CN111653730A - Method for double heat treatment and rapid formation of battery cell coated with artificial SEI film negative pole piece - Google Patents

Method for double heat treatment and rapid formation of battery cell coated with artificial SEI film negative pole piece Download PDF

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Publication number
CN111653730A
CN111653730A CN202010536724.3A CN202010536724A CN111653730A CN 111653730 A CN111653730 A CN 111653730A CN 202010536724 A CN202010536724 A CN 202010536724A CN 111653730 A CN111653730 A CN 111653730A
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negative electrode
formation
battery cell
sei film
heat treatment
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CN111653730B (en
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周朝辉
廉亚娟
吴波涛
杨洪
周鼎
孙延先
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Huading Guolian Sichuan Power Battery Co ltd
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Huading Guolian Sichuan Power Battery 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0421—Methods of deposition of the material involving vapour deposition
    • H01M4/0428—Chemical vapour deposition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • 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

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

A method for double heat treatment and rapid formation of a battery core coated with an artificial SEI film negative pole piece comprises the steps of preparing the negative pole piece, laminating, carrying out hot pressing treatment according to the technology of the invention, and carrying out special hot pressing treatment on the battery core during formation of the battery core so as to realize the battery core with high efficiency and good performance. The invention has the advantages of improving the battery circulation stability, ensuring the cell voltage consistency, and quickly and efficiently realizing excellent formation results by regulating and controlling the specific voltage of the cell formation.

Description

Method for double heat treatment and rapid formation of battery cell coated with artificial SEI film negative pole piece
Technical Field
The application relates to the field of lithium battery manufacturing, in particular to a method for double heat treatment and rapid formation of a battery cell coated with an artificial SEI (solid electrolyte interface) film negative electrode plate.
Technical Field
In recent years, with the popularization of new energy automobiles, the market demand of power batteries is increasing, wherein high-end electric automobiles also have larger requirements on the capacity of the batteries, and therefore, a larger space still exists for further improving the effective capacity of the power batteries.
In order to improve the effective capacity of the power battery, the current main ideas are respectively carried out from the aspects of improving the first effect, reducing the ohmic internal resistance and the polarization internal resistance and the like. The first effect can be improved by using the electrolyte film-forming additive for the positive and negative electrode materials, and the structure of the positive and negative electrode materials can be modified to reduce the phenomena of particle pulverization and structure collapse; in the aspect of reducing ohmic internal resistance and polarization internal resistance, the electronic conductivity and the ionic conductivity of the positive and negative electrode plates are optimized, in the aspect of improving the ionic conductivity, except for improving the positive and negative electrode material structures, electrolyte related additives, binder modification and the like, part of manufacturers still adopt a mode of carrying out thermal composite treatment on the core package, usually, after lamination or winding, the core package is subjected to hot pressing, or in the formation process, the core package is subjected to heating and pressurizing formation treatment, and through the modes, the capacity improvement of a certain degree can be realized.
In the prior art, manufacturers have made a series of research and applications on the aspect of thermal compounding of the battery core, from the aspects of improving the performance of the diaphragm, stacking and folding the core pack, and how to perform thermal compounding treatment on the core pack.
In the aspect of thermal composite treatment, CN 103959539B forms two a-type and C-type battery cells by stacking/folding of a pole piece and a diaphragm, however, the technical complexity is high, and further the product cost is high; the heating effect of the battery unit is difficult to be unified, the surface of the diaphragm is easily heated unevenly, the binder coated on the surface layer of the diaphragm cannot well form affinity with the pole piece, the surface of the negative pole piece is easily formed into an SEI film which is uneven and poor in quality, and the phenomenon of lithium precipitation or black spot is easily formed at the later stage of the use of the battery.
The patent CN 107403945A introduces a soft package lithium ion battery formation rolling method, the working procedure of the invention is more complex, the temperature of the battery core after hot pressing is higher, and the temperature reduction and cold pressing are needed, thus prolonging the working hours and further increasing the production cost; after the electric core is subjected to hot pressing, part of electrolyte can be gasified, so that more bubbles are remained on the surface of the pole piece, and the gas amount in the air bag can be increased sharply. Even if the core is subjected to subsequent cold pressing, part of gas still remains in the core package, and black spots are easily formed on the surface of the negative pole piece after the battery core is circulated, so that capacity loss is caused; the technology is easy to cause the phenomenon of uneven distribution of the internal temperature of the battery core, the surface of the diaphragm is easy to be heated unevenly, the binder coated on the surface layer of the diaphragm cannot well form affinity with the pole piece, and the electrolyte is easy to decompose at high temperature, so that an uneven SEI film with poor quality is easy to form on the surface of the negative pole piece, and black spots or lithium precipitation phenomena are easy to form at the later stage of the use of the battery, thereby bringing about capacity loss or safety risk;
in patent CN 106099202A, the consistency of the capacity of the finally formed battery cell is low by using 8% -15% of reversible capacity as a method for regulating SEI; in the formation and exhaust stage of the technology, the used pressure is high, and the air bag can quickly bulge under the conditions of high temperature and high pressure; under pressure, the diaphragm is comparatively inseparable with the pole piece contact, and the electrolyte in the core package can not adsorb on pole piece and diaphragm surface well, easily leads to the phenomenon that the volume of protecting liquid is low to form harder electric core, this makes the circulation performance in energy type electric core later stage relatively poor.
Disclosure of Invention
In the prior art, the SEI film of the negative pole piece is difficult to realize better regulation and control, which has great influence on the capacity exertion and the cycle performance of a battery cell; most of the technologies are complicated, the process complexity is high, and the cost pressure is high. Therefore, the invention aims to solve the difficulties, and provides a method for double heat treatment and rapid formation of a battery cell coated with an artificial SEI film negative pole piece, so as to prepare the negative pole piece, perform hot pressing treatment according to the technology of the invention after lamination, and then perform special hot pressing treatment on the battery cell when the battery cell is formed, so as to realize a battery cell with high efficiency and good performance.
Specifically, the positive and negative surfaces of a current collector are coated with materials to obtain a negative pole piece, then a molecular layer deposition technology (MLD) is applied to form a nanoscale organic-inorganic hybrid layer on the surface of the negative pole, and then hot pressing treatment is carried out after lamination to carry out post-formation heat treatment.
Wherein, the organic-inorganic hybrid layer adopts molecular layer deposition equipment to alternately deposit trimethyl aluminum and ethylene glycol on the surface of the cathode layer to generate polymeric aluminum (molecular formula is [ Al (OCH) ]2)3]n) And the polymeric aluminum thin film layer is an artificial SEI film, and the thickness of the film is preferably 0.1-20 mu m.
The proportion, the film thickness and the consistency of reactants are controlled by controlling the pulse and the purging time of each layer of compound.
The formed polymeric aluminum film layer is an organic-inorganic hybrid layer, so that the interface reaction between the electrolyte and the surface of the negative electrode can be effectively inhibited, the de-intercalation efficiency of lithium ions in the negative electrode material is improved, and the cycling stability of the battery is further improved.
The positive plate used in the invention is a positive plate taking ternary nickel cobalt lithium manganate as an active material.
In addition, in view of the special process of the laminated soft-packaging battery core, the used diaphragm is a gluing diaphragm during lamination. After lamination, carrying out hot-pressing treatment on the core bag, and respectively carrying out hot-pressing regulation and control on the temperature of a pressing plate, the pressure of the pressing plate and the hot-pressing time; through the hot pressing treatment, the gluing diaphragm can closely adhere the negative pole piece with the artificial SEI film and the diaphragm, so that the transmission distance of a transmission channel of lithium ions is effectively reduced, and the effect of the artificial SEI film is fully exerted, and a powerful guarantee is provided.
Particularly, after hot pressing, a workshop cold air system is utilized to introduce cold air energy into the cold air blowing device, the air pressure of the cold air outlet is controlled, and cold air blowing treatment is carried out on the electric core. On the one hand, the cold air system of the workshop is fully utilized, the waste of resources is avoided, on the one hand, the rapid cooling of the core bag can be realized, and the production takt can be rapidly and effectively improved.
And in the formation stage after the liquid injection of the battery core, after the battery core with the air bag is put into a cabinet, the formation process steps are limited according to the set factors such as voltage, current, capacity, time and the like, and in the process, the pressure and temperature parameters of a clamp plate of a formation clamp are added.
In particular, the formation stage control of the present invention is defined by introducing a voltage factor as a main condition, unlike the prior art. Because the voltage and the capacity form a certain relationship, a specific voltage range is usually determined by using an SOC-OCV characteristic curve, so that the SEI film on the surface of the negative pole piece of the battery cell is regulated and controlled, and the first effect, the capacity and the cycle performance of the battery cell are improved.
In a specific voltage range, the battery cell is charged according to a set constant current, so that the film forming effect on the surface of the negative electrode is ensured; in addition, the voltage consistency of the battery cells can be ensured, the situation that the voltage consistency is poor due to reversible capacity limitation designed according to theory, and the situation that partial battery cells are misjudged as bad battery cells due to overlarge self-discharge because the voltage difference is relatively large is avoided.
Particularly, the lithium ion transmission distance is effectively reduced by a special heat treatment mode for the core package after lamination; the regulation and control of the SEI film formation on the surface of the negative pole piece of the battery cell are further realized by a special heat treatment mode of the battery cell during formation, so that excellent first charge-discharge efficiency, first reversible capacity and excellent cycle performance are realized.
Preparing a negative pole piece:
1) coating silicon carbon or graphite cathode material on the surface of a current collector to form a cathode layer, wherein the thickness of the cathode layer is 10-180 mu m;
2) and (2) depositing trimethyl aluminum and ethylene glycol on the surface of the coating alternately by adopting a molecular layer deposition method to form a polymeric aluminum film layer, wherein the mass ratio of the trimethyl aluminum to the ethylene glycol is 1 (3-20), and the thickness of the polymeric aluminum film layer is 0.1-20 mu m.
Hot pressing after lamination:
1) during lamination, the hot-pressing tool needs to be subjected to advanced parameter adjustment;
particularly, the temperature of an upper clamping plate and a lower clamping plate of the hot pressing tool is set to be 40-125 ℃, the pressure of the upper clamping plate and the lower clamping plate is 0.1-1 MPa, and the hot pressing time is 10-120 s;
after the temperature, pressure and time parameters are adjusted, the core package after lamination is placed on a clamping plate for hot pressing treatment.
Rapidly cooling the core package after hot pressing by using a cold air blowing system in a workshop, wherein the temperature of cold air is 2-15 ℃, the air pressure of a cold air outlet is 0.1-0.3 MPa, and the blowing time is 5-70 s;
carrying out heat treatment after formation:
when the battery cell with the air bag is formed, firstly charging the battery cell with the air bag to 3.2-3.5V by using a small-magnification constant current of 0.01-0.05C, and then starting to set the pressure of a clamping plate on a forming clamp and heating;
particularly, the pressure of the formation clamp is 0.1MPa to 0.8MPa, and the temperature is 30 ℃ to 60 ℃;
when the battery cell is charged to 3.5V-3.6V by constant current, the pressure of the formation clamp is kept, and heating is cancelled;
particularly, the charging constant current is 0.05 to 0.5 ℃, the pressure of the formation clamp is still 0.1 to 0.8MPa, and the pressure is kept unchanged from the pressure of the clamp in the previous step;
then, the battery cell can be continuously charged with constant current of 0.2C-1C until the voltage is 3.6V-4.35V, and then the voltage is constant until the voltage is 0.1C-0.02C;
through the formation mechanism, the rapid and efficient formation method with excellent performance for the battery cell can be realized.
The invention has the advantages of
1) The invention adopts a molecular layer deposition technology (MLD), and the polymeric aluminum film layer formed on the surface of the negative electrode is an organic-inorganic hybrid layer, so that the interface reaction of the electrolyte and the surface of the negative electrode can be effectively inhibited, the de-intercalation efficiency of lithium ions in the negative electrode material is improved, and the cycle stability of the battery is further improved.
2) After lamination, the core cladding is subjected to hot-pressing treatment, the temperature and the pressure of a pressing plate are higher, and the core cladding is subjected to hot-pressing regulation and control in a short time, so that the transmission distance of a transmission channel of lithium ions is effectively reduced, and a powerful guarantee is provided for fully playing the role of an artificial SEI film.
3) Particularly, after hot pressing, a workshop cold air system is utilized to introduce cold air energy into the cold air blowing device, the air pressure of the cold air outlet is controlled, and cold air blowing treatment is carried out on the electric core. On the one hand, the cold air system of the workshop is fully utilized, the waste of resources is avoided, on the one hand, the rapid cooling of the core bag can be realized, and the production takt can be rapidly and effectively improved.
4) In a specific voltage range, the battery cell is charged according to a set constant current, so that the film forming effect on the surface of the negative electrode is ensured; in addition, the voltage consistency of the battery cells can be ensured, the situation that the voltage consistency is poor due to reversible capacity limitation designed according to theory, and the situation that partial battery cells are misjudged as bad battery cells due to overlarge self-discharge because the voltage difference is relatively large is avoided.
5) The specific voltage regulation and control are carried out on the formation of the battery core, so that the excellent formation result can be quickly and efficiently realized.
Detailed Description
Example 1
1) Coating a silicon-carbon negative electrode material ([ SiO ] with the concentration of 45 wt% on the surface of a copper current collector2@ Graphite) water solution, wherein the content of silica in the silicon-carbon negative electrode material is 2 wt%, and then the silicon-carbon negative electrode material is dried for 2 hours at 90 ℃ to form a silicon-carbon negative electrode layer with the thickness of 117 mu m on the surface of a current collector;
2) with a molecular layer deposition apparatus (note: boinst MLD, Beijing Bergen technologies, Inc., Boinst-PMLD100) Trimethylaluminum (TMA) was mixed with Ethylene Glycol (EG) as follows: TMA-pulse (0.01s) -purge (40s) -EG-pulse (0.01s) -purge (70s) were deposited alternately on the silicon carbon coating surface. The thickness of the formed polymeric aluminum film layer is 0.8 mu m, and the mass ratio of trimethylaluminum to ethylene glycol is 1: 3;
3) the temperature of the upper and lower clamping plates of the hot pressing tool after lamination is set to be 80 ℃, the pressure of the upper and lower clamping plates is 0.8MPa, and the hot pressing time is 90 s;
after the temperature, pressure and time parameters are adjusted, the core package after lamination is placed on a clamping plate, and hot pressing treatment is carried out;
blowing the core bag subjected to hot pressing by cold air to rapidly cool;
the temperature of the cold air is 5 ℃, the air pressure of a cold air outlet is 0.11MPa, and the purging time is 10 s;
4) when the battery cell with the air bag is formed, firstly charging the battery cell to 3.2V at a low-multiplying-power constant current of 0.02C, and then setting the pressure of a clamping plate on a forming clamp and heating;
the pressure of the formation clamp is 0.2Mpa, and the temperature is 60 ℃;
when the battery cell is charged to 3.5V by constant current, the pressure of the formation clamp is kept, and heating is cancelled;
the charging constant current is 0.5C, the pressure of the formation clamp is still 0.2Mpa, and the pressure is kept unchanged from the pressure of the clamp in the previous step;
and then, the battery cell can be continuously charged with constant current of 0.5C until the voltage is cut off at 3.9V, and is switched to be constant voltage until the voltage is cut off at 0.1C.
Example 2
1) Coating a silicon-carbon negative electrode material ([ SiO2@ Graphite) aqueous solution with the concentration of 45 wt% on the surface of a copper current collector, wherein the content of silicon monoxide in the silicon-carbon negative electrode material is 2 wt%, and then drying the silicon-carbon negative electrode material at 90 ℃ for 2 hours to form a silicon-carbon negative electrode layer with the thickness of 117 mu m on the surface of the current collector;
2) with a molecular layer deposition apparatus (note: boinst MLD, Beijing Bergen technologies, Inc., Boinst-PMLD100) Trimethylaluminum (TMA) was mixed with Ethylene Glycol (EG) as follows: TMA-pulse (0.01s) -purge (40s) -EG-pulse (0.01s) -purge (70s) were deposited alternately on the silicon carbon coating surface. The thickness of the formed polymeric aluminum film layer is 0.8 mu m, and the mass ratio of trimethylaluminum to ethylene glycol is 1: 3;
3) the temperature of the upper and lower clamping plates of the hot pressing tool after lamination is set to be 100 ℃, the pressure of the upper and lower clamping plates is 0.6MPa, and the hot pressing time is 80 s;
after the temperature, pressure and time parameters are adjusted, the core package after lamination is placed on a clamping plate, and hot pressing treatment is carried out;
blowing the core bag subjected to hot pressing by cold air to rapidly cool;
the temperature of the cold air is 10 ℃, the air pressure of a cold air outlet is 0.12MPa, and the purging time is 20 s;
4) when the battery cell with the air bag is formed, firstly charging the battery cell to 3.4V by using a small-magnification constant current of 0.05C, and then setting the pressure of a clamping plate on a forming clamp and heating;
particularly, the pressure of the formation clamp is 0.3Mpa, and the temperature is 50 ℃;
when the constant current of the battery cell is charged to 3.56V, the pressure of the formation clamp is kept, and heating is cancelled;
particularly, the charging constant current is 0.5C, the pressure of the formation clamp is still 0.3Mpa, and the pressure is kept unchanged from the pressure of the clamp in the previous process step;
and then, the battery cell can be continuously charged by constant current 0.5C until the battery cell is cut off at 4V, and is switched to be constant voltage until the battery cell is cut off at 0.1C.
Example 3
1) Coating a silicon-carbon negative electrode material ([ SiO ] with the concentration of 45 wt% on the surface of a copper current collector2@ Graphite) water solution, wherein the content of silica in the silicon-carbon negative electrode material is 2 wt%, and then the silicon-carbon negative electrode material is dried for 2 hours at 90 ℃ to form a silicon-carbon negative electrode layer with the thickness of 117 mu m on the surface of a current collector;
2) with a molecular layer deposition apparatus (note: boinst MLD, Beijing Bergen technologies, Inc., Boinst-PMLD100) Trimethylaluminum (TMA) was mixed with Ethylene Glycol (EG) as follows: TMA-pulse (0.01s) -purge (40s) -EG-pulse (0.01s) -purge (70s) were deposited alternately on the silicon carbon coating surface. The thickness of the formed polymeric aluminum film layer is 0.8 mu m, and the mass ratio of trimethylaluminum to ethylene glycol is 1: 3;
3) the temperature of the upper and lower clamping plates of the hot pressing tool after lamination is set to be 120 ℃, the pressure of the upper and lower clamping plates is 0.4MPa, and the hot pressing time is 50 s;
after the temperature, pressure and time parameters are adjusted, the core package after lamination is placed on a clamping plate, and hot pressing treatment is carried out;
blowing the core bag subjected to hot pressing by cold air to rapidly cool;
the temperature of the cold air is 5 ℃, the air pressure of a cold air outlet is 0.12MPa, and the purging time is 10 s;
4) when the battery cell with the air bag is formed, firstly charging the battery cell with the air bag to 3.5V by using a small-magnification constant current of 0.1C, and then setting the pressure of a clamping plate on a forming clamp and heating the forming clamp;
particularly, the pressure of the formation clamp is 0.3Mpa, and the temperature is 50 ℃;
when the battery cell is charged to 3.6V by constant current, the pressure of the formation clamp is kept, and heating is cancelled;
particularly, the charging constant current is 0.5C, the pressure of the formation clamp is still 0.3Mpa, and the pressure is kept unchanged from the pressure of the clamp in the previous process step;
and then, the battery cell can be continuously charged by the constant current 1C until the voltage is cut off to 4V, and is turned to be constant to 0.05C and cut off.
Example 4
1) Coating a graphite negative electrode material aqueous solution with the concentration of 45 wt% on the surface of a copper current collector, and then drying for 2h at 90 ℃ to form a graphite negative electrode layer with the thickness of 117 mu m on the surface of the current collector;
2) with a molecular layer deposition apparatus (note: boinst MLD, Beijing Bergen technologies, Inc., Boinst-PMLD100) Trimethylaluminum (TMA) was mixed with Ethylene Glycol (EG) as follows: TMA-pulse (0.01s) -purge (40s) -EG-pulse (0.01s) -purge (70s) were deposited alternately on the graphite coating surface. The thickness of the formed polymeric aluminum film layer is 0.8 mu m, and the mass ratio of trimethylaluminum to ethylene glycol is 1: 3;
3) the temperature of the upper and lower clamping plates of the hot pressing tool after lamination is set to be 120 ℃, the pressure of the upper and lower clamping plates is 0.4MPa, and the hot pressing time is 50 s;
after the temperature, pressure and time parameters are adjusted, the core package after lamination is placed on a clamping plate, and hot pressing treatment is carried out;
blowing the core bag subjected to hot pressing by cold air to rapidly cool;
the temperature of the cold air is 5 ℃, the air pressure of a cold air outlet is 0.12MPa, and the purging time is 10 s;
4) when the battery cell with the air bag is formed, firstly charging the battery cell with the air bag to 3.5V by using a small-magnification constant current of 0.1C, and then setting the pressure of a clamping plate on a forming clamp and heating the forming clamp;
particularly, the pressure of the formation clamp is 0.3Mpa, and the temperature is 50 ℃;
when the battery cell is charged to 3.6V by constant current, the pressure of the formation clamp is kept, and heating is cancelled;
particularly, the charging constant current is 0.5C, the pressure of the formation clamp is still 0.3Mpa, and the pressure is kept unchanged from the pressure of the clamp in the previous process step;
and then, the battery cell can be continuously charged by the constant current 1C until the voltage is cut off to 4V, and is turned to be constant to 0.05C and cut off.
Comparative example 1
1) Coating a silicon-carbon negative electrode material ([ SiO ] with the concentration of 45 wt% on the surface of a copper current collector2@ Graphite) water solution, wherein the content of silica in the silicon-carbon negative electrode material is 2 wt%, and then the silicon-carbon negative electrode material is dried for 2 hours at 90 ℃ to form a silicon-carbon negative electrode layer with the thickness of 117 mu m on the surface of a current collector;
2) with a molecular layer deposition apparatus (note: boinst MLD, Beijing Bergen technologies, Inc., Boinst-PMLD100) Trimethylaluminum (TMA) was mixed with Ethylene Glycol (EG) as follows: TMA-pulse (0.01s) -purge (40s) -EG-pulse (0.01s) -purge (70s) were deposited alternately on the silicon carbon coating surface. The thickness of the formed polymeric aluminum film layer is 0.8 mu m, and the mass ratio of trimethylaluminum to ethylene glycol is 1: 3;
3) the temperature of the upper and lower clamping plates of the hot pressing tool after lamination is set to be 120 ℃, the pressure of the upper and lower clamping plates is 0.4MPa, and the hot pressing time is 50 s;
after the temperature, pressure and time parameters are adjusted, the core package after lamination is placed on a clamping plate, and hot pressing treatment is carried out;
blowing the core bag subjected to hot pressing by cold air to rapidly cool;
the temperature of the cold air is 5 ℃, the air pressure of a cold air outlet is 0.12MPa, and the purging time is 10 s;
4) when the battery cell with the air bag is formed, the battery cell is charged to 3.5V by using a small-multiplying-power constant current of 0.1C, then the battery cell is charged to 3.6V by using a 0.5C constant current, then the battery cell is continuously charged to 4V by using a constant current of 1C, and then the battery cell is turned off by using a constant voltage of 0.05C.
Comparative example 2
1) Coating a silicon-carbon negative electrode material ([ SiO ] with the concentration of 45 wt% on the surface of a copper current collector2@ Graphite) aqueous solution, siliconThe content of the silicon monoxide in the carbon negative electrode material is 2 wt%, and then the carbon negative electrode material is dried for 2 hours at 90 ℃ to form a silicon-carbon negative electrode layer with the thickness of 117 mu m on the surface of the current collector;
2) with a molecular layer deposition apparatus (note: boinst MLD, Beijing Bergen technologies, Inc., Boinst-PMLD100) Trimethylaluminum (TMA) was mixed with Ethylene Glycol (EG) as follows: TMA-pulse (0.01s) -purge (40s) -EG-pulse (0.01s) -purge (70s) were deposited alternately on the silicon carbon coating surface. The thickness of the formed polymeric aluminum film layer is 0.8 μm, the mass ratio of the trimethylaluminum to the ethylene glycol is 1: 3;
3) the core package is not subjected to hot pressing and cold air blowing treatment after lamination;
4) when the battery cell with the air bag is formed, the battery cell is charged to 3.5V by using a small-multiplying-power constant current of 0.1C, then the battery cell is charged to 3.6V by using a 0.5C constant current, then the battery cell is continuously charged to 4V by using a constant current of 1C, and then the battery cell is turned off by using a constant voltage of 0.05C.
Comparative example 3
1) Coating a silicon-carbon negative electrode material ([ SiO ] with the concentration of 45 wt% on the surface of a copper current collector2@ Graphite) water solution, wherein the content of silica in the silicon-carbon negative electrode material is 2 wt%, and then the silicon-carbon negative electrode material is dried for 2 hours at 90 ℃ to form a silicon-carbon negative electrode layer with the thickness of 117 mu m on the surface of a current collector;
2) the surface of the silicon-carbon negative pole piece is not subjected to artificial SEI film treatment;
3) the temperature of the upper and lower clamping plates of the hot pressing tool after lamination is set to be 120 ℃, the pressure of the upper and lower clamping plates is 0.4MPa, and the hot pressing time is 50 s;
after the temperature, pressure and time parameters are adjusted, the core package after lamination is placed on a clamping plate, and hot pressing treatment is carried out;
blowing the core bag subjected to hot pressing by cold air to rapidly cool;
the temperature of the cold air is 5 ℃, the air pressure of a cold air outlet is 0.12MPa, and the purging time is 10 s;
5) when the battery cell with the air bag is formed, the battery cell is charged to 3.5V by using a small-multiplying-power constant current of 0.1C, then the battery cell is charged to 3.6V by using a 0.5C constant current, then the battery cell is continuously charged to 4V by using a constant current of 1C, and then the battery cell is turned off by using a constant voltage of 0.05C.
Comparative example 4
1) Coating a graphite negative electrode material aqueous solution with the concentration of 45 wt% on the surface of a copper current collector, and then drying for 2h at 90 ℃ to form a graphite negative electrode layer with the thickness of 117 mu m on the surface of the current collector;
2) the surface of the graphite negative pole piece is not processed by an artificial SEI film;
3) the temperature of the upper and lower clamping plates of the hot pressing tool after lamination is set to be 120 ℃, the pressure of the upper and lower clamping plates is 0.4MPa, and the hot pressing time is 50 s;
after the temperature, pressure and time parameters are adjusted, the core package after lamination is placed on a clamping plate, and hot pressing treatment is carried out;
blowing the core bag subjected to hot pressing by cold air to rapidly cool;
the temperature of the cold air is 5 ℃, the air pressure of a cold air outlet is 0.12MPa, and the purging time is 10 s;
4) when the battery cell with the air bag is formed, the battery cell is charged to 3.5V by using a small-multiplying-power constant current of 0.1C, then the battery cell is charged to 3.6V by using a 0.5C constant current, then the battery cell is continuously charged to 4V by using a constant current of 1C, and then the battery cell is turned off by using a constant voltage of 0.05C.
Soft package battery cycling stability test
Cutting the negative electrode plate coated with the polymeric aluminum thin film prepared in examples 1, 2, 3 and 4 and comparative examples 1, 2, 3 and 4 into long pieces 73mm wide and 122mm long; cutting the pole piece containing the NCM622 positive pole material with the content of 98% into wide pieces: 70mm, length: 118 mm's long piece, the PE diaphragm cuts into 76mm, the long piece of 126mm, and the plastic-aluminum membrane fifty percent discount back is cut into the width: 83mm, length: 142 mm. Assembling a battery in a glove box according to a layer of diaphragm, a layer of negative plate, a layer of diaphragm, a layer of positive plate, a layer of diaphragm and a layer of negative plate … …, wherein the number of the positive plate layers is set to be 10, the number of the negative plate layers is set to be 11, and the number of the diaphragm layers is set to be 22; in the assembled pouch cell, 30g of 1M LiPF was injected with a syringe6EC (1)/DEC (1)/DMC (1) electrolyte, after standing at room temperature for 24 hours, was cycled for 5 times at 0.1C/0.1C, and then cycled for 500 times at 1C/1C. The first charge-discharge efficiency and capacity retention rate of each battery sample after 1C/1C cycle for 500 times were measured, and the results are shown in table 1:
TABLE 1
Figure BDA0002537326860000111
The comparison between examples 1-4 and comparative examples 1-4 shows that the first charge-discharge efficiency of the soft-package battery obtained by the method is over 100 percent, while the first charge-discharge efficiency of the soft-package battery of the comparative example is not up to 98 percent; the capacity retention rate of the soft package battery is higher than 95%, the capacity retention rate of the soft package battery in the two-pair proportion is 92.13% at most, and the capacity retention rate in example 3 is only 84.23%; the OCV at 30% SOC of the example is not much different from that of the comparative example. Therefore, the method can effectively improve the de-intercalation efficiency of the lithium ions in the cathode material, and further improve the cycling stability of the battery.

Claims (10)

1. A method for double heat treatment and rapid formation of a battery core coated with an artificial SEI film negative pole piece is characterized in that materials are coated on the front surface and the back surface of a current collector to form a negative pole layer, and a negative pole piece is obtained; then, a molecular layer deposition technology (MLD) is applied to form a nanoscale organic-inorganic hybrid layer, namely an SEI film layer, on the surface of the negative electrode; and then carrying out hot pressing treatment after lamination, and carrying out post-formation heat treatment.
2. The method for double heat treatment and rapid formation of the battery core coated with the artificial SEI film negative electrode plate according to claim 1, wherein the negative electrode layer is a silicon carbon or graphite negative electrode layer, and the thickness of the layer is 10-180 μm.
3. The method for double heat treatment and rapid formation of the battery core coated with the artificial SEI film negative electrode plate is characterized in that the SEI film layer is prepared by alternately depositing trimethyl aluminum and ethylene glycol on the surface of a coating by a molecular layer deposition method to form a polymeric aluminum film layer, the mass ratio of trimethyl aluminum to ethylene glycol is 1 (3-20), and the thickness of the polymeric aluminum film layer is 0.1-20 μm.
4. The method for double heat treatment and rapid formation of the battery core coated with the artificial SEI film negative electrode plate as claimed in claim 1, wherein the parameters of the hot pressing treatment after lamination are that the temperature of an upper clamping plate and a lower clamping plate of a hot pressing tool is set to be 40-125 ℃, the pressure of the upper clamping plate and the lower clamping plate is 0.1-1 MPa, and the hot pressing time is 10-120 s.
5. The method for dual heat treatment and rapid formation of the battery core coated with the artificial SEI film negative electrode plate is characterized in that after the hot pressing treatment after lamination is finished, a workshop cold air system is utilized to carry out cold air blowing to carry out rapid cooling, wherein the temperature of cold air is 2-15 ℃, the air pressure of a cold air outlet is 0.1-0.3 MPa, and the blowing time is 5-70 s.
6. The method for dual thermal treatment and rapid formation of the battery core coated with the artificial SEI film negative electrode plate as claimed in claim 1, wherein the post-formation thermal treatment is mainly conditioned by a voltage factor.
7. The method for double heat treatment and rapid formation of the battery cell coated with the artificial SEI film negative electrode plate, according to claim 6, is characterized in that, during formation of the battery cell with the air bag, the battery cell is charged to 3.2V to 3.5V at a constant current of 0.01C to 0.05C with a small multiplying power, and then the clamp plate pressure is set for the formation clamp and the temperature is raised, wherein the pressure of the formation clamp is 0.1MPa to 0.8MPa, and the temperature is 30 ℃ to 60 ℃.
8. The method for double heat treatment and rapid formation of the battery cell coated with the artificial SEI film negative electrode plate, according to claim 7, is characterized in that after the temperature of the clamping plate is raised, when the battery cell is charged to 3.5V-3.6V by constant current, the pressure of the formation clamp is maintained, and the heating is cancelled.
9. The method for double heat treatment and rapid formation of the battery cell coated with the artificial SEI film negative electrode plate, according to claim 8, is characterized in that after heating is cancelled, the battery cell is continuously charged at a constant current of 0.2C-1C until the voltage is cut off at 3.6V-4.35V, and is then constantly charged at a constant voltage of 0.1C-0.02C.
10. A cell obtained by the method of any of claims 1-9.
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