Battery formation method and manufacturing method thereof
By performing charge-discharge cycles with a set cutoff voltage on lithium batteries, the problem of high moisture control costs in lithium battery production was solved, and effective decomposition of moisture inside the battery and performance improvement were achieved.
Patent Information
- Application Number
- CN202510740709.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-04
- Publication Date
- 2025-10-17
AI Technical Summary
The cost of moisture control in the existing lithium battery production process is high and the effect is poor, resulting in reduced battery performance or safety hazards.
By injecting electrolyte into the battery and then performing charge-discharge cycles at a set cutoff voltage, the moisture decomposes during the battery charging process. Combined with controlling the moisture content during the formation process, additional processing steps are avoided.
It effectively controls the moisture content during the formation process, reduces costs, prevents battery flatulence, and improves battery performance and life.
Smart Images
Figure CN120809982A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of battery manufacturing, in particular to a battery formation method and a manufacturing method thereof. BACKGROUND
[0002] In the production process of lithium batteries, water content needs to be controlled. For example, the water content of the environment in the process of assembling battery pole pieces and core packages needs to be strictly controlled to prevent water from being adsorbed to the surface of the electrode and the separator, and then reacting with the electrolyte to generate hydrofluoric acid, thereby causing the performance of the battery to decrease or posing a safety hazard.
[0003] The control of water content in the production process of lithium batteries mainly relies on strict environmental humidity management and material drying treatment. Environmental humidity management increases the cost of process environment control, and material drying treatment involves baking the battery core before liquid injection, which increases the baking cost and causes thermal damage to the separator. SUMMARY
[0004] Embodiments of the present application provide a battery formation method and a manufacturing method thereof, which can improve the technical problems of high cost or poor effect of water content control in the existing battery production process.
[0005] In a first aspect, embodiments of the present application provide a battery formation method, comprising:
[0006] After the battery is injected with liquid, the battery is subjected to a charge-discharge cycle at a set cut-off voltage, and the set cut-off voltage is not lower than the decomposition voltage of water.
[0007] In an embodiment, the set cut-off voltage is 1.5V-3.2V.
[0008] In an embodiment, the charge-discharge cycle of the battery at the set cut-off voltage comprises:
[0009] Obtaining the water content of the battery before liquid injection, obtaining the charge-discharge rate and the charge-discharge cycle number of the battery according to the water content, and performing a charge-discharge cycle at the charge-discharge rate and the charge-discharge cycle number.
[0010] In an embodiment, the obtaining of the water content of the battery before liquid injection comprises: obtaining the water content of the electrode and / or the separator before liquid injection.
[0011] In an embodiment,
[0012] The higher the water content, the smaller the charge-discharge rate; and / or
[0013] The higher the water content, the more the charge-discharge cycle number.
[0014] In an embodiment, the charge-discharge rate is 0.01C-0.6C; and / or
[0015] The number of charge-discharge cycles is 1-20 times.
[0016] In an embodiment, the water content is less than 200 ppm, the charge-discharge rate is 0.3C-0.5C, and the number of charge-discharge cycles is 1 time; and / or
[0017] The water content is not less than 200 ppm and less than 300 ppm, the charge-discharge rate is 0.2C-0.6C, and the number of charge-discharge cycles is 1 time; and / or
[0018] The water content is not less than 300 ppm and less than 600 ppm, the charge-discharge rate is 0.15C-0.5C, and the number of charge-discharge cycles is 1-10 times; and / or
[0019] The water content is not less than 600 ppm and less than 700 ppm, the charge-discharge rate is 0.1C-0.5C, and the number of charge-discharge cycles is 1-10 times; and / or
[0020] The water content is not less than 700 ppm and less than 1000 ppm, the charge-discharge rate is 0.05C-0.5C, and the number of charge-discharge cycles is 1-10 times; and / or
[0021] The water content is not less than 1000 ppm, the charge-discharge rate is 0.01C-0.3C, and the number of charge-discharge cycles is 1-20 times.
[0022] In an embodiment, each of the charge-discharge cycles includes charging the battery to 3% SOC-50% SOC and then discharging to 0% SOC.
[0023] In an embodiment, the method further includes:
[0024] After the battery is subjected to the charge-discharge cycle at the set cutoff voltage, the water content of the electrolyte of the battery is obtained.
[0025] When the water content of the electrolyte is greater than or equal to a set threshold, the step of subjecting the battery to the charge-discharge cycle at the set cutoff voltage is performed again.
[0026] In an embodiment, the set threshold is 50 ppm.
[0027] In a second aspect, embodiments of the present application provide a battery manufacturing method, including the above-mentioned battery formation method.
[0028] In the embodiment of the present application, by charging and discharging the battery at a set cut-off voltage, the formation of the battery can be realized, and by setting the cut-off voltage to be not lower than the decomposition voltage of water, the water in the battery can be decomposed during the charging of the battery, so that the control of the water content in the battery during the formation of the battery is realized. The method combines the water treatment process in the formation process, and does not need to increase the processing steps, and is simple to operate. BRIEF DESCRIPTION OF DRAWINGS
[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0030] Figure 1 is a schematic diagram of water decomposition of the battery formation method provided by the embodiment of the present application. DETAILED DESCRIPTION
[0031] The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, the orientation words such as "upper" and "lower" generally refer to the upper and lower of the device in the actual use or working state, and the specific is the direction of the drawing surface in the drawings; and "inner" and "outer" are relative to the outline of the device.
[0032] The technical solutions of the present application are as follows:
[0033] In a first aspect, the embodiment of the present application provides a battery formation method, comprising: after the battery is injected with liquid, charging and discharging the battery at a set cut-off voltage, the set cut-off voltage being not lower than the decomposition voltage of water.
[0034] In the present application, by charging and discharging the battery at a set cut-off voltage, the formation of the battery can be realized, and by setting the cut-off voltage to be no lower than the decomposition voltage of water, the water in the battery can be decomposed during the charging process of the battery, thereby realizing the control of the water content in the battery during the formation process of the battery. The method combines the water treatment process in the formation process, without the need to increase the processing steps, and the operation is simple. At the same time, the charging and discharging process of the battery can promote the diffusion of particles on the electrode surface and generate temperature rise, thereby driving the movement of water molecules and increasing the decomposition efficiency of water.
[0035] In the present application, as shown in Figure 1 When charging the battery at a cut-off voltage no lower than the decomposition voltage of water, the negative electrode of the battery will act as the anode, and the positive electrode of the battery will act as the cathode. Water molecules will undergo oxidation-reduction reaction at the cathode and the anode, and the overall reaction is:
[0036] 2H2O→2H2+O2(ΔG°=+237kJ / mol)
[0037] Cathode (hydrogen evolution reaction, HER): 2H + +2e - →H2
[0038] Anode (oxygen evolution reaction, OER): 2H2O→O2+4H + +4e -
[0039] In the present application, during the formation of the battery, the battery is not completely sealed, so the gas generated by the decomposition of water can be fully discharged from the battery, thereby preventing the battery from swelling.
[0040] In some embodiments, the set cut-off voltage is 1.5V-3.2V, for example, it can be 1.5V, 1.7V, 1.9V, 2.0V, 2.2V, 2.5V, 2.7V, 2.9V, 3.0V, 3.2V, etc. In this way, the water can be fully decomposed, and at the same time, the overpotential of part of the system in the battery can be prevented to cause the performance of the battery to decrease.
[0041] It can be understood that the theoretical decomposition voltage of water is 1.23V (under standard conditions), and in actual application, due to factors such as electrode polarization and electrolyte resistance, a voltage of 1.5V or more is needed to start the decomposition reaction of water.
[0042] In some embodiments, the charging and discharging cycle of the battery at the set cut-off voltage comprises:
[0043] The water content of the battery before liquid injection is obtained, the charge-discharge rate and the charge-discharge cycle number of the battery are obtained according to the water content, and the charge-discharge cycle is performed at the charge-discharge rate and the charge-discharge cycle number. In this way, the water decomposition rate and the charge-discharge cycle number in the battery can be balanced, time and cost can be saved, and the performance and life of the battery can be balanced.
[0044] In some embodiments, the water content of the battery before liquid injection includes: obtaining the water content of the electrode and / or the separator before liquid injection of the battery. In this way, the operation and sampling can be facilitated, and the electrode and the separator of the battery are key parts that are easy to absorb water and affect the performance of the battery. By obtaining the water content of the electrode and / or the separator before liquid injection of the battery, the water content in the battery after the charge-discharge cycle can be better controlled.
[0045] In this application, the water content of the electrode and / or the separator before liquid injection of the battery can be measured by Karl Fischer water test method. The electrode includes a positive electrode sheet and a negative electrode sheet. As an example, the active material of the positive electrode sheet can be lithium iron phosphate, lithium manganese iron phosphate, ternary material (NCM), and lithium-rich positive electrode material. The active material of the negative electrode sheet can be graphite.
[0046] In some embodiments, the higher the water content, the smaller the charge-discharge rate; and / or
[0047] The higher the water content, the more the charge-discharge cycle number.
[0048] In this application, the smaller the charge-discharge rate, the faster the decomposition rate of water. The higher the water content, the smaller the charge-discharge rate, and the faster the decomposition rate; the higher the water content, the more the charge-discharge cycle number. By balancing the water decomposition rate and the charge-discharge cycle number in the battery, time and cost can be saved.
[0049] In some embodiments, the charge-discharge rate is 0.01C-0.6C, for example, it can be 0.01C, 0.03C, 0.05C, 0.08C, 0.1C, 0.2C, 0.3C, 0.4C, 0.5C, 0.6C, etc. In this way, the decomposition rate of water, the charge-discharge cycle number and the performance of the battery can be balanced.
[0050] In this application, the charge-discharge rate is also related to the material system of the battery. The charge-discharge rate can be adjusted within the interval according to the material system of the battery.
[0051] In some embodiments, the charge-discharge cycle number is 1-20 times, for example, it can be 1 time, 3 times, 5 times, 8 times, 10 times, 12 times, 15 times, 17 times, 20 times, etc.
[0052] In this application, "C" represents the charge-discharge rate, that is, the ratio of the charge-discharge current to the rated capacity of the battery.
[0053] In some embodiments, the water content is less than 200 ppm, for example, can be 195 ppm, 190 ppm, 185 ppm, 180 ppm, 175 ppm, 170 ppm, etc., the charge-discharge rate is 0.3C-0.5C, for example, can be 0.3C, 0.32C, 0.35C, 0.37C, 0.4C, 0.42C, 0.46C, 0.48C, 0.5C, etc., the number of charge-discharge cycles is 1 time; and / or
[0054] The water content is not less than 200 ppm and less than 300 ppm, for example, can be 200 ppm, 210 ppm, 220 ppm, 230 ppm, 240 ppm, 250 ppm, 260 ppm, 270 ppm, 280 ppm, 290 ppm, etc., the charge-discharge rate is 0.2C-0.6C, for example, can be 0.2C, 0.25C, 0.27C, 0.3C, 0.32C, 0.35C, 0.37C, 0.4C, 0.42C, 0.46C, 0.5C, 0.55C, 0.57C, 0.6C, etc., the number of charge-discharge cycles is 1 time; and / or
[0055] The water content is not less than 300 ppm and less than 600 ppm, for example, can be 300 ppm, 330 ppm, 350 ppm, 370 ppm, 400 ppm, 450 ppm, 500 ppm, 550 ppm, 570 ppm, etc., the charge-discharge rate is 0.15C-0.5C, for example, can be 0.15C, 0.17C, 0.2C, 0.25C, 0.3C, 0.35C, 0.4C, 0.45C, 0.47C, 0.5C, etc., the number of charge-discharge cycles is 1-10 times, for example, can be 1 time, 2 times, 3 times, 5 times, 7 times, 8 times, 9 times, 10 times, etc.; and / or
[0056] The water content is not less than 600 ppm and less than 700 ppm, for example, can be 600 ppm, 610 ppm, 620 ppm, 630 ppm, 650 ppm, 670 ppm, 680 ppm, 690 ppm, etc., the charge-discharge rate is 0.1C-0.5C, for example, can be 0.1C, 0.12C, 0.14C, 0.17C, 0.2C, 0.25C, 0.3C, 0.35C, 0.4C, 0.45C, 0.47C, 0.5C, etc., the number of charge-discharge cycles is 1-10 times, for example, can be 1 time, 2 times, 3 times, 5 times, 7 times, 8 times, 9 times, 10 times, etc.; and / or
[0057] The water content is not less than 700 ppm and less than 1000 ppm, for example, it can be 700 ppm, 720 ppm, 750 ppm, 800 ppm, 850 ppm, 900 ppm, 950 ppm, 990 ppm, etc., the charge and discharge rate is 0.05C-0.5C, for example, it can be 0.05C, 0.07C, 0.1C, 0.15C, 0.2C, 0.25C, 0.3C, 0.35C, 0.4C, 0.45C, 0.47C, 0.5C, etc., the number of charge and discharge cycles is 1-10 times, for example, it can be 1 time, 2 times, 3 times, 5 times, 7 times, 8 times, 9 times, 10 times, etc.; and / or
[0058] The water content is not less than 1000 ppm, for example, it can be 1000 ppm, 1050 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm, etc., the charge and discharge rate is 0.01C-0.3C, for example, it can be 0.01C, 0.02C, 0.04C, 0.07C, 0.1C, 0.15C, 0.2C, 0.25C, 0.27C, 0.3C, etc., the number of charge and discharge cycles is 1-20 times, for example, it can be 1 time, 2 times, 3 times, 5 times, 10 times, 15 times, 17 times, 19 times, 20 times, etc.
[0059] In some embodiments, each of the charge and discharge cycles includes: charging the battery to 3% SOC-50% SOC, and then discharging to 0% SOC. In this way, the charge and discharge energy consumption and cycle time can be reduced, thereby reducing the charge and discharge cost.
[0060] In this application, SOC (State of Charge) represents the state of charge of the battery, that is, the ratio of the current remaining capacity of the battery to the maximum capacity of the battery. It is usually expressed in percentage form, ranging from 0% to 100%, used to reflect the remaining capacity and energy storage state of the battery.
[0061] In some embodiments, the charge and discharge cycle further includes:
[0062] After the battery is charged and discharged at the set cut-off voltage, the water content of the electrolyte of the battery is obtained;
[0063] When the water content of the electrolyte is greater than or equal to a set threshold, the step of charging and discharging the battery at the set cut-off voltage is performed again. In this way, it can be verified whether the water content in the battery after the charge and discharge cycle reaches the requirement.
[0064] In the present application, after the charge-discharge cycle, the electrolyte is contained in the electrode and the separator of the battery, at this time, the water content in the test electrode and the separator is not accurate, and after the charge-discharge cycle, the water in the battery moves in the battery and enters the electrolyte, by controlling the water content in the electrolyte, the water content in the battery can be effectively controlled. The water content of the electrolyte of the battery after the charge-discharge cycle can be measured by Karl Fischer water test method.
[0065] In some embodiments, the set threshold value is 50 ppm.
[0066] In the second aspect, the embodiments of the present application provide a battery manufacturing method, comprising the battery formation method described above.
[0067] The battery formation method of the present application can be applied to the manufacturing process of lithium ion batteries, and also can be applied to the manufacturing process of sodium ion batteries.
[0068] The following is described in conjunction with specific embodiments.
[0069] Embodiment 1
[0070] A battery formation method, comprising the following steps:
[0071] (1) Before the battery is injected, the water content of the positive plate (the active material is lithium iron phosphate), the negative plate (graphite) and the separator of the battery is tested, and the water content of the battery is 273 ppm;
[0072] (2) The battery is injected, after injection, charged to 2.0V at 0.37C, and then discharged to 0% SOC at 0.37C, and the formation is completed;
[0073] (3) The electrolyte of the battery after formation is taken, and the water content of the electrolyte is tested, as shown in Table 1.
[0074] Embodiment 2
[0075] A battery formation method, comprising the following steps:
[0076] (1) Before the battery is injected, the water content of the positive plate (the active material is lithium iron phosphate), the negative plate (graphite) and the separator of the battery is tested, and the water content of the battery is 441 ppm;
[0077] (2) The battery is injected, after injection, charged to 2.5V at 0.22C, and then discharged to 0% SOC at 0.22C, and the formation is completed;
[0078] (3) The electrolyte of the battery after formation is taken, and the water content of the electrolyte is tested, as shown in Table 1.
[0079] Embodiment 3
[0080] A battery formation method, comprising the following steps:
[0081] (1) Before the battery is injected, the water content of the positive plate (active material is lithium iron phosphate), the negative plate (graphite), and the separator of the battery is tested, and the water content of the battery is 676 ppm;
[0082] (2) The battery is injected, and after injection, it is charged to a cut-off voltage of 2.7V at 0.13C, and then discharged to 0% SOC at 0.13C, and this cycle is repeated 5 times to complete the formation;
[0083] (3) The electrolyte of the battery after formation is taken, and the water content of the electrolyte is tested, as shown in Table 1.
[0084] Example 4
[0085] A battery formation method, comprising the following steps:
[0086] (1) Before the battery is injected, the water content of the positive plate (active material is lithium iron phosphate), the negative plate (graphite), and the separator of the battery is tested, and the water content of the battery is 805 ppm;
[0087] (2) The battery is injected, and after injection, it is charged to a cut-off voltage of 2.7V at 0.07C, and then discharged to 0% SOC at 0.07C, and this cycle is repeated 7 times to complete the formation;
[0088] (3) The electrolyte of the battery after formation is taken, and the water content of the electrolyte is tested, as shown in Table 1.
[0089] Example 5
[0090] A battery formation method, comprising the following steps:
[0091] (1) Before the battery is injected, the water content of the positive plate (active material is lithium iron phosphate), the negative plate (graphite), and the separator of the battery is tested, and the water content of the battery is 1077 ppm;
[0092] (2) The battery is injected, and after injection, it is charged to a cut-off voltage of 3.0V at 0.02C, and then discharged to 0% SOC at 0.02C, and this cycle is repeated 10 times to complete the formation;
[0093] (3) The electrolyte of the battery after formation is taken, and the water content of the electrolyte is tested, as shown in Table 1.
[0094] Comparative Example 1
[0095] This comparative example is basically the same as Example 1, except that the charge and discharge rate in this comparative example is 0.8C.
[0096] Test method:
[0097] Karl Fischer water content test method: calibration including reference, preparation of samples (positive plate, negative plate, separator and electrolyte) (0.1-5g), setting of test parameters, and test performance and result derivation;
[0098] Preparation: check whether the instrument equipment is complete, ensure that the pipeline, bottle cap, drying agent, etc. are connected correctly, and there is sufficient anhydrous methanol in the reagent and solvent bottles;
[0099] After turning on, calibrate according to the instructions, including weighing 20g of bricks on the sample disc, and confirming whether the weighing is normal;
[0100] Reagent preparation: inject an appropriate amount of Karl Fischer reagent (about 30mL of anhydrous methanol) into the titration cell for blank titration, consume the water in the solvent methanol in the titration cup to maintain anhydrous titration solvent environment;
[0101] Sample preparation: the sample needs to be pretreated, such as crushing and weighing 0.1-5g for solid samples, and adding the sample to the titration cell, covering the plug to ensure the sealing;
[0102] Titration operation: start the instrument, suck in Karl Fischer reagent, and titrate to the end point;
[0103] Result calculation: calculate the water content in the sample according to the volume of Karl Fischer reagent consumed by titration and the water equivalent.
[0104] The water content calculation formula is: water content = (water equivalent of Karl Fischer reagent x volume of Karl Fischer reagent consumed by titration) / sample weight.
[0105] Cycling capacity retention rate test method: after the battery is formed, the finished battery is made, charged at 25°C under 1C constant current and constant voltage to 3.65V, and cut off at 0.05C current; discharged at 1C constant current to 2.5V, and so on for 1000 cycles to obtain the cycling capacity retention rate.
[0106] Parameter table
[0107]
[0108] From Table 1, it can be seen that:
[0109] The water content of the batteries of Examples 1-5 before and after formation is reduced, and it can be seen that, by charging and discharging cycling at a specific cut-off voltage during battery formation, the water in the battery can be decomposed, and the battery obtained by the formation method has a good cycling capacity retention rate.
[0110] Compared with Comparative Example 1, the water content of the battery of Example 1 before and after formation is lower, and it can be seen that, by controlling the charge and discharge rate during battery formation, the water decomposition rate in the battery can be controlled, thereby controlling the water content in the battery, and further making the battery have a better cycle capacity retention rate.
[0111] The above describes the embodiments of the present application in detail, and the principles and implementation manners of the present application are described by applying specific examples; the above description of the embodiments is only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manner and application range will be changed, and the above description of the present application should not be understood as a limitation of the present application.
Claims
1. A battery formation method, characterized in that: include: After the battery is filled with liquid, the battery is subjected to a charge and discharge cycle at a set cut-off voltage, wherein the set cut-off voltage is not lower than the decomposition voltage of water.
2. The battery formation method according to claim 1, characterized in that The set cut-off voltage is 1.5V-3.2V.
3. The battery formation method according to claim 1, characterized in that The charging and discharging cycle of the battery at a set cut-off voltage comprises: The water content of the battery before liquid injection is obtained, the charge and discharge rate and the number of charge and discharge cycles of the battery are obtained according to the water content, and the charge and discharge cycle is performed at the charge and discharge rate and the number of charge and discharge cycles.
4. The battery formation method according to claim 3, characterized in that: The obtaining of the water content of the battery before liquid injection includes: The water content of the electrode and / or separator before the battery is injected with liquid is obtained.
5. The battery formation method according to claim 3, characterized in that: The higher the water content, the smaller the charge-discharge rate; and / or The higher the water content, the more charge and discharge cycles there are.
6. The battery formation method according to claim 3, characterized in that: The charge and discharge rate is 0.01C-0.6C; and / or The number of charge and discharge cycles is 1 to 20 times.
7. The battery formation method according to claim 3, characterized in that: The water content is less than 200 ppm, the charge-discharge rate is 0.3C-0.5C, and the number of charge-discharge cycles is 1; and / or The water content is not less than 200 ppm and less than 300 ppm, the charge and discharge rate is 0.2C-0.6C, and the number of charge and discharge cycles is 1; and / or The water content is not less than 300 ppm and less than 600 ppm, the charge and discharge rate is 0.15C-0.5C, and the number of charge and discharge cycles is 1-10 times; and / or The water content is not less than 600 ppm and less than 700 ppm, the charge and discharge rate is 0.1C-0.5C, and the number of charge and discharge cycles is 1-10 times; and / or The water content is not less than 700ppm and less than 1000ppm, the charge and discharge rate is 0.05C-0.5C, and the number of charge and discharge cycles is 1-10 times; and / or The water content is not less than 1000 ppm, the charge and discharge rate is 0.01C-0.3C, and the number of charge and discharge cycles is 1-20 times.
8. The battery formation method according to claim 1, characterized in that: Each charge and discharge cycle includes: charging the battery to 3% SOC-50% SOC, and then discharging it to 0% SOC.
9. The battery formation method according to claim 1, characterized in that: The method further comprises: After the battery is subjected to a charge-discharge cycle at a set cutoff voltage, the water content of the electrolyte of the battery is obtained; When the water content of the electrolyte is greater than or equal to the set threshold, the step of charging and discharging the battery at the set cut-off voltage is performed again.
10. The battery formation method according to claim 9, characterized in that: The set threshold value is 50 ppm.
11. A method for manufacturing a battery, characterized in that: The method comprises the battery formation method according to any one of claims 1 to 10.