Method for the formation of spare lithium batteries and batteries

Abstract

The present invention discloses a method for charging a pre-lithiated battery and a battery. The charging method includes: performing a first charge on the pre-lithiated battery after liquid injection until a preset state of charge (SOC) to form a solid electrolyte interphase (SEI) film; performing a second charge to raise the voltage to V1, causing further delithiation of the positive electrode active material, and then standing still; and performing a third charge to raise the voltage to V2, where V2 is the cut-off voltage for the decomposition of the lithium supplement. The temperature of the first charge is T1, the temperature during standing still is T2, and the temperature of the third charge is T3, and T1 < T2, T2 < T3. The method of the present invention can obtain a sufficient lithium supplement effect, has a high charge gram capacity of the lithium supplement, can effectively solve the problem of lithium deposition on the surface of the negative electrode, and after disassembling the battery in a fully charged state, the negative electrode interface of the battery cell is good, no spots due to lithium deposition are observed, and the cycle performance of the battery is improved.

Description

Technical Field

[0001] The present invention relates to a method for the formation of a lithium battery, specifically to a method for the formation of a pre-lithiated battery and a battery.

Background Art

[0002] In recent years, the technology of pre-lithiation of the positive electrode has been developed and applied to improve the cycle life of energy storage battery cells (such as lithium iron phosphate battery cells). The positive electrode lithium replenishment technology adds lithium replenishment materials with high irreversible capacity, such as lithium-rich ferrite (Li5FeO4, LFO) and lithium-rich nickel oxide (Li2NiO2, LNO), to the positive electrode sheet. When the battery cell is initially formed, the lithium replenisher decomposes to release lithium ions, which are inserted into the negative electrode. During discharge, some lithium ions are stored in the negative electrode to compensate for lithium consumption in the later stage of the cycle.

[0003] The purpose of the formation of a lithium-ion battery is to form a solid electrolyte interface film that allows stable lithium ions to permeate through the surface of the negative electrode (such as a graphite negative electrode) and does not allow electrons to permeate during the first charge, which is abbreviated as the SEI film. In the case of different positive and negative electrode mixing ratios and electrolyte mixing ratios, the voltage range for forming the SEI film is also different. Usually, when charging to 20% SOC or less, the growth of the SEI is basically completed. Therefore, usually, when forming a lithium iron phosphate battery cell, it is only necessary to charge to 10% - 50% SOC, and then the battery cell proceeds to the high-temperature aging stage.

[0004] However, in a pre-lithiated battery cell, in order to completely decompose the positive electrode lithium replenisher, it is necessary to reach a voltage of about 4.2V, which is higher than the full charge voltage and 100% SOC voltage of a lithium iron phosphate battery cell. Therefore, to activate the lithium replenisher, the lithium iron phosphate battery cell has to be fully charged. However, when the battery cell is initially charged, the negative electrode sheet has not experienced the expansion associated with charging, and the electrolyte is not fully impregnated. Therefore, when the electrode is fully charged, lithium deposition is likely to occur on the surface of the negative electrode of the battery cell.

[0005] Therefore, providing a chemical conversion method that avoids lithium deposition problems, improves battery cell interface conditions, and enhances the capacity performance of lithium replenishers is an urgent technical challenge that needs to be addressed. [Overview of the project] [Problems that the invention aims to solve]

[0006] Regarding the technical problems that exist in conventional technology as described above, the object of the present invention is to propose a method for producing a spare lithium battery and a battery itself. [Means for solving the problem]

[0007] To achieve the above objective, the present invention employs the following technical solutions.

[0008] In a first aspect, the present invention provides a method for the formation of a spare lithium battery, the formation method being: The process involves performing a first charge on the pre-filled lithium battery to a predetermined state of charge (SOC) to form a solid electrolyte interface (SEI) film, and The second step involves performing a second charge, raising the voltage to V1, causing further delithiation of the positive electrode active material, and then allowing it to stand. The process includes a third step of charging, raising the voltage to V2, where V2 is the termination voltage for lithium replenishment decomposition, The temperature of the first charge is T1, the temperature of the standing area is T2, the temperature of the third charge is T3, and T1 <T2、T2<T3であり、20℃<T1<30℃、40℃<T2<50℃、50℃≦T3≦65℃であり、 After raising the voltage to V1, the standing time was 6h to 12h, and the voltage was 3.4V. <V1<3.65Vであり、V2は4.05V~4.3Vである。

[0009] In the method of the present invention, if the third charge is performed up to the termination voltage of lithium replenisher decomposition, the lithium replenisher is completely decomposed.

[0010] In some embodiments, the starting voltage for lithium replenishment decomposition is less than V1, the lithium replenishment is slightly decomposed and at a slow rate during the second charging interval, the lithium replenishment is significantly decomposed and at a much faster rate during the third charging interval, and when the voltage reaches the termination voltage for lithium replenishment decomposition, the lithium replenishment is completely decomposed.

[0011] In the chemical conversion method of the present invention, the first charging step is carried out at a low temperature, which is advantageous for the formation of a dense SEI film. If the second charging is carried out until the positive electrode active material undergoes delithiation, allowing it to stand at a high temperature allows for more sufficient impregnation of the electrolyte, improving the battery cell interface conditions and avoiding lithium deposition problems caused by high SOC during the third charging. The third charging is carried out at a higher temperature, making it possible to sufficiently decompose the lithium replenisher at a higher rate than in conventional techniques (e.g., 0.02C to 0.05C), which is advantageous for shortening the conversion time and improving the capacity utilization of the lithium replenisher. The combined effect of the above elements not only allows for the formation of a dense SEI film, but also enables sufficient impregnation of the pre-lithium battery into the electrolyte, promoting the effective decomposition of the lithium replenisher. Therefore, the method of the present invention can achieve a sufficient lithium replenishment effect, a high charge gram capacity of the lithium replenisher, and effectively solve the problem of lithium deposition on the negative electrode surface. After disassembling the battery in a fully charged state, the negative electrode interface of the battery cell is in good condition, no spots due to lithium deposition are observed, and the battery's cycle performance is improved.

[0012] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be achieved and realized more effectively by the following preferred technical solutions.

[0013] Preferably, 20°C < T1 < 30°C, and it may be, for example, 22°C, 24°C, 25°C, 26°C, or 28°C. Within this low temperature range, it is not only advantageous for obtaining a dense SEI film, but it can usually be carried out at room temperature without the need to additionally control the charging environment.

[0014] Preferably, 40°C < T2 < 50°C, and it may be, for example, 42°C, 43°C, 45°C, 47°C, or 48°C. Standing at this high temperature is advantageous for sufficient impregnation of the electrolyte, thereby avoiding the lithium deposition problem on the negative electrode during the battery charging process.

[0015] Preferably, 50°C ≤ T3 ≤ 65°C, and it may be, for example, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 61°C, 63°C, or 65°C, and preferably 50°C < T3 < 65°C. If the temperature T3 of the third charging is too low, the promoting effect on the decomposition of the lithium supplement agent is weak, the charging gram capacity of the lithium supplement agent decreases, the amount of lithium stored in the negative electrode decreases, and the cycle performance deteriorates. If the temperature T3 of the third charging is too high, it will affect the interface of the battery cell and the cycle performance will deteriorate.

[0016] Preferably, after raising the voltage to V1, the standing time is 6h - 12h, and it may be, for example, 6h, 7h, 8h, 9h, 10h, 11h, or 12h.

[0017] Preferably, the charging rate of the first charging is 0.02C - 0.3C. Conducting the first charging under low rate conditions is advantageous for forming a dense SEI film.

[0018] Preferably, the preset SOC range is 10% to 50% SOC, and does not include 50% SOC. For example, it could be 10% SOC, 12% SOC, 14% SOC, 15% SOC, 16% SOC, 17% SOC, 18% SOC, 20% SOC, 25% SOC, 30% SOC, 35% SOC, 40% SOC, 42% SOC, 45% SOC, 48% SOC, or 49% SOC. The basic growth of the SEI film is completed within this preset SOC range.

[0019] Preferably, after charging the spare lithium battery to a preset state of charge (SOC), charging is stopped and the battery is left to stand for 12 to 48 hours (e.g., 12h, 14h, 16h, 18h, 20h, 22h, 25h, 27h, 30h, 32h, 34h, 35h, 37h, 40h, 43h, 44h, 46h, or 48h) under conditions of 40°C to 50°C (e.g., 40°C, 42°C, 44°C, 44°C, 46h, or 48h). By implementing this step, the electrolyte can be sufficiently impregnated, and the second charge can not only avoid the problem of lithium deposition on the negative electrode at a high charge rate, but also shorten the conversion time.

[0020] Preferably, the charge ratio of the second charge is 0.3C to 0.6C, and may be, for example, 0.3C, 0.4C, 0.5C, or 0.6C.

[0021] Preferably, when the voltage is increased to V1, the reserve lithium battery is charged to a level greater than 80% SOC and less than or equal to 100% SOC, for example, 80% SOC, 82% SOC, 85% SOC, 88% SOC, 90% SOC, 93% SOC, 96% SOC, 98% SOC, or 100% SOC. At this time, most of the positive electrode active material undergoes delithiation, and some of the lithium replenisher also undergoes delithiation.

[0022] Preferably, the temperature of the second charge is 40°C to 50°C, and may be, for example, 40°C, 42°C, 43°C, 45°C, 47°C, 48°C, or 50°C.

[0023] Preferably, 3.4V < V1 < 3.65V. Exemplarily, V1 may be 3.4V, 3.42V, 3.45V, 3.47V, 3.5V, 3.53V, 3.56V, 3.58V, or 3.6V, etc.

[0024] Preferably, the charging rate of the third charging is 0.1C to 0.3C, and may be, for example, 0.1C, 0.12C, 0.14C, 0.16C, 0.18C, 0.2C, 0.22C, 0.25C, 0.27C, or 0.3C, etc.

[0025] Preferably, V2 is 4.05V to 4.3V, and may be, for example, 4.05V, 4.08V, 4.1V, 4.12V, 4.14V, 4.15V, 4.18V, 4.2V, 4.23V, 4.26V, 4.28V, or 4.3V, etc.

[0026] Preferably, after raising the voltage to V2, charging is stopped, and the preliminary lithium - ion battery is left standing at 40°C to 50°C (such as 40°C, 42°C, 44°C, 46°C, 48°C, or 50°C, etc.) for 12h to 48h (such as 12h, 14h, 16h, 18h, 20h, 22h, 25h, 27h, 30h, 32h, 34h, 35h, 37h, 40h, 43h, 44h, 46h, or 48h, etc.). This process fully impregnates the electrolyte, makes the SEI film on the negative electrode surface more stable, and at the same time, the side reaction between the lithium supplement agent and the electrolyte is sufficient, which is beneficial to the discharge of side - reaction gases.

[0027] Preferably, the preliminary lithium - ion battery after electrolyte injection includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. The positive electrode plate includes a positive electrode current collector and a positive electrode material layer provided on the surface of the positive electrode current collector. The positive electrode material layer contains a positive electrode active material and a lithium supplement agent.

[0028] Preferably, the mass of the lithium supplement agent accounts for 0.5% to 5% of the mass of the positive electrode material layer, and may be, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, etc.

[0029] In a second aspect, the present invention provides a battery, which is manufactured by the following method, wherein a pre-lithium battery after liquid injection is converted by the method of the first aspect, followed by secondary liquid injection, sealing treatment and capacity polarization.

[0030] The numerical range in this invention includes the point values ​​listed above, as well as any point values ​​between the above numerical ranges that are not listed. For the sake of brevity and length, this invention does not enumerate all specific point values ​​that include this invention. [Effects of the Invention]

[0031] Compared to conventional technologies, the present invention has the following beneficial effects. (1) In the chemical conversion method of the present invention, the first charging step is carried out at a low temperature, which is advantageous for the formation of a dense SEI film. If the second charging is carried out until the positive electrode active material undergoes delithiation, then by allowing it to stand at a high temperature, the impregnation of the electrolyte is made more sufficient, improving the battery cell interface conditions and avoiding the lithium deposition problem caused by high SOC during the third charging. The third charging is carried out at a higher temperature, making it possible to sufficiently decompose the lithium replenisher at a higher rate than in conventional techniques (e.g., 0.02C to 0.05C), which is advantageous for shortening the chemical conversion time. The combined effect of the above elements not only allows for the formation of a dense SEI film, but also enables sufficient impregnation of the pre-lithium battery into the electrolyte, effectively promoting the decomposition of the lithium replenisher. Therefore, the method of the present invention can achieve a sufficient lithium replenishment effect, a high charge gram capacity of the lithium replenisher, and effectively solve the problem of lithium deposition on the negative electrode surface. After disassembling the battery in a fully charged state, the negative electrode interface of the battery cell is in good condition, no spots due to lithium deposition are observed, and the battery's cycle performance is improved. (2) The chemical conversion method of the present invention can improve the charge gram capacity of the lithium replenisher, and the charge gram capacity of the lithium replenisher LFO is 650 mAh / g or more, and the battery obtained after the chemical conversion has an energy retention rate of 100% or more after 1000 cycles. [Modes for carrying out the invention]

[0032] The technical solutions of the present invention will be further described below through specific embodiments.

[0033] Manufacturing Example 1

[0034] We provide a spare lithium battery after liquid injection, and the manufacturing method thereof includes the following:

[0035] Manufacturing of positive electrode pieces: Lithium iron phosphate is used as the positive electrode active material, and lithium-rich ferrite (Li5FeO4, LFO) is used as the positive electrode lithium replenisher. The positive electrode active material, positive electrode lithium replenisher, conductive agent Super P, and binder PVDF are uniformly mixed in NMP, with a mass ratio of positive electrode active material:lithium replenisher:conductive agent:binder = 93:2:2:3. A positive electrode slurry is prepared, the positive electrode slurry is applied to aluminum foil, and after drying and roll rolling, a positive electrode material layer is formed on the surface of the aluminum foil to obtain a positive electrode piece.

[0036] Manufacturing of negative electrode pieces: Graphite is used as the negative electrode active material. The negative electrode active material, conductive agent Super P, SBR, and CMC are uniformly mixed in water to obtain a negative electrode slurry with a mass ratio of negative electrode active material:conductive agent:SBR:CMC = 96:1:1.5:1.5. The negative electrode slurry is applied to copper foil, dried, and roll-rolled to form a negative electrode material layer on the surface of the copper foil, thereby obtaining a negative electrode piece.

[0037] The electrolyte is lithium hexafluoride phosphate.

[0038] A positive electrode piece, a negative electrode piece, and a separator were stacked in order, and the positive and negative electrode pieces were separated by the separator to obtain a battery cell. After injecting the electrolyte, the cell was impregnated at 45°C for 36 hours to obtain a pre-filled lithium-ion battery. The pre-filled lithium-ion battery is a rectangular aluminum shell battery cell with a capacity of 320 Ah.

[0039] Example 1

[0040] This embodiment provides a method for the formation of a spare lithium battery, the formation method comprising the following steps.

[0041] Under an ambient temperature of 25°C, a first charge is performed on the pre-filled lithium battery (Manufacturing Example 1), which consists of first charging to 10% SOC at 0.02C, and then continuing to charging to 20% SOC at 0.1C.

[0042] Charging was stopped, and the battery cells were left undisturbed at 45°C for 12 hours.

[0043] Under an ambient temperature of 45°C, a second charge is performed, which involves charging at 0.3C up to 3.5V, thereby charging the battery to 85% SOC. At this voltage, most of the positive electrode active material undergoes delithiation, and a portion of the lithium replenisher also undergoes delithiation.

[0044] Charging was stopped, and the battery cells were left undisturbed at 45°C for 12 hours.

[0045] Under an ambient temperature of 55°C, a third charge is performed, which involves charging to 4.2V at 0.2C, at which voltage the lithium replenisher in the positive electrode decomposes.

[0046] Stop charging and leave the battery cells undisturbed at 45°C for 24 hours to complete the chemical reaction.

[0047] The battery cells, after the above chemical conversion, were subjected to secondary injection and sealing, and then discharged at 0.5P to perform capacitive polarization.

[0048] Example 2 This method differs from Example 1 in that the temperature of the third charge is adjusted to 50°C.

[0049] Example 3 This method differs from Example 1 in that the temperature of the third charge is adjusted to 65°C.

[0050] Example 4 This embodiment provides a method for the formation of a spare lithium battery, the formation method comprising the following steps.

[0051] Under an ambient temperature of 20°C, the spare lithium battery (Manufacturing Example 1) after electrolyte injection is subjected to a first charge, which consists of first charging to 10% SOC at 0.02C, and then continuing to charging to 20% SOC at 0.05C.

[0052] Charging was stopped, and the battery cells were left undisturbed at 40°C for 48 hours.

[0053] Under an ambient temperature of 47°C, a second charge is performed, which involves charging at 0.4C up to 3.55V. At this time, the battery is charged to 90% SOC, and at this voltage, most of the positive electrode active material undergoes delithiation, while a portion of the lithium replenisher undergoes delithiation.

[0054] Charging was stopped, and the battery cells were left undisturbed at 46°C for 18 hours.

[0055] Under an ambient temperature of 52°C, a third charge was performed, which involved charging to 4.1V at 0.1C, at which voltage the lithium replenisher in the positive electrode decomposed.

[0056] Charging was stopped, and the battery cells were left to stand at 40°C for 12 hours to complete the chemical reaction.

[0057] The battery cells, after the above chemical conversion, were subjected to secondary injection and sealing, and then discharged at 0.5P to perform capacitive polarization.

[0058] Example 5 This embodiment provides a method for the formation of a spare lithium battery, the formation method comprising the following steps.

[0059] Under an ambient temperature of 30°C, the spare lithium battery (manufacturing example 1) after electrolyte injection is subjected to a first charge, which involves first charging to 10% SOC at 0.03C, and then continuing to charge to 20% SOC at 0.15C.

[0060] Charging was stopped, and the battery cells were left undisturbed at 50°C for 12 hours.

[0061] Under an ambient temperature of 42°C, a second charge is performed, which involves charging to 3.45V at 0.6C, at which voltage the positive electrode active material undergoes lithium delithion.

[0062] Charging was stopped, and the battery cells were left undisturbed at 49°C for 13 hours.

[0063] Under an ambient temperature of 64°C, a third charge was performed, which involved charging to 4.25V at 0.3C. At this voltage, the lithium replenisher in the positive electrode decomposed.

[0064] Charging was stopped, and the battery cells were left to stand at 50°C for 12 hours to complete the chemical reaction.

[0065] The battery cells, after the above chemical conversion, were subjected to secondary injection and sealing, and then discharged at 0.5P to perform capacitive polarization.

[0066] Comparative Example 1 This comparative example differs from Example 1 in that it was not left to stand at 45°C for 12 hours after the first charge and before the second charge, nor was it left to stand at 45°C for 12 hours after the second charge and before the third charge, both the second and third charges were performed at an ambient temperature of 25°C, and the standing time after the third charge was changed to 48 hours.

[0067] Comparative Example 2 This comparative example differs from Example 1 in that the temperature of the third charge is adjusted to 45°C.

[0068] Comparative Example 3 This comparative example differs from Example 1 in that it was not left standing at 45°C for 12 hours after the second charge and before the third charge.

[0069] Comparative Example 4 This comparative example differs from Example 1 in that the temperature of the third charge is adjusted to 25°C and the third charge ratio is adjusted to 0.05C.

[0070] Performance test: (1) Observation of the negative electrode interface of the battery cell: After capacitive polarization, the battery cell was fully charged, disassembled in a drying chamber, and observed for the presence or absence of gray lithium deposition spots on the surface of the negative electrode piece. If there were no lithium deposition spots, it was recorded as good. (2) Calculation of the charge gram capacity of lithium replenisher LFO: The chemical charge capacity of the battery cell is measured, and the charge gram capacity C2 of lithium iron phosphate is determined. Based on the composition of the positive electrode active material, the charge gram capacity C2 of the positive electrode active material is determined. Based on the chemical charge capacity of the battery cell, the charge gram capacity of lithium iron phosphate, the mass of lithium iron phosphate in the battery cell (in g), the mass of lithium replenisher in the battery cell (in g), the mass percentage of lithium iron phosphate in the battery cell (in %), and the mass percentage of lithium replenisher LFO in the battery cell (in %), the charge gram capacity of lithium replenisher LFO is calculated. The calculation formula is as follows: The charge gram capacity of the lithium replenisher LFO is given by (C1 - C2 × m1) / +m2, where C1 is the chemical charge capacity of the battery cell, C2 is the charge gram capacity of lithium iron phosphate, m1 is the mass of lithium iron phosphate in the battery cell, and m2 is the mass of the lithium replenisher in the battery cell. (3) Cycle performance test: The battery cells after capacitance polarization are tested for charge and discharge performance at a power of 0.5P (P=1024W) within the range of 2.5~3.65V, and 1000 cycles are performed. The energy retention rate relative to the initial energy at 1000 cycles is then calculated. The results are shown in Table 1.

[0071] [Table 1]

[0072] As can be seen from Table 1, the chemical conversion method of the present invention can obtain a sufficient lithium replenishment effect, the lithium replenisher has a high charge gram capacity, and can effectively solve the problem of lithium deposition on the negative electrode surface. The negative electrode interface of the battery cell after fully charging and disassembling the battery is good, no lithium deposition spots are observed, and the battery's cycle performance is improved.

[0073] As can be seen from the comparison between Example 1 and Examples 2-3, when the temperature of the third charge was too low (Example 2), the gram-to-charge capacity of the lithium replenisher decreased, and the energy retention rate over 1000 cycles decreased. When the temperature of the third charge was too high (Example 3), the gram-to-charge capacity of the lithium replenisher remained essentially the same, but the cycle performance decreased slightly, which is thought to be due to a certain degree of degradation at the battery cell interface caused by the excessively high temperature.

[0074] As can be seen from the comparison between Example 1 and Comparative Example 1, charging was performed under ambient temperatures of 25°C and no high-temperature standing was performed. As a result, the negative electrode pieces were not sufficiently impregnated, some of the graphite active material was not fully utilized, some lithium ions could not be embedded in the graphite during charging, lithium deposition occurred on the negative electrode surface of the graphite, and both the charging gram capacity and cycle performance of the lithium replenisher LFO decreased.

[0075] As can be seen from the comparison between Example 1 and Comparative Example 2, in the high-voltage region where the lithium replenisher decomposes, increasing the temperature is advantageous for increasing the gram charge capacity of the lithium replenisher, and further increases the amount of lithium stored in the negative electrode, thereby improving cycle performance.

[0076] As can be seen from the comparison between Example 1 and Comparative Example 3, the battery cells were not left to stand during this step, resulting in low electrolyte impregnation, deterioration of the battery cell interface, and the potential for lithium deposition during the third charge, leading to reduced cycle performance.

[0077] As can be seen from the comparison between Example 1 and Comparative Example 4, due to the low temperature, the lithium replenishment material itself has poor magnification performance, and even with a small current, the decomposition reaction is insufficient, resulting in a poor lithium replenishment effect, and therefore no clear improvement in cycle performance is observed.

[0078] In the above examples and comparative examples, lithium iron phosphate was used as the positive electrode active material, LFO as the lithium replenisher, and graphite as the negative electrode active material to verify the manufacturing and chemical conversion methods of pre-lithium-ion batteries. However, the methods are not limited to the above materials, and other positive electrode active materials (e.g., ternary materials), other lithium replenishers (e.g., LNO), and other negative electrode active materials (e.g., silicon) can similarly effectively improve the interface, enhance the lithium replenishment effect, and improve battery performance.

[0079] The applicant argues that while the present invention illustrates detailed methods by the above embodiments, the present invention is not limited to the above detailed methods, nor does it mean that one must rely on the above detailed methods to carry out the present invention. Those skilled in the art should understand that any improvements to the present invention, such as equivalent substitutions of raw materials in the product of the present invention, addition of auxiliary components, and selection of specific methods, are also included within the scope of protection and disclosure of the present invention. Cross-reference to related applications

[0080] This application is proposed based on the Chinese patent application No. 202511316672.8, filed on September 16, 2025, claiming priority from said Chinese patent application, and the entire contents of said Chinese patent application are incorporated into this application by reference.

Claims

1. A method for the formation of a spare lithium battery, The process involves performing a first charge on the pre-filled lithium battery to a predetermined state of charge (SOC) to form a solid electrolyte interface (SEI) film, and Perform a second charge and set the voltage to V １ The step involves raising the temperature to a certain level, causing further delithiation of the positive electrode active material, and then allowing it to stand. Perform a third charge and set the voltage to V ２ Raise it up to V ２ This includes a step which is the termination voltage for lithium replenishment decomposition, The temperature of the first charging is T １ and the temperature of the standing is T ２ and the temperature of the third charging is T ３ and T １ < T ２ , T ２ < T ３ and 20°C < T １ < 30°C, 40°C < T ２ < 50°C, 50°C ≤ T ３ ≤ 65°C The aforementioned voltage is V １ After raising the voltage to that level, the standing time was 6 to 12 hours, and 3.4V < V １ <3.65V, V ２ A method for producing a spare lithium battery, characterized in that the voltage is 4.05V to 4.3V.

2. The method for forming a spare lithium battery according to claim 1, characterized in that the charge ratio of the first charge is 0.02C to 0.3C.

3. The method for forming a preliminary lithium battery according to claim 1, characterized in that the preset SOC is 10% to 50% SOC and does not contain 50% SOC.

4. The method for preparing a spare lithium battery according to claim 1, characterized in that the spare lithium battery is charged to a preset SOC, the charging is stopped, and the battery is left to stand for 12 to 48 hours under conditions of 40°C to 50°C.

5. The method for forming a spare lithium battery according to claim 1, characterized in that the charge ratio of the second charge is 0.3C to 0.6C.

6. Voltage V １ The method for preparing a spare lithium battery according to claim 1, characterized in that when the temperature is raised to a certain level, the spare lithium battery is charged to a level greater than 80% SOC and less than or equal to 100% SOC.

7. The method for forming a spare lithium battery according to claim 1, characterized in that the temperature of the second charge is 40°C to 50°C.

8. The method for forming a spare lithium battery according to claim 1, characterized in that the charge ratio of the third charge is 0.1C to 0.3C.

9. The aforementioned voltage is V ２ The method for preparing a spare lithium battery according to claim 1, characterized in that after raising the temperature to a certain level, charging is stopped and the spare lithium battery is left to stand at 40°C to 50°C for 12 to 48 hours.

10. The method for forming a preliminary lithium battery according to claim 1, wherein the preliminary lithium battery after liquid injection comprises a positive electrode piece, a negative electrode piece, a separator, and an electrolyte, the positive electrode piece comprises a positive electrode current collector and a positive electrode material layer provided on the surface of the positive electrode current collector, and the positive electrode material layer contains a positive electrode active material and a lithium replenisher.

11. The method for forming a preliminary lithium battery according to claim 10, characterized in that the mass of the lithium replenisher accounts for 0.5% to 5% of the mass of the positive electrode material layer.

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