CN117525295A - Novel lithium foil composite pre-lithium method - Google Patents
Novel lithium foil composite pre-lithium method Download PDFInfo
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- CN117525295A CN117525295A CN202311747736.0A CN202311747736A CN117525295A CN 117525295 A CN117525295 A CN 117525295A CN 202311747736 A CN202311747736 A CN 202311747736A CN 117525295 A CN117525295 A CN 117525295A
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 154
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 151
- 239000011888 foil Substances 0.000 title claims abstract description 98
- 238000000034 method Methods 0.000 title claims abstract description 54
- 239000002131 composite material Substances 0.000 title claims abstract description 42
- 238000007731 hot pressing Methods 0.000 claims abstract description 47
- 238000003825 pressing Methods 0.000 claims abstract description 35
- 238000013329 compounding Methods 0.000 claims abstract description 27
- 238000005096 rolling process Methods 0.000 claims abstract description 21
- 238000000576 coating method Methods 0.000 claims abstract description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000007791 dehumidification Methods 0.000 claims abstract description 6
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 6
- 239000002210 silicon-based material Substances 0.000 claims abstract description 6
- 239000007770 graphite material Substances 0.000 claims abstract description 5
- 238000000265 homogenisation Methods 0.000 claims abstract description 4
- 238000003475 lamination Methods 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 10
- 238000005520 cutting process Methods 0.000 claims description 9
- 239000000126 substance Substances 0.000 claims description 9
- 238000002360 preparation method Methods 0.000 claims description 6
- 238000002347 injection Methods 0.000 claims description 3
- 239000007924 injection Substances 0.000 claims description 3
- 238000000840 electrochemical analysis Methods 0.000 claims description 2
- 238000010030 laminating Methods 0.000 claims description 2
- 238000006138 lithiation reaction Methods 0.000 abstract description 20
- 230000000694 effects Effects 0.000 abstract description 8
- 239000002245 particle Substances 0.000 abstract description 5
- 238000004804 winding Methods 0.000 description 28
- 239000010405 anode material Substances 0.000 description 13
- 239000011248 coating agent Substances 0.000 description 13
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 7
- 229910001416 lithium ion Inorganic materials 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 6
- 239000000919 ceramic Substances 0.000 description 6
- 239000006258 conductive agent Substances 0.000 description 6
- 238000013461 design Methods 0.000 description 6
- 238000001035 drying Methods 0.000 description 6
- 239000012528 membrane Substances 0.000 description 6
- 238000004806 packaging method and process Methods 0.000 description 6
- 239000007774 positive electrode material Substances 0.000 description 6
- 238000011112 process operation Methods 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 229910052814 silicon oxide Inorganic materials 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 238000005056 compaction Methods 0.000 description 4
- 230000037303 wrinkles Effects 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000003490 calendering Methods 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000002427 irreversible effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000011265 semifinished product Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000011267 electrode slurry Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
Classifications
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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
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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
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- 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
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- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a novel lithium foil composite pre-lithium method, which comprises the steps of carrying out conventional anode wet homogenization and coating process on graphite/silicon-based materials to prepare normally available anode coils; pre-lithium compounding is carried out on the cathode coil which is not rolled in a dehumidification environment, and the cathode coil and the lithium foil coil are simultaneously placed at the front end of lithium foil pre-lithium compounding equipment; and (3) simultaneously feeding the negative electrode coil and the lithium foil into a hot flat pressing device, adjusting hot pressing temperature, pressure, time and speed, simultaneously hot pressing the negative electrode coil and the lithium foil, and compositing the lithium foil and the negative electrode coil together at high temperature to finish composite pre-lithium. According to the method, two times of rolling are changed into one time of hot pressing compounding, the operation steps and time are reduced, and meanwhile, the problem of wrinkling of the lithium foil caused by double-roll pressing is avoided in a hot flat pressing mode; meanwhile, the lithium foil is more uniformly contacted with the negative electrode plate and particles, the contact resistance is low, and the activity utilization of lithium is high, so that the first coulomb efficiency, the first discharge capacity and the energy density of the pre-lithiation are improved.
Description
Technical Field
The invention belongs to the field of lithium ion batteries, and particularly relates to a novel lithium foil composite pre-lithium method.
Background
The lithium ion battery adopts an embedded reaction cathode, such as graphite and silicon-based materials, but in the first charge and discharge process, SEI films can be formed to consume active lithium ions, and larger irreversible capacity loss is generated, so that the discharge capacity and the energy density of the lithium ion battery can be reduced, and the application of the material in the high specific energy lithium ion battery is restricted. The pre-lithiation technology provides an effective solution for solving irreversible capacity loss and improving coulombic efficiency and capacity retention rate, and has good application prospect.
The pre-lithiation technical methods include material pre-lithiation, slurry pre-lithiation, pole piece pre-lithiation, electrochemical pre-lithiation and the like, and have the difficulty of realizing engineering amplification. The method for carrying out pole piece surface pre-lithium by using lithium foil is not produced in large quantities at present, the application is still in the development stage, researchers and industries generally adopt the method for rolling the lithium foil to the surface of a negative pole piece, and the specific method comprises the steps of coating a negative pole (generally graphite-based or silicon-based material) pole roll, rolling by a roller press, and then carrying out secondary rolling and compounding on the rolled pole piece and the lithium foil on the roller press to realize the pre-lithiation of the lithium foil.
CN 112701253A discloses a pre-lithiated composite negative electrode sheet, a preparation method and application thereof, wherein the preparation method of the pre-lithiated composite negative electrode sheet comprises the following steps: prepressing the negative electrode plate, the lithium foil and the release film to obtain a composite semi-finished product; the negative electrode piece is positioned between two lithium foils, and the two lithium foils are positioned between two release films; and calendaring the obtained composite semi-finished product to obtain the pre-lithiated composite negative plate. The preparation method solves the problems of low cycle life and low initial efficiency of the anode material of the lithium secondary battery adopting metal lithium as the anode by providing an external lithium source, improves the capacity and cycle performance of the battery, has simple and safe process flow and high production efficiency, and has good industrial application prospect.
CN 108550780A provides a method for single-sided pre-lithiation of a lithium ion battery negative electrode by adopting a three-dimensional foil, wherein the negative electrode slurry is coated on the three-dimensional current collector and rolled to obtain a rolled pole piece; carrying out pre-lithiation compounding on the pole piece: the pre-lithiation method is divided into two types according to the difference of lithium metal raw materials, and the lithium metal powder is uniformly sprayed or coated on one surface of the rolled pole piece by adopting the pre-lithiation method of the lithium metal powder; and (3) adopting a lithium foil prelithiation method, and bonding and compounding one surface of the rolled pole piece with the lithium foil under a certain pressure: and assembling the positive electrode, the diaphragm and the negative electrode sheet subjected to the pre-lithiation compounding into a battery cell, and injecting liquid and forming the battery cell.
Currently, three main problems exist in the conventional method for calendering lithium foil: 1. the density of the lithium foil is low, and only 0.534g/cm 3 The texture is softer, compared with a silicon-based negative electrode, the elongation rate is greatly different, if the rolling is carried out by adopting a roller press at the same time, the problem of lithium foil fold deformation appears, and the problem can lead to the surface defect of the pole piece and is not beneficial to the insertion and extraction of lithium ions; 2. the rolling and pre-lithium compounding processes of the negative electrode are both required, the process flow is complex, and the negative electrode particles can be broken to cause failure after multiple rolling; 3. the problem of lithium foil wrinkling or poor interface contact caused by secondary rolling can lead to poor pre-lithiation effect, the problem of uneven lithium separation and cycle performance degradation occur in capacity test after battery manufacturing, and short circuit occurs in the battery due to the fact that the separator is pierced by uneven lithium separation when serious.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a novel lithium foil composite pre-lithium method, which is simple and efficient in process operation, can reduce equipment used in the process operation (two-time rolling is changed into one-time hot-pressing composite), reduces operation steps and time, and simultaneously avoids the possible wrinkling problem of the lithium foil caused by double-roll pressing in a hot flat pressing mode; the high-temperature hot-pressing process is adopted to ensure that the lithium foil contacts with the negative electrode plate and particles more uniformly, the contact resistance is low and the activity utilization of lithium is high. Finally, the double effects of obvious improvement of the first coulombic efficiency, the first discharge capacity and the energy density of the pre-lithiation and simple and efficient pre-lithiation process are achieved.
In order to solve the technical problems, the invention adopts the following technical scheme:
a novel lithium foil composite pre-lithium method, which comprises the following steps:
(1) Carrying out conventional anode wet homogenization and coating processes on graphite or silicon-based materials to prepare a normally available anode roll;
(2) Carrying out preparation work of pre-lithium compounding on the non-rolled negative electrode roll in a dehumidification environment, and simultaneously placing the negative electrode roll and the lithium foil roll at the front end of lithium foil pre-lithium compounding equipment;
(3) And (3) simultaneously feeding the negative electrode roll and the lithium foil roll into a hot leveling device, adjusting hot pressing temperature, pressure, time and speed, simultaneously hot pressing the negative electrode roll and the lithium foil roll, and compositing the lithium foil roll and the negative electrode roll together at high temperature to finish composite pre-lithium.
Further, the dew point temperature in the dehumidifying environment of the step (2) is < -50 ℃.
Further, the hot pressing temperature is 50-100 ℃.
Further, the hot pressing pressure is 5000 to 10000kgf.
Further, the hot pressing time is 15 to 30 seconds.
Further, the hot pressing speed is 2-5m/min.
And further, winding the pole coil subjected to hot-pressing compounding, and cutting the pole piece into a size suitable for lamination after winding.
Further, the sliced negative plate and the sliced positive plate are respectively laminated and assembled on a lamination machine, and finally are subjected to chemical composition and electrochemical test after liquid injection.
Further, the lithium foil pre-lithium composite equipment comprises an unreeling device, a reeling device and a hot flat pressing device, wherein the hot flat pressing device is positioned between the unreeling device and the reeling device. The unreeling device comprises an unreeling roller shaft A, an unreeling roller shaft B and an unreeling roller shaft C, wherein lithium foil rolls are respectively placed on the unreeling roller shaft A and the unreeling roller shaft C, and negative electrode rolls are placed on the unreeling roller shaft B.
Further, a pair of rollers A is arranged between the unreeling device and the hot leveling device.
Further, the winding device comprises a winding roll shaft, and a counter roll B is arranged between the hot platen roller and the winding roll shaft.
Further, the hot flat pressing device comprises a hot flat pressing plate and a control system, wherein the hot flat pressing plate is divided into an upper hot flat pressing plate and a lower hot flat pressing plate, the hot flat pressing plate is connected with an air cylinder, and the air cylinder is connected with an air pressure pipeline.
Further, a pressure gauge, a central control operation screen and a temperature display meter are arranged on the hot platen press device. The hot flat pressing plate is electrically connected with the control system, and the pressure gauge, the central control operation screen and the temperature display meter are electrically connected with the control system.
Further, the winding and unwinding tension of the unwinding device and the winding device is controlled by a compressed air expansion shaft, the hot flat pressing plate is controlled by compressed air pneumatic and electromagnetic valve electric control, the beat of the hot flat pressing plate is controlled to be 5ppm, and the winding and unwinding speed is 2-5m/min.
The invention has the beneficial effects that: the invention provides a novel lithium foil composite pre-lithium method, which is simple and efficient in process operation, can reduce equipment used in process operation (two-time rolling is changed into one-time hot-pressing composite), reduces operation steps and time, and simultaneously avoids the possible wrinkling problem of the lithium foil caused by double-roll pressing in a hot-pressing mode; the high-temperature hot-pressing process is adopted to ensure that the lithium foil contacts with the negative electrode plate and particles more uniformly, the contact resistance is low and the activity utilization of lithium is high. Finally, the double effects of obvious improvement of the first coulombic efficiency, the first discharge capacity and the energy density of the pre-lithiation and simple and efficient pre-lithiation process are achieved.
Drawings
FIG. 1 is a schematic diagram of a lithium foil pre-lithium composite device according to the present invention;
fig. 2 is a schematic structural view of the hot platen device in fig. 1.
Detailed Description
The invention will be further illustrated with reference to specific examples. It is to be understood that the following examples are intended to illustrate the present invention and are not to be construed as limiting the scope of the invention, and that numerous insubstantial modifications and adaptations can be made by those skilled in the art in light of the foregoing disclosure.
The lithium foil pre-lithium composite equipment disclosed by the invention is shown in fig. 1, and comprises an unreeling device, a reeling device and a hot leveling device 8, wherein the hot leveling device 8 is positioned between the unreeling device and the reeling device. Namely, the unreeling device and the reeling device are respectively arranged at the front end and the rear end of the equipment, and the hot leveling device is arranged in the middle. The unreeling device comprises an unreeling roller shaft A1, an unreeling roller shaft B2 and an unreeling roller shaft C3, wherein a lithium foil roll 7 is respectively placed on the unreeling roller shaft A1 and the unreeling roller shaft C3, and a negative electrode roll is placed on the unreeling roller shaft B2. A pair roller A4 is arranged between the unreeling device and the hot leveling device 8 and is used for pre-pressing and bonding the lithium foil roll and the negative electrode roll and providing certain power. The unreeling roll shaft A1, the unreeling roll shaft B2, the unreeling roll shaft C3 and the counter roll A are fixed by adopting air expansion shafts, and material rolls of the unreeling roll shaft A1, the unreeling roll shaft B2 and the unreeling roll shaft C3 enter the hot leveling device at the same time.
The winding device comprises a winding roll shaft 6, and a counter roll B5 is arranged between the hot leveling device 8 and the winding roll shaft 6 and used for integrating the lithium foil roll and the negative electrode roll after hot pressing. The winding roll shaft 6 and the counter roll B5 are fixed by an inflatable shaft. The hot flat pressing device comprises a hot flat pressing plate 11 and a control unit, wherein the hot flat pressing plate 11 is divided into an upper hot flat pressing plate and a lower hot flat pressing plate, and the hot flat pressing plate 11 is connected with an air cylinder 16.
The hot platen press device is provided with a pressure gauge 12, an air pressure pipeline 13, a central control operation screen 14 and a temperature display gauge 15. The pressure and hot-pressing time of the lithium foil and the negative electrode roll composition are controlled by the central control operation screen 14, the pressure can be set to 5000-10000kgf, and the hot-pressing time can be set to 15-30s. The temperature display table 15 can be set to 50-100 ℃ by controlling the central control operation screen 14.
The winding and unwinding tension is controlled by adopting a compressed air expansion shaft, the hot flat pressing plate is controlled by adopting compressed air pneumatic and electromagnetic valve electric control, the beat of the hot flat pressing plate can be controlled to be 5ppm, and the winding and unwinding speed is set to be 2-5m/min. The lithium foil pre-lithium composite device performs an internal pre-lithium operation in a chamber with a dew point less than 50 ℃.
The novel lithium foil composite pre-lithium method comprises the following steps:
(1) Carrying out conventional anode wet homogenization and coating processes on graphite or silicon-based materials to prepare a normally available anode roll;
(2) Carrying out preparation work of pre-lithium compounding on the non-rolled negative electrode roll in a dehumidification environment, and simultaneously placing the negative electrode roll and the lithium foil roll at the front end of lithium foil pre-lithium compounding equipment;
(3) Simultaneously feeding the negative electrode roll and the lithium foil roll into a hot leveling device, adjusting hot pressing temperature (50-100 ℃) and pressure (5000-10000 kgf), leveling time (15-30 s) and leveling speed (2-5 m/min), simultaneously hot pressing the negative electrode roll and the lithium foil roll, and compositing the lithium foil roll and the negative electrode roll together at high temperature to finish composite pre-lithium.
(4) Winding the pole coil subjected to hot-pressing compounding, and cutting the pole piece into a size suitable for lamination after winding;
(5) And (3) respectively laminating and assembling the sliced negative plate and positive plate on a lamination machine, and finally performing chemical composition and electrochemical performance test after liquid injection.
Example 1
The novel lithium foil composite pre-lithium method in the embodiment is as follows:
(1) The adopted anode material is SiOx/C-550 (Bei Terui product), the anode homogenate proportion is 96:2:2 (anode material: conductive agent: binder), and the anode coating surface density is 10mg/cm 2 Coating and drying the anode roll (single side) to prepare the anode roll of about 100 meters for standby;
(2) Placing the negative electrode roll in a dehumidification environment (the dew point temperature is < -50 ℃) for about 12 hours, then simultaneously placing a lithium foil roll (the thickness is 10 um) and the negative electrode roll at the front end of lithium foil pre-lithium composite equipment, wherein the lithium foil roll 7 is respectively placed on an unreeling roll shaft A1 and an unreeling roll shaft C3, the negative electrode roll is placed on an unreeling roll shaft B2, and unreeling is prepared after the lithium foil roll and the negative electrode roll are placed;
(3) Simultaneously feeding the negative electrode roll and the lithium foil roll into a hot flat pressing device 8, adjusting the hot pressing temperature to 50 ℃, the pressure to 0.35MPa, and the hot pressing time to 20s and the beat to 5ppm, simultaneously hot pressing the negative electrode and the lithium foil, and finally flatly pressing and compositing the lithium foil and the electrode roll together to finish composite pre-lithium;
(4) Winding the pole coil subjected to hot-pressing compounding, wherein winding tension is consistent with unreeling tension to ensure that the pole coil is aligned and does not wrinkle, and then cutting the pole piece into a size (76 mm for the negative electrode) suitable for lamination;
(5) The matched positive electrode roll prepared in the earlier stage (the positive electrode adopts Ni90 positive electrode material produced by fir with the surface density of 25 mg/cm) 2 ) Slicing (slice size 74×103mm), and stacking with conventional ceramic membrane (9+3+1+1 mm), wherein the positive electrode stack 10 layers, the negative electrode stack 11 layers, and the design capacity is 8.5Ah;
(6) And packaging the battery cells, injecting liquid and carrying out subsequent chemical composition flow, and preparing the pre-lithiated battery for testing. The first charge capacity of 0.1C is 9.5Ah, the first discharge capacity is 8.8Ah, the first charge and discharge efficiency is 90.5% after calculation, and the energy density is about 360Wh/kg.
Example 2
The novel lithium foil composite pre-lithium method in the embodiment is as follows:
(1) The anode material is SiOx/C-500 (Bei Terui product), the anode homogenate proportion is 96:2:2 (anode material: conductive agent: binder), and the anode coating surface density is 10mg/cm 2 Coating and drying the anode roll (single side) to prepare the anode roll of about 100 meters for standby;
(2) Placing the negative electrode roll in a dehumidification environment (the dew point temperature is < -50 ℃) for about 12 hours, then simultaneously placing lithium foil (the thickness is 6 um) and the negative electrode roll at the front end of lithium foil pre-lithium composite equipment, wherein the lithium foil roll 7 is respectively placed on an unreeling roll shaft A1 and an unreeling roll shaft C3, the negative electrode roll is placed on an unreeling roll shaft B2, and unreeling is prepared after the negative electrode roll is placed;
(3) Simultaneously feeding the negative electrode roll and the lithium foil roll into a hot leveling device 8, adjusting the hot pressing temperature to 55 ℃, the pressure to 0.3Mpa, and the hot leveling time to 20s and beat (5 ppm), simultaneously hot pressing the negative electrode and the lithium foil, and leveling and compounding the lithium foil and the electrode roll to complete composite pre-lithium;
(4) Winding the pole coil subjected to hot-pressing compounding, wherein winding tension is consistent with unreeling tension to ensure that the pole coil is aligned and does not wrinkle, and then cutting the pole piece into a size (76 mm for the negative electrode) suitable for lamination;
(5) The matched positive electrode roll prepared in the earlier stage (the positive electrode adopts Ni90 positive electrode material produced by fir with the surface density of 25 mg/cm) 2 ) Slicing (slice size 74×103mm), and stacking with conventional ceramic membrane (9+3+1+1 mm), wherein the positive electrode stack 10 layers, the negative electrode stack 11 layers, and the design capacity is 8.5Ah;
(6) And packaging the battery cells, injecting liquid and carrying out subsequent chemical composition flow, and preparing the pre-lithiated battery for testing. The first charge capacity is 9.6Ah, the first discharge capacity is 8.9Ah, the first charge and discharge efficiency is 92.4% after calculation, and the energy density is about 369Wh/kg.
Comparative example 1
A lithium foil composite pre-lithium method comprises the following steps:
(1) The experiment adopts the anode material SiOx/C-550 (Bei Terui product), the anode homogenate proportion is 96:2:2 (anode material: conductive agent: binder), and the anode coating surface density is 10mg/cm 2 Coating and drying the anode roll (single side) to prepare the anode roll of about 100 meters for standby;
(2) Rolling the cathode coil by a roller press, wherein the rolling compaction density is 1.6g/m 3 ；
(3) Carrying out secondary casting compounding on the lithium foil and the rolled negative electrode roll on a roll squeezer, wherein the pressing pressure is about 0.3MPa;
(4) Winding the pole coil subjected to hot-pressing compounding, keeping the winding tension consistent with the unwinding tension, and cutting the pole piece into a size (76 mm for the negative electrode) suitable for lamination;
(5) The matched positive electrode roll prepared in the earlier stage (the positive electrode adopts Ni90 positive electrode material produced by fir with the surface density of 25 mg/cm) 2 ) Slicing (slice size 74×103mm), and stacking with conventional ceramic membrane (9+3+1+1 mm), wherein the positive electrode stack 10 layers, the negative electrode stack 11 layers, and the design capacity is 8.5Ah;
(6) And packaging the battery cells, injecting liquid and carrying out subsequent chemical composition flow, and preparing the pre-lithiated battery for testing. The first charge capacity of 0.1C is 9.6Ah, the first discharge capacity is 8Ah, the first charge-discharge efficiency is 83.3% after calculation, and the energy density is about 325Wh/kg.
Comparative example 2
A lithium foil composite pre-lithium method comprises the following steps:
(1) The experiment adopts the anode material SiOx/C-500 (Bei Terui product), the anode homogenate proportion is 96:2:2 (anode material: conductive agent: binder), and the anode coating surface density is 10mg/cm 2 Coating and drying the anode roll (single side) to prepare the anode roll of about 100 meters for standby;
(2) Rolling the cathode coil by a roller press, wherein the rolling compaction density is 1.6g/m 3 ；
(3) Carrying out secondary casting compounding on the lithium foil and the rolled negative electrode roll on a roll squeezer, wherein the pressing pressure is about 0.3MPa;
(4) Winding the pole coil subjected to hot-pressing compounding, keeping the winding tension consistent with the unwinding tension, and cutting the pole piece into a size (76 mm for the negative electrode) suitable for lamination;
(5) The matched positive electrode roll prepared in the earlier stage (the positive electrode adopts Ni90 positive electrode material produced by fir with the surface density of 25 mg/cm) 2 ) Slicing (slice size 74×103mm), and stacking with conventional ceramic membrane (9+3+1+1 mm), wherein the positive electrode stack 10 layers, the negative electrode stack 11 layers, and the design capacity is 8.5Ah;
(6) And packaging the battery cells, injecting liquid and carrying out subsequent chemical composition flow, and preparing the pre-lithiated battery for testing. The first charge capacity of 0.1C was tested to be 9.5Ah, the first discharge capacity was calculated to be 8.2Ah, the first charge-discharge efficiency was calculated to be 86.3%, and the energy density was calculated to be about 332Wh/kg.
Comparative example 3
A lithium foil composite pre-lithium method comprises the following steps:
(1) The adopted anode material is SiOx/C-550 (Bei Terui product), the anode homogenate proportion is 96:2:2 (anode material: conductive agent: binder), and the anode coating surface density is 10mg/cm 2 Coating and drying the anode roll (single side) to prepare the anode roll of about 100 meters for standby;
(2) Rolling the cathode coil by a roller press, wherein the rolling compaction density is 1.6g/m 3 The method comprises the steps of carrying out a first treatment on the surface of the Then the lithium foil is rolled (thickness 10 um) andthe negative electrode roll is simultaneously placed at the front end of the lithium foil pre-lithium composite equipment, wherein the lithium foil roll 7 is respectively placed on an unreeling roll shaft A1 and an unreeling roll shaft C3, the negative electrode roll is placed on an unreeling roll shaft B2, and unreeling is prepared after the negative electrode roll is placed;
(3) Simultaneously feeding the negative electrode roll and the lithium foil roll into a hot flat pressing device 8, adjusting the hot pressing temperature to 50 ℃, the pressure to 0.35MPa, and the hot pressing time to 20s and the beat to 5ppm, simultaneously hot pressing the negative electrode and the lithium foil, and finally flatly pressing and compositing the lithium foil and the electrode roll together to finish composite pre-lithium;
(4) Winding the pole coil subjected to hot-pressing compounding, wherein winding tension is consistent with unreeling tension to ensure that the pole coil is aligned and does not wrinkle, and then cutting the pole piece into a size (76 mm for the negative electrode) suitable for lamination;
(5) The matched positive electrode roll prepared in the earlier stage (the positive electrode adopts Ni90 positive electrode material produced by fir with the surface density of 25 mg/cm) 2 ) Slicing (slice size 74×103mm), and stacking with conventional ceramic membrane (9+3+1+1 mm), wherein the positive electrode stack 10 layers, the negative electrode stack 11 layers, and the design capacity is 8.5Ah;
(6) And packaging the battery cells, injecting liquid and carrying out subsequent chemical composition flow, and preparing the pre-lithiated battery for testing. The first charge capacity of 0.1C was tested to be 9.8Ah, the first discharge capacity was calculated to be 8.3Ah, the first charge-discharge efficiency was calculated to be 84.7%, and the energy density was calculated to be about 335Wh/kg.
Comparative example 4
A lithium foil composite pre-lithium method comprises the following steps:
(1) The anode material is SiOx/C-500 (Bei Terui product), the anode homogenate proportion is 96:2:2 (anode material: conductive agent: binder), and the anode coating surface density is 10mg/cm 2 Coating and drying the anode roll (single side) to prepare the anode roll of about 100 meters for standby;
(2) Rolling the cathode coil by a roller press, wherein the rolling compaction density is 1.6g/m 3 The method comprises the steps of carrying out a first treatment on the surface of the Then simultaneously placing lithium foil (with the thickness of 6 um) and a negative electrode roll on the front end of lithium foil pre-lithium composite equipment, wherein the lithium foil roll 7 is respectively placed on an unreeling roll shaft A1 and an unreeling roll shaft C3, the negative electrode roll is placed on an unreeling roll shaft B2, and unreeling is prepared after the lithium foil roll 7 is placed;
(3) Simultaneously feeding the negative electrode roll and the lithium foil roll into a hot leveling device 8, adjusting the hot pressing temperature to 55 ℃, the pressure to 0.3Mpa, and the hot leveling time to 20s and beat (5 ppm), simultaneously hot pressing the negative electrode and the lithium foil, and leveling and compounding the lithium foil and the electrode roll to complete composite pre-lithium;
(4) Winding the pole coil subjected to hot-pressing compounding, wherein winding tension is consistent with unreeling tension to ensure that the pole coil is aligned and does not wrinkle, and then cutting the pole piece into a size (76 mm for the negative electrode) suitable for lamination;
(5) The matched positive electrode roll prepared in the earlier stage (the positive electrode adopts Ni90 positive electrode material produced by fir with the surface density of 25 mg/cm) 2 ) Slicing (slice size 74×103mm), and stacking with conventional ceramic membrane (9+3+1+1 mm), wherein the positive electrode stack 10 layers, the negative electrode stack 11 layers, and the design capacity is 8.5Ah;
(6) And packaging the battery cells, injecting liquid and carrying out subsequent chemical composition flow, and preparing the pre-lithiated battery for testing. The first charge capacity was measured to be 9.5Ah, the first discharge capacity was measured to be 8.3Ah, the first charge-discharge efficiency was calculated to be 86.9%, and the energy density was calculated to be about 337Wh/kg.
Table 1 results of performance test for examples and comparative examples to prepare pre-lithiated batteries
The invention provides a novel lithium foil composite pre-lithium method, which is simple and efficient in process operation, can reduce equipment used in process operation (two-time rolling is changed into one-time hot-pressing composite), reduces operation steps and time, and simultaneously avoids the possible wrinkling problem of the lithium foil caused by double-roll pressing in a hot-pressing mode; the high-temperature hot-pressing process is adopted to ensure that the lithium foil contacts with the negative electrode plate and particles more uniformly, the contact resistance is low and the activity utilization of lithium is high. Finally, the double effects of obvious improvement of the first coulombic efficiency, the first discharge capacity and the energy density of the pre-lithiation and simple and efficient pre-lithiation process are achieved.
The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (10)
1. The novel lithium foil composite pre-lithium method is characterized by comprising the following steps of:
(1) Carrying out conventional anode wet homogenization and coating processes on graphite or silicon-based materials to prepare a normally available anode roll;
(2) Carrying out preparation work of pre-lithium compounding on the non-rolled negative electrode roll in a dehumidification environment, and simultaneously placing the negative electrode roll and the lithium foil roll at the front end of lithium foil pre-lithium compounding equipment;
(3) And (3) simultaneously feeding the negative electrode roll and the lithium foil roll into a hot leveling device, adjusting hot pressing temperature, pressure, time and speed, simultaneously hot pressing the negative electrode roll and the lithium foil roll, and compositing the lithium foil roll and the negative electrode roll together at high temperature to finish composite pre-lithium.
2. The method of claim 1, wherein the method comprises: the dew point temperature of the step (2) in the dehumidifying environment is < -50 ℃.
3. The method of claim 1, wherein the method comprises: the lithium foil pre-lithium composite equipment comprises an unreeling device, a reeling device and a hot flat pressing device, wherein the hot flat pressing device is positioned between the unreeling device and the reeling device.
4. A novel lithium foil composite pre-lithium method according to claim 3, characterized in that: unreeling device includes unreeling roller A (1), unreels roller B (2) and unreels roller C (3), and wherein lithium foil roll (7) are placed respectively on unreeling roller A (1) and unreels roller C (3), and the negative pole is then placed on unreeling roller B (2).
5. The method of claim 1, wherein the method comprises: the hot pressing temperature is 50-100 ℃.
6. The method of claim 1, wherein the method comprises: the hot pressing pressure is 5000-10000 kgf.
7. The method of claim 1, wherein the method comprises: the hot pressing time is 15-30s.
8. The method of claim 1, wherein the method comprises: the hot pressing speed is 2-5m/min.
9. The method of claim 1, wherein the method comprises: and rolling the pole coil subjected to hot-pressing compounding, and cutting the pole piece into a size suitable for lamination after rolling.
10. The method of claim 1, wherein the method comprises: and (3) respectively laminating and assembling the sliced negative plate and positive plate on a lamination machine, and finally performing chemical composition and electrochemical test after liquid injection.
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