CN115207476A - Low-temperature lithium ion battery and preparation method thereof - Google Patents

Low-temperature lithium ion battery and preparation method thereof Download PDF

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Publication number
CN115207476A
CN115207476A CN202210751035.3A CN202210751035A CN115207476A CN 115207476 A CN115207476 A CN 115207476A CN 202210751035 A CN202210751035 A CN 202210751035A CN 115207476 A CN115207476 A CN 115207476A
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low
lithium ion
ion battery
electrolyte
negative electrode
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刘爱芳
杜鹃
白伟
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Shanxi Zhongke Huaneng Technology Co ltd
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Shanxi Zhongke Huaneng Technology Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention provides a low-temperature lithium ion battery and a preparation method thereof, wherein the low-temperature lithium ion battery comprises a positive electrode material, a negative electrode material and electrolyte, wherein the positive electrode material is nickel-cobalt-aluminum-lithium oxide, and the negative electrode material is high-conductivity graphite, a conductive agent and a bonding agent; the negative electrode material is pressed and bonded to form a negative electrode sheet, and the negative electrode sheet adopts a single-pole lug or double-pole lug structure; the compaction density of the pressed bonding is 1.5-1.65 g/cm 3 (ii) a Controlling the water content of the negative pole piece to be 100-400 ppm; the invention adopts graphite with high conductivity and special low-temperature electrolyte, so that the discharge capacity of the lithium ion battery can be kept above 90% under the conditions of low temperature of minus 40 ℃ and multiplying power of 3C. The traditional sodium carboxymethylcellulose and styrene butadiene rubber are replaced by the glue acrylic glue, so that the wettability between the electrode and the electrolyte under the low-temperature condition is improved, and the interface resistance is improved; the conductivity of the adhesive film is about 10 ‑7 S/cm, improved affinity of two-phase interface, and improved cell performanceAnd (4) safety performance.

Description

Low-temperature lithium ion battery and preparation method thereof
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a low-temperature lithium ion battery and a preparation method thereof.
Background
Lithium batteries are classified into lithium batteries and lithium ion batteries. The lithium ion battery has the advantages of high specific energy, light weight, long service life, no memory effect and the like, and is widely applied to various civil electronic equipment and the fields of electric automobiles, energy storage, mobile power supplies and the like. Lithium ion batteries have met with great success in both power automobiles and consumer electronics applications, however, in some special areas and extreme climatic conditions, lithium ion batteries are limited due to their narrow temperature range of use. Because of the change of materials, the rated voltage of the lithium ion battery is generally 3.7V, and the rated voltage of the lithium iron phosphate anode is 3.2V. The final charging voltage at full charge is generally 4.2V, and the lithium iron phosphate is 3.65V. Generally, the charging temperature is 0 to 60 ℃ and the discharging temperature is-20 to 5 ℃. Under the condition of 20 ℃ below zero, the electrolyte has too high viscosity and even forms crystals, so that the electrolyte cannot be used as a conductive carrier of lithium ions. In addition, under low temperature conditions, the interfacial resistance of the electrode/electrolyte and the lithium ion charge transfer resistance become large, which results in that the electrochemical process cannot be performed, and in order to realize wider application of the lithium ion battery, the low temperature performance of the lithium ion battery needs to be improved.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a low-temperature lithium ion battery and a preparation method thereof, which improve the interface resistance and the affinity of a two-phase interface and improve the safety performance of the battery; and the discharge capacity of the lithium ion battery is kept above 90% under the condition of low temperature minus 40 ℃ multiplying power 3C.
In order to achieve the above object, the present invention provides a low-temperature lithium ion battery, which includes a positive electrode material, a negative electrode material and an electrolyte, wherein the negative electrode material is pressed and bonded to form a negative electrode sheet, and the negative electrode sheet adopts a single-pole lug or double-pole lug structure; the unipolar ear structure is formed by arranging a tab at the head or the tail of the negative plate; the bipolar lug structure is formed by arranging one lug at each of the head and the tail of the negative plate; the compaction density of the pressing bonding is 1.5-1.65 g/cm 3 (ii) a The water content of the negative pole piece is controlled to be 100-400 ppm.
The above-mentionedThe positive electrode material is nickel-cobalt-aluminum-lithium oxide (NCA), the nickel-cobalt-aluminum-lithium oxide is sintered at high temperature to form the positive electrode, and the specific component is LiNi 0.8 Co 0.15 Al 0.05 O 2 。
The cathode material is high-conductivity graphite, the cathode material further comprises a conductive agent and a bonding agent, and the conductive agent is one or a mixture of a plurality of single-walled carbon nanotubes, graphene and superconducting carbon; the negative electrode adopts high-conductivity graphite, so that the conductivity is good; the low-resistance adhesive acrylic adhesive replaces the traditional insulating adhesive and the bipolar lug design, the negative plate reaches the state of no water pole to form a good SEI film, and the above factors all play a role in low-temperature rate discharge. Meanwhile, the rate performance is considered, the discharge rate can reach 10 ℃, and the temperature rise is limited not to exceed 60 ℃.
The adhesive is acrylic glue of a water-based adhesive, and the content of the adhesive is 1-3%; the acryl glue replaces the adhesive of the original CMC and SBR, the novel glue replaces the traditional SBR and CMC, the novel glue has higher ionic conductivity than the traditional glue, and the wettability and the affinity of the electrode and the electrolyte are improved.
The electrolyte is a low-temperature special electrolyte, the electrolyte salt concentration of the electrolyte is 1.15-1.2 mol/L, and the electrolyte is lithium hexafluorophosphate (LiPF) 6 ) One or more of lithium difluoro borate oxalate (LiDFOB) and lithium trifluoromethanesulfonate (LiTSIF). The low-temperature electrolyte is adopted, so that the discharge capacity of the lithium ion battery can be kept above 90% under the conditions of low temperature of-40 ℃ and multiplying power of 3C.
0.5-1.5% of additive is used in the electrolyte; the additive is one or a mixture of more of 0.5-1% of Vinylene Carbonate (VC), 0.5-1% of Propylene Sulfite (PS) and 1-1.5% of ethylene sulfate (DTD); the conventional organic solvents DEC and DMC are not used, the interfacial resistance and the affinity of a two-phase interface are improved, the heat release is greatly reduced even under the condition of high-rate discharge, and the safety performance of the battery is improved.
The low-temperature lithium ion battery prepared by the material has the advantages that the high-conductivity graphite has good conductivity, the low-resistance binder acrylic adhesive replaces the traditional insulating adhesive, the bipolar lug design is adopted, the negative plate reaches the state of no water pole to form a good SEI film, and the factors play an important role in low-temperature rate discharge; conventional organic solvents diethyl carbonate (DEC) and dimethyl carbonate (DMC) are not used as additives; meanwhile, the multiplying power performance is considered, the discharge multiplying power can reach 10 ℃ and the temperature rise does not exceed 60 ℃; the acrylic adhesive is adopted to replace 1-3% of the adhesive content of the original CMC and SBR, and the novel adhesive has higher ionic conductivity than the traditional adhesive, so that the wettability and the affinity of the electrode and the electrolyte are improved.
In order to achieve the above object, the present invention further provides a preparation method of a low temperature lithium ion battery, which comprises a preparation process of a negative plate:
the preparation process of the negative plate adopts a stirring process, and the stirring process comprises the following steps:
weighing the negative electrode material, the conductive agent and the binder in proportion; and dissolving the binder into a solution;
the negative electrode material and the conductive agent are subjected to dry mixing and stirring, and then a binder is added for wet mixing and stirring to obtain a negative electrode sheet material;
and pressing the anode and cathode sheet materials to obtain the low-temperature lithium ion battery.
Further, the ratio of the negative electrode material to the conductive agent to the binder is 97:1.5:1.5; the dry mixing and stirring time is 1-3 hours, and the wet mixing and stirring time is 8-24 hours. Because the novel acrylic glue is used as the binder, the process time is greatly shortened, no additional thickening agent is needed, and because the binder glue has suspension performance, the binder glue does not settle after aging. At low temperature of minus 40 ℃, the initial polarization of discharge is greatly reduced.
Compared with the prior art, the invention has the following beneficial effects:
the low-temperature lithium ion battery adopts the novel glue acrylic glue to replace the traditional sodium carboxymethyl cellulose (CMC) and Styrene Butadiene Rubber (SBR), so that the wettability between an electrode and electrolyte under a low-temperature condition is improved, and the interface resistance is improved; on the other hand, the acrylic adhesive has certain ionic conductivity (the conductivity of the adhesive film is about 10) -7 S/cm)，The traditional glue belongs to the field of insulators, and the affinity of a two-phase interface is improved; namely, even under the condition of high-rate discharge, the heat release quantity can be greatly reduced, and the safety performance of the battery is improved. In addition, the material coordination is increased, and the discharge capacity of the lithium ion battery can be kept more than 90% at the low temperature of minus 40 ℃ and the multiplying power of 3C by adopting high-conductivity graphite and special low-temperature electrolyte.
According to the preparation method of the low-temperature lithium ion battery, the wettability between the electrode and the electrolyte is improved by the acrylic glue, the interface resistance and the affinity of a two-phase interface are improved, the heat release amount is greatly reduced even under the high-rate discharge condition, and the safety performance of the battery is improved; and the low-temperature electrolyte is adopted, so that the discharge capacity of the lithium ion battery can be kept above 90% under the conditions of low temperature of-40 ℃ and multiplying power of 3C.
Drawings
FIG. 1 is a graph of different rate discharge curves (single-pole ears) of a low-temperature lithium ion battery of the present invention under low-temperature conditions;
FIG. 2 is a graph of different rate discharge curves (bipolar tabs) of the low temperature lithium ion battery of the present invention at low temperature;
FIG. 3 shows a unipolar design rate discharge curve and temperature rise diagram of a low temperature lithium ion battery of the present invention;
FIG. 4 shows a bipolar ear design rate discharge curve and temperature rise diagram of the low temperature lithium ion battery of the present invention;
fig. 5 is a surface state diagram of a negative electrode after the end of discharge in the low-temperature lithium ion battery of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples, so that those skilled in the art can fully understand the technical contents of the present invention. It should be noted that the specific embodiments described herein are only for explaining the present invention and are not used to limit the present invention.
The preparation method of the low-temperature lithium ion battery comprises a negative plate preparation process, wherein the negative plate preparation process is carried out by adopting a stirring process: weighing the negative electrode material, the conductive agent and the binder in proportion; dissolving the binder into a solution; mixing the negative electrode material and the conductive agent in a dry mode, adding the binder, mixing in a wet mode and stirring to obtain a negative electrode plate material; pressing the anode and cathode sheet materials to obtain a low-temperature lithium ion battery;
the low-temperature lithium ion battery comprises a positive electrode material, a negative electrode material and electrolyte, wherein the negative electrode material is pressed and bonded to form a negative electrode sheet, and the negative electrode sheet adopts a single-pole lug or double-pole lug structure; the single-pole ear structure is formed by arranging a pole ear at the head or the tail of the negative plate; the bipolar lug structure is formed by arranging one lug at the head and the tail of the negative plate respectively; the compaction density of the pressed bonding is 1.5-1.65 g/cm 3 (ii) a Controlling the water content of the negative pole piece to be 100-400 ppm; the cathode material is high-conductivity graphite, and also comprises a conductive agent and a bonding agent, wherein the conductive agent is one or a mixture of a plurality of single-walled carbon nanotubes, graphene and superconducting carbon; the negative electrode adopts high-conductivity graphite, so that the conductivity is good; the low-resistance adhesive acrylic adhesive replaces the traditional insulating adhesive and the bipolar lug design, the negative plate reaches the state of no water pole to form a good SEI film, and the above factors all play a role in low-temperature rate discharge. Meanwhile, the rate performance is considered, the discharge rate can reach 10 ℃, and the temperature rise is not more than 60 ℃.
The adhesive is acrylic glue of water-based adhesive, and the content of the adhesive is 1-3%; the acryl rubber replaces the adhesive of the original CMC and SBR, the novel glue replaces the traditional SBR and the CMC, the novel glue has higher ionic conductivity than the traditional glue, and the wettability and the affinity of the electrode and the electrolyte are improved.
The electrolyte adopts low-temperature special electrolyte, the electrolyte salt concentration of the electrolyte is 1.15-1.2 mol/L, and the electrolyte is lithium hexafluorophosphate (LiPF) 6 ) One or more of lithium difluoro borate oxalate (LiDFOB) and lithium trifluoro methane sulfonate (LiTSIF). The low-temperature electrolyte is adopted, so that the discharge capacity of the lithium ion battery can be kept above 90% under the conditions of low temperature of-40 ℃ and multiplying power of 3C; 0.5 to 1.5 percent of additive is used in the electrolyte; the additive is 0.5 to 1 percent of Vinylene Carbonate (VC) and 0.5 to 1 percent of propylene sulfiteOne or more of ester (PS) and 1-1.5% ethylene sulfate (DTD); the conventional organic solvents DEC and DMC are not used, the interfacial resistance and the affinity of a two-phase interface are improved, the heat release is greatly reduced even under the condition of high-rate discharge, and the safety performance of the battery is improved.
The positive electrode material is nickel-cobalt-aluminum-lithium oxide (NCA) which is sintered at high temperature to form a positive electrode, and the specific component is LiNi 0.8 Co 0.15 Al 0.05 O 2 . The low-temperature lithium ion battery adopts the acrylic glue to improve the wettability between the electrode and the electrolyte, improve the interface resistance and the affinity of a two-phase interface, greatly reduce the heat release even under the high-rate discharge condition and improve the safety performance of the battery; and the low-temperature electrolyte is adopted, so that the discharge capacity of the lithium ion battery can be kept above 90% under the conditions of low temperature of-40 ℃ and multiplying power of 3C.
Example 1
The invention provides a preparation method of a low-temperature lithium ion battery, which adopts a single-pole ear battery core (the capacity is 2.6Ah, the positive electrode NCA, the negative electrode is high-conductivity graphite, the negative electrode binder is acrylic adhesive), the positive electrode material is nickel-cobalt-aluminum-lithium oxide (NCA), and the compaction density of the press bonding of the negative electrode sheets is 1.55g/cm 3 (ii) a Controlling the moisture content of the negative pole piece to be 250ppm; the negative electrode material is high-conductivity graphite, and the conductive agent is graphene; the adhesive is acrylic glue of water-based adhesive, and the content of the adhesive is 1.3 percent; the electrolyte adopts a low-temperature special electrolyte, the electrolyte salt concentration of the electrolyte is 1.17mol/L, and the electrolyte is lithium hexafluorophosphate (LiPF) 6 ). The additives are 0.5% of Vinylene Carbonate (VC), 0.5% of Propylene Sulfite (PS) and 1% of ethylene sulfate (DTD); fully charging the charged cell at the rate of 1C, standing the cell in a low-temperature (-40 ℃) box for 16 hours, and then discharging at different currents (0.5C, 1C and 2C) with the cut-off voltage of 4.2V to 2.5V. The voltage is quickly recovered to be more than 3.0V after the initial voltage affected by polarization of a discharge platform of the battery cell is reduced under the conditions of extremely low temperature and high-rate 3C discharge, and normal discharge is shown, and a discharge curve with different rates under the low-temperature condition of FIG. 1 is referred.
Example 2
The preparation method of the low-temperature lithium ion battery adopts a double-tab battery cell (the capacity is 2.6Ah, and the anode is NCA (LiNi) 0.8 Co 0.15 Al 0.05 O 2 ) And, negative electrode: high-conductivity graphite, negative electrode binder: acrylic adhesive), the positive electrode material is nickel cobalt aluminum lithium oxide (NCA), the compacted density of the pressed and bonded negative electrode sheet is 1.5-1.65 g/cm 3 (ii) a Controlling the water content of the negative pole piece to be 100-400 ppm; the cathode material is high-conductivity graphite, and the conductive agent is one or a mixture of a plurality of single-walled carbon nanotubes, graphene and superconducting carbon; the adhesive is acrylic glue of water-based adhesive, and the content of the adhesive is 1-3%; the electrolyte adopts a low-temperature special electrolyte, the electrolyte salt concentration of the electrolyte is 1.15-1.2 mol/L, and the electrolyte is lithium hexafluorophosphate (LiPF) 6 ) One or more of lithium difluoro borate oxalate (LiDFOB) and lithium trifluoro methane sulfonate (LiTSIF). The electrolyte uses one or more additives of 0.5 to 1 percent of Vinylene Carbonate (VC), 0.5 to 1 percent of Propylene Sulfite (PS) and 1 to 1.5 percent of ethylene sulfate (DTD); the battery core is filled with 1C current to 4.2V, then stored in a low-temperature (-40 ℃) box for 16 hours, and then discharged at different currents (0.2C, 0.5C, 1C, 2C and 3C), the cut-off voltage is 4.2V to 2.5V, and the capacity retention rates are 94%, 90%, 94% and 91% respectively. The voltage is quickly recovered to be more than 3.0V under the conditions of extremely low temperature and high-rate 3C discharge after the initial polarization-affected voltage of the discharge platform of the battery cell is reduced, and the capacity retention rate reaches 91 percent, which indicates that the battery cell can normally discharge. Referring to different multiplying power discharge curves of the lithium ion battery under low temperature conditions in the figure 2, the bipolar lug electric core has a low temperature (-40 ℃) different multiplying power discharge curve and a cut-off voltage of 4.2-2.0V.
Example 3
The preparation method of the low-temperature lithium ion battery adopts the design of the single-electrode lug, the anode material is nickel-cobalt-aluminum-lithium oxide (NCA), and the compacted density of the pressed and bonded cathode sheet is 1.5-1.65 g/cm 3 (ii) a Controlling the water content of the negative pole piece to be 100-400 ppm; the cathode material is high-conductivity graphite, and the conductive agent is one or a mixture of a plurality of single-walled carbon nanotubes, graphene and superconducting carbon; the adhesive is water-based adhesive acrylic1-3% of glue; the electrolyte adopts a low-temperature special electrolyte, the electrolyte salt concentration of the electrolyte is 1.15-1.2 mol/L, and the electrolyte is lithium hexafluorophosphate (LiPF) 6 ) One or more of lithium difluoro borate oxalate (LiDFOB) and lithium trifluoromethanesulfonate (LiTSIF). The electrolyte uses one or more additives of 0.5 to 1 percent of Vinylene Carbonate (VC), 0.5 to 1 percent of Propylene Sulfite (PS) and 1 to 1.5 percent of ethylene sulfate (DTD); at normal temperature (25 deg.C), different currents discharge, 4.2V to 2.8V. The 4C discharge temperature has reached 60 degrees. So the highest current discharge is recommended to be 3C. Under the charge-discharge condition of 0.2C multiplying power of discharge 3C/charge, the capacity retention rate is 100 percent, and the temperature is 49.5 ℃ at most. Referring to a normal-temperature multiplying power discharge curve and a temperature rise curve corresponding to multiplying power of the single-lug design battery core in fig. 3, the multiplying power discharge curve and the temperature rise curve are designed for the single-lug, and the multiplying power 3C discharge temperature rise can exceed 60 degrees.
Example 4
The preparation method of the low-temperature lithium ion battery adopts a bipolar lug design, the anode material is nickel-cobalt-aluminum-lithium oxide (NCA), and the compacted density of the pressed and bonded cathode sheet is 1.5-1.65 g/cm 3 (ii) a Controlling the water content of the negative pole piece to be 100-400 ppm; the cathode material is high-conductivity graphite, and the conductive agent is one or a mixture of a plurality of single-walled carbon nanotubes, graphene and superconducting carbon; the adhesive is acrylic glue of water-based adhesive, and the content of the adhesive is 1-3%; the electrolyte adopts low-temperature special electrolyte, the electrolyte salt concentration of the electrolyte is 1.15-1.2 mol/L, and the electrolyte is lithium hexafluorophosphate (LiPF) 6 ) One or more of lithium difluoro borate oxalate (LiDFOB) and lithium trifluoro methane sulfonate (LiTSIF). 0.5 to 1.5 percent of additive is used in the electrolyte. Under normal temperature (25 ℃), different currents discharge, 4.2V to 2.8V, and the discharge temperature of 5C is less than 60 ℃. It is recommended to discharge 5C at the highest current. Under the condition of 5C/0.2C discharge charge multiplying power, the capacity retention rate is 99.85 percent, and the temperature is 54.4 ℃ at most. Referring to a normal-temperature rate discharge curve and a temperature rise curve of a corresponding rate of a bipolar ear design 18650 battery cell of fig. 4, a rate discharge curve and a temperature rise curve of the bipolar ear design are shown, and the discharge temperature rise of a rate 5C does not exceed 60 ℃.
Example 5
The preparation method of the low-temperature lithium ion battery adopts a bipolar lug design, the positive electrode material is nickel-cobalt-aluminum-lithium oxide (NCA), and the compacted density of the pressed and bonded negative electrode piece is 1.65g/cm 3 (ii) a Controlling the water content of the negative pole piece to be 100ppm; the negative electrode material is high-conductivity graphite, and the conductive agent is graphene; the adhesive is acrylic glue of a water-based adhesive, and the content of the adhesive is 1.5%; the electrolyte adopts a low-temperature special electrolyte, the electrolyte salt concentration of the electrolyte is 1.18mol/L, and the electrolyte is lithium hexafluorophosphate (LiPF) 6 ) Lithium difluoroborate oxalate (LiDFOB) and lithium trifluoromethanesulfonate (LiTSIF). The electrolyte contains one or more additives selected from 0.5% Vinylene Carbonate (VC), 0.8% Propylene Sulfite (PS) and 1.5% ethylene sulfate (DTD). Discharging at low temperature (-40 ℃) until the voltage reaches 2.8V at 0.5C, disassembling the battery cell after the discharge is finished, and observing the surface state of the negative electrode. Referring to fig. 5, the surface state of the negative electrode after discharging at-40 ℃ and 0.5C to 2.8V indicates that no lithium precipitation occurs, and after discharging at low temperature, the battery is disassembled and no metallic lithium is precipitated.
It should be noted that the above-mentioned preferred embodiments are merely illustrative of the technical concepts and features of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered in the protection scope of the present invention.

Claims (10)

1. A low-temperature lithium ion battery is characterized by comprising a positive electrode material, a negative electrode material and electrolyte, wherein the negative electrode material is pressed and bonded to form a negative electrode sheet, and the negative electrode sheet adopts a single-pole lug or double-pole lug structure; the compaction density of the pressing bonding is 1.5-1.65 g/cm 3 (ii) a The water content of the negative pole piece is controlled to be 100-400 ppm.
2. The low temperature lithium ion battery of claim 1, wherein: the negative electrode material is high-conductivity graphite, and the positive electrode material is nickel-cobalt-aluminum-lithium oxide.
3. The method for preparing a low-temperature lithium ion battery according to claim 2, wherein the method comprises the following steps: the cathode material also comprises a conductive agent and a bonding agent, wherein the conductive agent is one or a mixture of a plurality of single-walled carbon nanotubes, graphene and superconducting carbon.
4. The low temperature lithium ion battery of claim 3, wherein: the adhesive is acrylic glue of a water-based adhesive, and the content of the adhesive is 1-3%.
5. The low temperature lithium ion battery of claim 1, wherein: the electrolyte is a low-temperature special electrolyte, and the electrolyte salt concentration of the electrolyte is 1.15-1.2 mol/L.
6. The low temperature lithium ion battery of claim 5, wherein: the electrolyte is one or a mixture of more of lithium hexafluorophosphate, lithium oxalate difluoride and lithium trifluoromethanesulfonate.
7. The low temperature lithium ion battery of claim 6, wherein: 0.5 to 1.5 percent of additive is used in the electrolyte.
8. The low temperature lithium ion battery of claim 7, wherein: the additive is one or a mixture of more of 0.5 to 1 percent of vinylene carbonate, 0.5 to 1 percent of propylene sulfite and 1 to 1.5 percent of ethylene sulfate.
9. The method for preparing a low-temperature lithium ion battery according to any one of claims 1 to 8, wherein: the preparation method comprises a negative plate preparation process, wherein the negative plate preparation process adopts a stirring process, and the stirring process comprises weighing the negative material, the conductive agent and the binder in proportion; and dissolving the binder into a solution; and (3) dry-mixing and stirring the negative electrode material and the conductive agent, and then adding a binder for wet mixing and stirring to obtain a negative electrode plate material.
10. The method for preparing a low-temperature lithium ion battery according to claim 9, wherein the method comprises the following steps: the dry mixing and stirring time is 1-3 hours, and the wet mixing and stirring time is 8-24 hours.
CN202210751035.3A 2022-06-28 2022-06-28 Low-temperature lithium ion battery and preparation method thereof Pending CN115207476A (en)

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