Lithium battery preparation method and system

Abstract

The present application is about a method for preparing a lithium battery and a system thereof, which relates to the technical field of lithium batteries and is used to solve the problem that positive electrode lithium supplementation will reduce battery performance. The method for preparing a lithium battery includes: based on a preset battery balance value and a target gram capacity of the battery, calculating the amount of lithium supplementation of the positive electrode; the amount of lithium supplementation of the positive electrode has a positive correlation with the target gram capacity. When preparing the positive electrode of the battery, a positive electrode lithium supplementation material is used to supplement the positive electrode with lithium according to the amount of lithium supplementation.

Description

Technical Field

[0001] The embodiments of the present application relate to a lithium battery, and more particularly to a method for preparing a lithium battery and a system thereof. 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 that use materials with higher gram 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 positive electrode lithium replenishment 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, which are used to solve the problem that positive electrode lithium supplementation reduces 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 comprising: calculating the amount of lithium replenishment of a positive electrode based on a preset battery balance value and a target gram capacity of the battery; the amount of lithium replenishment of the positive electrode is positively correlated with the target gram capacity. When preparing the positive electrode of the battery, a positive electrode lithium replenishment material is used to replenish the positive electrode with lithium according to the amount of lithium replenishment.

[0007] In the present application, the lithium replenishment demand of the lithium battery is met by replenishing lithium to the positive electrode.

[0008] It should be noted that the above lithium replenishment amounts all refer to the surface density of the lithium replenishment materials. In addition, even if they are all positive electrode lithium replenishment materials, due to the different gram capacities of the positive electrode lithium replenishment materials, the calculated lithium replenishment amounts corresponding to different positive electrode lithium replenishment materials may also be different. The gram capacity of each lithium replenishment material can be obtained by testing the lithium replenishment material after it is made and charged.

[0009] The method for preparing a lithium battery provided in an embodiment of the present application first calculates the amount of lithium replenishment for the positive electrode through the target gram capacity and the battery balance value. In this way, the amount of lithium replenishment for the positive electrode is calculated through the logical relationship between the various parameters inside the battery, which can better reflect the actual impact of each parameter on the amount of lithium replenishment, thereby improving the accuracy of the amount of lithium replenishment at the positive electrode. The high-precision amount of lithium replenishment at the positive electrode can reduce or even avoid the phenomenon of deteriorating cycle performance or poor battery energy density due to poor accuracy of the amount of lithium replenishment, reduce or even avoid the negative impact of positive electrode lithium replenishment on battery performance, and improve the battery's cycle performance and battery energy density.

[0010] In a possible implementation of the first aspect, the lithium battery further includes a negative electrode. Before calculating the amount of lithium replenishment of the positive electrode, the method includes: obtaining a first effective value of the negative electrode. Based on the first effective value of the negative electrode, determining a target gram capacity of the battery.

[0011] In this implementation, the target gram capacity is calculated using the logical relationship between the first effective value of the negative electrode and the target gram capacity of the battery. Compared with estimating the target gram capacity based on experience, the calculation accuracy of the target gram capacity can be improved, thereby helping to improve the calculation accuracy of the lithium replenishment amount of the positive electrode.

[0012] In another possible implementation of the first aspect, obtaining the first effectiveness value of the negative electrode includes: obtaining the charge gram capacity of the negative electrode material, obtaining the discharge gram capacity of the negative electrode material, and calculating the ratio of the discharge gram capacity of the negative electrode to the charge gram capacity of the negative electrode to obtain the first effectiveness value of the negative electrode.

[0013] In this implementation, the first effective value of the negative electrode is calculated by using the logical relationship between the discharge gram capacity of the negative electrode, the charge gram capacity of the negative electrode and the first effective value of the negative electrode. Compared with estimating the first effective value of the negative electrode based on experience, the calculation accuracy of the first effective value of the negative electrode can be improved, thereby helping to improve the calculation accuracy of the lithium replenishment amount of the positive electrode.

[0014] In another possible implementation of the first aspect, before calculating the amount of lithium replenishment of the positive electrode, the method includes: obtaining the charge gram capacity of the positive electrode. Obtaining the discharge gram capacity of the positive electrode. Based on the charge gram capacity of the positive electrode and the discharge gram capacity of the positive electrode, determining the target gram capacity of the battery, wherein the target gram capacity is greater than or equal to the product of the charge gram capacity of the positive electrode and the first effective value of the negative electrode, and the target gram capacity is less than or equal to the discharge gram capacity of the positive electrode.

[0015] In this implementation, the target gram capacity of the battery is calculated by using the logical relationship between the positive electrode's charge gram capacity, the positive electrode's discharge gram capacity and the battery's target gram capacity. Compared with estimating the battery's target gram capacity based on experience, the calculation accuracy of the battery's target gram capacity can be improved, thereby helping to improve the calculation accuracy of the positive electrode's lithium replenishment amount.

[0016] In another possible implementation of the first aspect, based on a preset battery balance value and a target gram capacity of the battery, the amount of lithium replenishment of the positive electrode is calculated, including: based on the battery balance value and the target gram capacity, the surface capacity of the positive electrode lithium replenishment material is calculated. The surface capacity of the positive electrode lithium replenishment material has a positive correlation with the target gram capacity. Based on the surface capacity of the positive electrode lithium replenishment material, the amount of lithium replenishment of the positive electrode lithium replenishment material is calculated.

[0017] In this implementation, the surface capacity of the positive electrode lithium supplement material is calculated by using the logical relationship between the battery balance value, the target gram capacity and the surface capacity of the positive electrode lithium supplement material. Compared with estimating the surface capacity of the positive electrode lithium supplement material based on experience, the calculation accuracy of the surface capacity of the positive electrode lithium supplement material can be improved.

[0018] The surface capacity of the positive electrode lithium replenishing material is then used to calculate the lithium replenishment amount of the positive electrode lithium replenishing material, which can improve the calculation accuracy of the lithium replenishment amount of the positive electrode lithium replenishing material.

[0019] In another possible implementation of the first aspect, the areal capacity of the positive electrode lithium supplement material is calculated based on the battery balance value and the target gram capacity, including: obtaining the areal density of the positive electrode material. The areal capacity of the positive electrode lithium supplement material is calculated based on the battery balance value, the target gram capacity and the areal density of the positive electrode material; the areal capacity of the positive electrode lithium supplement material has a positive correlation with the target gram capacity.

[0020] In this implementation, the surface capacity of the positive electrode lithium supplement material is calculated by using the logical relationship between the battery balance value, the target gram capacity, the surface density of the positive electrode material and the surface capacity of the positive electrode lithium supplement material. Compared with estimating the surface capacity of the positive electrode lithium supplement material based on experience, the calculation accuracy of the surface capacity of the positive electrode lithium supplement material can be improved.

[0021] In another possible implementation of the first aspect, based on the surface capacity of the positive electrode lithium replenishing material, calculating the amount of lithium replenishment of the positive electrode lithium replenishing material includes: obtaining the gram capacity of the positive electrode lithium replenishing material. Calculating the ratio of the surface capacity of the positive electrode lithium replenishing material to the gram capacity of the positive electrode lithium replenishing material to obtain the amount of lithium replenishment of the positive electrode lithium replenishing material.

[0022] In this implementation, the amount of lithium replenishment of the positive electrode replenishment material is calculated by using the logical relationship between the surface capacity of the positive electrode replenishment material, the ratio of the gram capacity of the positive electrode replenishment material, and the amount of lithium replenishment of the positive electrode replenishment material. Compared with estimating the amount of lithium replenishment of the positive electrode replenishment material based on experience, the calculation accuracy of the amount of lithium replenishment of the positive electrode replenishment material can be improved.

[0023] In another possible implementation of the first aspect, the positive electrode lithium replenishing material is used to replenish lithium to the positive electrode according to the lithium replenishing amount, including: adding the positive electrode lithium replenishing material in the lithium replenishing amount to form a positive electrode slurry to replenish lithium to the positive electrode.

[0024] In this implementation, the positive electrode lithium supplement material is mixed with the positive electrode material and other components to obtain a positive electrode slurry. The positive electrode slurry is coated with other processes to obtain a positive electrode to achieve positive electrode lithium supplementation.

[0025] In another possible implementation of the first aspect, after calculating the amount of lithium replenishment of the positive electrode lithium replenishment material, it also includes: obtaining the surface density of the positive electrode material. Based on the surface density of the positive electrode material and the amount of lithium replenishment of the positive electrode lithium replenishment material, the proportion of the positive electrode lithium replenishment material in the positive electrode slurry is calculated. Based on the proportion of the positive electrode lithium replenishment material in the positive electrode slurry, a positive electrode slurry after lithium replenishment is prepared to replenish lithium to the positive electrode.

[0026] In this implementation, the logical relationship between the surface density of the positive electrode material, the amount of lithium replenishment of the positive electrode replenishment material, and the proportion of the positive electrode replenishment material in the positive electrode slurry is used to calculate the proportion of the positive electrode replenishment material in the positive electrode slurry. Compared with estimating the proportion of the positive electrode replenishment material in the positive electrode slurry based on experience, the calculation accuracy of the proportion of the positive electrode replenishment material in the positive electrode slurry can be improved.

[0027] In a second aspect, the present application provides a lithium battery preparation system. The lithium battery preparation system includes a lithium replenishment amount calculation device and a lithium replenishment device. The lithium replenishment amount calculation device is used in any of the lithium battery preparation methods of the first aspect to calculate the amount of lithium replenishment required when replenishing the positive electrode. The lithium replenishment device is coupled to the lithium replenishment amount calculation device. In any of the lithium battery preparation methods of the first aspect, the lithium replenishment device is used to replenish the positive electrode of the lithium battery according to the lithium replenishment amount.

[0028] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flow chart of a lithium battery manufacturing process provided in an embodiment of the present application;

[0030] Figure 2 A flow chart for calculating the positive electrode slurry ratio during the preparation of a lithium battery provided in an embodiment of the present application;

[0031] Figure 3 for Figure 2 Flowchart for calculating the amount of lithium replenished at the positive electrode. DETAILED DESCRIPTION

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] “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.

[0037] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0038] 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.

[0039] 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).

[0040] To facilitate understanding, some descriptions of concepts related to the embodiments of the present application are exemplarily given for reference.

[0041] 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).

[0042] 2. Gram capacity refers to the ratio of the capacity that can be released by the active material inside the battery to the mass of the active material. The commonly used unit is mAh / g (milliampere-hour per gram).

[0043] 3. The first efficiency of a battery (referred to as first efficiency) 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] During the first charge and discharge process of the battery, some active lithium is consumed to undergo irreversible reaction to form the SEI film.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053]

[0054]

[0055] Table 1

[0056] 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.

[0057] 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.

[0058] 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.

[0059] However, in the method of replenishing lithium at the positive electrode, how to reasonably design the amount of lithium replenishment is a key issue in the lithium replenishment process. The current lithium replenishment process easily leads to the actual amount of lithium replenishment being too high or too low. Among them, if the amount of lithium replenishment at the positive electrode is too high, it will cause lithium deposition at the negative electrode, reduce the transmission capacity of the battery cycle interface and thus deteriorate the cycle performance. In addition, a large amount of gas is generated during battery formation and / or capacity separation, which poses a risk of harming the battery; and if the amount of lithium replenishment at the positive electrode is too low, the battery's initial efficiency will not reach the target, making the battery energy density fail to reach the ideal level.

[0060] It can be seen that the current positive electrode lithium supplementation has the problem of reducing battery performance.

[0061] Based on this, the embodiments of the present application provide a method for preparing a lithium battery and a system thereof, which reduces or even avoids the problem of reducing battery performance due to poor accuracy of lithium replenishment by improving the accuracy of the amount of lithium replenishment to the positive electrode during the preparation process. The method for preparing a lithium battery provided in the embodiments of the present application first calculates the amount of lithium replenishment for the positive electrode through the target gram capacity and the battery balance value. In this way, the amount of lithium replenishment for the positive electrode is calculated through the logical relationship between the various parameters inside the battery, which can better reflect the actual influence of each parameter on the amount of lithium replenishment, thereby improving the accuracy of the amount of lithium replenishment at the positive electrode. High-precision positive electrode lithium replenishment can reduce or even avoid the phenomenon of deteriorating cycle performance or poor battery energy density due to poor accuracy of lithium replenishment, reduce or even avoid the negative impact of positive electrode lithium replenishment on battery performance, and improve the battery's cycle performance and battery energy density.

[0062] The battery provided in the embodiments of the present application may be a consumer battery used in consumer products such as laptop computers, mobile phones, smart phones, tablet computers, smart vehicle-mounted devices, navigators, sports cameras, smart home appliances, artificial intelligence devices, wearable devices, or virtual reality / augmented reality / mixed reality devices, or a power battery used in power products such as electric vehicles, electric bicycles, power-assisted bicycles, and electric wheelchairs. The embodiments of the present application are not limited to this.

[0063] The present application uses a lithium battery preparation system to execute a lithium battery preparation method to prepare a lithium battery. Exemplarily, the lithium battery preparation system may include a lithium replenishment amount calculation device, a lithium replenishment device, and a manufacturing device.

[0064] The lithium replenishment amount calculation device can be used to calculate the lithium replenishment amount for the positive electrode (also called the positive electrode lithium replenishment amount).

[0065] The lithium replenishing device is used to replenish lithium to the positive electrode according to the positive electrode lithium replenishing amount when the lithium replenishing amount calculating device calculates the positive electrode lithium replenishing amount.

[0066] 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.

[0067] It should be noted that the above-mentioned positive electrode lithium replenishment amounts all refer to the surface density of the lithium replenishment material. In addition, even if they are all positive electrode lithium replenishment materials, due to the different gram capacities of the positive electrode lithium replenishment materials, the calculated lithium replenishment amounts corresponding to different positive lithium replenishment materials may also be different. The gram capacity of each lithium replenishment material can be obtained by testing the lithium replenishment material after it is made into a buckle (hereinafter referred to as the buckle test).

[0068] 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.

[0069] Figure 1 A flow chart of the preparation process of a lithium battery is shown. The preparation process of a battery may include the preparation of a negative electrode, the preparation of a positive electrode, and the assembly and testing of the battery, a total of three parts. Among them, the preparation time of the negative electrode may be before the preparation time of the positive electrode, the preparation time of the negative electrode may also be after the preparation time of the positive electrode, and the preparation time of the negative electrode may also overlap with the preparation time of the positive electrode, and the embodiments of the present application do not limit this. For ease of understanding, Figure 1 The example of making the positive electrode first is used for explanation.

[0070] The preparation of the negative electrode may include:

[0071] 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.

[0072] 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.

[0073] 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. 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 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.

[0074] 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.

[0075] 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.

[0076] The preparation of the positive electrode may include:

[0077] Since positive electrode lithium replenishment is usually performed by mixing positive electrode lithium replenishment materials with positive electrode materials, conductive agents, binders, glue and other components to form positive electrode slurry for lithium replenishment, before making the positive electrode slurry, the lithium replenishment amount for replenishing the positive electrode can be calculated in advance using a lithium replenishment amount calculation device. And the proportion of the positive electrode slurry is obtained based on the lithium replenishment amount for the positive electrode.

[0078] Figure 2 A flow chart for calculating the positive electrode slurry ratio is shown.

[0079] like Figure 2 As shown, the lithium replenishment amount calculation device can be any electronic device with a calculation function. For example, the lithium replenishment amount calculation device can be a laptop computer, a smart phone, a tablet computer, a server, a personal digital assistant (PDA), and other suitable electronic devices, and the embodiments of the present application are not limited to this.

[0080] In some embodiments, before calculating the amount of lithium replenishment for the positive electrode, the negative electrode material used to make the negative electrode can be subjected to a charge test to obtain the charge capacity C of the negative electrode material. 负充 and the discharge capacity C of the negative electrode material 负放 .

[0081] 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 .

[0082] 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 .

[0083] 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 .

[0084] 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.

[0085] After the above data are obtained through testing, the lithium replenishment amount calculation device can be manually input with data so that the lithium replenishment amount calculation device can obtain the above data, or the lithium replenishment amount calculation 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.

[0086] In other embodiments, before calculating the amount of lithium replenishment for the positive electrode, the gram capacity test may be completed for each possible material before the battery is manufactured, and the gram capacity data of each material may be stored in the lithium replenishment amount calculation device. In this way, the user can directly select which material to use as the negative electrode material in the lithium replenishment amount calculation device, and the lithium replenishment amount 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 .

[0087] Based on this method, the lithium replenishment amount calculation device can also obtain the charge gram 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.

[0088] In addition to obtaining the above test data, the lithium replenishment amount 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 manufacturers for the actual needs and purposes of battery production.

[0089] 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 ).

[0090] Furthermore, the surface density D of the positive electrode material is obtained by the lithium replenishment amount 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 .

[0091] 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 surface density of the negative electrode material D 负 The discharge capacity C of the negative electrode material 负放 Have a negative correlation.

[0092] For example, the surface density D of the positive electrode material can be 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 ).

[0093] After acquiring the above test data and the above setting data, the lithium replenishment amount calculation device can calculate the lithium replenishment amount for the positive electrode. Figure 3 Shows Figure 2 Flowchart for calculating the amount of lithium replenished at the positive electrode.

[0094] like Figure 3 As shown, first, the lithium replenishment amount 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.

[0095] For example, the lithium replenishment amount 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 ).

[0096] Afterwards, the lithium replenishment amount 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 surface capacity A of the positive electrode lithium supplement material 正补 .

[0097] 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 The initial efficiency E of the negative electrode material can be 负’ Have a negative correlation.

[0098] For example, the lithium replenishment amount 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 and the battery balance value is taken as the intermediate value 1 (i.e., intermediate value 1 = CB*(1 / E 负’ -1). Then calculate the sum of 1 and the intermediate value 1 and the surface density D of the positive electrode material 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 surface capacity A of the positive electrode lithium supplement material 正补 (i.e. A 正补 =D 正 *C 正发 *(1+median value 1)-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 ).

[0099] Afterwards, the lithium replenishment amount calculation device can calculate the surface capacity A of the positive electrode lithium replenishment material 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 .

[0100] 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 amount 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 ).

[0101] In passing Figure 3 After the amount of lithium replenishment for the positive electrode is calculated by the calculation process shown in the figure, since the positive electrode lithium replenishment material needs to be mixed with the positive electrode material and other components according to the amount of lithium replenishment to form a positive electrode slurry, the lithium replenishment amount 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.

[0102] For example, the lithium replenishment amount 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.

[0103] After obtaining the proportion of the positive electrode slurry, the manufacturing device and the lithium replenishing device can manufacture the positive electrode slurry according to the proportion. For example, the manufacturing device adds the positive electrode material, the conductive agent, the binder, the glue and other components into the mixer according to the proportion in the proportion, and the lithium replenishing device adds the positive electrode lithium replenishing material into the mixer according to the proportion in the proportion, and stirs the mixture through the mixer to finally manufacture a uniformly stirred positive electrode slurry.

[0104] 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.

[0105] 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.

[0106] It should be noted that the number of cold pressing of the positive electrode sheet can be one, two, three or other appropriate times, and the embodiments of the present application are not limited to this.

[0107] Afterwards, the manufacturing device can use the slitting knife of the slitting machine to cut the positive electrode sheet, thereby cutting one positive electrode sheet into multiple positive electrodes.

[0108] Battery assembly and testing may include:

[0109] 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.

[0110] In the embodiments of the present application, the target gram capacity is first calculated by the battery balance value, and then based on the target gram capacity and the battery balance value, the amount of lithium replenishment for the positive electrode is further calculated. In this way, the amount of lithium replenishment for the positive electrode is calculated through the logical relationship between the various parameters inside the battery, which can better reflect the actual impact of each parameter on the amount of lithium replenishment, thereby improving the accuracy of the amount of lithium replenishment at the positive electrode. The high-precision amount of lithium replenishment at the positive electrode can reduce or even avoid the phenomenon of deteriorating cycle performance or poor battery energy density due to poor accuracy of the amount of lithium replenishment, reduce or even avoid the negative impact of positive electrode lithium replenishment on battery performance, and improve the battery's cycle performance and battery energy density.

[0111] Taking consumer batteries as an example, how to calculate the amount of lithium replenishment of the positive electrode by the positive electrode lithium replenishment material is explained.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] The lithium replenishment amount 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 =180mAh / g, positive electrode surface density D 正 =0.014g / cm 2 .

[0117] First, the lithium replenishment calculation device can calculate the initial efficiency E of the negative electrode. 负’ =C 负放 / C 负充 =450 / 575=78.26%.

[0118] Afterwards, the lithium replenishment amount 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 =0.014*180*[1+1.05*(1 / 0.7826-1)]-0.014*200=0.4550mAh / cm 2 .

[0119] Afterwards, the lithium replenishment amount calculation device can calculate the surface density D of the positive electrode lithium replenishment material. 正补 =A 正补 / C 正补 =0.4550 / 440=0.001034g / cm 2 .

[0120] Furthermore, the lithium replenishment amount 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)=0.001034 / (0.001034+0.014)=6.88%.

[0121] 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 Satisfy S 正 =S 负 =8cm×6cm×16×2=1536cm 2 .

[0122] The total area S of the positive electrode sheet is obtained by the lithium replenishment calculation device. 正 In this case, 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 sheet.

[0123] Taking a power battery as an example, how to calculate the amount of lithium replenishment of the positive electrode by the positive electrode lithium replenishment material is explained.

[0124] Power 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 Li5FeO4 as the positive electrode lithium supplement material.

[0125] 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 =385mAh / g, discharge capacity of negative electrode material C 负放 =350mAh / g.

[0126] By making lithium cobalt oxide and conducting a charge test, the charge capacity C of the positive electrode material is obtained. 正充 =156mAh / g, discharge capacity of positive electrode material C 正放 =150mAh / g.

[0127] By making Li5FeO4 and conducting a charge test, the gram capacity C of the positive electrode lithium supplement material was obtained. 正补 =500mAh / g.

[0128] The lithium replenishment amount calculation device obtains the above data, and also obtains the battery balance value CB=1.1, the battery target gram capacity exertion C 正发 =149mAh / g, positive electrode surface density D 正 =0.020g / cm 2.

[0129] First, the lithium replenishment calculation device can calculate the initial efficiency E of the negative electrode. 负’ =C 负放 / C 负充 =350 / 385=90.91%.

[0130] Afterwards, the lithium replenishment amount 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 =0.020*149*[1+1.1*(1 / 0.9091-1)]-0.020*156=0.1878mAh / cm 2 .

[0131] Afterwards, the lithium replenishment amount calculation device can calculate the surface density D of the positive electrode lithium replenishment material. 正补 =A 正补 / C 正补 =0.1878 / 500=0.000376g / cm 2 .

[0132] Furthermore, the lithium replenishment amount 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 )=0.000376 / (0.000376+0.020)=1.85%.

[0133] 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 Satisfy S 正 =S 负 =8cm×6cm×16×2=1536cm 2 .

[0134] The total area S of the positive electrode sheet is obtained by the lithium replenishment calculation device. 正 In this case, 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 sheet.

[0135] 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 amount calculation device, the lithium replenishment amount calculation device executes the various functions or steps performed in the above-mentioned embodiment to calculate the lithium replenishment amount of the positive electrode.

[0136] 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 the various functions or steps performed by the lithium replenishment amount calculation device in the above method embodiment to calculate the lithium replenishment amount for the positive electrode.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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: Calculate the sum of 1 and the intermediate value, the product of the positive electrode material surface density and the battery target gram capacity, and subtract the difference between the product of the positive electrode material surface density and the charged gram capacity of the positive electrode material to obtain the surface capacity of the positive electrode lithium supplement material; wherein the intermediate value is the ratio of the preset battery balance value to the first efficiency of the negative electrode material, and the difference between the battery balance value; Calculating the amount of lithium replenishment of the positive electrode lithium replenishment material based on the surface capacity of the positive electrode lithium replenishment material; When preparing the positive electrode of the battery, the positive electrode is replenished with lithium by using the positive electrode lithium replenishing material according to the lithium replenishing amount.

2. The method according to claim 1, characterized in that The lithium battery also includes a negative electrode; before calculating the amount of lithium replenishment of the positive electrode, the method includes: Obtaining the first effective value of the negative electrode; Based on the first effective value of the negative electrode, the target gram capacity of the battery is determined.

3. The method according to claim 2, characterized in that The obtaining of the first effective value of the negative electrode comprises: Obtain the charge gram capacity of the negative electrode material; Obtain the discharge gram capacity of the negative electrode material; The ratio of the discharge capacity in grams of the negative electrode to the charge capacity in grams of the negative electrode is calculated to obtain the first efficiency value of the negative electrode.

4. The method according to claim 2 or 3, characterized in that: Before calculating the amount of lithium replenishment of the positive electrode, the method includes: Obtaining the charge gram capacity of the positive electrode; Obtaining the discharge capacity in grams of the positive electrode; Based on the charged gram capacity of the positive electrode and the discharged gram capacity of the positive electrode, the target gram capacity performance of the battery is determined, wherein the target gram capacity performance is greater than or equal to the product of the charged gram capacity of the positive electrode and the first effective value of the negative electrode, and the target gram capacity performance is less than or equal to the discharged gram capacity of the positive electrode.

5. The method according to claim 1, characterized in that The calculating the surface capacity of the positive electrode lithium supplement material based on the battery balance value and the target gram capacity comprises: Obtaining the surface density of the positive electrode material; Based on the battery balance value, the target gram capacity and the surface density of the positive electrode material, the surface capacity of the positive electrode lithium supplement material is calculated; the surface capacity of the positive electrode lithium supplement material has a positive correlation with the target gram capacity.

6. The method according to claim 1, characterized in that The step of calculating the amount of lithium replenishment of the positive electrode lithium replenishment material based on the surface capacity of the positive electrode lithium replenishment material comprises: Obtaining the gram capacity of the positive electrode lithium supplement material; The ratio of the surface capacity of the positive electrode lithium replenishing material to the gram capacity of the positive electrode lithium replenishing material is calculated to obtain the lithium replenishing amount of the positive electrode lithium replenishing material.

7. The method according to claim 5 or 6, characterized in that: The method of using a positive electrode lithium replenishing material to replenish lithium to the positive electrode according to the lithium replenishing amount includes: Add the positive electrode lithium replenishing material in the lithium replenishing amount to form a positive electrode slurry to replenish the positive electrode lithium.

8. The method according to claim 7, characterized in that After calculating the lithium replenishment amount of the positive electrode lithium replenishment material, the method further includes: Obtaining the surface density of the positive electrode material; Calculating the proportion of the positive electrode lithium supplement material in the positive electrode slurry based on the surface density of the positive electrode material and the lithium supplement amount of the positive electrode lithium supplement material; Based on the proportion of the positive electrode lithium replenishing material in the positive electrode slurry, a positive electrode slurry after lithium replenishment is prepared to replenish lithium for the positive electrode.

9. A lithium battery preparation system, characterized in that: 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 8, used to calculate the lithium replenishment amount required for the positive electrode to replenish lithium; A lithium replenishing device is coupled to the lithium replenishment amount calculating device; the lithium replenishing device is used to replenish lithium to the positive electrode of the lithium battery according to the lithium replenishment amount in the lithium battery preparation method as described in any one of claims 1-8.

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