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to obtain the required positive electrode sheet.

[0133] Negative electrode of sodium ion battery: hard carbon is selected as the negative electrode material, and hard carbon, sodium carboxymethyl cellulose (CMC), carbon nanotubes (CNTs), and styrene-butadiene rubber (SBR) are evenly mixed in a ratio of 95.8:1.4:0.8:2.0, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0134] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0135] Electrolyte preparation:

[0136] In a glove box filled with argon with a moisture content of less than 0.1 ppm and an oxygen content of less than 0.1 ppm, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1, and 0.5 wt% of a functional additive was added. LiPF6 concentration is 1 mol·L -1 , and then 0.5 wt% of methylene methanedisulfonate (MMDS) was added.

[0137] Example 6

[0138] The positive electrode of sodium ion battery: choose Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2 is the positive electrode material, and the positive electrode material Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2, NaAlPO4(OH) 0.5 F 0.5 , carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 97.2:0.2:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to obtain the required positive electrode sheet.

[0139] Negative electrode of sodium ion battery: hard carbon is selected as the negative electrode material, hard carbon, NaAlPO4(OH) 0.5 F 0.5, sodium carboxymethyl cellulose (CMC), carbon nanotubes (CNTs), and styrene-butadiene rubber (SBR) are evenly mixed in a ratio of 95.7:0.1:1.4:0.8:2.0, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0140] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0141] Electrolyte preparation:

[0142] In a glove box filled with argon and containing less than 0.1 ppm of water and less than 0.1 ppm of oxygen, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1. The NaPF6 concentration was 1 mol·L -1 , add 0.5wt% of functional additives Then 0.5 wt% of vinylene carbonate (VC) was added.

[0143] Comparative Example 1

[0144] Battery production:

[0145] Select LiNi 0.6 Co 0.2 Mn 0.2 O2 positive electrode material, the positive electrode material LiNi 0.6 Co 0.2 Mn 0.2 O2, carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 97.4:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to produce the required positive electrode sheet.

[0146] Artificial graphite was selected as the negative electrode material. Graphite, CMC, carbon nanotubes (CNTs), and binder styrene-butadiene rubber (SBR) were evenly mixed in a mass ratio of 95.3:1.3:1.4:2.0, coated on a copper foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0147] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0148] Electrolyte preparation:

[0149] In a glove box filled with argon and containing less than 0.1 ppm of water and less than 0.1 ppm of oxygen, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1. The LiPF6 concentration was 1 mol·L -1 , and then 0.5 wt% of fluoroethylene carbonate (FEC) was added.

[0150] Comparative Example 2

[0151] The positive electrode of sodium ion battery: choose Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2 is the positive electrode material, and the positive electrode material Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2, carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 97.4:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to produce the required positive electrode sheet.

[0152] Negative electrode of sodium ion battery: hard carbon is selected as the negative electrode material, and hard carbon, sodium carboxymethyl cellulose (CMC), carbon nanotubes (CNTs), and styrene-butadiene rubber (SBR) are evenly mixed in a ratio of 95.8:1.4:0.8:2.0, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0153] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0154] Electrolyte preparation:

[0155] In a glove box filled with argon and containing less than 0.1 ppm of water and less than 0.1 ppm of oxygen, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1. The NaPF6 concentration was 1 mol·L -1 , and then 0.5 wt% of vinylene carbonate (VC) was added.

[0156] Comparative Example 3

[0157] Battery production:

[0158] Select LiNi 0.6 Co 0.2 Mn 0.2O2 positive electrode material, the positive electrode material LiNi 0.6 Co 0.2 Mn 0.2 O2, LiAlPO4F, carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 95.4:2:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to produce the required positive electrode sheet.

[0159] Artificial graphite was selected as the negative electrode material. Graphite, CMC, carbon nanotubes (CNTs), and binder styrene-butadiene rubber (SBR) were evenly mixed in a mass ratio of 95.3:1.3:1.4:2.0, coated on a copper foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0160] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0161] Electrolyte preparation:

[0162] In a glove box filled with argon and containing less than 0.1 ppm of water and less than 0.1 ppm of oxygen, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1. The LiPF6 concentration was 1 mol·L -1 , and then 0.5 wt% of fluoroethylene carbonate (FEC) was added.

[0163] Comparative Example 4

[0164] The positive electrode of sodium ion battery: choose Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2 is the positive electrode material, and the positive electrode material Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2, NaAlPO4F, carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 97.2:0.2:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to produce the required positive electrode sheet.

[0165] Negative electrode of sodium ion battery: hard carbon is selected as the negative electrode material, and hard carbon, sodium carboxymethyl cellulose (CMC), carbon nanotubes (CNTs), and styrene-butadiene rubber (SBR) are evenly mixed in a ratio of 95.8:1.4:0.8:2.0, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0166] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0167] Electrolyte preparation:

[0168] In a glove box filled with argon and containing less than 0.1 ppm of water and less than 0.1 ppm of oxygen, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1. The NaPF6 concentration was 1 mol·L -1 , and then 0.5 wt% of vinylene carbonate (VC) was added.

[0169] Comparative Example 5

[0170] Select LiNi 0.6 Co 0.2 Mn 0.2 O2 positive electrode material, the positive electrode material LiNi 0.6 Co 0.2 Mn 0.2 O2, LiAlPO4F, carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 95.4:2:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to produce the required positive electrode sheet.

[0171] Artificial graphite was selected as the negative electrode material. Graphite, CMC, carbon nanotubes (CNTs), and binder styrene-butadiene rubber (SBR) were evenly mixed in a mass ratio of 95.3:1.3:1.4:2.0, coated on a copper foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0172] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0173] Electrolyte preparation:

[0174] In a glove box filled with argon with a moisture content of less than 0.1 ppm and an oxygen content of less than 0.1 ppm, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1, and 0.5 wt% of a functional additive was added. LiPF6 concentration is 1 mol·L -1 , and then 0.5 wt% of fluoroethylene carbonate (FEC) was added.

[0175] Comparative Example 6

[0176] The positive electrode of sodium ion battery: choose Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2 is the positive electrode material, and the positive electrode material Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2, NaAlPO4F, carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) are evenly mixed in a mass ratio of 97.2:0.2:1.3:1.3, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to produce the required positive electrode sheet.

[0177] Negative electrode of sodium ion battery: hard carbon is selected as the negative electrode material, and hard carbon, sodium carboxymethyl cellulose (CMC), carbon nanotubes (CNTs), and styrene-butadiene rubber (SBR) are evenly mixed in a ratio of 95.8:1.4:0.8:2.0, coated on an aluminum foil current collector, dried in an oven, and rolled on a roller press to obtain the required negative electrode sheet.

[0178] A ceramic-coated polyethylene (PE) film was selected as the isolation membrane with a thickness of 2μm Al2O3+9μm PE+2μm Al2O3. The electrode was made into a 2Ah small soft-pack battery by lamination for electrolyte testing.

[0179] Electrolyte preparation:

[0180] In a glove box filled with argon and containing less than 0.1 ppm of water and less than 0.1 ppm of oxygen, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed in a mass ratio of 1:1:1. The NaPF6 concentration was 1 mol·L -1 , add 0.5wt% of functional additives Then 0.5 wt% of vinylene carbonate (VC) was added.

[0181] Lithium battery test conditions:

[0182] The charge and discharge voltage window is 2.75-4.3V; 2C, 1000 cycles; 5C rate discharge; 10C rate discharge.

[0183] Comparative Example 1, Comparative Example 3, Comparative Example 5, Example 1, Example 2, and Example 3 were tested using lithium batteries. The specific results are shown in Table 1 below.

[0184] Sodium battery test conditions:

[0185] The charge and discharge voltage window of the sodium battery is 1.5-4.0V; 2C, 1000 cycles; 5C rate discharge; 10C rate discharge.

[0186] Comparative Example 2, Comparative Example 4, Comparative Example 6, Example 4, Example 5, and Example 6 were tested using sodium batteries. The specific results are shown in Table 2 below.

[0187] Table 1

[0188] Table 2

[0189] It can be seen from Comparative Examples 1 and 3, and Comparative Examples 2 and 4 that the electrochemical performance is not significantly improved by adding alkali metal phosphate aluminum stone to the positive and negative electrodes; from Comparative Examples 1 and 5, the positive and negative electrodes are mixed with alkali metal phosphate aluminum stone, and the electrolyte contains only B additives, and the electrochemical performance is not significantly improved; from Comparative Examples 2 and 6, the positive and negative electrodes are mixed with alkali metal phosphate aluminum stone, and the electrolyte contains only -CN additives, and the electrochemical performance is not significantly improved; from Comparative Examples 1, 3, 5 and Examples 1, 2 and 3, as well as Comparative Examples 2, 4 and 6 and Examples 4, 5 and 6, it is found that the positive and negative electrodes are mixed with alkali metal phosphate aluminum stone, and the electrolyte contains both B and -CN additives, which have significant improvements in the first efficiency, 2C cycle 1000 circles, 5C rate discharge, 10C rate discharge, and internal resistance of lithium batteries and sodium batteries.

[0190] The secondary battery disclosed herein comprises a positive electrode, a negative electrode, a separator and an electrolyte, wherein the positive electrode and / or the negative electrode comprises alkali metal aluminum phosphate MAlPO4(OH) x F 1-x , wherein 0≤x<1; M is an alkali metal Li or Na, the electrolyte includes a functional additive, and the functional additive is selected from a compound having a structure shown in Formula I; wherein R1, R2, and R3 are independently selected from a hydrocarbon group, a hydrocarbon group substituted by B, N, F, Si, P, S, Cl, Br, or I, an alkoxy group, an aryl group, or a heteroaryl group. In the present disclosure, the B atom in the functional additive added to the electrolyte is sp 2In the covalent molecule formed by hybridization, the remaining empty orbital can act as a Lewis acid to accept an external lone pair of electrons to form a sp 3 The fluorine atom in the alkali metal phosphate has a strong electronegativity and can form a complex FB with the B atom through the action of the electron cloud; the -CN in the functional additive added to the electrolyte is an unsaturated group with an electron-withdrawing effect, which can complex with metal ions to form a complex; the functional additive contains both cyano and B atoms, which can simultaneously combine with the fluorine ions and metal ions of the alkali metal phosphate, causing the alkali metal phosphate to dissociate, thereby increasing the solubility of the alkali metal phosphate, dissolving in the electrolyte, and forming a porous structure in the electrode. Under the action of the electric field, the dissolved alkali metal phosphate forms AlF and Li3PO at the positive electrode. 4、 Na3PO4 forms LiF and NaF at the negative electrode, thereby improving the battery's initial efficiency, rate and cycle performance. Industrial Applicability

[0191] The present disclosure provides a secondary battery. The secondary battery of the present disclosure comprises a positive electrode, a negative electrode, a separator and an electrolyte, wherein the positive electrode and / or the negative electrode comprises alkali metal aluminum phosphate MAlPO4(OH) x F 1-x The electrolyte includes B functional additives, which improves the battery's initial efficiency, rate and cycle performance.

Claims

1. A secondary battery, characterized in that: The invention comprises a positive electrode, a negative electrode, a separator and an electrolyte, wherein the positive electrode and / or the negative electrode comprises alkali metal aluminum phosphate MAlPO4(OH) x F 1-x , wherein 0≤x<1; M is an alkali metal Li or Na, and the electrolyte includes a functional additive, and the functional additive is selected from any one of the compounds having the structures shown in Formulas I, II, and III; Wherein, R1, R2, and R3 are independently selected from a hydrocarbon group, a hydrocarbon group substituted by B, N, F, Si, P, S, Cl, Br, or I, an alkoxy group, an aryl group, or a heteroaryl group.

2. The secondary battery according to claim 1, characterized in that: The hydrocarbon group is C a H 2a+1 , C b H 2b-1 , C c H 2c-3 , where 0<a≤6, 0<b≤6, 0<c≤6; Alkoxy is C a H 2a+1 O.C b H 2b-1 O.C c H 2c-3 O, where 0<a≤6, 0<b≤6, 0<c≤6; The aryl group includes any one of phenyl, anthracenyl, naphthyl or biphenyl; The heteroaryl group has 1 to 20 carbon atoms, including 1 to 3 heteroatoms selected from O, S, P and N.

3. The secondary battery according to claim 1, characterized in that: The heteroaryl group includes any one of pyridyl, indolyl, pyrrolyl, imidazolyl, thienyl, furyl, 1,2-thiazolyl, 1,3-thiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, thiadiazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, pyridyl, pyrazinyl, pyrimidinyl, 1,3,5-triazinyl, 1,2,4-triazinyl, 1,2,3-triazinyl, isoindolyl, benzimidazolyl, naphthioimidazolyl, phenanthioimidazolyl, benzotriazolyl, benzoxazolyl, naphthioxazolyl, phenanthioxazolyl, benzothiadiazolyl, benzotriazolyl, quinolyl, isoquinolyl, benzopyrazinyl, benzothienyl, benzofuranyl, benzopyrrolyl, carbazolyl, and naphthiodiazolyl.

4. The secondary battery according to claim 1, characterized in that: The functional additive is selected from one or more of the following compounds:

5. The secondary battery according to claim 1, characterized in that: The electrolyte comprises: 0.1 wt% to 20 wt% of an electrolyte salt; 0.1wt% to 10wt% of functional additives; 0.1wt% to 10wt% of auxiliary additives; 60 wt% to 90 wt% of solvent.

6. The secondary battery according to claim 5, characterized in that: The electrolyte salt includes one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate, lithium bisoxalate borate, lithium difluorooxalate borate, bis(trifluoromethylsulfonyl imide) lithium and bis(fluorosulfonyl imide) lithium, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium difluorophosphate, sodium bisoxalate borate, sodium difluorooxalate borate, bis(trifluoromethylsulfonyl imide) sodium and bis(fluorosulfonyl imide) sodium; The solvent includes: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, 1,4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, ethyl butyrate, and a mixture of one or more of their halogenated derivatives; The auxiliary additives include any one or more of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, 1,3-(1-propylene) sultone, methylene disulfonate, succinonitrile, adiponitrile, lithium bis(trimethylsilyl)imide, vinyl sulfate, tris(trimethylsilane)borate, tris(trimethylsilane)phosphite or tris(trimethylsilane)phosphate.

7. The secondary battery according to claim 1, characterized in that: The alkali metal phosphate is selected from LiAlPO4F, LiAlPO4(OH) 0.9 F 0.1 、LiAlPO4(OH) 0.5 F 0.5 、NaAlPO4F、NaAlPO4(OH) 0.9 F 0.1 、NaAlPO4(OH) 0.5 F 0.5 .

8. The secondary battery according to claim 1, characterized in that: The positive electrode comprises a current collector and a positive electrode membrane. The positive electrode membrane is prepared from a positive electrode active material, a conductive agent, a binder and alkali metal phosphate aluminum stone. The mass percentage of the alkali metal phosphate aluminum stone in the positive electrode membrane is 0.1% to 5%.

9. The secondary battery according to claim 1, characterized in that: The negative electrode comprises a current collector and a negative electrode membrane. The negative electrode membrane is prepared from a negative electrode active material, a conductive agent, a binder and alkali metal phosphate aluminum stone. The mass percentage of the alkali metal phosphate aluminum stone in the negative electrode membrane is 0.1% to 5%.

10. The secondary battery according to claim 1, characterized in that: The secondary battery is a lithium ion battery or a sodium ion battery.

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