A rubidium / cesium-containing low-temperature battery electrolyte and its battery

Abstract

This invention discloses a rubidium / cesium-containing low-temperature battery electrolyte and its battery. The electrolyte comprises cesium and / or rubidium compounds, film-forming additives, lithium or sodium salts, and an organic solvent; the total molar concentration of the cesium and / or rubidium compounds is 0.3-1 mol / L; the content of the film-forming additives is 0.5-5 wt%; and the content of the lithium or sodium salts is 0-15 wt%. This invention fully utilizes the positive effects of rubidium and cesium compounds. By adding cesium and / or rubidium compounds, it effectively suppresses the side reactions of carbonate solvent co-intercalation at the negative electrode, reduces the barrier to desolvation of active ions, and extends the cycle life of the battery under low-temperature conditions. Furthermore, the addition of high concentrations of rubidium / cesium compounds lowers the glass transition temperature of the electrolyte, improves its fluidity and viscosity, increases its conductivity, and provides better migration performance of active ions, suppressing dendrite formation, thereby improving the low-temperature rate performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, specifically to a rubidium / cesium-containing low-temperature battery electrolyte and its battery. Background Technology

[0002] Polyanionic cathode materials are widely used in electric vehicles, electrochemical energy storage, and other fields due to their high safety, environmental friendliness, and long cycle life. However, at low temperatures, electrolyte viscosity increases, conductivity decreases, and the electrolyte / electrode interface film impedance and charge transfer impedance increase. Furthermore, the electron-lattice coupling phenomenon in polyanionic cathode materials results in low electron and ion mobility, leading to a severe decline in capacity and cycle performance at low temperatures. Functional electrolytes can achieve lower viscosity and higher conductivity at low temperatures, reducing interfacial impedance, increasing ion migration rates, and slowing dendrite formation on the negative electrode surface, thus improving the battery's electrical performance at low temperatures. This is of great significance in overcoming the application barriers of polyanionic cathode materials in cold regions and extreme environments; therefore, developing a low-temperature electrolyte and battery is extremely important.

[0003] Chinese patent application CN106159324A discloses a non-aqueous electrolyte and a lithium secondary battery using the non-aqueous electrolyte. By adding cesium salt compounds, it maintains good cycle stability of the lithium secondary battery while significantly improving low-temperature performance and rate performance. Chinese patent application CN108878980A prepares a functional electrolyte; the addition of cesium ions significantly increases the number of charge-discharge cycles, effectively extending battery life. Chinese patent application CN115842158A provides an electrolyte for secondary batteries containing one or more cations selected from potassium ions, rubidium ions, cesium ions, barium ions, strontium ions, and calcium ions, improving the retention of cell cycle capacity and cycle life.

[0004] In the above schemes, the amount of rubidium and cesium ions added is relatively small, and their main function is to promote the formation of a stable and robust SEI film on the negative electrode. However, under low-temperature conditions, the viscosity and conductivity of the electrolyte have a greater impact on the low-temperature performance of the battery. Improving the SEI film alone cannot guarantee the rate capability and cycle performance of the battery at low temperatures. Usually, the conductivity, viscosity, and impedance of the electrolyte are improved by optimizing the composition and ratio of the solvent. EC and PC have a promoting effect on the low-temperature performance of the electrolyte, but they will cause an increase in impedance, graphite co-intercalation side reactions, and barriers to the desolvation of active ions, thereby affecting the low-temperature cycle performance of the battery. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide a rubidium / cesium-containing low-temperature battery electrolyte and a battery thereof.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A rubidium / cesium-containing low-temperature battery electrolyte comprises a cesium compound and / or a rubidium compound, a film-forming additive, a lithium salt or a sodium salt, and an organic solvent; the total molar concentration of the cesium compound and / or the rubidium compound is 0.3-1 mol / L; the content of the film-forming additive is 0.5-5 wt%; and the content of the lithium salt or sodium salt is 0-15 wt%.

[0008] Furthermore, the cesium compound includes one or more of cesium hexafluorophosphate, cesium tetrafluoroborate, cesium difluorosulfonylimide, and cesium trifluoromethanesulfonylimide.

[0009] Furthermore, the rubidium compound includes one or more of rubidium hexafluorophosphate, rubidium tetrafluoroborate, rubidium bis(fluorosulfonyl)imide, and rubidium trifluoromethanesulfonylimide.

[0010] Furthermore, the film-forming additive includes one or more of vinylene carbonate, fluoroethylene carbonate, tris(trimethylsilyl) phosphate, tris(trifluoroethyl) carbonate, tris(trimethylsilyl) borate, lithium difluorophosphate, and lithium difluorobis(oxalato) phosphate.

[0011] Furthermore, the lithium salt includes one or more of lithium tetrafluoroborate, lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluorosulfonyl)imide, lithium difluorooxalateborate, and lithium di(oxalateborate).

[0012] Furthermore, the sodium salt includes one or more of sodium hexafluorophosphate, sodium difluorosulfonamide, and sodium difluorosulfonamide salt.

[0013] Further, the organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate, acetonitrile, propionitrile, and butyronitrile.

[0014] The present invention also provides a battery comprising a positive electrode, a negative electrode, a separator, and the above-mentioned rubidium / cesium low-temperature battery electrolyte.

[0015] Further, the positive electrode is composed of a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder; the positive electrode active material includes one or more of lithium iron phosphate, lithium manganese iron phosphate, sodium iron phosphate, sodium iron pyrophosphate, and sodium iron pyrophosphate; the positive electrode conductive agent includes one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, carbon fiber, conductive graphite, and conductive carbon black; the positive electrode binder includes polyvinylidene fluoride; the weight ratio of the positive electrode active material, positive electrode conductive agent, and positive electrode binder is 90-94:3-5:3-5; the areal density of the positive electrode sheet is 290-340 g / m³. 2 ;

[0016] The negative electrode is composed of a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder; the negative electrode active material includes one or more of natural graphite, artificial graphite, hard carbon, lithium titanate, silicon carbide, and silicon oxide; the negative electrode conductive agent includes one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, carbon fiber, conductive graphite, and conductive carbon black; the negative electrode binder includes one or more of sodium carboxymethyl cellulose, styrene-butadiene rubber, acrylate, modified acrylate, and polyvinylidene fluoride; the weight ratio of the negative electrode active material, negative electrode conductive agent, and negative electrode binder is 90-96:2-4:2-6; the electrode surface density of the negative electrode is 130-190 g / m³. 2 ;

[0017] The base material of the diaphragm is either polyethylene or polypropylene, and the diaphragm thickness is 6μm-14μm.

[0018] Furthermore, the substrate material of the diaphragm has a ceramic coating or a polymer coating on its surface.

[0019] The beneficial effects of this invention are as follows: The method of this invention fully utilizes the positive effects of rubidium and cesium compounds. By adding cesium and / or rubidium compounds, it effectively suppresses the side reactions of carbonate solvents co-intercalation at the negative electrode, reduces the barrier to desolvation of active ions, and extends the cycle life of the battery under low-temperature conditions. Furthermore, the addition of high concentrations of rubidium / cesium compounds lowers the glass transition temperature of the electrolyte, improves the fluidity and viscosity of the electrolyte, increases the conductivity of the electrolyte, and gives active ions better migration performance, suppressing dendrite formation, thereby improving the low-temperature rate performance of the battery. Detailed Implementation

[0020] The present invention will be further described below. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0021] Example 1

[0022] In an argon-filled glove box, ethylene carbonate, propylene carbonate, and methyl ethyl carbonate were mixed uniformly in a mass ratio of 1:1:8 to obtain an organic solvent. Then, lithium bisfluorosulfonylimide (13 wt%), ethylene carbonate (3 wt%), and fluoroethylene carbonate (0.5 wt%) based on the total mass of the electrolyte were slowly added to the organic solvent. After stirring until completely dissolved, cesium bisfluorosulfonylimide (0.5 mol / L) was added to obtain a cesium-containing lithium-ion battery electrolyte.

[0023] The fabrication of lithium-ion batteries:

[0024] Lithium iron phosphate, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) were thoroughly mixed in N-methylpyrrolidone (NMP) at a mass ratio of 93.5:3.5:3. This mixture was then coated onto a 12μm aluminum foil current collector, dried, rolled, and die-cut into 80mm*100mm positive electrode sheets. Graphite, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) were thoroughly mixed in N-methylpyrrolidone (NMP) at a mass ratio of 93:2:5. This mixture was then coated onto a copper foil current collector, dried, rolled, and die-cut into 83mm*104mm negative electrode sheets. Using 14μm polyethylene (PE) as a separator, the positive electrode sheets, separator, and negative electrode sheets were stacked and assembled into a 10Ah lithium-ion soft-pack battery. After liquid filling and capacity testing, electrochemical performance was tested on a high-performance battery.

[0025] Example 2

[0026] The difference between this embodiment and Example 1 is that the molar concentration of cesium difluorosulfonylimide added is 0.3 mol / L.

[0027] Example 3

[0028] The difference between this embodiment and Example 1 is that the molar concentration of cesium difluorosulfonylimide added is 0.8 mol / L.

[0029] Example 4

[0030] The difference between this embodiment and Example 1 is that bis(fluorosulfonyl)imide cesium is not added, but bis(fluorosulfonyl)imide rubidium is added. The molar concentration of bis(fluorosulfonyl)imide rubidium in the electrolyte is 0.5 mol / L, and a rubidium-containing lithium-ion battery electrolyte is prepared.

[0031] Example 5

[0032] The difference between this embodiment and Example 1 is that instead of adding cesium difluorosulfonylimide, rubidium trifluoromethanesulfonylimide is added. The molar concentration of rubidium trifluoromethanesulfonylimide in the electrolyte is 0.5 mol / L, and a rubidium-containing lithium-ion battery electrolyte is prepared.

[0033] Example 6

[0034] The difference between this embodiment and Example 1 is that, in the preparation of the electrolyte, lithium hexafluorophosphate, lithium bisfluorosulfonyl imide, vinylene carbonate, and fluoroethylene carbonate are added to the organic solvent at a total mass of 12 wt% based on the electrolyte. Cesium hexafluorophosphate is used instead of bisfluorosulfonyl imide, and the molar concentration of cesium hexafluorophosphate in the electrolyte is 0.5 mol / L.

[0035] Example 7

[0036] The difference between this embodiment and Example 1 is that, in the preparation of the electrolyte, instead of just adding cesium bisfluorosulfonylimide, cesium bisfluorosulfonylimide and rubidium bisfluorosulfonylimide are added, and the molar concentrations of cesium bisfluorosulfonylimide and rubidium bisfluorosulfonylimide in the electrolyte are 0.5 mol / L, respectively.

[0037] Example 8

[0038] The difference between this embodiment and Embodiment 1 is that in the preparation of the lithium-ion battery, the active material lithium iron phosphate is replaced with lithium manganese iron phosphate.

[0039] Example 9

[0040] Preparation of cesium sodium-ion battery electrolyte:

[0041] In an argon-filled glove box, ethylene carbonate, propylene carbonate, and methyl ethyl carbonate were mixed uniformly in a mass ratio of 1:1:8 to obtain an organic solvent. Then, sodium bis(fluorosulfonyl)imide, 3 wt% ethylene carbonate, and 0.5 wt% fluoroethylene carbonate were slowly added to the organic solvent based on the total mass of the electrolyte. After stirring until completely dissolved, cesium bis(fluorosulfonyl)imide was added. The molar concentration of cesium bis(fluorosulfonyl)imide in the electrolyte was 0.5 mol / L, thus obtaining a cesium-containing sodium-ion battery electrolyte.

[0042] Preparation of sodium-ion batteries:

[0043] Sodium iron pyrophosphate, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) were thoroughly mixed in N-methylpyrrolidone (NMP) at a mass ratio of 93.5:3.5:3. This mixture was then coated onto a 12μm aluminum foil current collector, dried, rolled, and die-cut into 80mm*100mm positive electrode sheets. Hard carbon, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) were thoroughly mixed in N-methylpyrrolidone (NMP) at a mass ratio of 93:2:5. This mixture was then coated onto a copper foil current collector, dried, rolled, and die-cut into 83mm*104mm negative electrode sheets. Using 14μm polyethylene (PE) as a separator, the positive electrode sheets, separator, and negative electrode sheets were stacked and assembled into a 10Ah sodium-ion soft-pack battery. After liquid filling and capacity testing, electrochemical performance was tested on a high-performance battery.

[0044] Comparative Example 1

[0045] Preparation of lithium-ion battery electrolyte:

[0046] In an argon-filled glove box, ethylene carbonate, propylene carbonate, and methyl ethyl carbonate are mixed evenly in a mass ratio of 1:1:8 to obtain an organic solvent. Then, lithium bis(fluorosulfonyl)imide (13 wt%), ethylene carbonate (3 wt%), and fluoroethylene carbonate (0.5 wt%) are slowly added to the organic solvent based on the total mass of the electrolyte. After stirring until completely dissolved, a lithium-ion battery electrolyte is obtained.

[0047] The fabrication of lithium-ion batteries:

[0048] Lithium iron phosphate, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) were thoroughly mixed in N-methylpyrrolidone (NMP) at a mass ratio of 93.5:3.5:3. This mixture was then coated onto a 12μm aluminum foil current collector, dried, rolled, and die-cut into 80mm*100mm positive electrode sheets. Graphite, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) were thoroughly mixed in N-methylpyrrolidone (NMP) at a mass ratio of 93:2:5. This mixture was then coated onto a copper foil current collector, dried, rolled, and die-cut into 83mm*104mm negative electrode sheets. Using 14μm polyethylene (PE) as a separator, the positive electrode sheets, separator, and negative electrode sheets were stacked and assembled into a 10Ah lithium-ion soft-pack battery. After liquefaction and capacity testing, electrochemical performance was tested on a high-performance battery.

[0049] Comparative Example 2

[0050] Unlike Comparative Example 1, the preparation of the lithium-ion battery differs in that the active material lithium iron phosphate is replaced with lithium manganese iron phosphate.

[0051] Comparative Example 3

[0052] Preparation of sodium-ion battery electrolyte:

[0053] In an argon-filled glove box, ethylene carbonate, propylene carbonate, and methyl ethyl carbonate are mixed evenly in a mass ratio of 1:1:8. Then, 13 wt% sodium difluorosulfonamide, 3 wt% ethylene carbonate, and 0.5 wt% fluoroethylene carbonate (based on the total mass of the electrolyte) are slowly added to the mixed solution and stirred until completely dissolved to obtain the sodium-ion battery electrolyte.

[0054] Preparation of sodium-ion batteries:

[0055] Sodium iron pyrophosphate, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) were thoroughly mixed in N-methylpyrrolidone (NMP) at a mass ratio of 93.5:3.5:3. This mixture was then coated onto a 12μm aluminum foil current collector, dried, rolled, and die-cut into 80mm*100mm positive electrode sheets. Hard carbon, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) were thoroughly mixed in N-methylpyrrolidone (NMP) at a mass ratio of 93:2:5. This mixture was then coated onto a copper foil current collector, dried, rolled, and die-cut into 83mm*104mm negative electrode sheets. Using 14μm polyethylene (PE) as a separator, the positive electrode sheets, separator, and negative electrode sheets were stacked and assembled into a 10Ah sodium-ion soft-pack battery. After liquid filling and capacity testing, electrochemical performance was tested on a high-performance battery.

[0056] The electrolytes and battery compositions of the above embodiments and comparative examples are shown in Table 1.

[0057] Table 1

[0058] Serial Number Electrolyte lithium salt or sodium salt solvent Rubidium / cesium compounds Film-forming additives cathode materials Example 1 LiFSI: 13wt% EC / PC / EMC=1 / 1 / 8 CsFSI: 0.5 mol / L VC: 3wt% FEC: 0.5wt% Lithium iron phosphate Example 2 LiFSI: 13wt% EC / PC / EMC=1 / 1 / 8 CsFSI: 0.3 mol / L VC: 3wt% FEC: 0.5wt% Lithium iron phosphate Example 3 LiFSI: 13wt% EC / PC / EMC=1 / 1 / 8 CsFSI: 0.8 mol / L VC: 3wt% FEC: 0.5wt% Lithium iron phosphate Example 4 LiFSI: 13wt% EC / PC / EMC=1 / 1 / 8 RbFSI: 0.5 mol / L VC: 3wt% FEC: 0.5wt% Lithium iron phosphate Example 5 LiFSI: 13wt% EC / PC / EMC=1 / 1 / 8 RbTFSI: 0.5 mol / L VC: 3wt% FEC: 0.5wt% Lithium iron phosphate Example 6 <![CDATA[LiPF6:12wt %LiFSI:1wt %]]> EC / PC / EMC=1 / 1 / 8 <![CDATA[CsPF6:0.5mol / L]]> VC: 3wt% FEC: 0.5wt% Lithium iron phosphate Example 7 LiFSI: 13wt% EC / PC / EMC=1 / 1 / 8 CsFSI: 0.5 mol / L LbFSI: 0.5 mol / L VC: 3wt% FEC: 0.5wt% Lithium iron phosphate Example 8 LiFSI: 13wt% EC / PC / EMC=1 / 1 / 8 CsFSI: 0.5 mol / L VC: 3wt% FEC: 0.5wt% Lithium manganese iron phosphate Example 9 NaFSI: 13wt% EC / PC / EMC=1 / 1 / 8 CsFSI: 0.5 mol / L VC: 3wt% FEC: 0.5wt% Sodium iron pyrophosphate Comparative Example 1 LiFSI: 13wt% EC / PC / EMC=1 / 1 / 8 VC: 3wt% FEC: 0.5wt% Lithium iron phosphate Comparative Example 2 LiFSI: 13wt% EC / PC / EMC=1 / 1 / 8 VC: 3wt% FEC: 0.5wt% Lithium manganese iron phosphate Comparative Example 3 NaFSI: 13wt% EC / PC / EMC=1 / 1 / 8 VC: 3wt% FEC: 0.5wt% Sodium iron pyrophosphate

[0059] The performance test results of the above embodiments and comparative examples are shown in Table 2.

[0060] Table 2

[0061] Serial Number Glass transition temperature / °C <![CDATA[Conductivity / (ms·cm -1 )]]> 25℃, 1C discharge capacity / Ah 0℃, 1C discharge efficiency / % -20℃, 1C discharge efficiency / % -20℃, 2C discharge efficiency / % Capacity retention rate after 100 cycles at -20℃ / % Example 1 -124.74 11.41 10.24 92.64 84.98 71.51 91.63 Example 2 -106.12 9.56 10.23 86.34 77.06 63.32 80.34 Example 3 -107.96 9.35 10.34 86.53 79.09 63.08 81.71 Example 4 -123.1 10.73 10.32 89.56 81.35 68.54 88.14 Example 5 -107.1 10.27 10.37 87.91 79.27 64.23 82.44 Example 6 -119.09 10.82 10.25 87.71 77.22 67.22 87.29 Example 7 -114.76 11.25 10.36 86.35 79.38 68.27 90.42 Example 8 -124.91 11.42 10.26 85.33 79.23 64.36 84.11 Example 9 -124.74 11.43 10.24 88.47 81.41 66.09 81.16 Comparative Example 1 -105.09 9.22 10.25 85.26 75.39 62.01 79.34 Comparative Example 2 -105.12 9.22 10.32 80.58 71.55 59.71 72.27 Comparative Example 3 -104.19 9.21 10.22 82.35 72.27 60.52 73.09

[0062] As demonstrated in Examples 1-7 and Comparative Example 1, the addition of rubidium / cesium compounds lowers the glass transition temperature of the electrolyte, improves its viscosity and conductivity at low temperatures, and increases the electrolyte's conductivity, resulting in higher discharge capacity for lithium iron phosphate at low temperatures. Furthermore, rubidium and cesium ions effectively suppress the side reactions of PC co-intercalation in the graphite anode, improving the compatibility between PC and graphite, and also lowering the barrier to lithium ion desolvation in EC solvent, thus significantly improving the battery's cycle performance under low-temperature conditions. As demonstrated in Examples 8 and 9 and Comparative Examples 2 and 3, electrolytes containing rubidium / cesium compounds generally improve the low-temperature performance of polyanionic cathode materials.

[0063] For those skilled in the art, various corresponding changes and modifications can be made based on the above technical solutions and concepts, and all such changes and modifications should be included within the protection scope of the claims of this invention.

Claims

1. A low temperature battery electrolyte containing rubidium / cesium, characterized in that, The cesium compound and / or rubidium compound, film-forming additive, lithium salt or sodium salt, organic solvent; the total molar concentration of the cesium compound and / or rubidium compound is 0.3-1 mol / L; the content of the film-forming additive is 0.5-5 wt%; the content of the lithium salt or sodium salt is 0-15 wt%; The cesium compound includes one or more of cesium hexafluorophosphate, cesium tetrafluoroborate, cesium bisfluorosulfonimide, cesium trifluoromethanesulfonimide; The rubidium compound includes one or more of rubidium hexafluorophosphate, rubidium tetrafluoroborate, rubidium bisfluorosulfonimide, rubidium trifluoromethanesulfonimide; The organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate.

2. The rubidium / cesium-containing cryogenic battery electrolyte of claim 1, wherein, The film-forming additive includes one or more of vinylene carbonate, fluorinated ethylene carbonate, tris(trimethylsilyl)phosphate, tris(trifluoroethyl)carbonate, tris(trimethylsilyl)borate, lithium difluorophosphate, lithium difluorobisoxalate phosphate.

3. The rubidium / cesium-containing cryogenic battery electrolyte of claim 1, wherein, The lithium salt includes one or more of lithium tetrafluoroborate, lithium hexafluorophosphate, lithium bisfluorosulfonimide, lithium bis-trifluorosulfonimide, lithium difluorophosphate boric acid, lithium difluorophosphate boric acid.

4. The rubidium / cesium-containing cryogenic battery electrolyte of claim 1, wherein, The sodium salt includes one or more of sodium hexafluorophosphate, sodium bisfluorosulfonimide, sodium bisfluorosulfonimide.

5. A battery, characterized by The positive electrode, the negative electrode, the separator, and the low-temperature battery electrolyte containing rubidium / cesium according to any one of claims 1-4.

6. The battery of claim 5, wherein, The positive electrode is composed of a positive electrode active material, a positive electrode conductive agent and a positive electrode binder; the positive electrode active material comprises one or more of lithium iron phosphate, lithium manganese iron phosphate, sodium iron phosphate, sodium iron pyrophosphate, sodium iron pyrophosphate phosphate; the positive electrode conductive agent comprises one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, carbon fibers, conductive graphite, conductive carbon black; the positive electrode binder comprises polyvinylidene fluoride; the weight ratio of the positive electrode active material, the positive electrode conductive agent and the positive electrode binder is 90-94:3-5:3-5; the positive electrode tab surface density is 290-340 g / m 2 ; The negative electrode is composed of a negative electrode active material, a negative electrode conductive agent and a negative electrode binder; the negative electrode active material comprises one or more of natural graphite, artificial graphite, hard carbon, lithium titanate, silicon-carbon, silicon-oxygen; the negative electrode conductive agent comprises one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, carbon fibers, conductive graphite, conductive carbon black; the negative electrode binder comprises one or more of sodium carboxymethyl cellulose, butadiene rubber, acrylate, modified acrylate, polyvinylidene fluoride; the weight ratio of the negative electrode active material, the negative electrode conductive agent and the negative electrode binder is 90-96:2-4:2-6; the areal density of the negative electrode tab is 130-190 g / m 2 ; The base material of the separator is one of polyethylene and polypropylene, and the thickness of the separator is 6-14 μm.

7. The battery of claim 6, wherein, The base material of the separator has a ceramic coating or a high polymer coating on the surface.