WO2023072110A1

WO2023072110A1 - Battery

Info

Publication number: WO2023072110A1
Application number: PCT/CN2022/127500
Authority: WO
Inventors: 母英迪; 张祖来; 王海; 李素丽
Original assignee: 珠海冠宇电池股份有限公司
Priority date: 2021-10-25
Filing date: 2022-10-25
Publication date: 2023-05-04
Also published as: CN114024035B; CN114024035A

Abstract

Disclosed in the present disclosure is a battery. The battery comprises a positive electrode plate, a negative electrode plate, a separator, and a non-aqueous electrolyte; the non-aqueous electrolyte comprises a non-aqueous organic solvent and an additive; the non-aqueous organic solvent at least comprises ethyl propionate; the additive comprises 1,3-propanesultone and lithium difluoro(oxalato)borate; the separator comprises a substrate, a heat-resistant layer, and a gluing layer; the heat-resistant layer is oppositely arranged on the two surfaces of the substrate, and the gluing layer is arranged on the heat-resistant layer; and a ratio of the percentage by mass of ethyl propionate in the non-aqueous electrolyte to the percentage by mass of HFP in a hexafluoropropylene-vinylidene fluoride copolymer in an adhesive of the gluing layer is 0.2-60. According to the present invention, the battery is manufactured by means of the synergistic effect of the separator and the electrolyte after a positive electrode material and a negative electrode material are used in combination, and thus, the cycle service life of the battery can be effectively prolonged, the cycle expansion of the battery can further be effectively reduced, and the low-temperature performance of the battery is considered.

Description

a battery

technical field

The disclosure belongs to the technical field of batteries, and in particular relates to a battery.

Background technique

In recent years, lithium-ion batteries have been widely used in smartphones, tablet computers, smart wearables, power tools, and electric vehicles. With the wide application of lithium-ion batteries, consumers' demands on the service life and application environment of lithium-ion batteries continue to increase, which requires lithium-ion batteries to have a long cycle life while taking into account high and low temperature performance.

At present, there are safety hazards in the use of lithium-ion batteries. For example, when the battery is used for a long time and the ambient temperature is too high, the battery will have problems such as lithium deposition and increased thickness expansion, which will easily lead to serious safety accidents, such as fire. Even explode. At the same time, it is difficult to discharge the battery when it is used in a lower ambient temperature, and then the automatic shutdown will affect the use. The main reason for the above problems is that the structure of the active material is unstable under high temperature and high voltage. Metal ions are easily dissolved from the positive electrode and deposited on the surface of the negative electrode. The SEI film structure leads to the continuous increase of the negative electrode impedance and battery thickness, which in turn causes the battery temperature to continue to rise and cause safety accidents; on the other hand, the battery impedance increases at low temperatures, and the high SEI film impedance affects low-temperature discharge.

Based on this situation, there is an urgent need to develop high-voltage lithium-ion batteries with long cycle life and low expansion. For example, the cycle performance can be improved by adding negative electrode film-forming agents to the electrolyte, but the use of negative electrode film-forming agents often leads to serious deterioration of battery low-temperature performance. . Therefore, the ability to develop high-voltage lithium-ion batteries with long cycle life and low expansion without affecting the low-temperature performance of the battery is the current priority.

Contents of the invention

The purpose of this disclosure is to solve the problems of potential safety hazards in the use process of existing batteries, failure to balance battery cycle life and low temperature performance, and provide a battery with high voltage, long cycle life and low expansion performance .

In order to achieve the above purpose, the present disclosure adopts the following technical solutions:

A battery comprising a positive electrode sheet, a negative electrode sheet, a separator placed between the positive electrode sheet and the negative electrode sheet, and a non-aqueous electrolyte;

The non-aqueous electrolytic solution includes a non-aqueous organic solvent and an additive, wherein the non-aqueous organic solvent includes at least ethyl propionate; the additive includes 1,3-propane sultone and lithium difluorooxalate borate;

The diaphragm includes a base material, a heat-resistant layer and a glue layer, the heat-resistant layer is relatively arranged on both sides of the base material, and the glue layer is arranged on the heat-resistant layer; the glue layer includes Adhesive, including hexafluoropropylene-vinylidene fluoride copolymer in the adhesive;

The ratio of the mass proportion of ethyl propionate in the non-aqueous electrolyte to the mass proportion of hexafluoropropylene (HFP) in the hexafluoropropylene-vinylidene fluoride copolymer is 0.2 to 60, exemplarily 0.26, 0.5, 1, 2.4, 5.8, 9.2, 11.3, 13.7, 15, 20, 30, 35, 36.7, 40, 50, 60 or any point value within the range composed of two pairs of the above point values. .

According to the present invention, the change rate of the adhesive force between the adhesive layer of the separator and the positive and negative electrodes is within 10% in the first 100 cycles (including the 100th cycle) of the battery cycle, that is, when the battery cycle is ≤ 100 cycles ( For example, when the battery is cycled for 1 week, 5 weeks, 10 weeks, 50 weeks or 100 cycles), the change rate of the adhesive force between the adhesive layer and the positive electrode sheet or the negative electrode sheet is within 10%.

In one embodiment, the ratio of the mass proportion of ethyl propionate in the non-aqueous electrolyte to the mass proportion of hexafluoropropylene in the hexafluoropropylene-vinylidene fluoride copolymer is 0.5-35.

In one embodiment, the mass proportion of hexafluoropropylene in the hexafluoropropylene-vinylidene fluoride copolymer is 1wt.% to 25wt.%, preferably 1.5wt.% to 15wt.%, exemplarily 1wt. %, 1.5wt.%, 2wt.%, 2.5wt.%, 3wt.%, 3.5wt.%, 5wt.%, 6.5wt.%, 9wt.%, 10wt.%, 15wt.%, 20wt.%, 23wt.%, 25wt.%, or any value within the range composed of the aforementioned pairwise values.

In one embodiment, the hexafluoropropylene-vinylidene fluoride copolymer is, for example, polyvinylidene fluoride-hexafluoropropylene copolymer.

The "polyvinylidene fluoride-hexafluoropropylene copolymer" refers to polyvinylidene fluoride modified by hexafluoropropylene.

In one embodiment, the number average molecular weight of the polyvinylidene fluoride (PVDF) is 500,000 Da to 2 million Da, exemplarily 500,000 Da, 600,000 Da, 700,000 Da, 800,000 Da, and 1 million Da , 2,000,000 Da or any point value within the range composed of two pairs of the above point values.

In one example, in the hexafluoropropylene-vinylidene fluoride copolymer, the sum of the molecular weights of vinylidene fluoride units is 500,000 Da to 2 million Da, exemplarily 500,000 Da, 600,000 Da, and 700,000 Da .

In one embodiment, in the nonaqueous organic solvent, the quality of ethyl propionate is 5wt.%～60wt.% of the total mass of the nonaqueous electrolytic solution, (that is, the amount of ethyl propionate in the nonaqueous electrolytic solution % by mass) is 5wt.%～60wt.%; preferably 10wt.%～40wt.%, exemplarily 5wt.%, 6wt.%, 10wt.%, 12wt.%, 15wt.%, 20wt.%, 22wt.%, 23wt.%, 25wt.%, 30wt.%, 34wt.%, 35wt.%, 38wt.%, 40wt.%, 48wt.%, 50wt.%, 55wt.%, 60wt.% or the above Any point value within a range consisting of two pairs of values.

In one embodiment, the additives used can be prepared by methods known in the art, or purchased from commercial channels.

In one embodiment, in the non-aqueous electrolyte, the mass proportion of the 1,3-propane sultone is 0.5wt.%～5wt.%, preferably 2～4wt.%, exemplarily 1wt.%, 2wt.%, 3wt.%, 3.5wt.%, 4wt.%, 4.5wt.%, 5wt.%, or any value within the range composed of the aforementioned pairwise values.

In one embodiment, in the non-aqueous electrolyte, the mass proportion of lithium difluorooxalate borate is 0.01wt.%～2wt.%, exemplarily 0.01wt.%, 0.02wt.%, 0.05wt. .%, 0.1wt.%, 0.2wt.%, 0.5wt.%, 1wt.%, 2wt.%, or any value within the range composed of the aforementioned pairwise values.

In one embodiment, the additives may also include other additives, for example, the other additives may be tris(trimethylsilyl) phosphite, tris(trimethylsilyl) borate, bistrifluoro Lithium methanesulfonyl imide, lithium bisfluorosulfonyl imide, 1,3-propene sultone, vinyl sulfite, vinyl sulfate, vinylene carbonate, lithium dioxalate borate, lithium difluorooxalate phosphate and At least one of vinyl ethylene carbonate.

In one embodiment, in the non-aqueous electrolyte, the mass proportion of the other additives is 0wt.% to 10wt%, exemplarily 0wt.%, 1wt.%, 2wt.%, 5wt.%, 8wt. %, 10wt.%, or any value within the range composed of the aforementioned pairwise values.

In one embodiment, the non-aqueous organic solvent also includes ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl propionate (PP) and at least one of propyl acetate.

According to an exemplary embodiment of the present disclosure, the nonaqueous organic solvent includes ethylene carbonate (EC), propylene carbonate (PC), and propyl propionate (PP). Exemplarily, the mass ratio of the ethylene carbonate (EC), the propylene carbonate (PC) and the propyl propionate (PP) is 2:(1-2):2, for example 2:1.5 :2.

In one embodiment, the non-aqueous electrolytic solution further includes lithium salt.

In one embodiment, the lithium salt is selected from at least one of lithium bistrifluoromethanesulfonyl imide, lithium bisfluorosulfonyl imide and lithium hexafluorophosphate (LiPF ₆ ), preferably lithium hexafluorophosphate (LiPF ₆ ).

In one embodiment, in the non-aqueous electrolyte, the mass proportion of the lithium salt is 13wt.% to 20wt.%, exemplarily 13wt.%, 14wt.%, 15wt.%, 16wt.%, 17wt. .%, 18wt.%, 19wt.%, 20wt.%, or any value within the range composed of the aforementioned pairwise values.

In one embodiment, the heat-resistant layer includes ceramic and adhesive.

In one embodiment, in the heat-resistant layer, the mass proportion of the ceramic is 20wt.% to 99wt.%, for example, 20wt.%, 30wt.%, 40wt.%, 60wt.%, 80wt.%. %, 90wt.%, 95wt.%, 99wt.%, or any value within the range of the aforementioned pairwise values.

In one embodiment, in the heat-resistant layer, the mass proportion of the binder is 1-80wt.%, exemplarily 1wt.%, 5wt.%, 10wt.%, 20wt.%, 30wt.%. %, 50wt.%, 60wt.%, 80wt.%, or any value within the range of the aforementioned pairwise values.

In one embodiment, the ceramic is selected from one, two or more of alumina, boehmite, magnesium oxide, boron nitride and magnesium hydroxide.

In one embodiment, the binder in the heat-resistant layer is selected from polytetrafluoroethylene, polyvinylidene fluoride, hexafluoropropylene-vinylidene fluoride copolymer (for example, polyvinylidene fluoride-hexafluoropropylene copolymer ), polyimide, polyacrylonitrile and polymethyl methacrylate, two or more.

In one embodiment, the glue layer has a thickness of 0.5 μm˜2 μm, exemplarily 0.5 μm, 1 μm or 2 μm.

In one embodiment, the solvent used in the heat-resistant layer and the adhesive layer is selected from acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone, cyclohexane At least one of alkanes, methanol, ethanol, isopropanol and water.

In one embodiment, the battery is, for example, a Li-ion battery.

In one embodiment, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on one or both sides of the positive electrode current collector.

In one embodiment, the positive active material layer includes a positive active material, a conductive agent and a binder.

According to an exemplary embodiment of the present disclosure, the mass ratio of the positive electrode active material, the conductive agent and the binder is 98:1.0:1.0.

In one embodiment, the positive electrode active material is selected from lithium cobaltate (LiCoO ₂ ) or lithium cobaltate that has been doped and coated with two or more elements among Al, Mg, Mn, Cr, Ti, and Zr. (LiCoO ₂ ), the chemical formula of lithium cobalt oxide that has been doped and coated with two or more elements in Al, Mg, Mn, Cr, Ti, Zr is Li _x Co _{1-y1-y2-y3-y4} A _y1 B _y2 C _y3 D _y4 O ₂ ; 0.95≤x≤1.05, 0.01≤y1≤0.1, 0.01≤y2≤0.1, 0≤y3≤0.1, 0≤y4≤0.1, A, B, C, D are selected from Two or more elements in Al, Mg, Mn, Cr, Ti, Zr.

In one embodiment, the conductive agent in the positive electrode active material layer is selected from acetylene black.

In one embodiment, the binder in the positive electrode active material layer is selected from polyvinylidene fluoride (PVDF).

In one embodiment, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both sides of the negative electrode current collector, the negative electrode active material layer includes the negative electrode active material, the conductive agent and the binder.

In one embodiment, the negative electrode active material is selected from graphite.

In one embodiment, the negative active material further optionally contains SiOx/C or Si/C, where 0<x<2. For example, the negative electrode active material also contains 1wt%-15wt% SiOx/C or Si/C, exemplarily 1wt.%, 2wt.%, 5wt.%, 8wt.%, 10wt.%, 12wt.%, 15wt .% or any value within the range composed of the aforementioned pairwise values. .

In one embodiment, the charging cut-off voltage of the battery is 4.45V or above.

Beneficial effects of the present disclosure:

(1) The present disclosure provides a battery, which is prepared through the synergistic effect of the separator and the non-aqueous electrolyte, and is used in combination with positive and negative electrode materials, while effectively improving the cycle life of the battery and reducing the cycle expansion of the battery It can also take into account the low temperature performance of the battery.

(2) The battery of the present disclosure includes a positive electrode sheet, a negative electrode sheet, a separator interposed between the positive electrode sheet and the negative electrode sheet, and a non-aqueous electrolyte. The ratio of the mass proportion of ethyl propionate in the non-aqueous electrolyte to the mass proportion of hexafluoropropylene (HFP) in the hexafluoropropylene-vinylidene fluoride copolymer is controlled between 0.2 and 60, wherein: propionic acid Ethyl non-aqueous organic solvent has a strong swelling effect on polyvinylidene fluoride (PVDF) in the diaphragm, and the synergistic effect of ethyl propionate non-aqueous organic solvent and hexafluoropropylene (HFP) can enhance the swelling of the diaphragm. Effect. Based on this, by controlling the content ratio of ethyl propionate and hexafluoropropylene (HFP), the present disclosure can not only improve the adhesion between the separator and the positive and negative electrodes, but also ensure the adhesion between the diaphragm coating layer and the positive and negative electrodes. The change rate of the relay in the first 100 weeks of the battery cycle is within 10%, and it can also make the positive and negative electrodes of the battery have a better interface to reduce cycle expansion, thereby reducing the damage and reorganization of the CEI film, thereby improving the performance of the positive electrode material at high temperature. Stability under high voltage; at the same time, ethyl propionate can also reduce the viscosity of the solvent to improve the wettability and ion conductivity of the electrolyte, thereby improving the low-temperature performance of the battery. In addition, the synergistic effect between the additives in the electrolyte formula further ensures the long cycle life of the battery, in which 1,3-propane sultone and lithium difluorooxalate borate additives can form a strong and stable compound on the surface of the positive and negative electrodes. SEI protective film to prevent the electrolyte from being decomposed by redox on the surface of the positive and negative electrodes, thereby reducing the heat release of side reactions and cycle expansion, while improving the battery cycle life.

Detailed ways

The present disclosure will be further described in detail in conjunction with specific embodiments below. It should be understood that the following examples are only for illustrating and explaining the present disclosure, and should not be construed as limiting the protection scope of the present disclosure. All technologies implemented based on the above contents of the present disclosure are covered within the intended protection scope of the present disclosure.

The experimental methods used in the following examples are conventional methods unless otherwise specified; the reagents and materials used in the following examples can be obtained from commercial sources unless otherwise specified.

Comparative Examples 1-5 and Examples 1-8

The lithium-ion batteries of Comparative Examples 1-5 and Examples 1-8 were prepared according to the following preparation methods, the only difference being the choice of diaphragm and non-aqueous electrolyte, and the specific differences are shown in Table 1.

(1) Preparation of positive electrode sheet

Mix the positive electrode active material LiCoO ₂ , the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black at a weight ratio of 98:1.0:1.0, add N-methylpyrrolidone (NMP), and stir under the action of a vacuum mixer. Until the mixed system becomes a positive electrode slurry with uniform fluidity; the positive electrode slurry is evenly coated on an aluminum foil with a thickness of 10 μm; after the above-mentioned coated aluminum foil is baked in an oven with 5 different temperature gradients, Dry in an oven at 120° C. for 8 hours, and then roll and cut to obtain the desired positive electrode sheet.

(2) Negative sheet preparation

The artificial graphite negative electrode material with a mass proportion of 97%, the single-walled carbon nanotube (SWCNT) conductive agent with a mass proportion of 0.1%, the conductive carbon black (SP) conductive agent with a mass proportion of 0.8%, and the mass proportion A 1% sodium carboxymethylcellulose (CMC) binder and a 1.1% styrene-butadiene rubber (SBR) binder are made into a slurry by a wet process and coated on the negative electrode current collector copper foil The surface was dried (temperature: 85° C., time: 5 h), rolled and die-cut to obtain the negative electrode sheet.

(3) Preparation of non-aqueous electrolyte

In an argon-filled glove box (moisture <10ppm, oxygen <1ppm), mix ethylene carbonate (EC), propylene carbonate (PC), and propyl propionate (PP) in a mass ratio of 2:1.5:2 Uniformly, slowly add 14wt.% LiPF ₆ based on the total mass of the non-aqueous electrolytic solution, and 5-60 wt.% ethyl propionate based on the total mass of the non-aqueous electrolytic solution (the specific amount of ethyl propionate is shown in Table 1 shown) and additives (the specific dosage and selection of additives are shown in Table 1), and stirred evenly to obtain non-aqueous electrolyte.

(4) Preparation of diaphragm

A layer of aluminum oxide ceramic layer with a thickness of 2 μm is coated on both sides of a polyethylene substrate with a thickness of 5 μm, and a glue layer with a thickness of 1 μm is coated on the surface of the ceramic coating, and the glue layer adopts The adhesive is polyvinylidene fluoride (PVDF)-hexafluoropropylene (HFP) copolymer, and the mass percentage of hexafluoropropylene in polyvinylidene fluoride (PVDF)-hexafluoropropylene (HFP) copolymer is detailed in the table 1.

(5) Preparation of lithium ion battery

Wind the above-prepared positive electrode sheet, separator, and negative electrode sheet to obtain a bare cell without liquid injection; place the bare cell in the outer packaging foil, inject the above-mentioned prepared electrolyte into the dried bare cell, and vacuum Encapsulation, standing, formation, shaping, sorting and other processes to obtain the required lithium-ion batteries.

Table 1 Lithium-ion batteries prepared in Comparative Examples 1-5 and Examples 1-8

Electrochemical performance test is carried out to the battery obtained in the above-mentioned comparative examples and examples, and the relevant instructions are as follows:

25°C cycle test: Place the batteries obtained in the above examples and comparative examples in an environment of (25±2)°C, and let them stand for 2-3 hours. Charging, the cut-off current is 0.05C, and the battery is left for 5 minutes after it is fully charged, and then discharged to a cut-off voltage of 3.0V with a constant current of 1C, and the highest discharge capacity of the first three cycles is recorded as the initial capacity Q. When the number of cycles reaches 1000, record The last discharge capacity Q ₁ of the battery; record the initial thickness T of the battery cell, and record the thickness after 1000 cycles as T ₁ , and record the results as shown in Table 2.

The calculation formula used therein is as follows: capacity retention rate (%)=Q1/Q×100%; thickness change rate (%)=(T ₁ −T)/T×100%.

10°C cycle test: Place the batteries obtained in the above examples and comparative examples in an environment of (10±2)°C, and let them stand for 2-3 hours. When the battery body reaches (10±2)°C, the battery will The current charging cut-off current is 0.05C. After the battery is fully charged, it is left for 5 minutes, and then discharged at a constant current of 0.5C to a cut-off voltage of 3.0V. The highest discharge capacity recorded in the first 3 cycles is the initial capacity Q ₂ . When the cycle reaches 300 times, Record the last discharge capacity Q ₃ of the battery; record the initial thickness T ₂ of the cell, select the thickness after 300 cycles as T ₃ , and record the results as shown in Table 2.

The calculation formula used therein is as follows: capacity retention rate (%)=Q ₃ /Q ₂ ×100%; thickness change rate (%)=(T ₃ −T ₂ )/T ₂ ×100%.

Low-temperature discharge experiment: Discharge the battery obtained in the above examples and comparative examples at an ambient temperature of 25±3°C to 3.0V at 0.2C, and leave it for 5 minutes; charge at 0.7C, when the battery terminal voltage reaches the charging limit voltage, change to Charge at a constant voltage until the charging current ≤ cut-off current, stop charging, and then discharge to 3.0V at 0.2C after standing aside for 5 minutes, record the discharge capacity as room temperature capacity Q ₄ . Then the battery is charged at 0.7C. When the terminal voltage of the battery reaches the charging limit voltage, change to constant voltage charging until the charging current is less than or equal to the cut-off current, then stop charging; put the fully charged battery at -20±2℃ for 4 hours Afterwards, discharge at a current of 0.25C to a cut-off voltage of 3.0V, record the discharge capacity Q ₅ , and calculate the low-temperature discharge capacity retention rate. The recorded results are shown in Table 2.

The calculation formula used therein is as follows: low-temperature discharge capacity retention (%)=Q ₅ /Q ₄ ×100%.

130°C thermal shock test: The batteries obtained in the above examples and comparative examples were heated at an initial temperature of (25±3)°C in a convection mode or a circulating hot air box, with a temperature change rate of (5±2)°C/min, and the temperature was raised to (130±2)°C, keep the test for 60 minutes and end the test, record the battery status results as shown in Table 2.

The measurement method of the adhesive force between the diaphragm coating layer and the negative electrode:

Place the batteries obtained in the above examples and comparative examples in an environment of (25±2)°C, and let them stand for 2-3 hours. When the battery body reaches (25±2)°C, charge the battery at a constant current of 0.7C, and The current is 0.05C. When the battery terminal voltage reaches the charging limit voltage, change to constant voltage charging until the charging current ≤ cut-off current, stop charging and put it aside for 5 minutes, dissect the fully charged battery, and choose a length of 30mm along the direction of the tab* 15mm wide diaphragm and negative electrode as a whole sample, the separator and the negative electrode at an angle of 180 degrees are tested on a universal stretching machine at a speed of 100mm/min and a test displacement of 50mm, and the test result is recorded as the adhesion between the diaphragm and the negative electrode N (unit N/m), the adhesive force of fresh battery (not cycled after battery preparation) test is N ₁ (unit N/m), the adhesive force of cycle 100 cycle battery test is N ₂ (unit N/m );

The calculation formula used in it is as follows:

Change rate of adhesion between separator coating and negative electrode (%)=(N ₁ -N ₂ )/N ₁ ×100%

Table 2 Comparative Examples 1-5 and Examples 1-8 Gained Battery Experimental Test Results

It can be seen from the results in Table 2 that the lithium-ion battery prepared by the present disclosure through the synergistic effect of the diaphragm and the electrolyte and the combination of positive and negative materials can effectively improve the battery cycle life and reduce battery cycle expansion. It can also take into account the low temperature performance of the battery.

The embodiments of the present disclosure have been described above. However, the present disclosure is not limited to the above-mentioned embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

A battery, characterized in that the battery comprises a positive electrode sheet, a negative electrode sheet, a separator placed between the positive electrode sheet and the negative electrode sheet, and a non-aqueous electrolyte;

The non-aqueous electrolytic solution includes a non-aqueous organic solvent and an additive, wherein the non-aqueous organic solvent includes at least ethyl propionate; the additive includes 1,3-propane sultone and lithium difluorooxalate borate;

The diaphragm includes a base material, a heat-resistant layer and a glue layer, the heat-resistant layer is relatively arranged on both sides of the base material, and the glue layer is arranged on the heat-resistant layer; the glue layer includes Adhesive, including hexafluoropropylene-vinylidene fluoride copolymer in the adhesive;

The ratio of the mass proportion of ethyl propionate in the non-aqueous electrolyte to the mass proportion of hexafluoropropylene in the hexafluoropropylene-vinylidene fluoride copolymer is 0.2-60.
The battery according to claim 1, wherein the ratio of the mass percentage of ethyl propionate in the non-aqueous electrolyte to the mass proportion of hexafluoropropylene in the hexafluoropropylene-vinylidene fluoride copolymer is 0.5～35.
The battery according to claim 1 or 2, characterized in that the number average molecular weight of the hexafluoropropylene-vinylidene fluoride copolymer is 500,000 Da to 2 million Da;

Preferably, in the hexafluoropropylene-vinylidene fluoride copolymer, the sum of the molecular weights of the vinylidene fluoride units is 500,000 Da to 2 million Da.
The battery according to any one of claims 1-3, characterized in that the mass proportion of hexafluoropropylene in the hexafluoropropylene-vinylidene fluoride copolymer is 1wt.%-25wt.%.
The battery according to claims 1-4, characterized in that, in the non-aqueous organic solvent, the mass proportion of ethyl propionate in the non-aqueous electrolyte is 5wt.%˜60wt.%.
The battery according to any one of claims 1-5, characterized in that, in the non-aqueous electrolyte, the mass proportion of the 1,3-propane sultone is 0.5wt.%～5wt. %;

Preferably, in the non-aqueous electrolytic solution, the mass proportion of lithium difluorooxalate borate is 0.01wt.%˜2wt.%.
The battery according to any one of claims 1-6, wherein the additives also include other additives;

Preferably, the other additives are tris(trimethylsilyl) phosphite, tris(trimethylsilyl) borate, lithium bistrifluoromethanesulfonyl imide, lithium bisfluorosulfonyl imide, At least one of 1,3-propene sultone, vinyl sulfite, vinyl sulfate, vinylene carbonate, lithium dioxalate borate, lithium difluorooxalate phosphate, and vinyl vinyl carbonate;

Preferably, in the non-aqueous electrolyte, the mass proportion of the other additives is 0wt%-10wt%.
The battery according to any one of claims 1-7, wherein the non-aqueous organic solvent also includes ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, at least one of propyl acetate and propyl acetate.
The battery according to any one of claims 1-8, wherein the non-aqueous electrolytic solution also includes a lithium salt;

Preferably, the lithium salt is selected from at least one of lithium bistrifluoromethanesulfonimide, lithium bisfluorosulfonimide and lithium hexafluorophosphate;

Preferably, in the non-aqueous electrolytic solution, the mass proportion of the lithium salt is 13wt.%˜20wt.%.
The battery according to any one of claims 1-9, wherein the heat-resistant layer comprises ceramics and a binder;

Preferably, in the heat-resistant layer, the mass proportion of the ceramic is 20wt.%-99wt.%;

Preferably, in the heat-resistant layer, the mass proportion of the binder is 1wt.%-80wt.%;
The battery according to any one of claim 10, wherein the ceramic is selected from one, two or more of alumina, boehmite, magnesium oxide, boron nitride and magnesium hydroxide;

Preferably, the binder in the heat-resistant layer is selected from polytetrafluoroethylene, polyvinylidene fluoride, hexafluoropropylene-vinylidene fluoride copolymer, polyimide, polyacrylonitrile and polymethylmethacrylate one, two or more of
The battery according to any one of claims 1-11, characterized in that, the thickness of the adhesive layer is 0.5 μm˜2 μm.
The battery according to any one of claims 1-12, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer coated on one or both sides of the positive electrode current collector, and the positive electrode active material The layer includes a positive electrode active material, a conductive agent and a binder;

Preferably, the positive electrode active material is selected from lithium cobaltate or lithium cobaltate that has been doped with two or more elements of Al, Mg, Mn, Cr, Ti, and Zr. , Mn, Cr, Ti, Zr with two or more elements doped and coated with lithium cobalt oxide, the chemical formula is Li x Co 1-y1-y2-y3-y4 A y1 B y2 C y3 D y4 O 2 ; 0.95≤x≤1.05, 0.01≤y1≤0.1, 0.01≤y2≤0.1, 0≤y3≤0.1, 0≤y4≤0.1, A, B, C, D are selected from Al, Mg, Mn, Cr, Ti, Zr two or more elements in
The battery according to any one of claims 1-13, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer coated on one or both sides of the negative electrode current collector, the negative electrode active material The layer includes a negative electrode active material, a conductive agent and a binder;

Preferably, the negative electrode active material is selected from graphite.
The battery according to claim 14, wherein the negative electrode active material also optionally contains SiO x /C or Si/C, wherein 0<x<2;

Preferably, the negative electrode active material further contains 1wt.%˜15wt.% of SiO x /C or Si/C.