CN115863807A - Method for improving black spots on lithium ion battery interface, chemical composition and capacity grading method and application - Google Patents
Method for improving black spots on lithium ion battery interface, chemical composition and capacity grading method and application Download PDFInfo
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Abstract
The invention relates to a method for improving black spots on an interface of a lithium ion battery, a chemical composition and capacitance method and application, and belongs to the technical field of lithium ion batteries. The process method comprises the following steps: and carrying out formation, aging, negative pressure discharge and capacity grading on the battery core of the lithium ion battery. According to the method, a negative pressure discharge process is added after aging is finished in the existing chemical composition and capacitance grading process flow, so that the purpose of discharging gas generated in the aging process is achieved, interface black spots caused by gas residue are avoided, and the problem of the interface black spots of the lithium ion battery, particularly the high-energy density system lithium ion battery is solved; and discharging in-process battery SoC reduces, and the pole piece interval increases, carries out the negative pressure extraction gas this moment, and the extraction effect is better, and more effectual avoiding gas remains inside the pole piece.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a method for improving black spots on an interface of a lithium ion battery, a chemical composition and capacity grading method and application.
Background
Lithium ion batteries are increasingly widely applied to vehicle-mounted power, and the market requirements for the lithium ion batteries are gradually increased. The continuous improvement of the energy density of the battery is one of the important requirements, and the traditional graphite cathode system is difficult to meet the requirements of a new generation of high specific energy lithium ion battery. The theoretical capacity of the Si material can reach 4200mAh/g, which is more than ten times of that of the graphite material, and the Si material is an ideal negative electrode material. However, si material undergoes huge volume expansion during lithium intercalation, which not only causes pulverization and breakage of particles themselves to cause damage to electrode structure, but also causes damage to Solid Electrolyte Interface (SEI) film on the surface of negative electrode. By adding FEC into the electrolyte, a layer of SEI film rich in LiF is generated on the surface of the negative electrode, and the cycle stability of the Si-containing negative electrode can be remarkably improved.
However, electrolytes containing FEC (fluoroethylene carbonate) tend to become unstable at high temperatures, and studies have shown that FEC tends to be prone to Lewis acids (e.g., PF) in the electrolyte at high temperatures 5 ) The effect of (2) is to carry out the F-removing reaction to generate HF, and other acids (e.g. H) 3 OPF 6 ，HPO 2 F 2 ，H 2 PO 3 F，H 3 PO 4), and further with residual Li on the surface of the ternary cathode material 2 CO 3 Reaction to produce large quantities of CO/CO 2 A gas. A large amount of gas generated in the formation and aging stages of lithium ion battery production is easy to remain in the middle of a pole piece, the traditional formation and grading process method carries out grading after aging, the initial stage of grading is full charge under normal pressure, and bubbles remained in the pole piece in the charging process can cause black spots to be formed on the interface, thereby seriously affecting the performance and the safety of the battery. And the gas yield of the battery cell of the Si-based negative electrode + FEC-based electrolyte chemical system in the aging process is obviously higher than that of the conventional graphite negative electrode + EC (ethylene carbonate) based electrolyte chemical system.
The existing chemical composition capacity grading section process for producing the battery cell mainly has two means for improving the gas production of the chemical composition capacity grading section aiming at a material system of a Si system cathode in an FEC-based electrolyte, the first means is that: adding an additive for removing HF and other acids into the electrolyte, and reducing HF and Li on the surface of the ternary cathode material by reducing the content of HF in the electrolyte 2 CO 3 Side reaction occurs to achieve the purpose of reducing the gas production in the process; and the second method comprises the following steps: and increasing negative pressure in the formation and aging stages, and exhausting gas generated in the process through the negative pressure. The first mode undoubtedly increases the cost of the electrolyte, affects the overall cost of the battery, and other additives added into the battery can have other negative effects; the negative pressure generation in the second method is widely used at present. However, compared withThe aging time is longer, the duration is 24-72h, if negative pressure is used in the aging process, the energy consumption is higher, and meanwhile, the electrolyte is more lost due to long-time negative pressure; and the battery core is generally above SoC70% in the aging stage, the negative electrode expansion is large, the pole piece spacing is small, the generated gas extraction difficulty is large, and the risk of interface black spots caused by gas residue still exists.
Disclosure of Invention
Therefore, the technical problem to be solved by the present invention is to overcome the problem of interface black spots of the battery core of the lithium ion battery in the chemical composition capacity section, so as to provide a method for improving the interface black spots of the lithium ion battery, a chemical composition capacity method for improving the interface black spots of the lithium ion battery, and an application thereof.
The technical scheme of the invention is as follows:
a method for improving interface black spots of a lithium ion battery comprises formation and aging steps, and negative-pressure discharge is carried out after the aging step is finished.
The lithium ion battery is a high-energy-density system lithium ion battery with the energy density of more than 200 Wh/kg; preferably, the chemical system of the high energy density system lithium ion battery is a Si negative electrode, an FEC (fluoroethylene carbonate) based electrolyte and a ternary positive electrode; more preferably, the ternary positive electrode is an NCM (nickel, cobalt, manganese) ternary positive electrode.
The discharge voltage in the negative pressure discharge step is 3.6-2.5V, and the vacuum degree is not more than-10 Kpa; the preferred vacuum is-10 to-80 Kpa. The duration of discharging and vacuumizing is 10-30 min.
The formation is a negative pressure formation, the negative pressure formation being: after the battery cell is vacuumized to-10 Kpa to-80 Kpa, a voltage of 3.8V to 2.5V and a current of 0.1C to 2C are applied to carry out formation, and the formation time is 1 min to 180min.
The aging is high-temperature aging, and the aging temperature is 45-60 ℃; preferably, the aging time is 24-72h.
The step of negative pressure discharge comprises the step of standing the battery cell aged at high temperature at normal temperature; and carrying out negative-pressure discharge on the battery cell after the battery cell is kept at the normal temperature.
Injecting liquid and standing the battery cell subjected to liquid injection at a high temperature before the formation step; the standing temperature is 20-48 ℃, and preferably, the standing time is 14-48h.
A chemical composition and partial capacity method for improving black spots on an interface of a lithium ion battery comprises the chemical composition and aging method and further comprises the step of performing partial capacity after negative pressure discharge is finished.
Standing at normal temperature for at least one time after the capacity grading step is finished; the method also comprises the step of testing the open-circuit voltage of the battery cell; preferably, the open circuit voltage test is performed after the high temperature standing step and after the normal temperature standing step. The step of sealing the battery cell after the negative-pressure discharge is finished is also included; and/or, further comprising a step of carrying out secondary liquid injection on the battery cell after the negative-pressure discharge is finished; and/or carrying out secondary liquid injection on the battery cell after the negative pressure discharge is finished, and sealing the battery cell after the secondary liquid injection; and grading the sealed battery cell.
The method for improving the black spots on the lithium ion battery interface or the application of the method for improving the black spots on the lithium ion battery interface in the formation and the capacity grading are used for preparing the lithium ion battery cell.
The technical scheme of the invention has the following advantages:
according to the method, the negative pressure discharge process is added after the aging is finished in the existing chemical composition and capacitance process flow, so that the aim of completely discharging gas generated in the aging process is fulfilled as far as possible, and interface black spots caused by residual gas are avoided, so that the problem of the interface black spots of the lithium ion battery, particularly the high-energy density system lithium ion battery, is solved. Compared with the existing common improvement means, the method has the following advantages: firstly, additives which increase the cost do not need to be added into the electrolyte; secondly, compared with negative pressure air extraction in the aging process, the negative pressure discharge time is far shorter than the aging time, so that the energy consumption increase and electrolyte loss caused by long-time negative pressure are avoided; thirdly, the SoC of the battery is reduced in the discharging process, the distance between the pole pieces is increased, negative pressure extraction gas is extracted at the moment, the extraction effect is better, and gas is more effectively prevented from remaining inside the pole pieces.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a flowchart of a chemical composition capacitance method for improving black spots on an interface of a lithium ion battery according to an embodiment of the present invention;
FIG. 2 is a flow chart of a chemical composition and capacity grading method for a lithium ion battery cell of comparative example 1 of the present invention;
FIG. 3 is a flow chart of a chemical composition and capacity grading method for a lithium ion battery cell of comparative example 2 of the present invention;
FIG. 4 is a schematic illustration of a conventional compositional/volumetric process of comparative example 1;
FIG. 5 is a schematic illustration of the chemical composition and capacitance method of example 1 after the negative pressure discharge step is added;
fig. 6 is a comparative graph of cell interfaces of example 1 and comparative examples 1 and 2; fig. 6 (a) is a cell interface diagram of example 1; fig. 6 (b) is a cell interface diagram of comparative example 1; fig. 6 (c) is a cell interface diagram of comparative example 2.
Detailed Description
Example 1
As shown in FIG. 1, a formation and partial volume method for improving black spots on the interface of a high-energy density system lithium ion battery comprises the steps of negative pressure formation, high-temperature aging, negative pressure discharge and partial volume. The chemical system of the high energy density system lithium ion battery is a Si negative electrode, an FEC-based electrolyte and an NCM ternary positive electrode, and the energy density is 260Wh/kg.
The negative pressure formation step is as follows: and vacuumizing the battery cell subjected to primary liquid injection and standing to-80 kpa, and applying 3.2V voltage and 0.1C current to form the battery cell. The standing temperature is 45 ℃, and the standing time is 24h.
After the negative voltage is formed, an open-circuit voltage test is performed to obtain an OCV1 (open-circuit voltage 1), and then aging is performed. The high-temperature aging step comprises the following steps: and (3) aging the battery cell subjected to negative pressure formation for 48h at 50 ℃.
The negative-pressure discharging step comprises the following steps: after the battery cell (the SoC is more than 70 percent at the moment) after the high-temperature aging is finished is subjected to normal-temperature standing 1, the battery cell subjected to the normal-temperature standing 1 is subjected to vacuum pumping and negative-pressure air pumping while discharging; the discharge voltage is 2.5V, the discharge current is set to be 1C, the negative pressure is-80 Kpa, the negative pressure discharge time is 30min, and the SoC of the battery cell after negative pressure discharge is 0%. After standing at normal temperature for 1, an open-circuit voltage test can be performed to obtain OCV2 (open-circuit voltage 2), and then negative-voltage discharge is performed.
The capacity grading step comprises the following steps: and grading the battery cell subjected to negative-pressure discharge. And after the negative pressure discharge is finished, the method also comprises the steps of secondary liquid injection, sealing and helium detection. Specifically, secondary liquid injection is carried out on the battery cell after negative-pressure discharge is finished until the liquid injection coefficient is 2.5g/Ah; carrying out laser sealing on the electric core subjected to secondary liquid injection; performing secondary helium detection on the sealed battery cell; grading the capacity of the battery cell qualified in the helium test; and (3) sequentially carrying out normal-temperature standing 2 and normal-temperature standing 3 on the capacity-divided battery cell, then carrying out film coating and capacity grouping, and respectively carrying out open-circuit voltage tests after the normal-temperature standing 2 and the normal-temperature standing 3 to obtain an OCV3 (open-circuit voltage 3) and an OCV4 (open-circuit voltage 4).
Example 2
As shown in FIG. 1, a formation and partial volume method for improving black spots on the interface of a high-energy density system lithium ion battery comprises the steps of negative pressure formation, high-temperature aging, negative pressure discharge and partial volume. The chemical system of the high energy density system lithium ion battery is a Si negative electrode, an FEC-based electrolyte and an NCM ternary positive electrode, and the energy density is 260Wh/kg.
The negative pressure formation step is as follows: and vacuumizing the battery cell subjected to primary liquid injection and standing to-80 kpa, and applying 3.2V voltage and 0.1C current to carry out formation. The standing temperature is 45 ℃, and the standing time is 24 hours.
After the negative voltage is formed, an open-circuit voltage test is performed to obtain an OCV1 (open-circuit voltage 1), and then aging is performed. The high-temperature aging step comprises the following steps: and (3) aging the battery cell subjected to negative pressure formation for 48 hours at 50 ℃.
The negative pressure discharging step comprises the following steps: after the battery cell (the SoC is more than 70 percent at the moment) after the high-temperature aging is finished is subjected to normal-temperature standing 1, the battery cell subjected to the normal-temperature standing 1 is subjected to vacuum pumping and negative-pressure air pumping while discharging; the discharge voltage is 3.6V, the discharge current is set to be 2C, the negative pressure is-10 Kpa, the negative pressure discharge time is 10min, and the SoC of the battery cell after negative pressure discharge is 40%. After standing at normal temperature for 1, an open-circuit voltage test can be performed to obtain OCV2 (open-circuit voltage 2), and then negative-voltage discharge is performed.
The capacity grading step comprises the following steps: and grading the battery cell subjected to negative-pressure discharge. And after the negative pressure discharge is finished, the method also comprises the steps of secondary liquid injection, sealing and helium detection. Specifically, secondary liquid injection is carried out on the battery cell after negative-pressure discharge is finished to 2.5g/Ah; carrying out laser sealing on the electric core subjected to secondary liquid injection; performing secondary helium detection on the sealed battery cell; grading the capacity of the battery cell qualified in the helium test; and (3) sequentially carrying out normal-temperature standing 2 and normal-temperature standing 3 on the capacity-divided battery cell, then carrying out film coating and capacity grouping, and respectively carrying out open-circuit voltage tests after the normal-temperature standing 2 and the normal-temperature standing 3 to obtain an OCV3 (open-circuit voltage 3) and an OCV4 (open-circuit voltage 4).
Example 3
As shown in FIG. 1, a formation and partial volume method for improving black spots on the interface of a high-energy density system lithium ion battery comprises the steps of negative pressure formation, high-temperature aging, negative pressure discharge and partial volume. The chemical system of the high energy density system lithium ion battery is a Si negative electrode, an FEC-based electrolyte and an NCM ternary positive electrode, and the energy density is 260Wh/kg.
The negative pressure formation step is as follows: and vacuumizing the battery cell subjected to primary liquid injection and standing to-80 kpa, and applying 3.2V voltage and 0.1C current to carry out formation. The standing temperature is 45 ℃, and the standing time is 24 hours.
After the negative voltage is formed, an open-circuit voltage test is performed to obtain an OCV1 (open-circuit voltage 1), and then aging is performed. The high-temperature aging step comprises the following steps: and (3) aging the battery cell subjected to negative pressure formation for 48h at 50 ℃.
The negative-pressure discharging step comprises the following steps: after the battery cell (the SoC is more than 70 percent at the moment) after the high-temperature aging is finished is subjected to normal-temperature standing 1, the battery cell subjected to the normal-temperature standing 1 is subjected to vacuum pumping and negative-pressure air pumping while discharging; the discharge voltage is 2.9V, the discharge current is set to be 1.5C, the negative pressure is-50 Kpa, the negative pressure discharge time is 20min, and the SoC of the battery cell after the negative pressure discharge is 20%. After standing at normal temperature for 1, an open-circuit voltage test can be performed to obtain OCV2 (open-circuit voltage 2), and then negative-voltage discharge is performed.
The capacity grading step comprises the following steps: and grading the battery cell subjected to negative-pressure discharge. And after the negative pressure discharge is finished, the method also comprises the steps of secondary liquid injection, sealing and helium detection. Specifically, secondary liquid injection is carried out on the battery cell after negative-pressure discharge is finished to 2.5g/Ah; carrying out laser sealing on the electric core subjected to secondary liquid injection; performing secondary helium detection on the sealed battery cell; grading the capacity of the battery cell qualified in the helium test; and (3) sequentially carrying out normal-temperature standing 2 and normal-temperature standing 3 on the split-capacity battery cell, then carrying out film coating and capacity grouping, and respectively carrying out open-circuit voltage tests after the normal-temperature standing 2 and the normal-temperature standing 3 to obtain an OCV3 (open-circuit voltage 3) and an OCV4 (open-circuit voltage 4).
Example 4
As shown in FIG. 1, a formation and partial volume method for improving black spots on the interface of a high-energy density system lithium ion battery comprises the steps of negative pressure formation, high-temperature aging, negative pressure discharge and partial volume. The chemical system of the high energy density system lithium ion battery is a Si negative electrode, an FEC-based electrolyte and an NCM ternary positive electrode, and the energy density is 260Wh/kg.
The negative pressure formation step comprises: and vacuumizing the battery cell subjected to primary liquid injection and standing to-80 kpa, and applying 3.2V voltage and 0.1C current to carry out formation. The standing temperature is 45 ℃, and the standing time is 24 hours.
After the negative voltage is formed, an open-circuit voltage test is performed to obtain an OCV1 (open-circuit voltage 1), and then aging is performed. The high-temperature aging step comprises: and (3) aging the battery cell subjected to negative pressure formation for 70 hours at 45 ℃.
The negative pressure discharging step comprises the following steps: after the battery cell (the SoC is more than 70 percent at the moment) after the high-temperature aging is finished is subjected to normal-temperature standing 1, the battery cell subjected to the normal-temperature standing 1 is subjected to vacuum pumping and negative-pressure air pumping while discharging; the discharge voltage is 3.3V, the discharge current is set to be 1.7C, the negative pressure is-30 Kpa, the negative pressure discharge time is 15min, and the SoC of the battery cell after negative pressure discharge is 10%. After standing at normal temperature for 1, an open-circuit voltage test can be performed to obtain OCV2 (open-circuit voltage 2), and then negative-voltage discharge is performed.
The capacity grading step comprises the following steps: and grading the battery cell subjected to negative-pressure discharge. And after the negative pressure discharge is finished, the method also comprises the steps of secondary liquid injection, sealing and helium detection. Specifically, secondary liquid injection is carried out on the battery cell after negative-pressure discharge is finished to 2.5g/Ah; carrying out laser sealing on the battery cell after secondary liquid injection; performing secondary helium detection on the sealed battery cell; grading the capacity of the battery cell qualified in the helium test; and (3) sequentially carrying out normal-temperature standing 2 and normal-temperature standing 3 on the split-capacity battery cell, then carrying out film coating and capacity grouping, and respectively carrying out open-circuit voltage tests after the normal-temperature standing 2 and the normal-temperature standing 3 to obtain an OCV3 (open-circuit voltage 3) and an OCV4 (open-circuit voltage 4).
Comparative example 1
As shown in fig. 2, a chemical composition and capacity grading process method for a high energy density system lithium ion battery cell includes steps of negative pressure chemical composition, high temperature aging and capacity grading. The chemical system of the high energy density system lithium ion battery is a Si negative electrode, an FEC-based electrolyte and an NCM ternary positive electrode, and the energy density is 260Wh/kg.
The negative pressure formation step comprises: and vacuumizing the battery cell subjected to primary liquid injection and standing to-80 kpa, and applying 3.2V voltage and 0.1C current to carry out formation. The standing temperature is 45 ℃, and the standing time is 24 hours.
The high-temperature aging step comprises the following steps: and (3) aging the battery cell subjected to negative pressure formation for 48h at 50 ℃. After the negative pressure formation, an open-circuit voltage test can be performed to obtain the OCV1 (open-circuit voltage 1), and then aging is performed.
The capacity grading step comprises the following steps: and (3) grading the cell after aging at high temperature and standing for 1 at normal temperature. And after the normal-temperature standing 1 of the high-temperature aging is finished, the method further comprises the steps of secondary liquid injection, sealing and helium detection. Specifically, the battery cell after standing at normal temperature for 1 is subjected to secondary liquid injection to 2.5g/Ah; carrying out laser sealing on the battery cell after secondary liquid injection; performing secondary helium detection on the sealed battery cell; grading the capacity of the battery cell qualified in the helium test; and (3) sequentially carrying out normal-temperature standing 2 and normal-temperature standing 3 on the capacity-divided battery cell, then carrying out film coating and capacity grouping, and respectively carrying out open-circuit voltage tests after the normal-temperature standing 2 and the normal-temperature standing 3 to obtain an OCV3 (open-circuit voltage 3) and an OCV4 (open-circuit voltage 4).
Comparative example 2
As shown in fig. 3, a chemical composition and capacitance method for improving black spots on the cell interface of a high-energy density system lithium ion battery includes the steps of negative pressure chemical composition, high-temperature aging, negative pressure exhaust and capacitance grading. The chemical system of the high energy density system lithium ion battery is a Si negative electrode, an FEC-based electrolyte and an NCM ternary positive electrode, and the energy density is 260Wh/kg.
The negative pressure formation step is as follows: and vacuumizing the battery cell subjected to primary liquid injection and standing to-80 kpa, and applying 3.2V voltage and 0.1C current to carry out formation. The standing temperature is 45 ℃, and the standing time is 24 hours.
After the negative voltage is formed, an open-circuit voltage test is performed to obtain an OCV1 (open-circuit voltage 1), and then aging is performed. The high-temperature aging step comprises the following steps: and (3) aging the battery cell subjected to negative pressure formation for 48h at 50 ℃.
The negative pressure exhausting step comprises the following steps: after the battery cell (the SoC is more than 70 percent at the moment) after the high-temperature aging is finished is subjected to normal-temperature standing 1, the battery cell subjected to the normal-temperature standing 1 is vacuumized to-80 Kpa, and negative-pressure air extraction is carried out; the time of negative pressure air exhaust is 30min. After standing at normal temperature for 1, an open-circuit voltage test can be performed to obtain OCV2 (open-circuit voltage 2), and then negative pressure exhaust is performed.
The capacity grading step comprises the following steps: and (4) grading the battery cell subjected to negative pressure exhaust. And the method also comprises the steps of secondary liquid injection, sealing and helium detection after the negative pressure exhaust is finished. Specifically, secondary liquid injection is carried out on the battery cell after negative pressure exhaust is finished to 2.5g/Ah; carrying out laser sealing on the electric core subjected to secondary liquid injection; performing secondary helium detection on the sealed battery cell; grading the capacity of the battery cell qualified in the helium test; and (3) sequentially carrying out normal-temperature standing 2 and normal-temperature standing 3 on the capacity-divided battery cell, then carrying out film coating and capacity grouping, and respectively carrying out open-circuit voltage tests after the normal-temperature standing 2 and the normal-temperature standing 3 to obtain an OCV3 (open-circuit voltage 3) and an OCV4 (open-circuit voltage 4).
Analysis of results
As shown in fig. 6 (a), by an optimized process method, the aging and capacitance method of embodiment 1 can effectively improve the problem of interface black spots of a high energy density system, and meanwhile, can avoid the risks of cell performance degradation and safety caused by the interface black spots. This is because in the aging and capacity grading process method in embodiment 1, after the aging is completed, the negative pressure discharge process is added, and the negative pressure is added to exhaust the gas while the SoC state of the battery cell is reduced, because the SoC state after the discharge is reduced to 0%, the negative electrode sheet starts to contract, the distance between the electrode sheets is increased, and at this time, the negative pressure is applied, so that the gas is sufficiently and thoroughly discharged, and the gas is prevented from remaining inside the battery cell, as shown in fig. 5.
As shown in fig. 6 (b), in the conventional process of comparative example 1, cell interface black spots were noticeable. This is because the gas formed during aging is not discharged, and the charge is fully charged at normal pressure in the initial stage of capacity separation, and the bubbles remaining in the pole piece during charging cause black spots to form at the interface, as shown in fig. 4.
As shown in fig. 6 (c), the improved process of comparative example 2 did not vent sufficiently, and black spots remained at the cell interface. This is because comparative example 2 only performs negative pressure exhaust after aging, and at this time, the SoC state of the battery cell is generally 70% to 100%, the negative electrode expansion is large, and the exhaust space inside the battery cell is small, so that gas is not easily exhausted, gas still remains inside the battery cell, and bubbles remaining in the pole piece during the capacity-divided charging process still cause black spots to form on the interface.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (10)
1. The method for improving the interface black spot of the lithium ion battery comprises formation and aging steps and is characterized in that negative-pressure discharge is carried out after the aging step is finished.
2. The method of claim 1, wherein the lithium ion battery is a high energy density system lithium ion battery having an energy density greater than 200 Wh/kg; preferably, the chemical systems of the high-energy density system lithium ion battery are a Si system negative electrode, an FEC (Forward error correction) base electrolyte and a ternary positive electrode; more preferably, the ternary cathode is an NCM ternary cathode.
3. The method according to claim 1 or 2, wherein the discharge voltage in the negative pressure discharge step is 3.6 to 2.5V, and the degree of vacuum is not more than-10 Kpa; the preferred vacuum is-10 to-80 Kpa.
4. A method according to any one of claims 1-3, characterized in that the formation is a negative pressure formation, which is: and vacuumizing the battery cell to-10 to-80 Kpa, and applying 3.8 to 2.5V voltage and 0.1 to 2C current to carry out formation for 1 to 180min.
5. The method according to any one of claims 1 to 4, wherein the aging is high temperature aging at a temperature of 45 to 60 ℃; preferably, the aging time is 24-72h.
6. The method of claim 5, wherein the step of discharging under negative pressure comprises standing the cell after aging at high temperature at normal temperature; and carrying out negative-pressure discharge on the battery cell after the battery cell is kept at the normal temperature.
7. The method according to any one of claims 1 to 6, further comprising a step of injecting liquid and a step of standing the injected battery cell at a high temperature before the step of forming, wherein the standing temperature is 20 to 48 ℃.
8. A chemical composition capacitance method for improving black spots on an interface of a lithium ion battery, which is characterized by comprising the method of any one of claims 1 to 7, and further comprising the step of performing capacitance separation after the negative pressure discharge is finished.
9. The chemical component capacity dividing method according to claim 8, wherein the standing at normal temperature is performed at least once after the capacity division is completed;
the method also comprises the step of testing the open-circuit voltage of the battery cell; preferably, the open circuit voltage test is performed after the high-temperature standing step and after the normal-temperature standing step;
and/or further comprising the step of sealing the battery cell after the negative-pressure discharge is finished;
and/or, further comprising the step of carrying out secondary liquid injection on the battery cell after the negative pressure discharge is finished;
and/or carrying out secondary liquid injection on the battery cell after the negative pressure discharge is finished, and sealing the battery cell after the secondary liquid injection; and grading the sealed battery cell.
10. The method for improving the interface black spot of the lithium ion battery according to any one of claims 1 to 6 or the application of the component capacitance method for improving the interface black spot of the lithium ion battery according to any one of claims 7 to 9, which is used for preparing the cell of the lithium ion battery.
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| CN117080361A (en) * | 2023-10-13 | 2023-11-17 | 瑞浦兰钧能源股份有限公司 | Secondary battery with silicon-based negative electrode |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117080361A (en) * | 2023-10-13 | 2023-11-17 | 瑞浦兰钧能源股份有限公司 | Secondary battery with silicon-based negative electrode |
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