Preparation method and system of lithium battery, lithium battery and electronic equipment

Abstract

The invention relates to a preparation method and system of a lithium battery, the lithium battery and electronic equipment, relates to the technical field of lithium batteries, and is used for solving the problem that the lithium supplementing technology can reduce the battery performance. The preparation method of the lithium battery comprises the following steps: preparing the first electrode and supplementing lithium for the first electrode according to a first lithium supplementing amount; wherein the first lithium supplementing amount is smaller than the preset lithium supplementing amount. The first electrode is the negative electrode of the lithium battery, and the preset lithium supplement amount is the lithium supplement amount corresponding to an excessive lithium supplement area at least partially formed in the estimated negative electrode lithium supplement process; or the first electrode is the positive electrode of the lithium battery, and the preset lithium supplement amount is the lithium supplement amount corresponding to the condition that the estimated gas production amount of the lithium supplement material is smaller than or equal to the preset safe gas storage amount. And preparing a second electrode and supplementing lithium to the second electrode according to a second lithium supplementing amount, wherein the second lithium supplementing amount and the first lithium supplementing amount have a negative correlation relationship.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of lithium battery technology, and in particular to a method for preparing a lithium battery and a system thereof, a lithium battery, and an electronic device. Background Art

[0002] With the continuous development of science and technology, people have higher and higher requirements for the battery life of consumer products (such as smart phones, laptops, etc.) and power products (such as electric cars, electric bicycles, etc.). In order to meet people's requirements for long battery life, manufacturers design the energy density (ED) of lithium-ion batteries to be higher and higher. Among them, increasing the gram capacity of electrode materials is one of the important measures to improve battery ED.

[0003] At present, batteries with materials with higher specific capacity (such as silicon) as negative electrodes have low initial efficiency, resulting in low total battery capacity and energy density. In order to improve the initial efficiency of the battery, lithium replenishment technology is usually used to replenish lithium in the battery. However, the current lithium replenishment technology has the problem of reducing battery performance. Summary of the invention

[0004] The embodiments of the present application provide a method for preparing a lithium battery and a system thereof, a lithium battery and an electronic device, which are used to solve the problem that lithium supplementation technology may reduce battery performance.

[0005] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0006] In a first aspect, a method for preparing a lithium battery is provided. The method comprises: preparing a first electrode and replenishing lithium for the first electrode according to a first lithium replenishment amount. Wherein, the first lithium replenishment amount is less than a preset lithium replenishment amount. The first electrode is the negative electrode of the lithium battery, and the preset lithium replenishment amount is the lithium replenishment amount corresponding to the estimated lithium replenishment amount corresponding to at least a partial formation of an excess lithium replenishment area during the negative electrode lithium replenishment process; or, the first electrode is the positive electrode of the lithium battery, and the preset lithium replenishment amount is the lithium replenishment amount corresponding to the estimated gas production of the lithium replenishment material being less than or equal to the preset safe gas storage capacity. Prepare a second electrode and replenish lithium for the second electrode according to a second lithium replenishment amount, and the second lithium replenishment amount is negatively correlated with the first lithium replenishment amount.

[0007] Since excessive lithium supplementation of the first electrode during the preparation of the lithium battery may reduce the battery performance, it is necessary to set the first lithium supplementation amount of the first electrode to be less than the preset lithium supplementation amount. The preset lithium supplementation amount can be determined according to actual conditions.

[0008] In some examples, the first electrode is the negative electrode of the lithium battery. Since excessive lithium supplementation of the negative electrode will result in an excess lithium supplementation zone that reduces battery performance in part or as a whole of the negative electrode, the preset lithium supplementation amount can be the lithium supplementation amount corresponding to the excess lithium supplementation zone that will appear at least partially during the negative electrode lithium supplementation process. It can be understood that the first lithium supplementation amount is less than the lithium supplementation amount corresponding to the excess lithium supplementation zone that will appear at least partially during the negative electrode lithium supplementation process, thereby avoiding the occurrence of an excess lithium supplementation zone during the negative electrode lithium supplementation process, achieving a uniform lithium supplementation interface for the negative electrode lithium supplementation, reducing or even avoiding the negative impact of lithium supplementation on battery performance, and improving the reliability and service life of the battery.

[0009] The above-mentioned lithium replenishment excess area may refer to an area where the amount of lithium replenishment during the lithium replenishment process is more than 10% of the set lithium replenishment amount.

[0010] Furthermore, since negative electrode lithium replenishment is usually performed by roller pressing, preparing the first electrode and replenishing the first electrode with the first lithium replenishment amount may mean first preparing the negative electrode and then roller pressing the negative electrode with the negative electrode lithium replenishment material.

[0011] In other examples, the first electrode is the positive electrode of a lithium battery. The positive electrode lithium replenishment material generates gas during lithium replenishment, so the preset lithium replenishment amount can be the lithium replenishment amount corresponding to the safe gas storage amount set for the battery during the positive electrode lithium replenishment process in which the gas production is less than or equal to the lithium replenishment amount corresponding to the safe gas storage amount set for the battery. It can be understood that the first lithium replenishment amount is less than the lithium replenishment amount corresponding to the safe gas storage amount set for the battery in which the gas production is less than or equal to, thereby avoiding the situation in which the lithium replenishment gas production exceeds the safe gas storage amount during the positive electrode lithium replenishment process, reducing or even avoiding the negative impact of lithium replenishment on battery performance, and improving the reliability and service life of the battery.

[0012] Furthermore, since positive electrode lithium replenishment is usually performed by adding positive electrode lithium replenishment material to positive electrode slurry, preparing the first electrode and replenishing lithium for the first electrode according to the first lithium replenishment amount may mean replenishing lithium using the positive electrode lithium replenishment material while manufacturing the positive electrode.

[0013] It should be noted that the first lithium supplement amount and the second lithium supplement amount both refer to the surface density of the lithium supplement material. Exemplarily, the first electrode is a positive electrode, and the first lithium supplement amount refers to the surface density of the positive electrode lithium supplement material. Exemplarily, the second electrode is a negative electrode, and the first lithium supplement amount refers to the surface density of the negative electrode lithium supplement material.

[0014] In addition, even if they are all positive electrode lithium replenishing materials, the calculated lithium replenishing amounts corresponding to different positive electrode lithium replenishing materials may be different due to the different gram capacities of the positive electrode lithium replenishing materials. The gram capacity of each lithium replenishing material can be obtained by testing the lithium replenishing material after it is made and charged.

[0015] The battery preparation method provided in the embodiment of the present application first replenishes lithium to the first electrode to ensure that the above-mentioned excessive lithium replenishment area or excessive gas production will not occur when replenishing lithium through the first electrode; then replenish lithium through the second electrode to supplement the insufficient lithium replenishment area after the lithium replenishment of the first electrode. In other words, the embodiment of the present application replenishes lithium once through each of the two electrodes of the battery. In this way, it is possible to avoid the occurrence of excessive lithium replenishment areas, excessive gas production and other situations that damage the battery when completing lithium replenishment, and achieve a uniform lithium replenishment interface under the premise of safe gas production, reduce or even avoid the negative impact of lithium replenishment on battery performance, and improve the reliability and service life of the battery.

[0016] In a possible implementation of the first aspect, before preparing the first electrode and replenishing lithium for the first electrode according to the first lithium replenishment amount, the method further includes: calculating the upper limit of the surface density of the lithium replenishment material of the first electrode based on a preset battery balance value. Determine the first lithium replenishment amount, and the first lithium replenishment amount is less than the upper limit of the surface density of the lithium replenishment material of the first electrode.

[0017] The upper limit of the surface density of the lithium supplement material of the first electrode may refer to the surface density of the lithium supplement required for the first electrode in order to complete the total amount of lithium supplement required for the battery. It can be understood that when the first electrode is supplemented with lithium according to the upper limit of the surface density of the lithium supplement material of the first electrode, the battery can supplement the required total amount of lithium supplement, so there is no need to supplement the second electrode with lithium.

[0018] Through the preset battery balance value of the lithium battery, the upper limit of the surface density of the lithium supplement material of the first electrode can be obtained based on the logical calculation of the internal parameters of the battery. By limiting the first lithium supplement amount to be less than the upper limit of the surface density of the lithium supplement material of the first electrode, it can be ensured that the lithium supplement amount of the first electrode will not exceed the lithium supplement amount required by the battery, thereby avoiding the problem of excessive lithium supplement area due to over-replenishment of the battery, damaging the lithium supplement interface and reducing the cycle performance of the lithium battery, and improving the reliability and service life of the battery.

[0019] In another possible implementation of the first aspect, the first electrode is a negative electrode and the second electrode is a positive electrode. After preparing the first electrode and replenishing lithium for the first electrode according to the first lithium replenishment amount, and before preparing the second electrode and replenishing lithium for the second electrode according to the second lithium replenishment amount, the method further includes: obtaining an actual lithium replenishment amount of the negative electrode. Based on a preset battery balance value and the actual lithium replenishment amount of the negative electrode, the second lithium replenishment amount is calculated; the second lithium replenishment amount is negatively correlated with the actual lithium replenishment amount of the negative electrode.

[0020] The second lithium replenishment amount is used to replenish the remaining lithium replenishment amount of the lithium battery after the lithium replenishment with the first lithium replenishment amount, so that after the first electrode is replenished with the first lithium replenishment amount and the second electrode is replenished with the second lithium replenishment amount, the total lithium replenishment amount of the lithium battery meets the total lithium replenishment amount required by the battery.

[0021] Since the lithium replenishment efficiency of the negative electrode replenishment material may not be 100% during the process of replenishing the negative electrode, the actual amount of lithium replenishment for the negative electrode according to the first amount of lithium replenishment is not the first amount of lithium replenishment. Therefore, by obtaining the actual amount of lithium replenishment for the negative electrode to calculate the second amount of lithium replenishment, the second amount of lithium replenishment can more accurately replenish the part that has not been replenished after the first lithium replenishment, improve the lithium replenishment accuracy of the lithium battery, reduce or even avoid the negative impact on the performance of the lithium battery caused by the low accuracy of lithium replenishment, and improve the reliability and service life of the battery.

[0022] In another possible implementation of the first aspect, preparing a first electrode and replenishing lithium for the first electrode according to a first lithium replenishment amount includes: preparing a negative electrode. Replenishing lithium for the negative electrode. After preparing the negative electrode and before replenishing lithium for the negative electrode, the method further includes: obtaining the negative electrode surface density of the negative electrode before replenishing lithium. The obtaining of the actual lithium replenishment amount of the negative electrode includes: obtaining the negative electrode surface density after replenishing lithium after the negative electrode is replenished with lithium. Calculating the difference between the negative electrode surface density after replenishing lithium and the negative electrode surface density before replenishing lithium to obtain the actual lithium replenishment amount of the negative electrode.

[0023] In this implementation, after preparing the negative electrode, the negative electrode surface density before lithium replenishment is obtained before the negative electrode is replenished with lithium, and the negative electrode surface density after lithium replenishment is obtained after the negative electrode is replenished with lithium. By calculating the difference between the negative electrode surface density after lithium replenishment and the negative electrode surface density before lithium replenishment, the effect of lithium replenishment on the negative electrode surface density is reflected, and the actual amount of lithium replenishment is obtained.

[0024] In another possible implementation of the first aspect, the second lithium replenishment amount is calculated based on the preset battery balance value and the actual lithium replenishment amount of the negative electrode, including: calculating the first effective value of the negative electrode after the negative electrode is replenished with lithium based on the actual lithium replenishment amount of the negative electrode; the first effective value of the negative electrode after the negative electrode is replenished with lithium has a positive correlation with the actual lithium replenishment amount of the negative electrode. Based on the battery balance value and the first effective value of the negative electrode, the surface capacity of the positive electrode lithium replenishment material is calculated; the surface capacity of the positive electrode lithium replenishment material has a negative correlation with the first effective value of the negative electrode. Based on the surface capacity of the positive electrode lithium replenishment material, the second lithium replenishment amount is calculated.

[0025] In this implementation, the surface capacity of the positive electrode lithium supplement material is calculated by using the relationship between the actual amount of lithium supplemented in the negative electrode and the negative electrode first efficiency value after the negative electrode lithium supplement, as well as the relationship between the battery balance value, the negative electrode first efficiency value and the surface capacity of the positive electrode lithium supplement material. It combines the calculation relationship between the parameters in the battery and the actual lithium supplement situation, thereby improving the calculation accuracy of the surface capacity of the positive electrode lithium supplement material.

[0026] Then, through the surface capacity of the positive electrode lithium replenishment material, the accurate second lithium replenishment amount can be obtained, thereby improving the overall lithium replenishment accuracy of the lithium battery, avoiding the situation where the battery capacity is reduced due to too little total lithium replenishment or the battery cycle performance is deteriorated due to too much total lithium replenishment, and improving the reliability and service life of the battery.

[0027] In another possible implementation of the first aspect, before preparing the first electrode and replenishing lithium for the first electrode according to the first lithium replenishment amount, it also includes: obtaining a preset battery target first efficiency value. Based on the battery target first efficiency value and the battery balance value, calculating the target negative electrode first efficiency value corresponding to the negative electrode. Based on the target negative electrode first efficiency value, calculating the first lithium replenishment amount; the target negative electrode first efficiency value has a positive correlation with the first lithium replenishment amount.

[0028] In this implementation, the first lithium replenishment amount is calculated by using the logical relationship between the battery target first efficiency value, the battery balance value and the target negative electrode first efficiency value, as well as the logical relationship between the target negative electrode first efficiency value and the first lithium replenishment amount. Compared with estimating the first lithium replenishment amount based on experience, the calculation accuracy of the first lithium replenishment amount can be improved.

[0029] In another possible implementation of the first aspect, based on the target negative electrode first effective value, the first lithium replenishment amount is calculated, including: based on the target negative electrode first effective value, the upper limit of the negative electrode lithium replenishment surface capacity of the negative electrode is calculated; the target negative electrode first effective value and the upper limit of the negative electrode lithium replenishment surface capacity of the negative electrode have a positive correlation. Based on the upper limit of the negative electrode lithium replenishment surface capacity, the upper limit of the surface density of the negative electrode lithium replenishment material is calculated. Based on the upper limit of the surface density of the negative electrode lithium replenishment material, the first lithium replenishment amount corresponding to the negative electrode is determined.

[0030] In this implementation, the upper limit of the surface density of the negative electrode lithium supplement material is calculated by using the logical relationship between the target negative electrode first effect value and the upper limit of the negative electrode lithium supplement surface capacity, and the logical relationship between the upper limit of the negative electrode lithium supplement surface capacity and the upper limit of the surface density of the negative electrode lithium supplement material. Compared with estimating the upper limit of the surface density of the negative electrode lithium supplement material based on experience, the calculation accuracy of the upper limit of the surface density of the negative electrode lithium supplement material can be improved.

[0031] Determining the first lithium supplement amount by the upper limit value of the surface density of the negative electrode lithium supplement material can help improve the calculation accuracy of the first lithium supplement amount.

[0032] In another possible implementation of the first aspect, determining a first lithium replenishment amount corresponding to the negative electrode based on an upper limit value of the surface density of the negative electrode lithium replenishment material includes: obtaining a preset negative electrode lithium replenishment error value. Determining the first lithium replenishment amount corresponding to the negative electrode based on the upper limit value of the surface density of the negative electrode lithium replenishment material and the negative electrode lithium replenishment error value, wherein the sum of the first lithium replenishment amount and the negative electrode lithium replenishment error value is less than or equal to the upper limit value of the surface density of the negative electrode lithium replenishment material.

[0033] In this implementation, the first lithium replenishment amount corresponding to the negative electrode is determined by combining the upper limit of the surface density of the negative electrode lithium replenishment material and the actual negative electrode lithium replenishment error value, which can reflect the actual lithium replenishment situation and improve the actual accuracy of the first lithium replenishment amount.

[0034] In another possible implementation of the first aspect, the first electrode is a positive electrode and the second electrode is a negative electrode. Before preparing the first electrode and replenishing lithium for the first electrode according to the first lithium replenishment amount, it also includes: obtaining the discharge gram capacity of the negative electrode material and the charge gram capacity of the negative electrode material. Based on the discharge gram capacity of the negative electrode material and the charge gram capacity of the negative electrode material, the first effective value of the negative electrode material is calculated. Based on the first effective value of the negative electrode material and the battery balance value, the first lithium replenishment amount is calculated.

[0035] In this implementation, the first lithium replenishment amount is calculated by using the logical relationship between the discharge gram capacity of the negative electrode material, the charge gram capacity of the negative electrode material and the first effective value of the negative electrode material, and the logical relationship between the first effective value of the negative electrode material, the battery balance value and the first lithium replenishment amount. Compared with estimating the first lithium replenishment amount based on experience, the calculation accuracy of the first lithium replenishment amount can be improved.

[0036] In another possible implementation of the first aspect, the first lithium replenishment amount is calculated based on the first effective value of the negative electrode material and the battery balance value, including: calculating the upper limit of the surface capacity of the positive electrode lithium replenishment material based on the first effective value of the negative electrode material. The first effective value of the negative electrode material is negatively correlated with the upper limit of the surface capacity of the positive electrode lithium replenishment material. Based on the upper limit of the surface capacity of the positive electrode lithium replenishment material, the upper limit of the surface density of the positive electrode lithium replenishment material is calculated. Based on the upper limit of the surface density of the positive electrode lithium replenishment material, the first lithium replenishment amount corresponding to the positive electrode is determined; the first lithium replenishment amount is less than or equal to the upper limit of the surface density of the positive electrode lithium replenishment material.

[0037] In this implementation, the upper limit of the surface density of the positive electrode replenishing lithium material is calculated by using the logical relationship between the first effective value of the negative electrode material and the upper limit of the surface capacity of the positive electrode replenishing lithium material, and the logical relationship between the upper limit of the surface capacity of the positive electrode replenishing lithium material and the upper limit of the surface density of the positive electrode replenishing lithium material. Compared with estimating the upper limit of the surface density of the positive electrode replenishing lithium material based on experience, the calculation accuracy of the upper limit of the surface density of the positive electrode replenishing lithium material can be improved.

[0038] The first lithium supplement amount is calculated by using the logical relationship between the upper limit value of the surface density of the positive electrode lithium supplement material and the first lithium supplement amount, which can help improve the calculation accuracy of the first lithium supplement amount.

[0039] In another possible implementation of the first aspect, before preparing the second electrode and replenishing lithium for the second electrode according to the second lithium replenishment amount, it also includes: obtaining the upper limit of the surface density of the positive electrode lithium replenishment material and the gram capacity of the positive electrode lithium replenishment material. Based on the first lithium replenishment amount, the upper limit of the surface density of the positive electrode lithium replenishment material and the gram capacity of the positive electrode lithium replenishment material, the surface capacity of the negative electrode lithium replenishment material is calculated; the surface capacity of the negative electrode lithium replenishment material has a positive correlation with the gram capacity of the positive electrode lithium replenishment material. Based on the surface capacity of the negative electrode lithium replenishment material, the second lithium replenishment amount is calculated.

[0040] In this embodiment, the surface capacity of the negative electrode lithium supplement material is calculated by using the logical relationship between the first lithium supplement amount, the upper limit of the surface density of the positive electrode lithium supplement material, the gram capacity of the positive electrode lithium supplement material, and the surface capacity of the negative electrode lithium supplement material. Compared with estimating the surface capacity of the negative electrode lithium supplement material based on experience, the calculation accuracy of the surface capacity of the negative electrode lithium supplement material can be improved.

[0041] By using the logical relationship between the surface capacity of the negative electrode lithium replenishing material and the second lithium replenishing amount to calculate the second lithium replenishing amount, the calculation accuracy of the second lithium replenishing amount can be improved.

[0042] In a second aspect, the present application provides a lithium battery preparation system. The lithium battery includes a first electrode and a second electrode. The lithium battery preparation system includes: a lithium replenishment amount calculation device and a lithium replenishment device. In the lithium battery preparation method as in any one of the first aspect, the lithium replenishment amount calculation device is used to calculate the lithium replenishment amount for the first electrode, and to calculate the lithium replenishment amount for the second electrode. The lithium replenishment device is coupled to the lithium replenishment amount calculation device. In the lithium battery preparation method as in any one of the first aspect, the lithium replenishment device is used to replenish the first electrode with a first lithium replenishment amount, and to replenish the second electrode with a second lithium replenishment amount.

[0043] The lithium replenishment amount calculation device and the lithium replenishment device can cooperate to complete the lithium battery preparation method of any one of the first aspects. Therefore, the lithium battery preparation system can have the beneficial effects of the lithium battery preparation method of any one of the first aspects, which will not be repeated here.

[0044] In a third aspect, the present application provides a method for calculating the amount of lithium replenishment of a lithium battery. The lithium battery includes a first electrode and a second electrode. The method includes: calculating a first lithium replenishment amount for the first electrode based on a preset battery balance value. Wherein, the first lithium replenishment amount is less than the preset lithium replenishment amount. The first electrode is the negative electrode of the lithium battery, and the preset lithium replenishment amount is the estimated lithium replenishment amount corresponding to the at least partially formed lithium replenishment excess area during the negative electrode lithium replenishment process; or, the first electrode is the positive electrode of the lithium battery, and the preset lithium replenishment amount is the lithium replenishment amount corresponding to the estimated gas production of the lithium replenishment material being less than or equal to the preset safe gas storage capacity. After obtaining the first lithium replenishment amount, the second lithium replenishment amount for the second electrode is calculated, and the second lithium replenishment amount has a negative correlation with the first lithium replenishment amount.

[0045] The method for calculating the amount of lithium replenishment of a lithium battery provided in the embodiment of the present application can ensure that the above-mentioned excessive lithium replenishment area or excessive gas production will not occur when the first electrode is replenished with lithium according to the first lithium replenishment amount. In this way, it is possible to avoid the excessive lithium replenishment area, excessive gas production and other situations that damage the battery when the lithium replenishment is completed, and to achieve a uniform lithium replenishment interface under the premise of safe gas production, reduce or even avoid the negative impact of lithium replenishment on battery performance, and improve the reliability and service life of the battery.

[0046] In another possible implementation of the third aspect, calculating a first lithium supplement amount for the first electrode based on a preset battery balance value includes: calculating an upper limit value of a surface density of a lithium supplement material of the first electrode based on the preset battery balance value. Determining the first lithium supplement amount, the first lithium supplement amount being less than the upper limit value of the surface density of the lithium supplement material of the first electrode.

[0047] Through the preset battery balance value of the lithium battery, the upper limit of the surface density of the lithium supplement material of the first electrode can be obtained based on the logical calculation of the internal parameters of the battery. By limiting the first lithium supplement amount to be less than the upper limit of the surface density of the lithium supplement material of the first electrode, it can be ensured that the lithium supplement amount of the first electrode will not exceed the lithium supplement amount required by the battery, thereby avoiding the problem of excessive lithium supplement area due to over-replenishment of the battery, damaging the lithium supplement interface and reducing the cycle performance of the lithium battery, and improving the reliability and service life of the battery.

[0048] In another possible implementation of the third aspect, the first electrode is a negative electrode and the second electrode is a positive electrode. Before calculating the second lithium replenishment amount for the second electrode, the method further includes: obtaining an actual lithium replenishment amount of the negative electrode. The second lithium replenishment amount is calculated based on a preset battery balance value and the actual lithium replenishment amount of the negative electrode; the second lithium replenishment amount is negatively correlated with the actual lithium replenishment amount of the negative electrode.

[0049] Since the lithium replenishment efficiency of the negative electrode replenishment material may not be 100% during the process of replenishing the negative electrode, the actual amount of lithium replenishment for the negative electrode according to the first amount of lithium replenishment is not the first amount of lithium replenishment. Therefore, by obtaining the actual amount of lithium replenishment for the negative electrode to calculate the second amount of lithium replenishment, the second amount of lithium replenishment can more accurately replenish the part that has not been replenished after the first lithium replenishment, improve the lithium replenishment accuracy of the lithium battery, reduce or even avoid the negative impact on the performance of the lithium battery caused by the low accuracy of lithium replenishment, and improve the reliability and service life of the battery.

[0050] In another possible implementation of the third aspect, calculating a first lithium replenishment amount for a first electrode based on a preset battery balance value includes: calculating a target negative electrode first efficiency value corresponding to the negative electrode based on a battery target first efficiency value and a battery balance value. Calculating the first lithium replenishment amount based on the target negative electrode first efficiency value. The target negative electrode first efficiency value is positively correlated with the first lithium replenishment amount.

[0051] In this implementation, the first lithium replenishment amount is calculated by using the logical relationship between the battery target first efficiency value, the battery balance value and the target negative electrode first efficiency value, as well as the logical relationship between the target negative electrode first efficiency value and the first lithium replenishment amount. Compared with estimating the first lithium replenishment amount based on experience, the calculation accuracy of the first lithium replenishment amount can be improved.

[0052] In another possible implementation of the third aspect, the first electrode is a positive electrode and the second electrode is a negative electrode. The first lithium replenishment amount for the first electrode is calculated based on a preset battery balance value, including: obtaining a discharge gram capacity of the negative electrode material and a charge gram capacity of the negative electrode material. Based on the discharge gram capacity of the negative electrode material and the charge gram capacity of the negative electrode material, the first effective value of the negative electrode material is calculated. Based on the first effective value of the negative electrode material and the battery balance value, the first lithium replenishment amount is calculated.

[0053] In this implementation, the first lithium replenishment amount is calculated by using the logical relationship between the discharge gram capacity of the negative electrode material, the charge gram capacity of the negative electrode material and the first effective value of the negative electrode material, and the logical relationship between the first effective value of the negative electrode material, the battery balance value and the first lithium replenishment amount. Compared with estimating the first lithium replenishment amount based on experience, the calculation accuracy of the first lithium replenishment amount can be improved.

[0054] In another possible implementation of the third aspect, based on the first effective value of the negative electrode material and the battery balance value, the first lithium replenishment amount is calculated, including: based on the first effective value of the negative electrode material, the upper limit of the surface capacity of the positive electrode lithium replenishment material is calculated; the first effective value of the negative electrode material and the upper limit of the surface capacity of the positive electrode lithium replenishment material have a negative correlation. Based on the upper limit of the surface capacity of the positive electrode lithium replenishment material, the upper limit of the surface density of the positive electrode lithium replenishment material is calculated. Based on the upper limit of the surface density of the positive electrode lithium replenishment material, the first lithium replenishment amount corresponding to the positive electrode is determined; the first lithium replenishment amount is less than or equal to the upper limit of the surface density of the positive electrode lithium replenishment material.

[0055] In this implementation, the upper limit of the surface density of the positive electrode replenishing lithium material is calculated by using the logical relationship between the first effective value of the negative electrode material and the upper limit of the surface capacity of the positive electrode replenishing lithium material, and the logical relationship between the upper limit of the surface capacity of the positive electrode replenishing lithium material and the upper limit of the surface density of the positive electrode replenishing lithium material. Compared with estimating the upper limit of the surface density of the positive electrode replenishing lithium material based on experience, the calculation accuracy of the upper limit of the surface density of the positive electrode replenishing lithium material can be improved.

[0056] The first lithium supplement amount is calculated by using the logical relationship between the upper limit value of the surface density of the positive electrode lithium supplement material and the first lithium supplement amount, which can help improve the calculation accuracy of the first lithium supplement amount.

[0057] In a fourth aspect, the present application provides a lithium battery. The lithium battery includes a positive electrode group, a negative electrode group and an electrolyte. The positive electrode group includes a positive electrode and a positive electrode lithium supplement material. The negative electrode group includes a negative electrode and a negative electrode lithium supplement material. The electrolyte contacts the positive electrode group and the negative electrode group at the same time.

[0058] In the present application, since lithium replenishment is performed once for the positive electrode and the negative electrode respectively, the positive electrode group may include a positive electrode and a positive electrode lithium replenishing material for replenishing lithium for the positive electrode; similarly, the negative electrode group may include a negative electrode and a negative electrode lithium replenishing material for replenishing lithium for the negative electrode.

[0059] Lithium replenishment is performed twice during the battery preparation process, that is, the present application performs lithium replenishment once through each of the two electrodes of the battery. In this way, it is possible to avoid the occurrence of excessive lithium replenishment areas, excessive gas production and other damage to the battery when lithium replenishment is completed, and to achieve a uniform lithium replenishment interface under the premise of safe gas production, thereby reducing or even avoiding the negative impact of lithium replenishment on battery performance and improving the reliability and service life of the battery.

[0060] In a fifth aspect, the present application provides an electronic device. The electronic device includes a circuit board and a battery. The battery is coupled to the circuit board to supply power to the circuit board. The battery includes the lithium battery of the fourth aspect.

[0061] The electronic device includes the lithium battery of the fourth aspect. Therefore, the electronic device can have the beneficial effects of the lithium battery of the fourth aspect, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 Schematic diagram of lithium ion distribution after negative electrode lithium replenishment in some schemes;

[0063] Figure 2 A flow chart of a battery preparation method provided in an embodiment of the present application;

[0064] Figure 3 for Figure 2 Schematic diagram of the process of replenishing lithium in the negative electrode;

[0065] Figure 4 for Figure 2 A flowchart of calculating the first lithium supplement amount in the embodiment shown;

[0066] Figure 5 for Figure 2 A flowchart of calculating the second lithium supplement amount in the embodiment shown;

[0067] Figure 6 A flow chart of another battery preparation method provided in an embodiment of the present application;

[0068] Figure 7 for Figure 6 Schematic diagram of the process of replenishing lithium in the positive electrode;

[0069] Figure 8 for Figure 6 A flowchart of calculating the first lithium supplement amount in the embodiment shown;

[0070] Fig. 9 for Figure 6 A flow chart for calculating the second lithium replenishment amount in the embodiment shown. DETAILED DESCRIPTION

[0071] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0072] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments provided by the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0073] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0074] When describing some embodiments, the expressions "connected", "connected" and their derivatives may be used. For example, when describing some embodiments, the term "connected" may be used to indicate that two or more components are in direct or indirect physical contact with each other. For example, A and B are connected, which may mean that A and B are connected, or that A and B are connected through other components. In addition, the term "coupled" may be a way of achieving electrical connection for signal transmission.

[0075] “At least one of A, B, and C” has the same meaning as “at least one of A, B, or C” and both include the following combinations of A, B, and C: A only, B only, C only, the combination of A and B, the combination of A and C, the combination of B and C, and the combination of A, B, and C.

[0076] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0077] It is mentioned herein that A and B have a positive correlation, which may mean that when the value of A increases, the value of B will also increase, or when the value of A decreases, the value of B will also decrease. It is understandable that A and B have the same trend of change. It is mentioned herein that A and B have a negative correlation, which may mean that when the value of A increases, the value of B will decrease, or when the value of A decreases, the value of B will increase. It is understandable that A and B have opposite trends of change. Among them, whether the trends of change of A and B have a linear relationship is not limited in the embodiments of the present application.

[0078] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of variation from the particular value as determined by one of ordinary skill in the art taking into account the measurements in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0079] To facilitate understanding, some descriptions of concepts related to the embodiments of the present application are exemplarily given for reference.

[0080] 1. Battery energy density, including mass energy density and volume energy density. Mass energy density refers to the ratio between battery energy and battery mass, also known as energy-to-weight ratio, and the commonly used unit is MJ / kg (megajoule / kilogram). Volume energy density refers to the ratio between battery energy and battery volume, also known as energy density, and the commonly used unit is MJ / L (megajoule / liter).

[0081] 2. Gram capacity refers to the ratio of the capacity that can be released by the active materials inside the battery to the mass of the active materials. The commonly used unit is mAh / g (milliampere-hour per gram).

[0082] 3. The first efficiency of a battery (referred to as the first efficiency value) refers to the ratio between the first discharge capacity of the battery and the first charge capacity of the battery. The first efficiency of a battery is less than 100%. The first efficiency of a battery can indicate the extent to which active substances are lost due to irreversible reactions during the first charge and discharge of the battery. For example, the higher the first efficiency of a battery, the lower the degree of loss of active substances; the lower the first efficiency of a battery, the higher the degree of loss of active substances.

[0083] 4. Lithium replenishment technology, also known as "pre-embedded lithium" or "pre-embedded lithium", is a technology that adds lithium replenishment materials to the inside of the battery to replenish lithium ions before the lithium-ion battery works. The lithium replenishment material is used to replenish the battery with lithium to offset the lithium lost due to irreversible reactions during the first charge and discharge of the battery, so as to increase the total capacity and energy density of the battery. Lithium replenishment technology includes negative electrode lithium replenishment and positive electrode lithium replenishment.

[0084] Negative electrode lithium replenishment refers to the introduction of active lithium into the negative electrode to compensate for the capacity loss caused by the first charge and discharge of the battery. The main methods of negative electrode lithium replenishment include pole piece roller pressing lithium replenishment, evaporation lithium replenishment, electrochemical lithium replenishment, lithium powder lithium replenishment and other appropriate methods.

[0085] Positive electrode lithium replenishment refers to the introduction of active lithium into the positive electrode to compensate for the capacity loss caused by the first charge and discharge of the battery. The main method of positive electrode lithium replenishment includes directly adding positive electrode lithium replenishment materials (also known as positive electrode lithium replenishment additives) into the positive electrode slurry. This method is suitable for the lithium-ion battery manufacturing process without the need for additional process improvements and has low cost. Positive electrode lithium replenishment materials can include suitable materials such as inorganic lithium compounds, positive electrode compounds and organic lithium compounds.

[0086] 5. The solid electrolyte interface (SEI) film is a passivation film layer with solid electrolyte properties. The SEI film is an excellent conductor of active lithium, allowing lithium ions to be transported in it, and performing lithium removal and lithium insertion. It is also a good electronic insulator. In addition, the SEI film can effectively prevent the co-embedding of solvent molecules, avoiding damage to the electrode material caused by the co-embedding of solvent molecules, thereby improving the cycle performance and service life of the electrode.

[0087] During the first charge and discharge process of the battery, some active lithium is consumed to undergo irreversible reaction to form the SEI film.

[0088] 6. Lithium battery formation refers to the process of charging the battery for the first time after the lithium battery is injected with electrolyte. Formation can activate the active substances in the battery and activate the lithium battery. At the same time, the lithium salt reacts with the electrolyte to form the above-mentioned SEI film on the negative electrode side.

[0089] 7. Lithium battery capacity classification refers to obtaining the data of each test point through computer management, so as to analyze the battery capacity, internal resistance and other data to determine the quality grade of the lithium battery.

[0090] 8. Cell balance (CB) refers to the ratio of the negative electrode capacity to the positive electrode capacity of the battery under the same conditions. The negative electrode is marked as negative and the positive electrode is marked as positive, so the cell balance value is also called the N / P ratio of the battery.

[0091] In addition, a number of data parameters appeared later. Please refer to Table 1 below for the type, meaning and unit of each data parameter.

[0092]

[0093] Table 1

[0094] At present, the gram capacity of graphite materials used in electrodes is close to the theoretical limit (372mAh / g). The gram capacity of silicon materials used in electrodes (theoretical limit is 4200mAh / g) is much higher than that of graphite materials, which can greatly increase the gram capacity of electrode materials, thereby improving battery ED. In addition, silicon materials have many advantages such as moderate lithium insertion and extraction potential, abundant reserves, low price, environmental protection and non-toxicity, and mature preparation technology. They are considered to be ideal materials to replace graphite materials as negative electrode active materials of batteries.

[0095] However, batteries that use silicon materials as negative electrodes have the problem of low initial efficiency. The specific reasons include: 1. Since the silicon particles are small and larger than the surface area of ​​the negative electrode, the formation of the SEI film consumes more active lithium, resulting in a large loss of active lithium. 2. The silicon dioxide (SiO2) present in the silicon material will undergo an irreversible reaction with the active lithium to form LixSiOy. 3. The conductivity of silicon materials is poor, resulting in the inability of some active lithium deep inside the silicon particles to escape during the battery discharge process, and become non-transportable lithium ions (also called dead lithium) inside the silicon particles.

[0096] In order to solve the problem of low initial efficiency of batteries, the industry's solution is to replenish lithium for batteries that use silicon materials as negative electrodes. Previously, the lithium replenishment technology has been explained in detail, including positive electrode lithium replenishment and negative electrode lithium replenishment, and the two lithium replenishment methods have been introduced in detail, which will not be repeated here. Whether it is positive electrode lithium replenishment or negative electrode lithium replenishment, it can have a certain effect on improving the initial efficiency of batteries that use silicon materials as negative electrodes, thereby improving the energy density of the battery.

[0097] However, on the one hand, negative electrode lithium replenishment has the characteristic of unstable lithium replenishment, which leads to a large deviation between the actual lithium replenishment and the designed lithium replenishment amount. Figure 1 Figure 2 shows a schematic diagram of lithium ion distribution after the negative electrode is replenished with lithium. Figure 1 As shown, the sample includes a normal lithium replenishment area 11, an insufficient lithium replenishment area 12, and an excessive lithium replenishment area 13. The amount of lithium replenishment in the normal lithium replenishment area 11 is roughly equal to the designed lithium replenishment amount; the amount of lithium replenishment in the insufficient lithium replenishment area 12 is 10%-50% lower than the designed lithium replenishment amount; the amount of lithium replenishment in the excessive lithium replenishment area 13 is 10%-50% higher than the designed lithium replenishment amount. It can be seen that the negative electrode lithium replenishment is prone to uneven lithium replenishment at multiple locations on the lithium replenishment interface.

[0098] Among them, the insufficient lithium supplement area 12 is prone to cause the battery capacity to be lower than the designed capacity due to the small amount of lithium ions. The excessive lithium supplement area 13 is prone to residual byproducts due to the large amount of lithium ions, which react with the electrolyte to consume the electrolyte. In addition, due to the uneven lithium supplement interface, the lithium ion transportation is blocked, resulting in a rapid decline in the battery cycle performance.

[0099] On the other hand, as mentioned above, positive electrode lithium replenishment is usually carried out by using positive electrode lithium replenishment materials, so that the positive electrode lithium replenishment materials will produce gas during the battery formation and / or capacity division process. For this reason, a gas bag is also provided in the battery to contain gas, but when the gas production of positive electrode lithium replenishment is too large, the gas will reduce the safety of the battery. In addition, in order to limit the gas production of positive electrode lithium replenishment, this method of positive electrode lithium replenishment will not be able to replenish more lithium for the battery, and there is a problem of limited lithium replenishment.

[0100] It can be seen that whether it is the negative electrode or the positive electrode that replenishes lithium, there is a problem of reducing battery performance.

[0101] Based on this, the embodiments of the present application provide a method for preparing a lithium battery and its system, a lithium battery and an electronic device, and perform lithium replenishment twice during the battery preparation process to overcome the above-mentioned problem of reducing battery performance. The battery preparation method provided in the embodiments of the present application first replenishes lithium to the first electrode to ensure that the above-mentioned excessive lithium replenishment area or excessive gas production will not occur when replenishing lithium through the first electrode; then replenish lithium through the second electrode to supplement the insufficient lithium replenishment area after the first electrode is replenished with lithium. In other words, the embodiments of the present application replenish lithium once through each of the two electrodes of the battery. In this way, it is possible to avoid the occurrence of excessive lithium replenishment areas, excessive gas production and other situations that damage the battery when completing lithium replenishment, and achieve a uniform lithium replenishment interface under the premise of safe gas production, reduce or even avoid the negative impact of lithium replenishment on battery performance, and improve the reliability and service life of the battery.

[0102] The electronic device provided in the embodiments of the present application may be a consumer product such as a laptop computer, a mobile phone, a smart phone, a tablet computer, a smart vehicle-mounted device, a navigator, a sports camera, a smart home appliance, an artificial intelligence device, a wearable device, or a virtual reality / augmented reality / mixed reality device, or may be a power product such as an electric car, an electric bicycle, a power-assisted bicycle, an electric wheelchair, etc., and the embodiments of the present application are not limited to this.

[0103] An electronic device may include a circuit board and a battery for supplying power to the circuit board. The circuit board may be a mainboard of the electronic device. For example, the circuit board may include functional devices such as a processor and a memory. The battery, by coupling with the circuit board, may provide operating voltage for functional devices such as the processor and the memory, thereby helping the electronic device to realize its functions.

[0104] The battery provided in the embodiments of the present application may be a consumer battery used in the above-mentioned consumer products, or a power battery used in the above-mentioned power products, and the embodiments of the present application are not limited to this. For example, the battery may be a lithium battery. For ease of understanding, the following description will be made using a lithium battery as an example.

[0105] A lithium battery may include a positive electrode group, a negative electrode group, and an electrolyte. The positive electrode group and the negative electrode group are both inserted into the electrolyte, so that the electrolyte is in contact with the positive electrode in the positive electrode group and the negative electrode in the negative electrode group at the same time. The electrolyte can undergo an electrochemical reaction with the positive electrode and the negative electrode, thereby removing lithium from the positive electrode and inserting lithium into the negative electrode, or inserting lithium into the positive electrode and removing lithium from the negative electrode. In addition, the electrolyte can help lithium ions to be transferred between the positive electrode and the negative electrode.

[0106] During the preparation of the lithium battery, the positive electrode is supplemented with lithium. Therefore, in addition to the positive electrode, the positive electrode group of the lithium battery may also include a positive electrode supplementing material for supplementing lithium to the positive electrode. For example, the positive electrode supplementing material includes Li2C4O4.

[0107] Similarly, during the preparation of the lithium battery, the negative electrode is also supplemented with lithium. Therefore, in addition to the negative electrode, the negative electrode group of the lithium battery may also include a negative electrode supplementing material for supplementing lithium to the negative electrode. For example, the negative electrode supplementing material includes metallic lithium.

[0108] The lithium battery manufacturing system provided in the embodiment of the present application is used to execute the lithium battery manufacturing method to manufacture the lithium battery. Exemplarily, the lithium battery manufacturing system may include a lithium replenishment amount calculation device, a lithium replenishment device, and a manufacturing device.

[0109] The lithium replenishment amount calculation device may be used to calculate the lithium replenishment amount for the first electrode and the lithium replenishment amount for the second electrode.

[0110] The lithium replenishment device is used to replenish lithium to the first electrode according to the first lithium replenishment amount when the lithium replenishment amount calculation device calculates a first lithium replenishment amount. The lithium replenishment device can also be used to replenish lithium to the second electrode according to the second lithium replenishment amount when the lithium replenishment amount calculation device calculates a second lithium replenishment amount.

[0111] The manufacturing device can be used to complete other tasks besides calculating the amount of lithium replenishment and replenishment during the lithium battery preparation process, such as rolling the pole pieces, assembling the positive and negative pole pieces, and injecting the electrolyte into the battery shell.

[0112] The following will describe in detail the lithium battery preparation method and lithium battery preparation system provided by the embodiments of the present application in combination with the lithium battery preparation process.

[0113] In the process of preparing a lithium battery, the steps of preparing a first electrode and replenishing lithium for the first electrode and the steps of preparing a second electrode and replenishing lithium for the second electrode can occur simultaneously, or the preparation of the second electrode and replenishing lithium can be started after the preparation of the first electrode and replenishing lithium are completed.

[0114] The sum of the first lithium replenishment amount for replenishing the first electrode and the second lithium replenishment amount for replenishing the second electrode is the total amount of lithium replenishment that the battery needs to complete in order to achieve the expected performance. For example, the total amount of lithium replenishment can be greater than or equal to the amount of lithium ions consumed in the SEI film formed inside the battery during the formation process. In other words, the first lithium replenishment amount for replenishing the first electrode is a part of the total amount of lithium replenishment for the battery, and the second lithium replenishment amount for replenishing the second electrode is another part of the total amount of lithium replenishment for the battery.

[0115] The second lithium replenishment amount is used to replenish the remaining lithium replenishment amount of the lithium battery after the lithium replenishment with the first lithium replenishment amount, so that after the first electrode is replenished with the first lithium replenishment amount and the second electrode is replenished with the second lithium replenishment amount, the total lithium replenishment amount of the lithium battery meets the total lithium replenishment amount required by the battery.

[0116] Furthermore, when the total amount of lithium replenishment required for the lithium battery to achieve expected performance remains unchanged, the first lithium replenishment amount and the second lithium replenishment amount have a negative correlation.

[0117] Since excessive lithium supplementation of the first electrode during the preparation of the lithium battery may reduce the battery performance, it is necessary to set the first lithium supplementation amount of the first electrode to be less than the preset lithium supplementation amount. The preset lithium supplementation amount can be determined according to actual conditions.

[0118] In some examples, the first electrode is the negative electrode of the lithium battery. Since excessive lithium supplementation of the negative electrode will result in an excess lithium supplementation zone that reduces battery performance in part or as a whole of the negative electrode, the preset lithium supplementation amount can be the lithium supplementation amount corresponding to the excess lithium supplementation zone that will appear at least partially during the negative electrode lithium supplementation process. It can be understood that the first lithium supplementation amount is less than the lithium supplementation amount corresponding to the excess lithium supplementation zone that will appear at least partially during the negative electrode lithium supplementation process, thereby avoiding the occurrence of an excess lithium supplementation zone during the negative electrode lithium supplementation process, achieving a uniform lithium supplementation interface for the negative electrode lithium supplementation, reducing or even avoiding the negative impact of lithium supplementation on battery performance, and improving the reliability and service life of the battery.

[0119] In other examples, the first electrode is the positive electrode of a lithium battery. The positive electrode lithium replenishment material generates gas during lithium replenishment, so the preset lithium replenishment amount can be the lithium replenishment amount corresponding to the safe gas storage amount set for the battery during the positive electrode lithium replenishment process in which the gas production is less than or equal to the lithium replenishment amount corresponding to the safe gas storage amount set for the battery. It can be understood that the first lithium replenishment amount is less than the lithium replenishment amount corresponding to the safe gas storage amount set for the battery in which the gas production is less than or equal to, thereby avoiding the situation in which the lithium replenishment gas production exceeds the safe gas storage amount during the positive electrode lithium replenishment process, reducing or even avoiding the negative impact of lithium replenishment on battery performance, and improving the reliability and service life of the battery.

[0120] It should be noted that the first lithium supplement amount and the second lithium supplement amount both refer to the surface density of the lithium supplement material. Exemplarily, the first electrode is a positive electrode, and the first lithium supplement amount refers to the surface density of the positive electrode lithium supplement material. Exemplarily, the second electrode is a negative electrode, and the first lithium supplement amount refers to the surface density of the negative electrode lithium supplement material.

[0121] In addition, even if they are all positive electrode lithium replenishing materials, the calculated lithium replenishing amounts corresponding to different positive electrode lithium replenishing materials may be different due to the different gram capacities of the positive electrode lithium replenishing materials. The gram capacity of each lithium replenishing material can be obtained by testing the lithium replenishing material after it is made and charged (hereinafter referred to as the charge test).

[0122] In some embodiments, the lithium replenishment amount calculation device can obtain the battery balance value set by the lithium battery manufacturer. When the lithium replenishment amount calculation device obtains the lithium battery balance value, it can calculate the upper limit of the surface density of the lithium replenishment material of the first electrode. Specifically, when the first electrode is a positive electrode or a negative electrode, the calculation process of how to calculate the upper limit of the surface density of the lithium replenishment material of the first electrode through the battery balance value can be found below.

[0123] The upper limit of the surface density of the lithium supplement material of the first electrode may refer to the surface density of the lithium supplement required for the first electrode in order to complete the total amount of lithium supplement required for the battery. It can be understood that when the first electrode is supplemented with lithium according to the upper limit of the surface density of the lithium supplement material of the first electrode, the battery can supplement the required total amount of lithium supplement, so there is no need to supplement the second electrode with lithium.

[0124] However, when the first electrode is replenished with lithium according to the upper limit of the surface density of the lithium replenishing material of the first electrode, it is easy to cause the phenomenon of excessive lithium replenishment area or excessive lithium replenishment gas production during the lithium replenishment process of the first electrode, which has a negative effect on the performance of the lithium battery. Therefore, in this embodiment, by setting the first lithium replenishment amount to be less than the upper limit of the surface density of the lithium replenishing material of the first electrode, the negative impact on the battery performance during the lithium replenishment of the first electrode can be reduced as much as possible or even avoided, thereby improving the reliability and service life of the battery.

[0125] Figure 2 A flow chart showing the process of preparing a battery. Figure 2 The battery preparation process is demonstrated by taking the example of making the negative electrode first and then the positive electrode. Figure 2 In the illustrated embodiment, the first electrode includes a cathode and the second electrode includes an anode.

[0126] First, a manufacturing device is used to manufacture negative electrode slurry. For example, silicon material, conductive agent, binder, glue and other components are added into a mixer in proportion, and the mixture is stirred by the mixer to finally manufacture a uniformly stirred negative electrode slurry.

[0127] Afterwards, the manufacturing device can use the coating roller to rotate and drive the negative electrode slurry so that the negative electrode slurry is evenly coated on the negative electrode current collector. During the coating process, the solvent in the slurry on the negative electrode current collector can be removed by drying and heating, so that the solid matter in the slurry can be better bonded to the negative electrode current collector to form a rough negative electrode sheet.

[0128] Afterwards, the manufacturing device can use the rollers of the rolling machine to compact the rough negative electrode sheet, so that the rough negative electrode sheet with a larger volume under the same weight becomes a negative electrode sheet with a suitable volume; it can be understood that the rolling machine increases the density of the negative electrode sheet. Appropriate density can increase the discharge capacity of the battery, reduce internal resistance, reduce polarization loss, extend the cycle life of the battery, and improve the utilization rate of lithium-ion batteries. During rolling, the rolling temperature of the negative electrode sheet can be reduced to facilitate the shaping of the negative electrode sheet. Therefore, this step can also be called cold pressing of the negative electrode sheet.

[0129] It should be noted that the number of cold pressing of the negative electrode sheet can be one, two, three or other appropriate times, and the embodiments of the present application are not limited to this.

[0130] Afterwards, the manufacturing device can use the slitting knife of the slitting machine to cut the negative electrode sheet, thereby cutting one negative electrode sheet into multiple negative electrodes.

[0131] After obtaining the negative electrode, the lithium replenishing device can replenish lithium to the negative electrode. Now, how to replenish lithium to the negative electrode is described in detail.

[0132] Figure 3 A schematic diagram of the process of replenishing lithium at the negative electrode is shown;

[0133] Before the lithium replenishing device replenishes lithium to the negative electrode, the lithium replenishing calculation device may be used to calculate a first lithium replenishing amount for replenishing lithium to the negative electrode.

[0134] The lithium-replenishing computing device may be any electronic device with computing functions, such as a laptop computer, a smart phone, a tablet computer, a server, a personal digital assistant (PDA), or other suitable electronic device, which is not limited in the embodiments of the present application.

[0135] In some embodiments, before calculating the first lithium replenishment amount, a negative electrode material used to make the negative electrode can be subjected to a charge test to obtain a charge capacity C of the negative electrode material. 负充 and the discharge capacity C of the negative electrode material 负放 .

[0136] Similarly, a negative electrode lithium replenishing material used to replenish lithium in the negative electrode is subjected to a charge-off test to obtain the gram capacity C of the negative electrode lithium replenishing material. 负补 .

[0137] Similarly, the positive electrode material used to make the positive electrode is subjected to a charge test to obtain the charge capacity C of the positive electrode material. 正充 and the discharge capacity C of the positive electrode material 正放 .

[0138] Similarly, a positive electrode replenishing lithium material used to replenish lithium in the positive electrode is subjected to a charge-off test to obtain the gram capacity C of the positive electrode replenishing lithium material. 正补 .

[0139] It should be noted that the above-mentioned positive electrode material charge-drop test does not require the production of the positive electrode first. Once the material of the positive electrode is determined, the charge-drop test can be performed on the material. Taking lithium cobalt oxide as the positive electrode active material as an example, the charge-drop test can be performed on lithium cobalt oxide before the positive electrode is produced, and the charge-drop capacity C of lithium cobalt oxide can be obtained as the charge-drop capacity C of the positive electrode material. 正充 .

[0140] Secondly, any two of the above data can be obtained by testing at the same time or by testing in time-sharing, and the embodiments of the present application do not limit this. In addition, the above data may not be tested at the beginning, and each data only needs to be tested before the data is used for calculation in the subsequent specific process, and the embodiments of the present application do not limit this.

[0141] After the above data are obtained through testing, the lithium replenishment computing device can be manually input with data so that the lithium replenishment computing device can obtain the above data, or the lithium replenishment computing device can be directly coupled with the test equipment to directly obtain the above data from the test equipment. This application does not limit this.

[0142] In other embodiments, before calculating the first lithium replenishment amount, the gram capacity test may be completed for various materials that may be used before the battery is manufactured, and the gram capacity data of various materials are stored in the lithium replenishment calculation device. In this way, the user can directly select which material to use as the negative electrode material in the lithium replenishment calculation device, and the lithium replenishment calculation device can use the gram capacity data of the material as the gram capacity data of the negative electrode material, thereby determining the charge gram capacity C of the negative electrode material during the battery manufacturing process. 负充 and the discharge capacity C of the negative electrode material 负放 .

[0143] Based on this method, the lithium replenishment calculation device can also obtain the charge capacity C of the negative electrode material. 负充 , the discharge capacity of the negative electrode material C 负放 , Gram capacity C of negative electrode lithium supplement material 负补 , the charge capacity C of the positive electrode material 正充 , discharge capacity C of positive electrode material 正放 and the gram capacity C of the positive electrode lithium supplement material 正补 The specific data of these data.

[0144] In addition to obtaining the above test data, the lithium replenishment calculation device can also obtain the battery balance value (CB) and the battery target gram capacity performance C that the manufacturer expects the battery to achieve after lithium replenishment. 正发 , positive electrode surface density D 正 It should be noted that these data are not obtained through actual testing, but are preset by the manufacturer for the actual needs and purposes of battery production.

[0145] The battery balance value may be greater than or equal to 1.01 and less than or equal to 1.30 (i.e., 1.01≤CB≤1.30). The charge capacity C of the positive electrode material 正充 The discharge capacity C of the negative electrode material 负放 The product of the charge capacity C of the negative electrode material 负充 The ratio between them is less than or equal to the battery target gram capacity C 正发 , and the battery target gram capacity is C 正发 Less than or equal to the discharge capacity C of the positive electrode material 正放 (i.e. C 正充 *C 负放 / C 负充 ≤C 正发 ≤C 正放 ). Positive electrode material surface density D 正 Can be greater than or equal to 0.005g / cm 2 And less than or equal to 0.050g / cm 2 (i.e. 0.005 g / cm 2 ≤D 正 ≤0.050g / cm 2 ).

[0146] Furthermore, the surface density D of the positive electrode material is obtained in the lithium replenishment calculation device. 正 、Battery target capacity: C 正发 , battery balance value and discharge capacity C of negative electrode material 负放 In the case of, the negative electrode material surface density D can be calculated based on the above data 负 .

[0147] For example, the negative electrode material surface density D 负 Can be related to the surface density D of the positive electrode material 正 、Battery target capacity: C 正发 It has a positive correlation with the battery balance value, and the negative electrode material surface density D 负 The discharge capacity C of the negative electrode material 负放 For example, the positive electrode material surface density D 正 、Battery target capacity: C 正发The product of the battery balance value and the discharge gram capacity C of the negative electrode material 负放 The surface density D of the negative electrode material is calculated by the ratio between 负 (i.e. D 负 =D 正 *C 正发 *CB / C 负放 ).

[0148] After obtaining the test data and the setting data, the lithium replenishment amount calculation device can calculate the first lithium replenishment amount for replenishing the negative electrode using the lithium replenishment amount calculation method for the lithium battery provided in the embodiment of the present application. Figure 4 Shows Figure 3 Flow chart for calculating the first lithium replenishment amount.

[0149] like Figure 4 As shown, first, the lithium replenishment calculation device can play C based on the battery target gram capacity 正发 and the charge capacity C of the positive electrode material 正充 Calculate the target initial efficiency E of the battery after lithium replenishment 电池-目 For example, the target initial efficiency E of the battery after lithium replenishment is 电池-目 Can be used with battery target gram capacity C 正发 There is a positive correlation, and the target initial efficiency E of the battery after lithium replenishment is 电池-目 Can be charged with the positive electrode material gram capacity C 正充 Have a negative correlation.

[0150] For example, the lithium replenishment calculation device can calculate the battery target gram capacity to play C 正发 The charge capacity C of the positive electrode material 正充 The ratio between them is used to obtain the target initial efficiency E of the battery after lithium replenishment. 电池-目 (i.e. E 电池-目 =C 正发 / C 正充 ).

[0151] Afterwards, the lithium replenishment calculation device can calculate the target initial efficiency E of the battery after lithium replenishment. 电池-目 The target initial efficiency E of the negative electrode is calculated by the battery balance value. 负目 (Also referred to as the target negative electrode first efficiency value). For example, the target first efficiency of the negative electrode E 负目 It can be compared with the target initial efficiency E of the battery after lithium replenishment. 电池-目 There is a positive correlation, and the target initial efficiency E of the negative electrode 负目 It may have a positive correlation with the battery balance value.

[0152] For example, the lithium replenishment calculation device can first calculate 1 minus the target initial efficiency E of the battery after lithium replenishment. 电池-目The ratio of the difference between the values ​​of and the battery balance value is taken as the intermediate value 1 (i.e., the intermediate value 1 = (1-E 电池-目 ) / CB), and then calculate the target initial efficiency E of the battery after lithium replenishment 电池-目 Divide by the target initial efficiency E of the battery after lithium replenishment 电池-目 The ratio of the sum of the intermediate value 1 and the target initial efficiency E of the negative electrode is obtained. 负目 (i.e. E 负目 =E 电池-目 / (E 电池-目 + intermediate value 1), understandably, E 负目 =E 电池-目 / [E 电池-目 +(1-E 电池-目 ) / CB].

[0153] Afterwards, the lithium-supplemented computing device can use the negative electrode material to charge the gram capacity C 负充 , negative electrode material discharge capacity C 负放 , the target initial efficiency of the negative electrode E 负目 and the negative electrode material surface density D 负 Calculate the upper limit of the surface capacity A of the negative electrode lithium supplement material 负补-上限 For example, the upper limit of the surface capacity of the negative electrode lithium supplement material is A 负补-上限 and the surface density of the negative electrode material D 负 There is a negative correlation between the upper limit of the surface capacity of the negative electrode lithium supplement material and the 负补-上限 Charge capacity C of negative electrode material 负充 There is a positive correlation between the upper limit of the surface capacity of the negative electrode lithium supplement material and the 负补-上限 Discharge capacity C of negative electrode material 负放 There is a negative correlation between the upper limit of the surface capacity of the negative electrode lithium supplement material and the 负补-上限 The target initial efficiency E of the negative electrode 负目 Have a positive correlation.

[0154] For example, the lithium replenishment calculation device can first calculate the discharge capacity C of the negative electrode material. 负放 The target initial efficiency E of the negative electrode 负目 The ratio between them is taken as the intermediate value 2 (i.e., intermediate value 2 = C 负放 / E 负目 ), and then calculate the negative electrode material charge capacity C 负充 The difference with the middle value 2 and the negative electrode material surface density D 负 The ratio of the negative electrode lithium supplement material is obtained to obtain the upper limit of the surface capacity A 负补-上限 (i.e. A 负补-上限 =(C 负充 - median value 2)*D 负 , understandably, A 负补-上限 =(C 负充 -C 负放 / E 负目 )*D 负 ).

[0155] After that, the lithium-replenishing computing device can be used to calculate the upper limit of the surface capacity of the negative electrode lithium-replenishing material A 负补-上限 and the gram capacity C of the negative electrode lithium supplement material 负补 The upper limit of the surface density D of the negative electrode lithium supplement material is calculated 负补-上限 In some examples, since the negative electrode lithium replenishment can directly use metallic lithium as the negative electrode lithium replenishment material, in this example, the upper limit of the surface capacity of the negative electrode lithium replenishment material A 负补-上限 and the gram capacity of metallic lithium C Li The upper limit of the surface density D of the negative electrode lithium supplement material is calculated 负补-上限 .

[0156] For example, the upper limit of the surface density of the negative electrode lithium supplement material is D 负补-上限 The upper limit of the surface capacity of the negative electrode lithium supplement material A 负补-上限 There is a positive correlation, and the upper limit of the surface density of the negative electrode lithium supplement material is D 负补-上限 The gram capacity C of the negative electrode lithium supplement material 负补 Have a negative correlation.

[0157] For example, the upper limit of the surface capacity of the negative electrode lithium supplement material A can be calculated 负补-上限 The gram capacity C of the negative electrode lithium supplement material 负补 The ratio between them gives the upper limit of the surface density D of the negative electrode lithium supplement material. 负补-上限 (D 负补-上限 =A 负补-上限 / C 负补 ).

[0158] In some embodiments, since there is an error between the actual amount of lithium replenishment at the negative electrode and the expected amount of lithium replenishment, the manufacturer can obtain the error value δ of the amount of lithium replenishment at the negative electrode based on experience or calculation. 负补 , and the error value δ 负补 Input the lithium replenishment calculation device. The lithium replenishment calculation device can be based on the upper limit of the surface density D of the negative electrode lithium replenishment material. 负补-上限 and the error value of negative electrode lithium replenishment δ 负补 Determine the surface density D of the negative electrode lithium supplement material 负补 The surface density of the negative electrode lithium supplement material is D 负补 That is, the first lithium replenishment amount for replenishing lithium for the negative electrode.

[0159] Exemplarily, the first lithium supplement amount D 负补 The error value of the negative electrode lithium replenishment amount δ 负补 The sum can be less than or equal to the upper limit of the surface density D of the negative electrode lithium supplement material 负补-上限 (i.e. D 负补 +δ 负补 ≤D负补-上限 In this way, it can be ensured that the first lithium supplement amount D is within the actual process error range. 负补 It will not exceed the upper limit of the surface density of the negative electrode lithium supplement material D 负补-上限 , thereby reducing or even avoiding the occurrence of insufficient lithium replenishment areas during the lithium replenishment process of the negative electrode, reducing or even avoiding the negative impact of lithium replenishment on battery performance, and improving the reliability and service life of the battery.

[0160] In passing Figure 4 After the calculation process shown calculates the first lithium replenishment amount, the lithium replenishment device can use the negative electrode lithium replenishment material to replenish the negative electrode according to the first lithium replenishment amount. Exemplarily, the lithium replenishment device can use a metal lithium belt to replenish the negative electrode. The specific lithium replenishment method can include suitable lithium replenishment methods such as roller pressing lithium replenishment and evaporation lithium replenishment, which are not limited here.

[0161] In some embodiments, before the negative electrode is supplemented with lithium, the average negative electrode surface density D before the negative electrode is supplemented with lithium can be weighed by punching. 负-前 After the negative electrode is replenished with lithium, the average negative electrode surface density D after the negative electrode is replenished with lithium can be weighed. 负-后 The average negative electrode surface density D before the negative electrode lithium supplementation obtained by two weighings 负-前 and the average negative electrode surface density D after negative electrode lithium supplementation 负-后 Can be input into lithium replenishment calculation device.

[0162] The lithium replenishment calculation device can be based on the average negative electrode surface density D before the negative electrode is replenished with lithium 负-前 and the average negative electrode surface density D after negative electrode lithium supplementation 负-后 Calculate the actual amount of lithium replenished in the negative electrode D 负补-实 For example, the actual amount of lithium replenishment of the negative electrode is D 负补-实 The average negative electrode surface density D before negative electrode lithium supplementation 负-前 There is a positive correlation, and the actual amount of lithium replenished at the negative electrode D 负补-实 The average negative electrode surface density D after negative electrode lithium supplementation 负-后 For example, the lithium replenishment calculation device can calculate the average negative electrode surface density D before the negative electrode is replenished with lithium. 负-前 The average negative electrode surface density D after negative electrode lithium supplementation 负-后 The difference between the two is used to obtain the actual amount of lithium replenishment D of the negative electrode. 负补-实 (i.e. D 负补-实 =D 负-后 -D 负-前 ).

[0163] After the negative electrode is replenished with lithium, the positive electrode slurry can be prepared. Since the positive electrode replenishment is usually performed by adding the positive electrode replenishment material into the positive electrode slurry for lithium replenishment, the second lithium replenishment amount for replenishing the positive electrode can be calculated in advance before the positive electrode slurry is prepared.

[0164] After the lithium replenishment calculation device calculates the first lithium replenishment amount for the negative electrode, the lithium replenishment calculation device can use the lithium replenishment amount calculation method for the lithium battery provided in the embodiment of the present application to calculate the second lithium replenishment amount for the positive electrode based on the first lithium replenishment amount. Figure 5 A schematic diagram of a flow chart for calculating the second lithium replenishment amount is shown.

[0165] like Figure 5 As shown, first, the lithium replenishment calculation device can be based on the discharge gram capacity C of the negative electrode material 负放 , negative electrode material surface density D 负 , the charge capacity C of the negative electrode material 负充 , Gram capacity C of negative electrode lithium supplement material 负补 and the actual amount of lithium replenished at the negative electrode D 负补-实 Calculate the initial efficiency E after the negative electrode is replenished with lithium 负 .

[0166] For example, the first efficiency E after the negative electrode is replenished with lithium 负 The discharge capacity C of the negative electrode material 负放 There is a positive correlation between the initial efficiency E after the negative electrode is replenished with lithium. 负 Can be charged with the negative electrode material gram capacity C 负充 There is a negative correlation between the initial efficiency E after the negative electrode is replenished with lithium. 负 The gram capacity C of the negative electrode lithium supplement material 负补 There is a positive correlation between the initial efficiency E after the negative electrode is replenished with lithium. 负 The actual amount of lithium replenished by the negative electrode D 负补-实 Have a positive correlation.

[0167] For example, the lithium replenishment calculation device can first calculate the charge capacity C of the negative electrode material. 负充 and the negative electrode material surface density D 负 The product of the gram capacity C of the negative electrode lithium supplement material 负补 and the actual amount of lithium replenished at the negative electrode D 负补-实 The difference between the products of 负充 *D 负 -C 负补 *D 负补-实 ). Then calculate the discharge capacity C of the negative electrode material 负放 and the negative electrode material surface density D 负 The ratio of the product of and the intermediate value 3 is used to obtain the first efficiency E after the negative electrode is replenished with lithium. 负 (i.e. E 负 =C 负放 *D 负 / Intermediate value 3, understandably, E 负 =C 负放 *D负 / (C 负充 *D 负 -C 负补 *D 负补-实 )).

[0168] Since the lithium replenishment efficiency of the negative electrode replenishment material may not be 100% during the process of replenishing the negative electrode, the actual amount of lithium replenishment for the negative electrode according to the first amount of lithium replenishment is not the first amount of lithium replenishment. Therefore, by obtaining the actual amount of lithium replenishment for the negative electrode to calculate the second amount of lithium replenishment, the second amount of lithium replenishment can more accurately replenish the part that has not been replenished after the first lithium replenishment, improve the lithium replenishment accuracy of the lithium battery, reduce or even avoid the negative impact on the performance of the lithium battery caused by the low accuracy of lithium replenishment, and improve the reliability and service life of the battery.

[0169] It should be noted that Figure 5 The actual amount of lithium replenished by the negative electrode is used. 负补-实 To calculate the initial efficiency E after the negative electrode is replenished with lithium 负 , which can improve the matching degree between the data in the lithium replenishment calculation device and the actual data, thereby improving the accuracy of the subsequent calculation of the second lithium replenishment amount. However, in some other implementations, the first lithium replenishment amount can also be directly substituted for the actual lithium replenishment amount D 负补-实 To calculate the initial efficiency E after the negative electrode is replenished with lithium 负 This can reduce the process of weighing the negative electrode surface density before and after the negative electrode lithium replenishment, improve the calculation efficiency of the second lithium replenishment amount, and thus improve the battery preparation efficiency.

[0170] Afterwards, the lithium replenishment calculation device can be based on the surface density D of the positive electrode material. 正 , battery balance value, positive electrode material charge capacity C 正充 , the first efficiency after the negative electrode is replenished with lithium E 负 , and the battery target capacity in grams 正发 Calculate the surface capacity A of the positive electrode lithium supplement material 正补 .

[0171] For example, the surface capacity A of the positive electrode lithium supplement material 正补 Can be used with battery target gram capacity C 正发 There is a positive correlation between the surface capacity of the positive electrode lithium supplement material A 正补 Can be charged with the positive electrode material gram capacity C 正充 There is a negative correlation between the surface capacity A of the positive electrode lithium supplement material and 正补 It can have a positive correlation with the battery balance value. The surface capacity A of the positive electrode lithium supplement material 正补 It can be compared with the initial efficiency E after the negative electrode is replenished with lithium 负 Have a negative correlation.

[0172] For example, the lithium replenishment calculation device can first calculate the battery balance value and the initial efficiency E after the negative electrode is replenished with lithium 负 The difference between the ratio of and the battery balance value is taken as the intermediate value 4 (i.e., the intermediate value 4 = CB*(1 / E 负 -1)). Then calculate the sum of 1 and the intermediate value 4 and the surface density D of the positive electrode material 正 、Battery target capacity: C 正发 The product of the positive electrode material density D 正 The charge capacity C of the positive electrode material 正充 The difference of the product of and obtains the surface capacity A of the positive electrode lithium supplement material 正补 (i.e. A 正补 =D 正 *C 正发 *(1+middle value 4)-D 正 *C 正充 , understandably, A 正补 =D 正 *C 正发 *[1+CB*(1 / E 负 -1)]-D 正 *C 正充 ).

[0173] Afterwards, the lithium replenishment calculation device can be based on the surface capacity A of the positive electrode lithium replenishment material. 正补 and the gram capacity C of the positive electrode lithium supplement material 正补 Calculate the surface density D of the positive electrode lithium supplement material 正补 .

[0174] For example, the surface density D of the positive electrode lithium supplement material is 正补 Can be used with the surface capacity of positive electrode lithium supplement material A 正补 There is a positive correlation between the surface density D of the positive electrode lithium supplement material and 正补 The gram capacity C of the positive electrode lithium supplement material 正补 For example, the lithium replenishment calculation device can calculate the surface capacity A of the positive electrode lithium replenishment material. 正补 The gram capacity C of the positive electrode lithium supplement material 正补 The ratio of the positive electrode lithium supplement material is obtained by 正补 (i.e. D 正补 =A 正补 / C 正补 ). The surface density D of the positive electrode lithium supplement material 正补 That is, the second lithium replenishment amount for replenishing lithium at the positive electrode.

[0175] In passing Figure 5 After the second lithium replenishment amount is calculated by the calculation process shown in the figure, since the positive electrode lithium replenishment material needs to be added to the positive electrode slurry according to the second lithium replenishment amount, the lithium replenishment calculation device can be based on the surface density D of the positive electrode lithium replenishment material.正补 and the surface density of the cathode material D 正 Calculate the proportion of positive electrode lithium supplement material in positive electrode slurry W 正补 , and obtain the ratio of positive electrode slurry.

[0176] For example, the lithium replenishment calculation device can calculate the surface density D of the positive electrode lithium replenishment material. 正补 Divide by the surface density D of the positive electrode lithium supplement material 正补 and the surface density of the positive electrode material D 正 The value of the sum of the positive electrode slurry and the positive electrode lithium supplement material ratio W are obtained. 正补 (i.e. W 正 =D 正补 / (D 正补 +D 正 )), thereby obtaining the ratio of positive electrode slurry.

[0177] After obtaining the ratio of the positive electrode slurry, the manufacturing device and the lithium replenishing device can manufacture the positive electrode slurry according to the ratio. The processes of manufacturing the positive electrode slurry and applying the positive electrode slurry on the positive electrode current collector and then rolling and cold pressing the positive electrode sheet are basically the same as the corresponding process principles of the aforementioned manufacturing of the negative electrode, and will not be repeated here.

[0178] Please continue to combine Figure 2 After obtaining the positive and negative electrodes after lithium supplementation, the manufacturing device can be assembled into a bare battery cell through lamination or winding and loaded into a battery shell, and then the electrolyte is injected into the battery shell through the reserved injection port of the battery shell. After that, the battery is formed so that the active substances in the positive and negative electrodes of the battery are excited, so that the battery has discharge capacity. After the formation is completed, the battery is subjected to an open circuit voltage (OCV) test to test the open circuit voltage, AC internal resistance, shell voltage and other parameters of the battery. After the battery passes the OCV test, the battery is considered to be completed.

[0179] Figure 2 In the embodiment shown, the battery preparation process is demonstrated by taking the example of first making the negative electrode and then making the positive electrode, wherein the negative electrode is first supplemented with lithium to ensure that the above-mentioned excessive lithium supplement area will not appear when the negative electrode is supplemented with lithium; then the positive electrode is supplemented with lithium to supplement the insufficient lithium supplement area after the negative electrode is supplemented with lithium. In this way, when the lithium supplement is completed, the excessive lithium supplement area and other situations that damage the battery can be avoided, a uniform lithium supplement interface can be obtained, the negative impact of lithium supplement on battery performance can be reduced or even avoided, and the reliability and service life of the battery can be improved.

[0180] Taking a consumer battery as an example, how to calculate the first lithium replenishment amount and the second lithium replenishment amount is described.

[0181] Consumer batteries can be assembled into stacked batteries using a mixture of graphite and pure silicon materials as the negative electrode active material, lithium cobalt oxide as the positive electrode active material, and Li2C4O4 as the positive electrode lithium supplement material.

[0182] By making a mixture of graphite and pure silicon materials and conducting a buckle test, the charge capacity C of the negative electrode material was obtained. 负充 =575mAh / g, discharge capacity of negative electrode material C 负放 =450mAh / g.

[0183] By making lithium cobalt oxide and conducting a charge test, the charge capacity C of the positive electrode material is obtained. 正充 =200mAh / g, discharge capacity of positive electrode material C 正放 =188mAh / g.

[0184] By making Li2C4O4 and conducting a charge test, the gram capacity C of the positive electrode lithium supplement material was obtained. 正补 =440mAh / g.

[0185] By making Li and conducting a charge test, the gram capacity C of the negative electrode lithium supplement material is obtained. 负补 =3860mAh / g.

[0186] The lithium replenishment calculation device obtains the above data, and also obtains the battery balance value CB=1.05 and the battery target gram capacity exertion C 正发 =185mAh / g, positive electrode surface density D 正 =0.015g / cm 2 Furthermore, the lithium replenishment calculation device can calculate the negative electrode material surface density D 负 =D 正 *C 正发 *CB / C 负放 =185*0.015*1.05 / 450=0.006475g / cm 2 .

[0187] In the process of calculating the first lithium supplement amount:

[0188] First, the lithium replenishment calculation device can calculate the target initial efficiency E of the battery after lithium replenishment. 电池-目 =C 正发 / C 正充 =185 / 200=92.5%.

[0189] Afterwards, the lithium replenishment calculation device can calculate the target initial efficiency E of the negative electrode. 负目 =E 电池-目 / [E 电池-目 +(1-E 电池-目) / CB]=92.5% / [92.5%+(1-92.5%) / 1.05]=92.83%.

[0190] Afterwards, the lithium replenishment calculation device can calculate the upper limit of the surface capacity A of the negative electrode lithium replenishment material. 负补-上限 =(C 负充 -C 负放 / E 负目 )*D 负 =(575-450 / 92.83%)*0.006475=0.5843mAh / cm 2 .

[0191] Afterwards, the lithium replenishment calculation device can calculate the upper limit of the surface density D of the negative electrode lithium replenishment material. 负补-上限 =A 负补-上限 / C 负补 =0.5843 / 3860=0.0001514g / cm 2 .

[0192] Afterwards, the lithium replenishment calculation device can obtain the error value δ of the negative electrode lithium replenishment amount 负补 =0.00003g / cm 2 . Thus, the first lithium supplement amount is determined as follows: the surface density D of the negative electrode lithium supplement material 负补 =0.00012g / cm 2 ≤D 负补-上限 -δ 负补 =0.0001514-0.00003=0.0001214g / cm 2 .

[0193] In the process of calculating the actual amount of lithium supplementation:

[0194] The lithium replenishment calculation device can obtain the average negative electrode surface density D before the negative electrode is replenished with lithium 负-前 =0.006475g / cm 2 , the average negative electrode surface density D after negative electrode lithium supplementation 负-后 =0.006585g / cm 2 .

[0195] Afterwards, the lithium replenishment calculation device can calculate the actual amount of lithium replenishment D of the negative electrode. 负补-实 =D 负-后 -D 负-前 =0.006585-0.006475=0.00011g / cm 2 .

[0196] In the process of calculating the second lithium supplement amount:

[0197] First, the lithium replenishment calculation device can calculate the initial efficiency E after the negative electrode is replenished with lithium 负=C 负放 *D 负 / (C 负充 *D 负 -C 负补 *D 负补-实 )=450*0.006475 / (575*0.006475-3860*0.00011)=88.34%.

[0198] Afterwards, the lithium replenishment calculation device can calculate the surface capacity A of the positive electrode lithium replenishment material. 正补 =D 正 *C 正发 *[1+CB*(1 / E 负 -1)]-D 正 *C 正充 )=0.015*185*[1+1.05*(1 / 0.8834-1)]-0.015*200=0.1596mAh / cm 2 .

[0199] Afterwards, the lithium replenishment calculation device can calculate the second lithium replenishment amount = the surface density D of the positive electrode lithium replenishment material 正补 =A 正补 / C 正补 =0.1596 / 440=0.0003627g / cm 2 .

[0200] Furthermore, the lithium replenishment calculation device can calculate the proportion of positive electrode lithium replenishment material in the positive electrode slurry W 正补 =D 正补 / (D 正补 +D 正 )=0.0003627 / (0.0003627+0.015)=2.36%.

[0201] Furthermore, the battery provided in the embodiment of the present application can be a laminated battery, in which the number of stacked positive electrode sheets is 16, and both the front and back sides of each positive electrode sheet are coated with positive electrode active materials; the number of stacked negative electrode sheets is 16, and both the front and back sides of each negative electrode sheet are coated with negative electrode active materials. The area of ​​each layer of electrode sheets is 8cm×6cm, so the total area of ​​the positive electrode sheets is S 正 and the total area of ​​the negative electrode S 负 Satisfaction: S 正 =S 负 =8cm×6cm×16×2=1536cm 2 .

[0202] The total area S of the positive electrode sheet is obtained by the lithium replenishment calculation device. 正In the case of , the amount of positive electrode slurry used in the entire battery and the amount of positive electrode lithium supplement material used can be determined based on the amount of positive electrode slurry used per unit area on the positive electrode plate. Similarly, when the lithium supplement calculation device obtains the total area S of the negative electrode plate, 负 In this case, the amount of negative electrode slurry used in the entire battery and the amount of negative electrode lithium supplement material used can be determined based on the amount of negative electrode slurry used per unit area on the negative electrode sheet.

[0203] Figure 6 Another flow chart showing the process of preparing a battery. Figure 6 The battery preparation process is demonstrated by taking the example of first making the positive electrode and then the negative electrode. Figure 6 In the illustrated embodiment, the first electrode includes a positive electrode and the second electrode includes a negative electrode.

[0204] First, before preparing the positive electrode slurry, a lithium replenishment calculation device may be used to calculate a first lithium replenishment amount for replenishing the positive electrode.

[0205] Figure 7 A flow chart for calculating the positive electrode slurry ratio is shown.

[0206] like Figure 7 As shown, the lithium replenishment calculation device can obtain the charge gram capacity C of the negative electrode material based on the method described above. 负充 , the discharge capacity of the negative electrode material C 负放 , Gram capacity C of negative electrode lithium supplement material 负补 , the charge capacity C of the positive electrode material 正充 , discharge capacity C of positive electrode material 正放 and the gram capacity C of the positive electrode lithium supplement material 正补 The lithium replenishment calculation device can also obtain the battery balance value (CB) and the battery target gram capacity (C) that the manufacturer expects the battery to achieve after lithium replenishment. 正发 , positive electrode surface density D 正 The embodiments of the present application will not be described in detail.

[0207] After acquiring the test data and the setting data, the lithium replenishment calculation device can calculate a first lithium replenishment amount for replenishing the positive electrode using the method for calculating the lithium replenishment amount of a lithium battery provided in an embodiment of the present application. Figure 8 Shows Figure 7 Flow chart for calculating the first lithium replenishment amount.

[0208] like Figure 8 As shown, first, the lithium replenishment calculation device can be based on the discharge gram capacity C of the negative electrode material 负放 and the charge capacity C of the negative electrode material 负充 Calculate the initial efficiency E of the negative electrode material负’ For example, the first efficiency E of the negative electrode material is 负’ The discharge capacity C of the negative electrode material 负放 There is a positive correlation between the initial efficiency E of the negative electrode material and 负’ Can be charged with the negative electrode material gram capacity C 负充 Have a negative correlation.

[0209] For example, the lithium replenishment calculation device can calculate the discharge gram capacity C of the negative electrode material. 负放 The charge capacity C of the negative electrode material 负充 The ratio of the negative electrode material to obtain the initial efficiency E 负’ (i.e. E 负’ =C 负放 / C 负充 ).

[0210] Afterwards, the lithium replenishment calculation device can be based on the positive electrode surface density D 正 、Battery target capacity: C 正发 , battery balance value, positive electrode material charge capacity C 正充 , and the initial efficiency E of the negative electrode material 负’ Calculate the upper limit of the surface capacity A of the positive electrode lithium supplement material 正补-上限 .

[0211] For example, the upper limit of the surface capacity of the positive electrode lithium supplement material is A 正补-上限 Can be used with battery target gram capacity C 正发 There is a positive correlation, and the upper limit of the surface capacity of the positive electrode lithium supplement material is A 正补-上限 Can be charged with the positive electrode material gram capacity C 正充 There is a negative correlation between the upper limit of the surface capacity of the positive electrode lithium supplement material and the 正补-上限 It can have a positive correlation with the battery balance value. The upper limit of the surface capacity of the positive electrode lithium supplement material is A 正补-上限 The initial efficiency E of the negative electrode material can be 负’ Have a negative correlation.

[0212] For example, the lithium replenishment calculation device can first calculate the battery balance value and the initial efficiency E of the negative electrode material. 负’ The difference between the ratio of 1 and the battery balance value is taken as the intermediate value 5. Then calculate the sum of 1 and the intermediate value 5 and the positive electrode material surface density D 正 、Battery target capacity: C 正发 The ratio of the positive electrode material surface density D 正 The charge capacity C of the positive electrode material 正充 The difference of the product of and obtains the upper limit of the surface capacity A of the positive electrode lithium supplement material 正补-上限 (i.e. A 正补-上限 =D 正 *C正发 *[1+CB*(1 / E 负’ -1))]-D 正 *C 正充 ).

[0213] Afterwards, the lithium replenishment calculation device can be based on the upper limit A of the surface capacity of the positive electrode lithium replenishment material. 正补-上限 and the gram capacity C of the positive electrode lithium supplement material 正补 Calculate the upper limit of the surface density D of the positive electrode lithium supplement material 正补-上限 .

[0214] For example, the upper limit of the surface density of the positive electrode lithium supplement material is D 正补-上限 The upper limit of the surface capacity of the positive electrode lithium supplement material A 正补-上限 There is a positive correlation between the upper limit of the surface density of the positive electrode lithium supplement material D 正补-上限 The gram capacity C of the positive electrode lithium supplement material 正补 For example, the lithium replenishment calculation device can calculate the upper limit of the surface capacity of the positive electrode lithium replenishment material A 正补-上限 The gram capacity C of the positive electrode lithium supplement material 正补 The ratio of the positive electrode lithium supplement material is obtained by 正补-上限 (i.e. D 正补-上限 =A 正补-上限 / C 正补 ).

[0215] In some embodiments, gas will be generated due to positive electrode lithium replenishment through positive electrode lithium replenishment materials. For example, when Li2C4O4 is used as the positive electrode lithium replenishment material, at least CO2 and other gases will be generated during the lithium replenishment process. The battery shell is provided with an air bag for accommodating gas, but the capacity of the air bag is limited. If the amount of gas generated by the positive electrode lithium replenishment material exceeds the capacity of the air bag (also known as the battery safe gas storage capacity), it will cause potential safety hazards to the battery. Therefore, manufacturers can obtain the upper limit D of gas replenishment corresponding to the gas production of the positive electrode lithium replenishment material based on experience or calculation. 产气-上限 , and set the upper limit of gas production and lithium supplementation D 产气-上限 Enter the lithium-replenishing computing device.

[0216] The lithium replenishment computing device can be based on the upper limit of the surface density D of the positive electrode lithium replenishment material 正补-上限 And the upper limit of gas production and lithium supplementation D 产气-上限 Determine the surface density D of the positive electrode lithium supplement material 正补 The surface density of the positive electrode lithium supplement material is D 正补 That is, the first lithium replenishment amount for replenishing lithium for the positive electrode.

[0217] Exemplarily, the first lithium supplement amount D 正补 Less than or equal to the upper limit of the surface density D of the positive electrode lithium supplement material 正补-上限 , and the first lithium supplement amount D 正补Less than or equal to the upper limit of gas production and lithium supplementation D 产气-上限 (i.e. D 正补 ≤D 正补-上限 , and D 正补 ≤D 产气-上限 ).

[0218] In passing Figure 8 After the first lithium replenishment amount is calculated by the calculation process shown in the figure, since the positive electrode lithium replenishment material needs to be added to the positive electrode slurry according to the first lithium replenishment amount, the lithium replenishment calculation device can be based on the surface density D of the positive electrode lithium replenishment material. 正补 and the surface density of the cathode material D 正 Calculate the proportion of positive electrode lithium supplement material in positive electrode slurry W 正补 , and obtain the ratio of positive electrode slurry.

[0219] For example, the lithium replenishment calculation device can calculate the surface density D of the positive electrode lithium replenishment material. 正补 Divide by the surface density D of the positive electrode lithium supplement material 正补 and the surface density of the positive electrode material D 正 The ratio of the sum of the positive electrode materials W in the positive electrode slurry is obtained. 正补 (i.e. W 正 =D 正补 / (D 正补 +D 正 )), thereby obtaining the ratio of positive electrode slurry.

[0220] After obtaining the ratio of the positive electrode slurry, the manufacturing device and the lithium replenishing device can manufacture the positive electrode slurry according to the ratio. For example, the positive electrode material, the positive electrode lithium replenishing additive, the conductive agent, the binder, the glue and other components are added to the mixer according to the ratio in the ratio, and the mixture is stirred by the mixer to finally manufacture the uniformly stirred positive electrode slurry.

[0221] Afterwards, the manufacturing device can use the coating roller to rotate and drive the positive electrode slurry so that the positive electrode slurry is evenly coated on the positive electrode current collector. During the coating process, the solvent in the slurry on the positive electrode current collector can be removed by drying and heating, so that the solid matter in the slurry can be better bonded to the positive electrode current collector to form a rough positive electrode sheet.

[0222] Afterwards, the manufacturing device can use the rollers of the rolling machine to compact the rough positive electrode sheet, so that the rough positive electrode sheet with a larger volume under the same weight becomes a positive electrode sheet with a suitable volume; it can be understood that the rolling machine increases the density of the positive electrode sheet. The appropriate density can increase the discharge capacity of the battery, reduce the internal resistance, reduce the polarization loss, extend the cycle life of the battery, and improve the utilization rate of the lithium-ion battery. During the rolling, the rolling temperature of the positive electrode sheet can be reduced to facilitate the shaping of the positive electrode sheet. Therefore, this step can also be called cold pressing of the positive electrode sheet.

[0223] In addition, after the lithium replenishment calculation device calculates the first lithium replenishment amount for the positive electrode, the lithium replenishment calculation device can use the lithium replenishment amount calculation method for the lithium battery provided in the embodiment of the present application to calculate the second lithium replenishment amount for the negative electrode based on the first lithium replenishment amount. Fig. 9 A flow chart for calculating the second lithium replenishment amount is shown.

[0224] like Fig. 9 As shown, first, the lithium replenishment calculation device can be based on the upper limit of the surface density D of the positive electrode lithium replenishment material 正补-上限 , the surface density D of the positive electrode lithium supplement material 正补 and the gram capacity C of the positive electrode lithium supplement material 正补 Calculate the surface capacity A of the negative electrode lithium supplement material 负补 .

[0225] For example, the surface capacity A of the negative electrode lithium supplement material 负补 The upper limit of the surface density of the positive electrode lithium supplement material D 正补-上限 There is a positive correlation between the surface capacity of the negative electrode lithium supplement material A 负补 It can be compared with the surface density D of the positive electrode lithium supplement material 正补 There is a negative correlation between the surface capacity A of the negative electrode lithium supplement material and 负补 The gram capacity C of the positive electrode lithium supplement material 正补 Have a positive correlation.

[0226] For example, the lithium replenishment calculation device can calculate the upper limit of the surface density D of the positive electrode lithium replenishment material. 正补-上限 The surface density D of the positive electrode lithium supplement material 正补 The difference between the positive electrode lithium supplement material and the gram capacity C 正补 The product of the negative electrode lithium supplement material is obtained as A 负补 (i.e. A 负补 =(D 正补-上限 -D 正补 )*C 正补 ).

[0227] Secondly, the lithium replenishment calculation device can be based on the surface capacity A of the negative electrode lithium replenishment material. 负补 and the gram capacity C of the negative electrode lithium supplement material 负补 Calculate the surface density D of the negative electrode lithium supplement material 负补 .

[0228] For example, the surface density D of the negative electrode lithium supplement material is 负补 Can be used with the negative electrode lithium supplement material surface capacity A 负补 There is a positive correlation between the surface density D of the negative electrode lithium supplement material and 负补 The gram capacity C of the negative electrode lithium supplement material 负补 Have a positive correlation.

[0229] For example, the lithium replenishment calculation device can calculate the surface capacity A of the negative electrode lithium replenishment material. 负补 The gram capacity C of the negative electrode lithium supplement material 负补 The ratio of the negative electrode lithium supplement material is obtained by 负补 (i.e. D 负补 =A 负补 / C 负补 ). Taking metallic lithium as the negative electrode lithium replenishment material as an example, the lithium replenishment calculation device can calculate the surface capacity A of the negative electrode lithium replenishment material 负补 The gram capacity C of metallic lithium Li The ratio of the negative electrode lithium supplement material is obtained by 负补 (i.e. D 负补 =A 负补 / C Li ).

[0230] The surface density D of the negative electrode lithium supplement material 负补 That is, the second lithium replenishment amount for replenishing lithium for the negative electrode.

[0231] In the battery preparation process, the manufacturing device also includes the following steps: preparing negative electrode slurry, evenly spreading the negative electrode slurry on the negative electrode current collector to form a rough negative electrode sheet, using the roller of the rolling machine to compact the rough negative electrode sheet into a negative electrode sheet of appropriate volume, and cutting the negative electrode sheet to obtain the negative electrode. After obtaining the negative electrode, the negative electrode is subjected to the following steps: Fig. 9 After the calculation process shown calculates the second lithium replenishment amount, the lithium replenishment device can use the negative electrode lithium replenishment material to replenish the negative electrode according to the second lithium replenishment amount. Exemplarily, the lithium replenishment device can use a metal lithium belt to replenish the negative electrode. The specific lithium replenishment method can include suitable lithium replenishment methods such as roller pressing lithium replenishment and evaporation lithium replenishment, which are not limited here.

[0232] Please continue to combine Figure 6 After obtaining the positive and negative electrodes after lithium supplementation, the manufacturing device can be assembled into bare cells through lamination or winding and loaded into a battery shell, and then the electrolyte is injected into the battery shell through the reserved injection port of the battery shell. After that, the battery is formed so that the active substances in the positive and negative electrodes of the battery are excited, so that the battery has discharge capacity. After the formation is completed, the battery is subjected to an OCV test to test the battery's open circuit voltage, AC internal resistance, shell voltage and other parameters. After the battery passes the OCV test, the battery is considered to be completed.

[0233] Figure 6In the embodiment shown, the battery preparation process is demonstrated by taking the example of first making the positive electrode and then making the negative electrode, wherein the positive electrode is first supplemented with lithium to ensure that the above-mentioned excessive gas production will not occur when the positive electrode is supplemented with lithium; then the negative electrode is supplemented with lithium to supplement the insufficient lithium supplement area after the positive electrode is supplemented with lithium. In this way, it is possible to avoid the situation of excessive gas production and other damage to the battery when the lithium supplement is completed, and the lithium supplement of the battery can be completed under the premise of safe gas production, reducing or even avoiding the negative impact of lithium supplement on battery performance, and improving the reliability and service life of the battery.

[0234] An embodiment of the present application also provides a computer-readable storage medium, which includes computer instructions. When the computer instructions are executed on the above-mentioned lithium replenishment calculation device, the lithium replenishment calculation device executes the various functions or steps performed in the above-mentioned embodiment to calculate the amount of lithium replenishment for the positive electrode and / or the negative electrode.

[0235] The embodiment of the present application also provides a computer program product. When the computer program product is run on a computer, the computer executes each function or step performed by the lithium replenishment calculation device in the above method embodiment to calculate the lithium replenishment amount for the positive electrode.

[0236] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0237] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0238] The units described as separate components may or may not be physically separated, and the components shown as units may be one physical unit or multiple physical units, that is, they may be located in one place or distributed in multiple different places. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0239] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0240] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium, including several instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) to perform all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

[0241] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing a lithium battery, characterized in that: The method comprises: A first electrode is prepared and lithium is replenished for the first electrode according to a first lithium replenishment amount; wherein the first lithium replenishment amount is less than a preset lithium replenishment amount; the first electrode is the negative electrode of the lithium battery, and the preset lithium replenishment amount is the estimated lithium replenishment amount corresponding to at least a partial lithium replenishment area formed during the lithium replenishment process of the negative electrode, or the first electrode is the positive electrode of the lithium battery, and the preset lithium replenishment amount is the lithium replenishment amount corresponding to the estimated gas production of the lithium replenishment material being less than or equal to a preset safe gas storage amount; A second electrode is prepared and lithium is supplemented to the second electrode according to a second lithium supplement amount, wherein the second lithium supplement amount is negatively correlated with the first lithium supplement amount.

2. The method according to claim 1, characterized in that Before preparing the first electrode and replenishing lithium for the first electrode according to the first lithium replenishing amount, the method further includes: Calculating an upper limit value of the surface density of the lithium supplement material of the first electrode based on a preset battery balance value; The first lithium supplement amount is determined, and the first lithium supplement amount is less than an upper limit value of the surface density of the lithium supplement material of the first electrode.

3. The method according to claim 1 or 2, characterized in that: The first electrode is the negative electrode, and the second electrode is the positive electrode; After preparing the first electrode and replenishing lithium for the first electrode according to the first lithium replenishing amount, and before preparing the second electrode and replenishing lithium for the second electrode according to the second lithium replenishing amount, the method further includes: Obtaining the actual amount of lithium replenishment of the negative electrode; The second lithium replenishment amount is calculated based on a preset battery balance value and the actual lithium replenishment amount of the negative electrode; the second lithium replenishment amount is negatively correlated with the actual lithium replenishment amount of the negative electrode.

4. The method according to claim 3, characterized in that The step of preparing the first electrode and replenishing lithium for the first electrode according to a first lithium replenishing amount comprises: preparing a negative electrode; replenishing lithium for the negative electrode; After preparing the negative electrode and before replenishing lithium for the negative electrode, the method further comprises: Obtaining the negative electrode surface density of the negative electrode before lithium supplementation; The obtaining of the actual amount of lithium replenishment of the negative electrode comprises: Obtaining the surface density of the negative electrode after lithium replenishment of the negative electrode; The difference between the surface density of the negative electrode after lithium supplementation and the surface density of the negative electrode before lithium supplementation is calculated to obtain the actual lithium supplementation amount of the negative electrode.

5. The method according to claim 3 or 4, characterized in that: The calculating the second lithium replenishment amount based on the preset battery balance value and the actual lithium replenishment amount of the negative electrode includes: Based on the actual amount of lithium replenished at the negative electrode, calculating the first effective value of the negative electrode after the negative electrode is replenished with lithium; the first effective value of the negative electrode after the negative electrode is replenished with lithium has a positive correlation with the actual amount of lithium replenished at the negative electrode; Based on the battery balance value and the negative electrode first efficiency value, the surface capacity of the positive electrode lithium supplement material is calculated; the surface capacity of the positive electrode lithium supplement material is negatively correlated with the negative electrode first efficiency value; The second lithium replenishment amount is calculated based on the surface capacity of the positive electrode lithium replenishment material.

6. The method according to any one of claims 3 to 5, characterized in that: Before preparing the first electrode and replenishing lithium for the first electrode according to the first lithium replenishing amount, the method further includes: Get the preset battery target first efficiency value; Calculating a target negative electrode first effectiveness value corresponding to the negative electrode based on the battery target first effectiveness value and the battery balance value; The first lithium supplement amount is calculated based on the target negative electrode first effectiveness value; the target negative electrode first effectiveness value and the first lithium supplement amount have a positive correlation.

7. The method according to claim 6, characterized in that The calculating the first lithium supplement amount based on the target negative electrode first effective value includes: Based on the target negative electrode first efficiency value, calculating the upper limit value of the negative electrode lithium replenishing surface capacity of the negative electrode; the target negative electrode first efficiency value and the upper limit value of the negative electrode lithium replenishing surface capacity of the negative electrode have a positive correlation; Calculating the upper limit of the surface density of the negative electrode lithium supplement material based on the upper limit of the negative electrode lithium supplement surface capacity; Based on the upper limit of the surface density of the negative electrode lithium supplement material, a first lithium supplement amount corresponding to the negative electrode is determined.

8. The method according to claim 7, characterized in that The determining, based on the upper limit value of the surface density of the negative electrode lithium supplement material, a first lithium supplement amount corresponding to the negative electrode comprises: Obtaining a preset negative electrode lithium replenishment error value; Based on the upper limit value of the surface density of the negative electrode lithium supplement material and the negative electrode lithium supplement error value, a first lithium supplement amount corresponding to the negative electrode is determined, wherein the sum of the first lithium supplement amount and the negative electrode lithium supplement error value is less than or equal to the upper limit value of the surface density of the negative electrode lithium supplement material.

9. The method according to claim 1 or 2, characterized in that: The first electrode is the positive electrode, and the second electrode is the negative electrode; before preparing the first electrode and replenishing lithium for the first electrode according to the first lithium replenishment amount, the method further includes: Obtain the discharge gram capacity of the negative electrode material and the charge gram capacity of the negative electrode material; Calculating the first efficiency value of the negative electrode material based on the discharge gram capacity of the negative electrode material and the charge gram capacity of the negative electrode material; The first lithium supplement amount is calculated based on the first effectiveness value of the negative electrode material and the battery balance value.

10. The method according to claim 9, characterized in that The calculating the first lithium replenishment amount based on the first efficiency value of the negative electrode material and the battery balance value includes: Based on the first effective value of the negative electrode material, the upper limit value of the surface capacity of the positive electrode lithium supplement material is calculated; the first effective value of the negative electrode material and the upper limit value of the surface capacity of the positive electrode lithium supplement material have a negative correlation; Calculating an upper limit value of the surface density of the positive electrode lithium supplement material based on the upper limit value of the surface capacity of the positive electrode lithium supplement material; Based on the upper limit of the surface density of the positive electrode lithium supplement material, a first lithium supplement amount corresponding to the positive electrode is determined; the first lithium supplement amount is less than or equal to the upper limit of the surface density of the positive electrode lithium supplement material.

11. The method according to claim 10, characterized in that Before preparing the second electrode and replenishing lithium for the second electrode according to the second lithium replenishing amount, the method further includes: Obtaining an upper limit value of the surface density of the positive electrode lithium supplement material and a gram capacity of the positive electrode lithium supplement material; Based on the first lithium supplement amount, the upper limit of the surface density of the positive electrode lithium supplement material and the gram capacity of the positive electrode lithium supplement material, the surface capacity of the negative electrode lithium supplement material is calculated; the surface capacity of the negative electrode lithium supplement material is positively correlated with the gram capacity of the positive electrode lithium supplement material; Based on the surface capacity of the negative electrode lithium replenishing material, the second lithium replenishing amount is calculated.

12. A lithium battery preparation system, characterized in that: The lithium battery comprises a first electrode and a second electrode; and the lithium battery preparation system comprises: A lithium replenishment amount calculation device, in the lithium battery preparation method according to any one of claims 1 to 11, used to calculate the lithium replenishment amount for the first electrode and the lithium replenishment amount for the second electrode; A lithium replenishment device coupled to the lithium replenishment amount calculation device; in the lithium battery preparation method as described in any one of claims 1 to 11, the lithium replenishment device is used to replenish lithium to the first electrode according to the first lithium replenishment amount, and to replenish lithium to the second electrode according to the second lithium replenishment amount.

13. A method for calculating the amount of lithium replenishment for a lithium battery, characterized in that: The lithium battery comprises a first electrode and a second electrode, and the method comprises: A first lithium replenishment amount for the first electrode is calculated based on a preset battery balance value; wherein the first lithium replenishment amount is less than a preset lithium replenishment amount; the first electrode is the negative electrode of the lithium battery, and the preset lithium replenishment amount is the estimated lithium replenishment amount corresponding to at least a partial formation of an excess lithium replenishment area during the negative electrode lithium replenishment process, or the first electrode is the positive electrode of the lithium battery, and the preset lithium replenishment amount is the lithium replenishment amount corresponding to an estimated gas production of the lithium replenishment material being less than or equal to a preset safe gas storage amount; After obtaining the first lithium replenishment amount, a second lithium replenishment amount for the second electrode is calculated, and the second lithium replenishment amount is negatively correlated with the first lithium replenishment amount.

14. The method according to claim 13, characterized in that The calculating a first lithium replenishment amount for the first electrode based on a preset battery balance value includes: Calculating an upper limit value of the surface density of the lithium supplement material of the first electrode based on a preset battery balance value; The first lithium supplement amount is determined, and the first lithium supplement amount is less than an upper limit value of the surface density of the lithium supplement material of the first electrode.

15. The method according to claim 13 or 14, characterized in that The first electrode is the negative electrode, and the second electrode is the positive electrode; Before calculating the second lithium replenishment amount for the second electrode, the method further includes: Obtaining the actual amount of lithium replenishment of the negative electrode; The second lithium replenishment amount is calculated based on a preset battery balance value and the actual lithium replenishment amount of the negative electrode; the second lithium replenishment amount is negatively correlated with the actual lithium replenishment amount of the negative electrode.

16. The method according to claim 15, characterized in that The calculating a first lithium replenishment amount for the first electrode based on a preset battery balance value includes: Calculating a target negative electrode first effectiveness value corresponding to the negative electrode based on the battery target first effectiveness value and the battery balance value; The first lithium supplement amount is calculated based on the target negative electrode first effectiveness value; the target negative electrode first effectiveness value and the first lithium supplement amount have a positive correlation.

17. The method according to claim 13, characterized in that The first electrode is the positive electrode, and the second electrode is the negative electrode; The calculating a first lithium replenishment amount for the first electrode based on a preset battery balance value includes: Obtain the discharge gram capacity of the negative electrode material and the charge gram capacity of the negative electrode material; Calculating the first efficiency value of the negative electrode material based on the discharge gram capacity of the negative electrode material and the charge gram capacity of the negative electrode material; The first lithium supplement amount is calculated based on the first effectiveness value of the negative electrode material and the battery balance value.

18. The method according to claim 17, characterized in that The calculating the first lithium replenishment amount based on the first efficiency value of the negative electrode material and the battery balance value includes: Based on the first effective value of the negative electrode material, the upper limit value of the surface capacity of the positive electrode lithium supplement material is calculated; the first effective value of the negative electrode material and the upper limit value of the surface capacity of the positive electrode lithium supplement material have a negative correlation; Calculating an upper limit value of the surface density of the positive electrode lithium supplement material based on the upper limit value of the surface capacity of the positive electrode lithium supplement material; Based on the upper limit of the surface density of the positive electrode lithium supplement material, a first lithium supplement amount corresponding to the positive electrode is determined; the first lithium supplement amount is less than or equal to the upper limit of the surface density of the positive electrode lithium supplement material.

19. A lithium battery, characterized in that: include: A positive electrode group, including a positive electrode and a positive electrode lithium supplement material; A negative electrode group, including a negative electrode and a negative electrode lithium supplement material; The electrolyte is in contact with the positive electrode group and the negative electrode group at the same time.

20. An electronic device, characterized in that: include: Circuit boards; a battery coupled to the circuit board to supply power to the circuit board; The battery comprises a lithium battery as described in claim 19.

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