阅读说明：本技术 一种耐低温锂离子电池的制备方法 (Preparation method of low-temperature-resistant lithium ion battery ) 是由 李培 赵恒� 沈顺灶 于 2021-06-24 设计创作，主要内容包括：本发明系提供一种耐低温锂离子电池的制备方法,包括以下步骤：低温电解液,混合锂盐、非水有机溶剂和耐低温添加剂；正极浆料,混合锂金属氧化物颗粒、导电剂、水性粘结剂和耐低温活性剂；负极浆料,混合石墨、导电剂、聚合物、纤维素、水性粘结剂和耐低温活性剂；将铝箔放入弱酸溶液中清洗；使用惰性气体携带纯铝颗粒喷射洁净铝片的表面；制备正极片,先喷涂纳米氧化银和/或导电碳纳米管,再喷涂正极浆料；制备负极片,先喷涂纳米氧化银和/或导电碳纳米管,再喷涂负极浆料；叠放正极片、隔膜和负极片放入电池壳中,注入耐低温电解液。本发明能够提高电解液低温下的电导率,且能够确保低温下电极片的活性,低温下的充放电性能好。(The invention provides a preparation method of a low-temperature-resistant lithium ion battery, which comprises the following steps: a low-temperature electrolyte, which is mixed with lithium salt, a non-aqueous organic solvent and a low-temperature resistant additive; the positive electrode slurry is mixed with lithium metal oxide particles, a conductive agent, a water-based binder and a low-temperature resistant active agent; the negative electrode slurry is mixed with graphite, a conductive agent, a polymer, cellulose, a water-based binder and a low-temperature resistant active agent; putting the aluminum foil into a weak acid solution for cleaning; using inert gas to carry pure aluminum particles to spray the surface of the clean aluminum sheet; preparing a positive plate, spraying nano silver oxide and/or a conductive carbon nanotube, and then spraying positive slurry; preparing a negative plate, spraying nano silver oxide and/or conductive carbon nano tubes, and then spraying negative slurry; and stacking the positive plate, the diaphragm and the negative plate into a battery shell, and injecting low-temperature-resistant electrolyte. The invention can improve the conductivity of the electrolyte at low temperature, ensure the activity of the electrode plate at low temperature and has good charge and discharge performance at low temperature.)

1. A preparation method of a low-temperature-resistant lithium ion battery is characterized by comprising the following steps:

s1, preparing low-temperature electrolyte, and mixing the following materials in parts by weight: 10-15 parts of lithium salt, 80-90 parts of non-aqueous organic solvent and 1-5 parts of low temperature resistant additive;

s2, preparing positive electrode slurry, and mixing the following materials in parts by mass: 88-95 parts of lithium metal oxide particles, 3-6 parts of a conductive agent, 3-7 parts of a water-based binder and 1-3 parts of a low-temperature resistant active agent;

s3, preparing negative electrode slurry, and mixing the following materials in parts by mass: 89-96 parts of graphite, 2-5 parts of a conductive agent, 3-8 parts of a polymer, 1-3 parts of cellulose, 2-6 parts of a water-based binder and 1-3 parts of a low-temperature resistant active agent;

s4, preparing a clean aluminum sheet, putting the aluminum foil into a weak acid solution and deionized water to clean an oxide layer on the surface, putting the cleaned aluminum foil into a closed space filled with inert gases, and drying the aluminum foil by using high-temperature airflow consisting of the inert gases to obtain the clean aluminum sheet;

s5, preparing an electrode substrate, and spraying pure aluminum particles carried by inert gas to the surface of a clean aluminum sheet in a closed space to form a rough structural surface on the surface of the clean aluminum sheet so as to obtain the electrode substrate;

s6, preparing a positive plate, spraying nano silver oxide and/or conductive carbon nano tubes on the surface of the electrode substrate in a closed space, spraying positive slurry on the electrode substrate, and drying to obtain the positive plate;

s7, preparing a negative plate, spraying nano silver oxide and/or conductive carbon nano tubes on the surface of the electrode substrate in a closed space, spraying negative slurry on the electrode substrate, and drying to obtain a positive plate;

and S8, assembling the lamination, preparing a diaphragm, a battery shell and a battery cover, stacking the positive plate, the diaphragm and the negative plate to obtain a battery core, putting the battery core into the battery shell, injecting low-temperature-resistant electrolyte into the battery shell, and sealing the battery shell by using the battery cover to obtain the low-temperature-resistant lithium ion battery.

2. The method of claim 1, wherein in step S1, the lithium salt comprises the following components in a molar ratio of 3: 7: the lithium difluoro oxalate borate and the lithium bis (oxalate) borate, wherein the nonaqueous organic solvent comprises the following components in parts by mass: 1 part of propylene carbonate, 2 parts of dimethyl sulfite and 1 part of propylene sulfite.

3. The preparation method of the low temperature resistant lithium ion battery according to claim 1 or 2, wherein in step S1, the low temperature resistant additive comprises the following components in parts by mass: 4 parts of methyl formate and 1 part of vinyl sulfite.

4. The method according to claim 1, wherein in step S2, the lithium metal oxide particles are lithium iron phosphate particles.

5. The method of claim 1, wherein in steps S2 and S3, the conductive agent is one or more of acetylene black, graphene and Ketjen black, and the aqueous binder is one of polyacrylate, polyvinyl alcohol or polytetrafluoroethylene emulsion.

6. The method for preparing a low temperature resistant lithium ion battery according to claim 1 or 5, wherein in steps S2 and S3, the low temperature resistant active agent comprises the following components in parts by mass: 5-10 parts of potassium chloride, 1-5 parts of tin methanesulfonate and 0.1-1 part of cobaltous tungstate.

7. The method according to claim 1, wherein in step S3, the polymer is polyaniline and the cellulose is carboxymethyl cellulose.

8. The method for preparing a low temperature resistant lithium ion battery according to claim 1, wherein in step S4, the drying temperature is 100-150 ℃.

9. The method of claim 1, wherein in step S5, the injection pressure of the pure aluminum particles is 1.2-2 MPa.

10. The method for preparing a low temperature resistant lithium ion battery according to claim 1, wherein in steps S6 and S7, the spraying thickness of the positive electrode slurry and the negative electrode slurry is 5-10 μm.

Technical Field

The invention relates to a lithium ion battery, and particularly discloses a preparation method of a low-temperature-resistant lithium ion battery.

Background

A lithium ion battery is a secondary battery, i.e., a rechargeable battery, commonly called a lithium battery, which operates by movement of lithium ions between a positive electrode and a negative electrode. The lithium ion battery realizes charge and discharge by back-and-forth insertion and extraction of lithium ions between two electrodes, and during charging, the lithium ions are extracted from a positive electrode and inserted into a negative electrode through an electrolyte, and the negative electrode is in a lithium-rich state; the discharge is reversed.

The lithium ion battery has the advantages of high voltage, large specific energy, long cycle life, good safety performance, small self-discharge, quick charge and the like, the working temperature of the common lithium ion battery is-25-40 ℃, along with the wider and wider application field, the lithium ion battery is required to be capable of normally working in an environment of-40 ℃, but in the prior art, the lithium ion battery has low diffusion coefficient of active substances and low ionic conductivity in a low-temperature environment, and the running efficiency of the lithium ion battery is seriously influenced.

Disclosure of Invention

Therefore, it is necessary to provide a method for preparing a low temperature resistant lithium ion battery, which can maintain high ion intercalation and deintercalation efficiency in a low temperature environment and has good charge and discharge performance under a low temperature condition, in order to solve the problems in the prior art.

In order to solve the problems of the prior art, the invention discloses a preparation method of a low-temperature-resistant lithium ion battery, which comprises the following steps:

s1, preparing low-temperature electrolyte, and mixing the following materials in parts by weight: 10-15 parts of lithium salt, 80-90 parts of non-aqueous organic solvent and 1-5 parts of low temperature resistant additive;

s2, preparing positive electrode slurry, and mixing the following materials in parts by mass: 88-95 parts of lithium metal oxide particles, 3-6 parts of a conductive agent, 3-7 parts of a water-based binder and 1-3 parts of a low-temperature resistant active agent;

s3, preparing negative electrode slurry, and mixing the following materials in parts by mass: 89-96 parts of graphite, 2-5 parts of a conductive agent, 3-8 parts of a polymer, 1-3 parts of cellulose, 2-6 parts of a water-based binder and 1-3 parts of a low-temperature resistant active agent;

s4, preparing a clean aluminum sheet, putting the aluminum foil into a weak acid solution and deionized water to clean an oxide layer on the surface, putting the cleaned aluminum foil into a closed space filled with inert gases, and drying the aluminum foil by using high-temperature airflow consisting of the inert gases to obtain the clean aluminum sheet;

s5, preparing an electrode substrate, and spraying pure aluminum particles carried by inert gas to the surface of a clean aluminum sheet in a closed space to form a rough structural surface on the surface of the clean aluminum sheet so as to obtain the electrode substrate;

s6, preparing a positive plate, spraying nano silver oxide and/or conductive carbon nano tubes on the surface of the electrode substrate in a closed space, spraying positive slurry on the electrode substrate, and drying to obtain the positive plate;

s7, preparing a negative plate, spraying nano silver oxide and/or conductive carbon nano tubes on the surface of the electrode substrate in a closed space, spraying negative slurry on the electrode substrate, and drying to obtain a positive plate;

and S8, assembling the lamination, preparing a diaphragm, a battery shell and a battery cover, stacking the positive plate, the diaphragm and the negative plate to obtain a battery core, putting the battery core into the battery shell, injecting low-temperature-resistant electrolyte into the battery shell, and sealing the battery shell by using the battery cover to obtain the low-temperature-resistant lithium ion battery.

Further, in step S1, the lithium salt includes the following components in a molar ratio of 3: 7: the lithium difluoro oxalate borate and the lithium bis (oxalate) borate, wherein the nonaqueous organic solvent comprises the following components in parts by mass: 1 part of propylene carbonate, 2 parts of dimethyl sulfite and 1 part of propylene sulfite.

Further, in step S1, the low temperature resistant additive includes the following components in parts by mass: 4 parts of methyl formate and 1 part of vinyl sulfite.

Further, in step S2, the lithium metal oxide particles are lithium iron phosphate particles.

Further, in steps S2 and S3, the conductive agent is one or more of acetylene black, graphene and ketjen black, and the aqueous binder is one of polyacrylate, polyvinyl alcohol or polytetrafluoroethylene emulsion.

Further, in steps S2 and S3, the low temperature resistant activator comprises the following components in parts by mass: 5-10 parts of potassium chloride, 1-5 parts of tin methanesulfonate and 0.1-1 part of cobaltous tungstate.

Further, in step S3, the polymer is polyaniline and the cellulose is carboxymethyl cellulose.

Further, in step S4, the drying temperature is 100-150 ℃.

Further, in step S5, the injection pressure of the pure aluminum particles is 1.2-2 MPa.

Further, in steps S6 and S7, the spraying thickness of the positive electrode slurry and the negative electrode slurry is 5-10 μm.

The invention has the beneficial effects that: the invention discloses a preparation method of a low-temperature-resistant lithium ion battery, which can effectively improve the conductivity of an electrolyte in a low-temperature environment by adding a low-temperature-resistant additive capable of being effectively melted with a wastewater organic solvent into the electrolyte, thereby effectively avoiding the impedance increase of the reciprocating motion of lithium ions between two electrodes at a low temperature; the aluminum foil is cleaned by weak acid and washed by pure aluminum particles before being sprayed with the electrode slurry, so that the aluminum foil can be effectively formed into a surface with good conductive effect and high adhesion efficiency, the close contact effect between the aluminum foil and the electrode slurry in the electrode plate can be further improved, and in addition, the conductive performance of the electrode plate can be further ensured by the nanoscale conductive material formed between the electrode slurry and the aluminum foil.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments in order to further understand the features and technical means of the invention and achieve specific objects and functions.

The embodiment of the invention discloses a preparation method of a low-temperature-resistant lithium ion battery, which comprises the following steps:

s1, preparing low-temperature electrolyte, and mixing the following materials in parts by weight by using a vacuum stirring barrel: 10-15 parts of lithium salt, 80-90 parts of non-aqueous organic solvent and 1-5 parts of low temperature resistant additive to obtain low temperature resistant electrolyte;

s2, preparing positive electrode slurry, and mixing the following materials in parts by weight by using a vacuum stirring barrel: 88-95 parts of lithium metal oxide particles, 3-6 parts of a conductive agent, 3-7 parts of a water-based binder and 1-3 parts of a low-temperature resistant active agent to obtain positive electrode slurry;

s3, preparing negative electrode slurry, and mixing the following materials in parts by weight by using a vacuum stirring barrel: 89-96 parts of graphite, 2-5 parts of a conductive agent, 3-8 parts of a polymer, 1-3 parts of cellulose, 2-6 parts of a water-based binder and 1-3 parts of a low-temperature resistant active agent to obtain a negative electrode slurry, wherein the graphite is preferably artificial graphite heated to 300 ℃, so that the mixing effect can be effectively improved, the activity of the graphite can be effectively improved, and the performance of the negative electrode slurry is improved;

s4, preparing a clean aluminum sheet, putting at least two aluminum foils into a weak acid solution and deionized water to clean an oxide layer on the surface of the aluminum foil, preferably, the weak acid is a nitric acid solution with the mass concentration of 3-5%, the mass part of the mixture of the weak acid and the deionized water is 6-10 parts and 30-40 parts, putting the cleaned aluminum foils into a closed space filled with inert gas, and drying the aluminum foils by using high-temperature airflow consisting of the inert gas to obtain the clean aluminum sheet;

s5, preparing an electrode substrate, spraying the surface of a clean aluminum sheet by using inert gas carried by an air pump or a spray gun to carry nano-scale pure aluminum particles in a closed space, further removing impurities on the surface of the clean aluminum sheet, and forming a rough structural surface on the surface of the clean aluminum sheet to obtain the electrode substrate;

s6, preparing a positive plate, spraying nano silver oxide and/or conductive carbon nano tubes on the surface of the electrode substrate in a closed space, spraying positive slurry on the electrode substrate coated with the nano silver oxide and/or conductive carbon nano tube layer, and drying to obtain the positive plate;

s7, preparing a negative plate, spraying nano silver oxide and/or conductive carbon nano tubes on the surface of the electrode substrate in a closed space, spraying negative slurry on the electrode substrate coated with the nano silver oxide and/or conductive carbon nano tube layer, and drying to obtain the positive plate;

s8, assembling the lamination, preparing a diaphragm, a battery case and a battery cover, stacking at least one group of positive plate, diaphragm and negative plate to obtain a battery core, namely alternately stacking the positive plate and the negative plate, stacking the diaphragm between the adjacent positive plate and the negative plate, putting the battery core into the battery case, injecting low-temperature-resistant electrolyte into the battery case, finally sealing the battery case by using the battery cover to obtain the low-temperature-resistant lithium ion battery, and forming the low-temperature-resistant lithium ion battery to activate the activity of the positive plate and the negative plate.

According to the invention, the low-temperature resistant additive capable of being effectively blended with the non-aqueous organic solvent is added in the low-temperature resistant electrolyte, so that the performance of the electrolyte in a low-temperature environment can be effectively improved, the low-temperature resistant active agent is added into the positive electrode slurry and the negative electrode slurry, so that the charge-discharge performance of the electrode slurry in the low-temperature environment can be effectively improved, and the surface of the electrode plate is the electrode slurry, so that the charge-discharge performance of the lithium ion battery in the low-temperature environment can be effectively improved; the aluminum oxide on the surface of the aluminum foil can influence the conductive effect between the aluminum foil and the electrode slurry, an oxide film on the surface of the aluminum foil can be effectively removed through weak acid, so that a reliable conductive contact effect can be ensured between the aluminum foil and the electrode slurry, and the airflow carrying pure aluminum particles can improve the reliability of subsequent electrode plate preparation by improving the surface roughness of the aluminum foil, can further remove impurities on the surface of the aluminum foil, and further improves the conductive contact effect between the aluminum foil and the electrode slurry; the nano-scale conductive material is sprayed between the electrode slurry, so that a good and reliable conductive contact structure can be further formed between the electrode slurry and the aluminum foil, and the charge and discharge performance of the electrode under various environmental conditions can be effectively improved.

In this embodiment, in step S1, the lithium salt includes the following components in a molar ratio of 3: 7: the lithium difluoro oxalate borate and the lithium bis (oxalate) borate, wherein the nonaqueous organic solvent comprises the following components in parts by mass: 1 part of propylene carbonate, 2 parts of dimethyl sulfite and 1 part of propylene sulfite.

In this embodiment, in step S1, the low temperature resistant additive includes the following components in parts by mass: 4 parts of methyl formate and 1 part of vinyl sulfite.

In the present embodiment, in step S2, the lithium metal oxide particles are lithium iron phosphate particles.

In this embodiment, in steps S2 and S3, the conductive agent is one or more of acetylene black, graphene, and ketjen black, and the aqueous binder is one of polyacrylate, polyvinyl alcohol, or polytetrafluoroethylene emulsion.

In this embodiment, in steps S2 and S3, the low temperature resistant activator includes the following components in parts by mass: 5 to 10 parts of

Potassium chloride, 1-5 parts of tin methanesulfonate and 0.1-1 part of cobaltous tungstate.

In this embodiment, in step S3, the polymer is polyaniline and the cellulose is carboxymethyl cellulose.

In this embodiment, in step S4, the drying temperature is 100-150 ℃.

In this embodiment, in step S5, the injection pressure of the pure aluminum particles is 1.2 to 2Mpa, so that the impact effect of the high-pressure pure aluminum particles on the surface of the clean aluminum sheet can be effectively ensured, and the cleaning and roughening effects can be improved.

In the present embodiment, in steps S6 and S7, the spraying thickness of the positive electrode slurry and the negative electrode slurry is 5 to 10 μm, preferably, the thickness of the aluminum foil is 12 to 30 μm, and the spraying pressure is 0.8 to 1.5 MPa.

Example one

A preparation method of a low-temperature-resistant lithium ion battery comprises the following steps:

s1, preparing low-temperature electrolyte, and mixing the following materials in parts by weight by using a vacuum stirring barrel: 12 parts of lithium salt, 85 parts of nonaqueous organic solvent and 2 parts of low-temperature resistant additive to obtain the low-temperature resistant electrolyte, wherein the lithium salt comprises the following components in a molar ratio of 3: 7: the lithium difluoro oxalate borate and the lithium bis (oxalate) borate, wherein the nonaqueous organic solvent comprises the following components in parts by mass: 1 part of propylene carbonate, 2 parts of dimethyl sulfite and 1 part of propylene sulfite, wherein the low-temperature resistant additive comprises the following components in parts by mass: 4 parts of methyl formate and 1 part of ethylene sulfite;

s2, preparing positive electrode slurry, and mixing the following materials in parts by weight by using a vacuum stirring barrel: the method comprises the following steps of obtaining anode slurry by using 90 parts of lithium metal oxide particles, 3 parts of a conductive agent, 4 parts of a water-based binder and 1 part of a low-temperature-resistant active agent, wherein the lithium metal oxide particles are lithium iron phosphate particles, the conductive agent is acetylene black, the water-based binder is polyacrylate, and the low-temperature-resistant active agent comprises the following components in parts by mass: 6 parts of potassium chloride, 2 parts of tin methanesulfonate and 0.3 part of cobaltous tungstate;

s3, preparing negative electrode slurry, and mixing the following materials in parts by weight by using a vacuum stirring barrel: 90 parts of graphite, 3 parts of a conductive agent, 4 parts of a polymer, 1 part of cellulose, 3 parts of a water-based binder and 1 part of a low-temperature resistant active agent to obtain negative electrode slurry, wherein the conductive agent is acetylene black, the water-based binder is polyacrylate, and the low-temperature resistant active agent comprises the following components in parts by mass: 6 parts of potassium chloride, 2 parts of tin methanesulfonate and 0.3 part of cobaltous tungstate, wherein the polymer is polyaniline, and the cellulose is carboxymethyl cellulose;

s4, preparing a clean aluminum sheet, putting at least two aluminum foils into a weak acid solution and deionized water to clean an oxide layer on the surface of the aluminum foil, wherein the weak acid is a 3% nitric acid solution, and the mass part of the mixture of the weak acid and the deionized water is 8 parts and 32 parts, putting the cleaned aluminum foils into a closed space filled with inert gas, and drying the aluminum foils by using 120 ℃ airflow formed by the inert gas to obtain the clean aluminum sheet, wherein the thickness of the aluminum foil is 20 mu m;

s5, preparing an electrode substrate, spraying the surface of a clean aluminum sheet by using inert gas carried by an air pump or a spray gun to carry nano-scale pure aluminum particles in a closed space, further removing impurities on the surface of the clean aluminum sheet, and forming a rough structural surface on the surface of the clean aluminum sheet to obtain the electrode substrate, wherein the spraying pressure of the pure aluminum particles is 1.8 Mpa;

s6, preparing a positive plate, spraying nano silver oxide and/or conductive carbon nanotubes on the surface of an electrode substrate in a closed space, spraying positive slurry on the electrode substrate coated with the nano silver oxide and/or conductive carbon nanotube layer, and drying to obtain the positive plate, wherein the spraying pressure is 1.2Mpa, and the spraying thickness of the positive slurry is 8 microns;

s7, preparing a negative plate, spraying nano silver oxide and/or conductive carbon nanotubes on the surface of the electrode substrate in a closed space, spraying negative slurry on the electrode substrate coated with the nano silver oxide and/or conductive carbon nanotube layer, and drying to obtain a positive plate, wherein the spraying pressure is 1.2Mpa, and the spraying thickness of the positive slurry is 5 microns;

s8, assembling the lamination, preparing a diaphragm, a battery case and a battery cover, stacking at least one group of positive plate, diaphragm and negative plate to obtain a battery core, putting the battery core into the battery case, injecting low-temperature-resistant electrolyte into the battery case, finally sealing the battery case by using the battery cover to obtain the low-temperature-resistant lithium ion battery, and chemically activating the activities of the positive plate and the negative plate of the low-temperature-resistant lithium ion battery.

The discharge efficiency of 2C in the environment of-40 ℃ is 81.2%, the first discharge efficiency of 2C in the environment of 25 ℃ is 87.1%, and the discharge efficiency of the lithium ion battery prepared in the first embodiment in the low-temperature environment of-40 ℃ is obviously higher than the low-temperature discharge efficiency of 50-60% of a common lithium ion battery.

Example two

A preparation method of a low-temperature-resistant lithium ion battery comprises the following steps:

s1, preparing low-temperature electrolyte, and mixing the following materials in parts by weight by using a vacuum stirring barrel: 13 parts of lithium salt, 86 parts of nonaqueous organic solvent and 3 parts of low-temperature resistant additive to obtain the low-temperature resistant electrolyte, wherein the lithium salt comprises the following components in a molar ratio of 3: 7: the lithium difluoro oxalate borate and the lithium bis (oxalate) borate, wherein the nonaqueous organic solvent comprises the following components in parts by mass: 1 part of propylene carbonate, 2 parts of dimethyl sulfite and 1 part of propylene sulfite, wherein the low-temperature resistant additive comprises the following components in parts by mass: 4 parts of methyl formate and 1 part of ethylene sulfite;

s2, preparing positive electrode slurry, and mixing the following materials in parts by weight by using a vacuum stirring barrel: the method comprises the following steps of obtaining a positive electrode slurry by using 92 parts of lithium metal oxide particles, 4 parts of a conductive agent, 4 parts of a water-based binder and 2 parts of a low-temperature-resistant active agent, wherein the lithium metal oxide particles are lithium iron phosphate particles, the conductive agent is acetylene black, the water-based binder is polyacrylate, and the low-temperature-resistant active agent comprises the following components in parts by mass: 6 parts of potassium chloride, 3 parts of tin methanesulfonate and 0.4 part of cobaltous tungstate;

s3, preparing negative electrode slurry, and mixing the following materials in parts by weight by using a vacuum stirring barrel: the negative electrode slurry is prepared from 91 parts of graphite, 4 parts of a conductive agent, 4 parts of a polymer, 2 parts of cellulose, 3 parts of a water-based binder and 2 parts of a low-temperature resistant active agent, wherein the conductive agent is acetylene black, the water-based binder is polyacrylate, and the low-temperature resistant active agent comprises the following components in parts by mass: 6 parts of potassium chloride, 3 parts of tin methanesulfonate and 0.4 part of cobaltous tungstate, wherein the polymer is polyaniline, and the cellulose is carboxymethyl cellulose;

s4, preparing a clean aluminum sheet, putting at least two aluminum foils into a weak acid solution and deionized water to clean an oxide layer on the surface of the aluminum foil, wherein the weak acid is a 3% nitric acid solution, and the mass part of the mixture of the weak acid and the deionized water is 8 parts and 32 parts, putting the cleaned aluminum foils into a closed space filled with inert gas, and drying the aluminum foils by using 120 ℃ airflow formed by the inert gas to obtain the clean aluminum sheet, wherein the thickness of the aluminum foil is 18 mu m;

s5, preparing an electrode substrate, spraying the surface of a clean aluminum sheet by using inert gas carried by an air pump or a spray gun to carry nano-scale pure aluminum particles in a closed space, further removing impurities on the surface of the clean aluminum sheet, and forming a rough structural surface on the surface of the clean aluminum sheet to obtain the electrode substrate, wherein the spraying pressure of the pure aluminum particles is 2 Mpa;

s6, preparing a positive plate, spraying nano silver oxide and/or conductive carbon nanotubes on the surface of an electrode substrate in a closed space, spraying positive slurry on the electrode substrate coated with the nano silver oxide and/or conductive carbon nanotube layer, and drying to obtain the positive plate, wherein the spraying pressure is 1.2Mpa, and the spraying thickness of the positive slurry is 7 microns;

s7, preparing a negative plate, spraying nano silver oxide and/or conductive carbon nanotubes on the surface of the electrode substrate in a closed space, spraying negative slurry on the electrode substrate coated with the nano silver oxide and/or conductive carbon nanotube layer, and drying to obtain a positive plate, wherein the spraying pressure is 1.2Mpa, and the spraying thickness of the positive slurry is 5 microns;

s8, assembling the lamination, preparing a diaphragm, a battery case and a battery cover, stacking at least one group of positive plate, diaphragm and negative plate to obtain a battery core, putting the battery core into the battery case, injecting low-temperature-resistant electrolyte into the battery case, finally sealing the battery case by using the battery cover to obtain the low-temperature-resistant lithium ion battery, and chemically activating the activities of the positive plate and the negative plate of the low-temperature-resistant lithium ion battery.

The discharge efficiency of the lithium ion battery prepared in the second embodiment at-40 ℃ under 2C is 83.4%, the first discharge efficiency of the lithium ion battery prepared in the second embodiment at 25 ℃ under 2C is 88.2%, and the discharge efficiency of the lithium ion battery prepared in the second embodiment at-40 ℃ is obviously higher than the low-temperature discharge efficiency of a common lithium ion battery by 50-60%.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.