Battery module, manufacturing method and equipment thereof, battery pack and device

Abstract

The invention relates to a battery module, a manufacturing method and equipment thereof, a battery pack and a device. The battery module comprises a first type of battery cells and a second type of battery cells which are connected in series, the first type of battery cells and the second type of battery cells meet the following relation: 1.01 * C1 / C2 < = N2 < = 1.25, C1 < C2, N2 being the rechargeable battery balance rate of the second type of battery cells; c1 and C2 are the capacities of the first type of battery cells and the second type of battery cells respectively. According to the battery module disclosed by the invention, the chemical systems of the battery cells with different capacities are reasonably assembled, so that the battery module has good safety and stability, and meanwhile, the battery cells with different capacities have high energy output characteristics in the charging and discharging processes, so that the energy density of the battery module is improved.

Description

[0001] This application is a divisional application based on the application number 202010763172.X, the application date August 1, 2020, the applicant is Contemporary Amperex Technology Co., Ltd., and the application name is "Battery module and its manufacturing method and equipment, battery pack and device". Technical Field

[0002] The present application belongs to the field of battery technology, and specifically relates to a battery module and a manufacturing method and equipment thereof, a battery pack and a device. Background Art

[0003] Lithium-ion batteries (also known as lithium batteries) are a clean energy and renewable resource. They are widely used in handheld tools, small electronic terminal products, and new energy vehicles as driving power sources or energy storage units. Different application scenarios usually have different performance requirements for lithium batteries. For example, the power lithium-ion batteries used in new energy vehicles have the highest possible operating voltage and energy density, which directly determines the endurance, charging performance, acceleration performance, and safety performance of new energy vehicles.

[0004] Lithium-ion batteries, as power driving power sources or large-capacity storage units, require multiple battery cells (i.e., battery cells) to be connected in series or parallel to form a battery pack (or battery package). Therefore, how to ensure the consistency of charge and discharge between multiple battery cells in a battery pack (or battery package) during long-term use, achieve high energy output characteristics of the battery module, and also have good safety performance has become one of the urgent issues to be solved in the field of lithium-ion battery research. Summary of the invention

[0005] Lithium-ion batteries are used as power driving power sources or large-capacity storage units. Multiple battery cells (i.e., battery cells) need to be connected in series or parallel to obtain a battery pack (or battery pack). However, due to the volatility of the process during the manufacturing process, there are certain differences between the actual charge and discharge performance parameters of the battery cells and the initial design parameters. This difference will be gradually amplified during the long-term charge and discharge process, which can easily lead to inconsistent charge and discharge characteristics of multiple battery cells in the same battery module (or battery pack). At the same time, in the same battery module (or battery pack), when the battery cells with similar initial design parameters are located in different positions in the vehicle or energy storage system, during the long-term charge and discharge process, due to the inconsistent ambient temperature, external force and other conditions, the capacity attenuation characteristics of the battery cells may also vary greatly.

[0006] The applicant has found that in order to improve the energy output of the battery module, it is often necessary to fully charge and discharge multiple battery cells simultaneously during the charging and discharging process. Therefore, when the battery charging and discharging characteristics of the battery cells in the battery pack (or battery pack) are not matched, some battery cells are prone to overcharge and overdischarge due to the "barrel effect" in the charging / discharging process of the battery pack, which makes it easy for these battery cells to undergo lithium deposition, thus causing safety risks. However, if, in order to avoid causing safety risks, battery cells with "short board" charging and discharging performance are used as the upper and lower limits of the battery module's charging and discharging, the energy output performance of the battery module (or battery pack) will be greatly affected.

[0007] Therefore, the present application provides a battery module, including a first type of battery cell and a second type of battery cell,

[0008] The first type of battery cell and the second type of battery cell satisfy the following relationship:

[0009] 1.01×C 1 / C 2 ≤N 2 ≤1.25, and C 1 <C 2 ,

[0010] Among them, N 2 is the charging battery balance rate of the second type of battery; C 1 and C 2 are the capacities of the first and second types of battery cells respectively.

[0011] In the present application, by combining the capacity and charge and discharge characteristics of the first type of battery cells and the second type of battery cells, the problem is effectively solved that a battery pack containing multiple battery cells with different battery design parameters can ensure the safety performance of the battery module and greatly reduce the risk of lithium plating of the battery module, while ensuring that the battery cells with multiple different battery design parameters have high energy output characteristics during the charge and discharge process.

[0012] The present application also provides a battery pack, including the battery module of the present application, and the battery pack not only ensures good safety performance, but also has higher energy output characteristics.

[0013] The present application also provides a device, comprising the battery module or battery pack of the present application, wherein the battery module or the battery pack is used to provide power for the device and / or is an energy storage unit for the device.

[0014] The present application also provides a method for manufacturing a battery module, comprising the following steps:

[0015] Obtaining the first type of battery cells and the second type of battery cells;

[0016] Connecting the first type of battery cells and the second type of battery cells in series to form the battery module;

[0017] The first type of battery cell and the second type of battery cell satisfy the following relationship:

[0018] 1.01×C 1 / C 2 ≤N 2 ≤1.25, and C 1 <C 2 ,

[0019] Among them, N 2 is the charging battery balance rate of the second type of battery; C 1 and C 2 are the capacities of the first and second types of battery cells respectively.

[0020] In the present application, the safety and stability of the battery module are improved by balanced combination of battery cells and their connection methods, while ensuring that the battery module has high energy output characteristics, effectively reducing the risk of lithium plating during the charging and discharging process of the battery pack composed of battery cells with different battery design parameters.

[0021] The present application also provides a battery module manufacturing device, the device comprising a processor,

[0022] The processor is used to control the clamping arm to obtain the first type of battery cells and the second type of battery cells;

[0023] The processor is also used to control the assembly components to connect the first type of battery cells and the second type of battery cells in series to form the battery module;

[0024] The first type of battery cell and the second type of battery cell satisfy the following relationship:

[0025] 1.01×C 1 / C 2 ≤N 2 ≤1.25, and C 1 <C 2 ,

[0026] Among them, N 2 is the charging battery balance rate of the second type of battery; C 1 and C 2 They are the capacities of the first type of battery cell and the second type of battery cell respectively.

[0027] In the present application, by using a manufacturing device including the above-mentioned mechanism, it can be ensured that the prepared battery module has good safety and stability as well as high energy output characteristics, thereby reducing the risk of lithium plating in battery packs with cell assemblies of different battery design parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 It is a schematic diagram of an implementation of a first type of battery cell or a second type of battery cell.

[0030] Figure 2 yes Figure 1 Exploded diagram of .

[0031] Figure 3 is a schematic diagram of an embodiment of a battery module.

[0032] Figure 4 is a schematic diagram of one embodiment of a battery pack.

[0033] Figure 5 yes Figure 4 Exploded diagram of .

[0034] Figure 6 is a schematic diagram of an embodiment of a device in which a battery pack is used as a power source.

[0035] The reference numerals are described as follows:

[0036] 1 battery pack

[0037] 2 upper box

[0038] 3 lower cabinets

[0039] 4Battery Module

[0040] 5 cells DETAILED DESCRIPTION

[0041] In order to make the invention purpose, technical scheme and beneficial technical effect of the present application clearer, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the embodiments described in this specification are only for explaining the present application, not for limiting the present application.

[0042] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range, and any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.

[0043] In the description of this article, it should be noted that, unless otherwise specified, "above" and "below" are inclusive of the number, and "several" in "one or several" means two or more.

[0044] The above-mentioned summary of the invention of the present application is not intended to describe each disclosed embodiment or each implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of examples, which can be used in various combinations. In each example, enumeration is only used as a representative group and should not be interpreted as exhaustive.

[0045] The technical solution proposed in this application is:

[0046] In a first aspect, the present application provides a battery module, comprising a first type of battery cell and a second type of battery cell connected in series;

[0047] The first type of battery cell and the second type of battery cell satisfy the following relationship:

[0048] 1.01×C 1 / C 2 ≤N 2 ≤1.25, and C 1 <C 2 ,

[0049] Among them, N 2 is the charging battery balance rate of the second type of battery; C 1 and C 2 are the capacities of the first and second types of battery cells respectively.

[0050] Battery Cell

[0051] In this application, "battery cell" refers to a battery cell that can be charged and discharged independently. This application has no particular restrictions on the shape of the battery cell, which can be cylindrical, square or any other shape. Figure 1 The battery cell 5 is a square structure as an example.

[0052] In some embodiments, the battery cell may include an outer packaging for encapsulating the positive electrode sheet, the negative electrode sheet and the electrolyte.

[0053] In some embodiments, the outer packaging of the battery cell may be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, such as one or more of polypropylene PP, polybutylene terephthalate PBT, polybutylene succinate PBS, etc. The outer packaging of the battery cell may also be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.

[0054] In some embodiments, reference Figure 2 The outer package may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity.

[0055] The positive electrode sheet, the negative electrode sheet and the separator can be stacked or wound to form a stacked electrode assembly or a wound electrode assembly 52. ​​The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte can be an electrolyte, and the electrolyte is soaked in the electrode assembly 52.

[0056] The number of electrode assemblies 52 included in the battery cell 5 may be one or more, which can be adjusted according to demand.

[0057] In this application, the capacity of the battery cell has a meaning known in the art and can be tested by conventional methods. As an example, the test can be carried out by the following method: at room temperature (25°C), charge / discharge at a constant current rate of 0.33C within the operating voltage range specified in the GBT certification document, and measure the discharge capacity of the battery cell, which is recorded as the capacity of the battery cell described in this application, wherein the charge / discharge rate is the ratio of the charge / discharge current to the rated capacity of the battery cell, and the above-mentioned rated capacity is based on the capacity recognized in the GBT certification document of the battery cell, the battery module to which the battery cell belongs, or the battery pack to which the battery cell belongs. Specifically, the test process of the capacity of the battery cell is as follows: 1) First, fully discharge the battery cell, charge it at a constant current of 0.33C to the upper cut-off voltage, and charge it at a constant voltage until the current is <0.05C; 2) Pause for 10 minutes; 3) Then discharge it at a constant current of 0.33C to the lower cut-off voltage, and record the measured discharge capacity of the battery cell as the capacity of the battery cell described in this application.

[0058] In the present application, the first type of battery cells and the second type of battery cells are divided according to the capacity of the battery cells. According to the above-mentioned battery cell capacity test method, the capacity of each battery cell in the battery module is measured, and the battery cells with a capacity deviation of no more than 1.5% are divided into a type of battery cells. In this type of battery cells, the capacity of each battery cell is taken, and the average value is calculated and recorded as the capacity of this type of battery cells. When there are more than two types of battery cells in the battery module, the type of battery cells with a smaller capacity mean is defined as the first type of battery cells, and the type of battery cells with a larger capacity mean is defined as the second type of battery cells. Those skilled in the art can understand that as long as 1.01×C 1 / C 2 ≤N 2 ≤1.25, and battery modules obtained by connecting battery cells with different capacities in series are all within the protection scope of this application.

[0059] In the present application, "a first type of battery cell and a second type of battery cell connected in series" means: at least one of the first type of battery cell and at least one of the second type of battery cell are electrically connected in series. That is to say, when at least a first type of battery cell is connected in series with at least one second type of battery cell, that is, within the scope of the definition of the present application, there is no limitation on the connection relationship between other first type of battery cells and other second type of battery cells, and there is no limitation on the connection relationship between the first type of battery cells and the connection relationship between the second type of battery cells.

[0060] It is well known to those skilled in the art that the charging battery balance rate N of a battery cell refers to the ratio of the charging capacity per unit area of ​​the negative electrode plate to the charging capacity per unit area of ​​the positive electrode plate in the battery cell. In the present application, the charging battery balance rate reflects the relative amount of active lithium in the battery cell and the vacancies that can be embedded / extracted during the charging / discharging process of the battery cell. For example, in a lithium-ion secondary battery, when the battery cell is charged, the lithium ions in the battery cell are extracted from the positive electrode and embedded in the negative electrode. If the lithium ions in the positive electrode are just completely embedded in all the vacancies in the negative electrode, it is recorded as N=1; if the lithium ions in the positive electrode cannot completely fill all the vacancies in the negative electrode, then N>1; if the vacancies in the negative electrode cannot completely accommodate all the lithium ions, then N<1.

[0061] Theoretically, when N=1, the vacancies in the negative electrode can just accommodate all lithium ions. When N>1, some of the vacancies in the negative electrode of the battery cell cannot be effectively utilized, but the volume and weight of the battery cell will increase, reducing the mass energy density and volume energy density of the battery cell. When N<1, the negative electrode vacancies cannot completely accommodate all lithium ions. During discharge, lithium ions will precipitate in the negative electrode in the form of lithium dendrites, causing lithium ion loss. The growth of lithium dendrites may pierce the diaphragm, causing a short circuit between the positive and negative electrodes, thereby affecting the cycle life of the battery and posing a risk of cell failure. However, during the initial formation and subsequent cyclic charge / discharge processes of lithium-ion batteries, lithium ions undergo repeated insertion and extraction between the positive and negative electrodes. Since the SEI film is constantly formed-decomposed-reformed during the charge / discharge process of the battery cell, irreversible loss of lithium ions will inevitably occur. Therefore, in order to ensure that all types of batteries in the battery module have high energy output characteristics and good safety performance at the same time, the chemical systems of various types of batteries need to be adjusted.

[0062] The inventor has found through research that when the first and second type of cells with different capacities in a battery module are electrically connected in series, the first and second type of cells will be charged and discharged synchronously, and the first type of cells with lower capacity will become the "short board" of the charging and discharging process. When the battery module needs to achieve higher output characteristics, the first type of cells are at risk of overcharging or over-discharging. In this application, the inventor has studied the charging battery balance rate (N) of the second type of cells used in conjunction with the first type of cells. 2 ) limits the range of the battery balance rate N of the second type of battery with higher average capacity. 2 Satisfy: 1.01×C 1 / C 2 ≤N 2 ≤1.25. The charging battery balance rate N of the second type of battery with higher capacity 2 When it is within the above range, it can avoid the over-discharge of the first type of battery cell and the precipitation of lithium dendrites caused by the excessive lithium ions in the second type of battery cell, thus ensuring the safety and stability of the battery cell, and at the same time avoid the problem of low battery cell energy utilization and high cost caused by the excessively high capacity of the second type of battery cell. In addition, due to the reasonable selection of battery cells, the vacancies of the positive and negative electrodes of the battery cells are reasonably matched with the lithium ion capacity, which also avoids the problem of excessive weight and volume of the battery module caused by too many vacancies of the positive and negative electrodes.

[0063] Optionally, 1.01×C 1 / C 2 ≤N 2 ≤1.20. Further optionally, 1.01×C 1 / C 2 ≤N 2 ≤1.18, or 1.01×C 1 / C2 ≤N 2 ≤1.01. When the capacity of the first type of battery cell and the second type of battery cell and the charging battery balance rate are within the above range, the weight and volume of the battery module can be further reduced, providing more possibilities for the application of the battery module in the direction of high energy density.

[0064] In the embodiment of the present application, the relationship between the capacity of the first type of battery cell and the capacity of the second type of battery cell can be further defined, that is, the capacity C of the first type of battery cell is 1 The capacity of the second type of battery C 2 Satisfaction: C 2 / C 1 ≤1.2. In particular, the capacity C of the first type of battery cell 1 The capacity of the second type of battery C 2 Satisfaction: C 2 / C 1 ≤1.1. Furthermore, C 2 / C 1 ≤1.05. When the capacity C of the first type of battery 1 The capacity of the second type of battery C 2 When the above range is met, the loss caused by the inability to fully utilize the capacity of the second type of battery cells can be reduced while ensuring the improvement of the energy density and safety performance of the battery module.

[0065] In this application, the mass of active material per unit area of ​​the positive and negative pole pieces of the battery cell and the charge capacity of the positive and negative pole pieces of the battery cell are key indicators of the battery cell chemical system design, which directly determine the range of the rechargeable battery balance rate N of the battery cell. The inventor of this application adjusts the rechargeable battery balance rate N of the first type of battery cell and the second type of battery cell according to the formula: N = WA × BA / (WC × BC). Among them, WA is the mass of active material per unit area of ​​the negative pole piece of the battery cell, unit: μg / mm 2 BA is the charge capacity of the negative electrode of the battery cell, unit: mAh / g, WC is the mass of active material per unit area of ​​the positive electrode of the battery cell, unit: μg / mm 2 , BC is the charge-discharge capacity of the positive electrode of the battery cell, unit: mAh / g. In the present application, by adjusting the mass of active material per unit area of ​​the positive and negative electrode in the battery cell and one or more variables in the charge-discharge capacity of the positive and negative electrode, the first type of battery cell and the second type of battery cell can have different charging battery balance rates, thereby matching the battery charge and discharge characteristics of the first type of battery cell and the second type of battery cell.

[0066] In some embodiments of the present application, the charging battery balance rate N of the first type of battery cell is 1 N 1 =WA1 ×BA 1 / (WC 1 ×BC 1 ). Among them, WA 1 is the mass of active material per unit area of ​​the negative electrode sheet of the first type of battery cell, BA 1 The negative electrode of the first type of battery cell is charged with a charge capacity of gram and WC 1 is the mass of active material per unit area of ​​the positive electrode sheet of the first type of battery cell, BC 1 Charge the positive electrode of the first type of battery cell and deduct the gram capacity.

[0067] Optionally, the first type of battery cell meets at least one of the following conditions:

[0068] (1) The mass of active material per unit area of ​​the negative electrode sheet of the first type of battery cell WA 1 60 μg / mm 2 ≤WA 1 ≤170μg / mm 2 ; optional, 80μg / mm 2 ≤WA 1 ≤130μg / mm 2 ; further optional, 90 μg / mm 2 ≤WA 1 ≤120μg / mm 2 ;

[0069] (2) The negative electrode charging capacity BA of the first type of battery cell 1 320mAh / g≤BA 1 ≤380mAh / g;

[0070] (3) The mass of active material per unit area of ​​the positive electrode sheet of the first type of battery cell WC 1 120 μg / mm 2 ≤WC 1 ≤280μg / mm 2 ; optional, 160μg / mm 2 ≤WC 1 ≤210μg / mm 2 ; further optional, 163 μg / mm 2 ≤WC 1 ≤208μg / mm 2 ;

[0071] (4) The positive electrode charge capacity BC of the first type of battery cell 1 100mAh / g≤BC 1 ≤230mAh / g; optional, 125mAh / g≤BC 1≤200mAh / g; further optional, 150mAh / g≤BC 1 ≤190mAh / g.

[0072] Optionally, the first type of battery cell satisfies the above conditions (1) to (4) at the same time. In the present application, when the first type of battery cell satisfies the above conditions (1) to (4) at the same time, on the one hand, it can ensure that the electrode is not prone to cracking during production, thereby improving the safety performance of the battery cell; and ensure that the mass energy density and volume energy density of the battery cell are high; on the other hand, it can also control the lithium ion transmission path, ensure that the battery cell has good power performance, and reduce the temperature rise of the battery cell during actual use.

[0073] In some embodiments of the present application, the charging battery balance rate N of the first type of battery cell is 1 Satisfy 0.9≤N 1 ≤1.3; optional, 0.95≤N 1 In the present application, when the rechargeable battery balance rate of the first type of battery cell is within the above range, the utilization rate of the positive and negative active materials in the first type of battery cell can be further improved, which is beneficial to improve the volume energy density of the battery cell while ensuring that the risk of lithium plating of the battery cell is low.

[0074] In some embodiments of the present application, the charging battery balance rate N of the second type of battery cell is 2 N 2 =WA 2 ×BA 2 / (WC 2 ×BC 2 ). Among them, WA 2 is the mass of active material per unit area of ​​the negative electrode sheet of the second type of battery cell, BA 2 Charge the negative electrode of the second type of battery cell to deduct the gram capacity, WC 2 is the mass of active material per unit area of ​​the positive electrode sheet of the second type of battery cell, BC 2 The positive electrode of the second type of battery cell is charged and the gram capacity is deducted. Optionally, the second type of battery cell meets at least one of the following conditions:

[0075] (1) The mass of active material per unit area of ​​the negative electrode sheet of the second type of battery cell WA 2 60 μg / mm 2 ≤WA 2 ≤170μg / mm 2 ; optional, 65μg / mm 2 ≤WA 2 ≤120μg / mm 2 ; further optional, 85 μg / mm 2 ≤WA 2 ≤110μg / mm2 ;

[0076] (2) The negative electrode charging capacity BA of the second type of battery 2 320mAh / g≤BA 2 ≤380mAh / g;

[0077] (3) The mass of active material per unit area of ​​the positive electrode sheet of the second type of battery cell WC 2 300 μg / mm 2 ≤WC 2 ≤650μg / mm 2 ; optional, 190 μg / mm 2 ≤WC 2 ≤210μg / mm 2 ; further optional, 195 μg / mm 2 ≤WC 2 ≤208μg / mm 2 ;

[0078] (4) The positive electrode charge capacity BC of the second type of battery cell 2 100mAh / g≤BC 2 ≤230mAh / g.

[0079] Optionally, the second type of battery cell satisfies the above conditions (1) to (4) at the same time. In the present application, when the second type of battery cell satisfies the above conditions (1) to (4) at the same time, on the one hand, it can ensure that the electrode is not prone to cracking during production, thereby improving the safety performance of the battery cell; at the same time, it can ensure that the mass energy density and volume energy density of the battery cell are high; on the other hand, it can also control the lithium ion transmission path to ensure that the battery cell has good fast charging performance.

[0080] In some embodiments of the present application, the charging battery balance rate N of the second type of battery cell is 2 Satisfy 0.8≤N 2 ≤1.25; optional, 0.9≤N 2 In the present application, when the rechargeable battery balance rate of the second type of battery cell is within the above range, the utilization rate of the positive and negative active materials in the second type of battery cell can be further improved, which is beneficial to improve the volume energy density of the battery cell while ensuring that the risk of lithium plating of the battery cell is low.

[0081] In some embodiments of the present application, the number of cells in the battery module is not particularly limited. The number of the first type of cells and the second type of cells in the battery module can be adjusted according to the use requirements, so as to further optimize the performance of the expected battery module. In the battery module, the number of the first type of cells is n 1 , the number of the second type of cells is n2 , n 1 and n 2 is a natural number, and the number of the first type of cells n 1 The number of the second type of cells n 2 Can satisfy: 0.01≤n 1 / n 2 ≤100. Optional, 0.05≤n 1 / n 2 ≤80, 0.08≤n 1 / n 2 ≤50, 0.1≤n 1 / n 2 ≤20, or 0.1≤n 1 / n 2 ≤10.

[0082] In some embodiments of the present application, in the battery module, the number of the first type of battery cells is n. 1 , the number of the second type of cells is n 2 , n 1 and n 2 is a natural number, and the total capacity of the second type of battery cells accounts for 10%-60% of the total capacity of the battery module, and optionally 12%-50%. That is: 10% ≤ n 2 ×C 2 / (n 1 ×C 1 +n 2 ×C 2 )≤60%; optional, 12%≤n 2 ×C 2 / (n 1 ×C 1 +n 2 ×C 2 )≤50%. When the total capacity of the second type of battery cells accounts for the total capacity of the battery module within the above range, the functions of the second type of battery cells can be maximized without affecting the performance of the first type of battery cells, thereby improving the comprehensive performance of the battery module.

[0083] In some embodiments of the present application, the chemical systems of the first type of battery cell and the second type of battery cell are selected the same as conventional lithium-ion batteries. Optionally, the chemical systems of the first type of battery cell and the second type of battery cell are independently selected from one of a lithium nickel cobalt manganese system, a lithium iron phosphate system, a lithium iron vanadium phosphate system, a lithium vanadium phosphate system, a lithium cobalt oxide system, a lithium nickel oxide system, a lithium-rich manganese system, a lithium nickel cobalt aluminum system, and a lithium manganese oxide system.

[0084] In some embodiments of the present application, the chemical system of the first type of battery cell is one of a lithium nickel cobalt manganese system, a lithium cobalt oxide system, a lithium nickel oxide system, a lithium-rich manganese-based system, a lithium nickel cobalt aluminum system, and a lithium manganese oxide system. The chemical system of the second type of battery cell is one of a lithium iron phosphate system, a lithium vanadium iron phosphate system, or a lithium vanadium phosphate system. In the present application, when the first type of battery cell and the second type of battery cell are battery cells of different chemical systems, since the coulombic efficiency of the first charge and discharge and the long-term capacity attenuation trend of the battery cells of different types of positive active materials are different, the battery cells of different chemical systems are combined. While ensuring that the safety performance and energy density of the battery module are both high, the advantages and disadvantages of different types of battery cells can be complemented, thereby further optimizing the comprehensive performance of the battery module.

[0085] Optionally, the first type of battery cell can be a lithium nickel cobalt manganese oxide system, and the second type of battery cell can be a lithium iron phosphate system. In the present application, when the capacity of the first type of battery cell and the second type of battery cell in the battery module is different, and the battery charging battery balance rate of the second type of battery cell is set within the above range, the first type of battery cell is selected as a lithium nickel cobalt manganese oxide system and the second type of battery cell is selected as a lithium iron phosphate system, the advantages of the lithium iron phosphate system, such as slow capacity decay and long life, can be used to reduce the actual capacity difference deviation between batteries of different battery designs when the battery module is in the middle and late stages of the cycle life, thereby extending the service life of the battery module.

[0086] Those skilled in the art will understand that individual differences in battery cells will lead to unbalanced voltages at the terminals of different battery cells. In order to avoid the deterioration of this unbalanced trend, before the battery module is used, it is necessary to increase the charging voltage of the battery module and activate the battery module to achieve balanced characteristics of each battery cell in the battery module, extend the life of the battery cell, and improve energy utilization. For example, optional bottom balancing / top balancing, active balancing / passive balancing charging / discharging strategies are available. This application does not limit the balancing strategy, and the battery module obtained after the balancing strategy is applied to the battery module of this application is also within the definition of the battery module of this application.

[0087] Figure 3 A battery module 4 is shown as an example. Figure 3 The battery module 4 may include a plurality of first-type battery cells 5a and a plurality of second-type battery cells 5b arranged along the length direction (eg, L direction) of the battery module 4. The battery cells may be further fixed by fasteners.

[0088] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0089] In the present application, the capacity of the battery cell, the capacity of the first type of battery cell, and the capacity of the second type of battery cell have meanings well known in the art and can be tested according to the aforementioned method.

[0090] In this application, the mass of active material per unit area of ​​the pole piece has a well-known meaning in the art, and refers to the mass of active material in the active material layer on one side of the current collector per unit area, which can be measured by methods known in the art. For example, take a pole piece that has been coated on one side and cold pressed (if it is a pole piece coated on both sides, the active material layer on one side can be wiped off first), and punch it into small discs with an area of ​​S1; then soak the active material layer on the surface of the pole piece with a solvent and completely peel it off from the surface of the current collector; repeatedly rinse the active material obtained above, dry it, and sinter it at 500°C in an air atmosphere. Finally, weigh the mass of the remaining material obtained after sintering, and record it as M. Therefore, the mass of active material per unit area of ​​the pole piece can be calculated according to the formula: mass of active material per unit area of ​​the pole piece = M / S1.

[0091] In this application, the charging capacity and charging capacity of the positive electrode sheet or the negative electrode sheet are well known in the art and can be tested by conventional methods. As an example, the following steps can be used for testing:

[0092] (1) The requirements for electrode sampling are as follows:

[0093] After fully discharging the battery cell, disassemble it, take out the positive and negative pole pieces, rinse them with DMC solution, and dry them for later use. The sampling position of the positive pole piece is: select any position in the middle that is >15mm away from the edge. The sampling position of the negative pole piece is: select the negative pole piece that is opposite to the selected positive pole piece; and the sampling area of ​​the positive pole piece is the same as that of the negative pole piece;

[0094] (2) Assembling a button cell using the above-cut positive electrode sheet, negative electrode sheet and lithium sheet as counter electrodes;

[0095] (3) Charging capacity of negative electrode sheet per unit area and charging capacity of negative electrode sheet:

[0096] The test voltage is 0.05-2.0V, the test temperature is 25°C, the charge / discharge rate is 0.1C, and no less than 10 parallel samples are taken to test the charging capacity of the button half-cell respectively. The lowest and highest values ​​are removed and the average value is taken to obtain the charging capacity of the negative electrode sheet under the area; the charging capacity of the negative electrode sheet obtained by the above test is divided by the area of ​​the negative electrode sheet to obtain the charging capacity of the negative electrode sheet per unit area;

[0097] Negative electrode sheet charge capacity = negative electrode sheet charge capacity per unit area / active material mass per unit area of ​​negative electrode sheet;

[0098] (4) Charging capacity of positive electrode per unit area and charging capacity of positive electrode:

[0099] Within the working voltage range specified in the GBT certification document of the sampled battery cell and at room temperature of 25°C, charge / discharge at 0.1C, take no less than 10 parallel samples, test the charging capacity of the button battery respectively, remove the lowest and highest values ​​and take the average value to obtain the charging capacity of the positive electrode sheet under the area; divide the charging capacity of the positive electrode sheet obtained by the above test by the area of ​​the positive electrode sheet to obtain the charging capacity of the positive electrode sheet per unit area;

[0100] The gram capacity of the positive electrode sheet when charged = the charging capacity of the positive electrode sheet per unit area / the mass of active material of the positive electrode sheet per unit area.

[0101] In this application, the rechargeable battery balance rate of the battery cell is a well-known meaning in the art and can be tested by conventional methods. As an example, the following test method can be used: according to the above method, the charging capacity per unit area of ​​the negative electrode sheet and the charging capacity per unit area of ​​the positive electrode sheet are tested respectively; then according to the formula: battery cell rechargeable battery balance rate = negative electrode sheet charging capacity per unit area / positive electrode sheet charging capacity per unit area, the rechargeable battery balance rate of the battery cell can be calculated.

[0102] In a second aspect, the present application proposes a battery pack, comprising the above-mentioned battery module.

[0103] In some embodiments, the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0104] Figure 4 and Figure 5 As an example, a battery pack 1 is shown. Figure 4 and Figure 5 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0105] In a third aspect, the present application proposes a device, comprising the above-mentioned battery module, wherein the battery module is a power source and / or energy storage unit of the device.

[0106] The device may be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.

[0107] The device can select a battery module or a battery pack according to its usage requirements.

[0108] Figure 6 The device is used as an example. The device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the device's requirements for high power and high energy density of secondary batteries, a battery pack or battery module can be used.

[0109] In a fourth aspect, the present application proposes a method for manufacturing a battery module, comprising the following steps:

[0110] Obtaining the first type of battery cells and the second type of battery cells;

[0111] Connecting the first type of battery cells and the second type of battery cells in series to form the battery module;

[0112] The first type of battery cell and the second type of battery cell satisfy the following relationship:

[0113] 1.01×C 1 / C 2 ≤N 2 ≤1.25, and C 1 <C 2 ,

[0114] Among them, N 2 is the charging battery balance rate of the second type of battery; C 1 and C 2 are the capacities of the first and second types of battery cells respectively.

[0115] The manufacturing method of the battery module of the present application designs the battery cells and their connection methods so that the assembled battery module can achieve a balanced combination of battery cells, thereby improving the safety and stability of the battery module, while ensuring that the battery module has high energy output characteristics, and effectively reducing the risk of lithium plating during the charging and discharging process of the battery pack composed of battery cells with different battery design parameters.

[0116] Further, obtaining the first type of battery cell and the second type of battery cell includes: obtaining n 1 The first type of cells and n 2 The second type of cells, n 1 and n 2 It can be understood that the battery cell obtained by the manufacturing method of the present application may include a plurality of first-type battery cells or a plurality of second-type battery cells, and the number of battery cells is not limited.

[0117] In a fifth aspect, the present application provides a manufacturing device for a battery module, the device comprising a processor, the processor being used to control a clamping arm to obtain a first type of battery cell and a second type of battery cell; the processor being further used to control an assembly component to connect the first type of battery cell and the second type of battery cell in series to form the battery module;

[0118] The first type of battery cell and the second type of battery cell satisfy the following relationship:

[0119] 1.01×C 1 / C 2 ≤N 2 ≤1.25, and C 1 <C 2 , where N 2 is the charging battery balance rate of the second type of battery; C 1 and C 2 are the capacities of the first and second types of battery cells respectively.

[0120] The battery module manufactured by the equipment of the present application can ensure that the prepared battery module has good safety and stability as well as high energy output characteristics by balanced assembly of battery cells and their connection methods, thereby reducing the risk of lithium plating in battery modules assembled with battery cells of different battery design parameters.

[0121] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application.

[0122] Example

[0123] The following examples more specifically describe the disclosure of the present application, which are intended for illustrative purposes only, as it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the disclosure of the present application. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0124] The performance parameters of the battery cells used in the examples and comparative examples of the present application are shown in Table 1. Among them, LFP-lithium iron phosphate, NCM-lithium nickel cobalt manganese oxide (LiNi 0.6 Co 0.2 Mn 0.2 O 2 ), LNMO-lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O 2 ), LMO-lithium manganate (LiMn 2 O 4 ), NCA-lithium nickel cobalt aluminum oxide (LiNi 0.8 Co 0.15 Al 0.05 O 2 ), lithium-rich manganese (Li 1.2 Mn 0.44 Ni0.4 Co 0.16 O 2 ).

[0125] Table 1 Battery performance parameters

[0126]

[0127]

[0128] The above-mentioned battery performance parameter test can be carried out by the following method:

[0129] 1. Mass of active material per unit area of ​​the positive electrode

[0130] Take the positive electrode sheet that has been coated on one side and cold pressed (if it is a positive electrode sheet coated on both sides, the active material layer on one side can be wiped off first), and punch it into small discs with an area of ​​S1; then place the positive electrode sheet in NMP solution to completely peel off the positive electrode active material layer; rinse and dry the negative electrode active material obtained after peeling; sinter the dried material at about 500℃ in air atmosphere for 4 to 5 hours. Finally, weigh the mass of the remaining material obtained after sintering, recorded as M c Therefore, the mass of active material per unit area of ​​the positive electrode sheet can be calculated according to the following formula:

[0131] The mass of active material per unit area of ​​the positive electrode = M c / S1.

[0132] 2. Mass of active material per unit area of ​​the negative electrode

[0133] Take the negative electrode sheet that has been coated on one side and cold pressed (if it is a negative electrode sheet coated on both sides, wipe off the active material layer on one side first), punch it into small discs with an area of ​​S1; then place the negative electrode sheet in deionized water to completely peel off the negative electrode active material layer; rinse and dry the positive electrode active material obtained after peeling; sinter it at about 500℃ in air atmosphere for 4 to 5 hours. Finally, weigh the mass of the remaining material obtained after sintering, record it as M A Therefore, the mass of active material per unit area of ​​the electrode can be calculated according to the formula: The mass of active material per unit area of ​​the electrode = M A / S1.

[0134] 2. Charging capacity and charging capacity of positive or negative electrode

[0135] (1) The requirements for electrode sampling are as follows:

[0136] After fully discharging the battery cell, disassemble it, take out the positive and negative pole pieces, rinse them with DMC solution, and dry them for later use. The sampling position of the positive pole piece is: select any position in the middle that is >15mm away from the edge. The sampling position of the negative pole piece is: select the negative pole piece that is opposite to the selected positive pole piece; and the sampling area of ​​the positive pole piece is the same as that of the negative pole piece;

[0137] (2) Assembling a button cell using the above-cut positive electrode sheet, negative electrode sheet and lithium sheet as counter electrodes;

[0138] (3) Charging capacity of negative electrode sheet per unit area and charging capacity of negative electrode sheet:

[0139] The test voltage is 0.05-2.0V, the test temperature is 25°C, the charge / discharge rate is 0.1C, and no less than 10 parallel samples are taken to test the charging capacity of the button half-cell respectively. The lowest and highest values ​​are removed and the average value is taken to obtain the charging capacity of the negative electrode sheet under the area; the charging capacity of the negative electrode sheet obtained by the above test is divided by the area of ​​the negative electrode sheet to obtain the charging capacity of the negative electrode sheet per unit area;

[0140] Negative electrode sheet charge capacity = negative electrode sheet charge capacity per unit area / active material mass per unit area of ​​negative electrode sheet;

[0141] (4) Charging capacity of positive electrode per unit area and charging capacity of positive electrode:

[0142] Within the working voltage range specified in the GBT certification document of the sampled battery cell and at room temperature of 25°C, charge / discharge at 0.1C, take no less than 10 parallel samples, test the charging capacity of the button battery respectively, remove the lowest and highest values ​​and take the average value to obtain the charging capacity of the positive electrode sheet under the area; divide the charging capacity of the positive electrode sheet obtained by the above test by the area of ​​the positive electrode sheet to obtain the charging capacity of the positive electrode sheet per unit area;

[0143] The gram capacity of the positive electrode sheet when charged = the charging capacity of the positive electrode sheet per unit area / the mass of active material of the positive electrode sheet per unit area.

[0144] 3. Battery cell charging battery balance rate test method:

[0145] According to the above method, the charging capacity of the negative electrode sheet per unit area and the charging capacity of the positive electrode sheet per unit area are tested respectively; then according to the formula: battery cell charging battery balance rate = negative electrode sheet charging capacity per unit area / positive electrode sheet charging capacity per unit area, the charging battery balance rate of the battery cell can be calculated.

[0146] 4. Cell mass energy density

[0147] The mass energy density of a cell is the maximum energy of the cell divided by the mass of the cell when it is within the operating voltage range specified in the GBT certification document for the sampled cell.

[0148] In the following examples and comparative examples, the battery module was tested as follows:

[0149] 1. Battery module lithium plating detection method

[0150] The test process is as follows:

[0151] 1) Charge the battery module at a constant current of 0.33C to the upper cut-off voltage specified in the GBT certification document, and then charge at a constant voltage until the current is less than 0.05C;

[0152] 2) Pause for 10 minutes;

[0153] 3) 0.33C constant current discharge to the lower cut-off voltage specified in the GBT certification document;

[0154] 4) The steps 1) to 3) are one charge-discharge cycle, and 20 cycles of charge-discharge are performed;

[0155] 5) Charge the battery module at a constant current of 0.33C to the upper cut-off voltage, and then charge at a constant voltage until the current is less than 0.05C; disassemble the battery cells in the battery module, take out the negative electrode plate and observe whether there is lithium precipitation on the surface of the plate. In the test results, the lithium precipitation detection data is expressed as the lithium precipitation detection pass rate, which is the number of cells with no lithium precipitation on the negative electrode plate / the total number of cells used for lithium precipitation detection.

[0156] 2. Battery module mass capacity density test method

[0157] The mass capacity density of a battery module is the sum of the capacities of all battery cells in the battery module divided by the mass of the battery module, excluding other components of the battery module (including but not limited to wiring harnesses, end plates and / or side plates, and top cover plates).

[0158] 3. Battery module volume capacity density test method

[0159] The volume capacity density of a battery module is the sum of the capacities of all battery cells in the battery module divided by the total volume of the battery module (length × width × height), wherein the total volume of the battery module includes the volume of all battery cells and other components of the battery module (including but not limited to wiring harnesses, end plates and / or side plates, and top cover plates).

[0160] Example 1

[0161] Embodiment 1 provides a battery module, which includes 6 battery cells 16 and 3 battery cells 22, and the 6 battery cells 16 and the 3 battery cells are connected in series. From the data in Table 1, it can be seen that the capacity of the battery cell 16 is smaller than the capacity of the battery cell 22, that is, the battery cell 16 is a first type of battery cell, the battery cell 22 is a second type of battery cell, and the charging battery balance rate N of the battery cell 22 is 2 Satisfy: 1.01×C 1 / C 2 ≤N 2 ≤1.25.

[0162] Embodiment 1 also proposes a method for manufacturing the above-mentioned battery module, comprising the following steps:

[0163] Obtain 6 first-type battery cells (battery cells 16) and 3 second-type battery cells (battery cells 22);

[0164] The battery cell 16 and the battery cell 22 are connected in series to form the battery module.

[0165] Example 1 also proposes a manufacturing device for the above-mentioned battery module, which includes a processor, and the processor is used to control the clamping arm to obtain the first type of battery cell (battery cell 16) and the second type of battery cell (battery cell 22); the processor is also used to control the assembly parts to connect the battery cell 16 and the battery cell 22 in series to form the battery module.

[0166] Example 2

[0167] Embodiment 2 provides a battery module, which includes six battery cells 8 and three battery cells 32 , wherein the battery cells 8 are first-type battery cells and the battery cells 32 are second-type battery cells, wherein one battery cell 8 is connected in series with two battery cells 32 .

[0168] Example 3

[0169] Embodiment 3 provides a battery module, which includes 6 battery cells 16 and 3 battery cells 1, wherein the battery cells 16 are first-type battery cells and the battery cells 1 are second-type battery cells, wherein one battery cell 16 is connected in series with two battery cells 1.

[0170] Example 4

[0171] Embodiment 4 provides a battery module, which includes 6 battery cells 10 and 3 battery cells 2, wherein the battery cells 10 are first-type battery cells, and the battery cells 2 are second-type battery cells, wherein one battery cell 10 is connected in series with two battery cells 2.

[0172] Example 5

[0173] Embodiment 5 provides a battery module, which includes 6 battery cells 10 and 3 battery cells 1, wherein the battery cells 10 are first-type battery cells and the battery cells 1 are second-type battery cells, wherein one battery cell 10 is connected in series with two battery cells 1.

[0174] Example 6

[0175] Embodiment 6 provides a battery module, which includes 6 battery cells 10 and 3 battery cells 4 , wherein the battery cells 10 are first-type battery cells and the battery cells 4 are second-type battery cells, wherein one battery cell 10 is connected in series with two battery cells 4 .

[0176] Example 7

[0177] Embodiment 7 provides a battery module, which includes 6 battery cells 8 and 3 battery cells 3 , wherein the battery cells 8 are first-type battery cells and the battery cells 3 are second-type battery cells, wherein one battery cell 8 is connected in series with two battery cells 3 .

[0178] Comparative Example 1

[0179] Comparative Example 1 provides a battery module, which includes 6 battery cells 10 and 3 battery cells 30, the battery cells 10 are first-type battery cells, and the battery cells 30 are second-type battery cells, wherein one battery cell 10 is connected in series with two battery cells 30.

[0180] Comparative Example 2

[0181] Comparative Example 2 provides a battery module, which includes 6 battery cells 9 and 3 battery cells 19, the battery cells 9 are first-type battery cells, and the battery cells 19 are second-type battery cells, wherein one battery cell 9 is connected in series with two battery cells 19.

[0182] Comparative Example 3

[0183] Comparative Example 3 provides a battery module, which includes 6 battery cells 10 and 3 battery cells 19, the battery cells 10 are first-type battery cells, and the battery cells 19 are second-type battery cells, wherein one battery cell 10 is connected in series with two battery cells 19.

[0184] Comparative Example 4

[0185] Comparative Example 4 provides a battery module, which includes 6 battery cells 10 and 3 battery cells 23, the battery cells 10 are first-type battery cells, and the battery cells 23 are second-type battery cells, wherein one battery cell 10 is connected in series with two battery cells 23.

[0186] The test data of the battery modules of Examples 1-7 and Comparative Examples 1-4 are shown in Table 2.

[0187] Table 2 Test data of battery modules of Examples 1-7 and Comparative Examples 1-4

[0188]

[0189] Note: The mass of mechanical parts is not included in the calculation of mass capacity density.

[0190] Comparing the data of Examples 1-7 and Comparative Examples 1-4, it can be seen that when N 2 Not at 1.01×C 1 / C 2 ≤N 2 When it is within the range of ≤1.25, the mass capacity density of the battery module will deteriorate or cause lithium plating problems. Specifically, in Comparative Example 1, although the mass capacity density of the battery module is relatively high, the lithium plating pass rate is only 10 over 6, and the safety performance has great hidden dangers. In Comparative Example 4, while the battery module has the risk of lithium plating, the mass capacity density of the battery module is also seriously deteriorated. In Comparative Examples 2 to 3, although the lithium plating pass rate of the battery module is relatively high, the mass capacity density of the battery module is seriously deteriorated, affecting the energy output performance of the battery module.

[0191] Example 8

[0192] Embodiment 8 provides a battery module, which includes six battery cells 10 and three battery cells 26 , wherein the battery cells 10 are first-type battery cells and the battery cells 26 are second-type battery cells, wherein one battery cell 10 is connected in series with two battery cells 26 .

[0193] Example 9

[0194] Embodiment 9 provides a battery module, which includes six battery cells 10 and three battery cells 27 , wherein the battery cells 10 are first-type battery cells and the battery cells 27 are second-type battery cells, wherein one battery cell 10 is connected in series with two battery cells 27 .

[0195] Example 10

[0196] Embodiment 10 provides a battery module, which includes 6 battery cells 10 and 3 battery cells 28 , wherein the battery cells 10 are first-type battery cells and the battery cells 28 are second-type battery cells, wherein one battery cell 10 is connected in series with two battery cells 28 .

[0197] Embodiment 11

[0198] Embodiment 11 provides a battery module, which includes 6 battery cells 10 and 3 battery cells 29 , wherein the battery cells 10 are first-type battery cells and the battery cells 29 are second-type battery cells, wherein one battery cell 10 is connected in series with two battery cells 29 .

[0199] The test data of the battery modules of Examples 8-11 are shown in Table 3.

[0200] Table 3 Test data of battery modules in Examples 8-11

[0201]

[0202]

[0203] It can be seen from Examples 8-11 that when the charging battery balance rate N of the second type of battery cell is 2 Meets 1.01×C 1 / C 2 ≤N 2 ≤1.25, the capacity of the first type of battery and the second type of battery further meets: C 2 / C 1 ≤1.2, especially C 2 / C 1 When the value of gradually decreases, for example, C 2 / C 1 When =1.1, lithium plating is not easy to occur in the battery module, and the volume capacity density and energy density of the battery module are getting higher and higher.

[0204] Example 12

[0205] Embodiment 12 provides a battery module, which includes one battery cell 16 and 100 battery cells 1, wherein the battery cell 16 is a first type of battery cell, and the battery cell 1 is a second type of battery cell, wherein the battery cell 16 is connected in series with 84 battery cells 1.

[0206] Example 13

[0207] Embodiment 13 provides a battery module, which includes one battery cell 16 and ten battery cells 1, wherein the battery cell 16 is a first type of battery cell, and the battery cell 1 is a second type of battery cell, wherein the battery cell 16 is connected in series with two battery cells 1.

[0208] Embodiment 14

[0209] Embodiment 14 provides a battery module, which includes one battery cell 16 and nine battery cells 1 , wherein the battery cell 16 is a first type of battery cell, and the battery cell 1 is a second type of battery cell, wherein the battery cell 16 is connected in series with two battery cells 1 .

[0210] Embodiment 15

[0211] Embodiment 15 provides a battery module, which includes 5 battery cells 16 and 5 battery cells 1, wherein the battery cells 16 are first-type battery cells, and the battery cells 1 are second-type battery cells, wherein 2 battery cells 16 are connected in series with 2 battery cells 1.

[0212] Example 16

[0213] Embodiment 16 provides a battery module, which includes 5 battery cells 16 and 1 battery cell 1, wherein the battery cell 16 is a first type of battery cell, and the battery cell 1 is a second type of battery cell, wherein the battery cell 16 is connected in series with the battery cell 1.

[0214] Embodiment 17

[0215] Embodiment 17 provides a battery module, which includes 10 battery cells 16 and 1 battery cell 1, wherein the battery cell 16 is a first type of battery cell, and the battery cell 1 is a second type of battery cell, wherein one battery cell 16 is connected in series with the battery cell 1.

[0216] Embodiment 18

[0217] Embodiment 18 provides a battery module, which includes 20 battery cells 16 and 1 battery cell 1, wherein the battery cell 16 is a first type of battery cell, and the battery cell 1 is a second type of battery cell, wherein three battery cells 16 are connected in series with the battery cell 1.

[0218] Embodiment 19

[0219] Embodiment 19 provides a battery module, which includes 50 battery cells 16 and 1 battery cell 1, the battery cell 16 is a first type of battery cell, the battery cell 1 is a second type of battery cell, wherein 12 battery cells 16 are connected in series with the battery cell 1.

[0220] Embodiment 20

[0221] Embodiment 20 provides a battery module, which includes 80 battery cells 16 and 1 battery cell 1, the battery cell 16 is a first type of battery cell, and the battery cell 1 is a second type of battery cell, wherein 63 battery cells 16 are connected in series with the battery cell 1.

[0222] Embodiment 21

[0223] Embodiment 21 provides a battery module, which includes 100 battery cells 16 and 1 battery cell 1, the battery cell 16 is a first type of battery cell, the battery cell 1 is a second type of battery cell, wherein 37 battery cells 16 are connected in series with the battery cell 1.

[0224] The test data of the battery modules of Examples 12-21 are shown in Table 4.

[0225] Table 4 Test data of battery modules in Examples 12-21

[0226]

[0227]

[0228] Comparing Examples 12 to 21, it can be seen that when the charging battery balance rate N of the second type of battery cell is 2 Meets 1.01×C 1 / C2 ≤N 2 ≤1.25, 0.01≤n 1 / n 2 When the charge balance rate N of the second type of battery is less than 100, there will be no lithium precipitation at the negative electrode of the battery cell that constitutes the battery module. 2 Meets 1.01×C 1 / C 2 ≤N 2 ≤1.25, 0.1≤n 1 / n 2 ≤10, especially 10%≤n 2 ×C 2 / (n 1 ×C 1 +n 2 ×C 2 )≤90%, increasing the number of the first type of battery cells can correspondingly increase the energy density and volume capacity density of the battery module. When in use, the number of battery cells in the battery module can be selected according to the performance requirements of the vehicle, such as energy density, volume and weight of the battery module.

[0229] Embodiment 22

[0230] Embodiment 22 proposes a battery pack, and the battery pack of Embodiment 22 is formed by connecting the battery modules of Embodiment 1, Embodiment 4, Embodiment 6 and Embodiment 18 in series.

[0231] Embodiment 23

[0232] Embodiment 23 proposes a battery pack, and the battery pack of Embodiment 23 is formed by connecting the battery modules of Embodiment 5, Embodiment 8, Embodiment 13, Embodiment 15 and Embodiment 22 in parallel.

[0233] Embodiment 24

[0234] Embodiment 24 proposes a battery pack. The battery pack of embodiment 24 is formed by connecting the battery packs of embodiment 1 and embodiment 3 in series and the battery module of embodiment 7 in parallel.

[0235] Embodiment 25

[0236] Embodiment 25 proposes an electric vehicle, in which the battery module of Embodiment 13 is arranged, and the battery module of Embodiment 13 is the power source and / or energy storage unit of the device.

[0237] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0238] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A battery module, It is characterized in that including a first type of battery cell and a second type of battery cell connected in series; The first type of battery cell and the second type of battery cell satisfy the following relationship: 1.01×C 1 / C 2 ≤N 2 ≤1.25, and C 1 <C 2 , 1.08≤N 2 ≤1.25, Among them, N 2 is the charging battery balance rate of the second type of battery; C 1 and C 2 are the capacities of the first and second types of battery cells respectively.

2. The battery module according to claim 1, It is characterized in that 1.01×C 1 / C 2 ≤N 2 ≤1.20; optional, 1.01×C 1 / C 2 ≤N 2 ≤1.

18.

3. The battery module according to claim 1 or 2, It is characterized in that The charging battery balance rate of the first type of battery is recorded as N 1 And satisfy 0.9≤N 1 ≤1.3; optional, 0.95≤N 1 ≤1.

2.

4. The battery module according to any one of claims 1 to 3, It is characterized in that C 2 / C 1 ≤1.2; Optionally, C 2 / C 1 ≤1.1; further optionally, C 2 / C 1 ≤1.

05.

5. The battery module according to any one of claims 1 to 4, It is characterized in that The first type of battery cell meets at least one of the following conditions: (1) The mass of active material per unit area of ​​the negative electrode sheet of the first type of battery cell WA 1 60 μg / mm 2 ≤WA 1 ≤170μg / mm 2 ; optional, 80μg / mm 2 ≤WA 1 ≤130μg / mm 2 ; further optional, 90 μg / mm 2 ≤WA 1 ≤120μg / mm 2 ; (2) The negative electrode charging capacity BA of the first type of battery cell 1 320mAh / g≤BA 1 ≤380mAh / g; (3) The mass of active material per unit area of ​​the positive electrode sheet of the first type of battery cell WC 1 120 μg / mm 2 ≤WC 1 ≤280μg / mm 2 ; optional, 160μg / mm 2 ≤WC 1 ≤210μg / mm 2 ; further optional, 163 μg / mm 2 ≤WC 1 ≤208μg / mm 2 ; (4) The positive electrode charge capacity BC of the first type of battery cell 1 100mAh / g≤BC 1 ≤230mAh / g; optional, 125mAh / g≤BC 1 ≤200mAh / g; further optional, 150mAh / g≤BC 1 ≤190mAh / g.

6. The battery module according to any one of claims 1 to 4, It is characterized in that The second type of battery cell meets at least one of the following conditions: (1) The mass of active material per unit area of ​​the negative electrode sheet of the second type of battery cell WA 2 60 μg / mm 2 ≤WA 2 ≤170μg / mm 2 ; optional, 65μg / mm 2 ≤WA 2 ≤120μg / mm 2 ; further optional, 85 μg / mm 2 ≤WA 2 ≤110μg / mm 2 ; (2) The negative electrode charging capacity BA of the second type of battery 2 320mAh / g≤BA 2 ≤380mAh / g; (3) The mass of active material per unit area of ​​the positive electrode sheet of the second type of battery cell WC 2 120 μg / mm 2 ≤WC 2 ≤280μg / mm 2 ; optional, 190 μg / mm 2 ≤WC 2 ≤210μg / mm 2 ; further optional, 195 μg / mm 2 ≤WC 2 ≤208μg / mm 2 ; (4) The positive electrode charge capacity BC of the second type of battery cell 2 100mAh / g≤BC 2 ≤230mAh / g.

7. The battery module according to any one of claims 1 to 6, It is characterized in that In the battery module, the number of the first type of battery cells is n 1 , the number of the second type of cells is n 2 , n 1 and n 2 is a natural number, and n 1 and n 2 At least one of the following conditions must be met: (1) 0.01≤n 1 / n 2 ≤100; optionally, 0.1≤n 1 / n 2 ≤10; (2)10%≤n 2 ×C 2 / (n 1 ×C 1 +n 2 ×C 2 )≤60%。 8. The battery module according to any one of claims 1 to 7, It is characterized in that The first type of battery cells and the second type of battery cells are battery cells of different chemical systems, and the chemical systems are divided according to the components of the positive electrode active materials of the battery cells; Optionally, the chemical systems of the first type of battery cell and the second type of battery cell are independently selected from one of a lithium nickel cobalt manganese system, a lithium iron phosphate system, a lithium vanadium iron phosphate system, a lithium vanadium phosphate system, a lithium cobalt oxide system, a lithium nickel oxide system, a lithium-rich manganese system, a lithium nickel cobalt aluminum system and a lithium manganese oxide system; Further optionally, the chemical system of the first type of battery cell is one of a lithium nickel cobalt manganese oxide system, a lithium cobalt oxide system, a lithium nickel oxide system, a lithium manganese-rich system, a lithium nickel cobalt aluminum system and a lithium manganese oxide system; and / or, the chemical system of the second type of battery cell is one of a lithium iron phosphate system, a lithium vanadium iron phosphate system or a lithium vanadium phosphate system.

9. A battery pack, comprising the battery module according to any one of claims 1 to 8.

10. A device, comprising the battery module according to any one of claims 1 to 8 or the battery pack according to claim 9, wherein the battery module or the battery pack is used to provide power for the device and / or is an energy storage unit for the device.

11. A method for manufacturing a battery module, It is characterized in that The steps include: Obtaining the first type of battery cells and the second type of battery cells; Connecting the first type of battery cells and the second type of battery cells in series to form the battery module; The first type of battery cell and the second type of battery cell satisfy the following relationship: 1.01×C 1 / C 2 ≤N 2 ≤1.25, and C 1 <C 2 , Among them, N 2 is the charging battery balance rate of the second type of battery; C 1 and C 2 are the capacities of the first and second types of battery cells respectively.

12. The manufacturing method according to claim 11, It is characterized in that Obtaining the first type of battery cell and the second type of battery cell includes: obtaining n 1 The first type of cells and n 2 The second type of battery cells, wherein n 1 and n 2 is a natural number; optional, 0.01≤n 1 / n 2 ≤100; optionally, 0.1≤n 1 / n 2 ≤10; further optionally, 10%≤n 2 ×C 2 / (n 1 ×C 1 +n 2 ×C 2 )≤60%.

13. A battery module manufacturing device, It is characterized in that The device comprises a processor, The processor is used to control the clamping arm to obtain the first type of battery cells and the second type of battery cells; The processor is also used to control the assembly components to connect the first type of battery cells and the second type of battery cells in series to form the battery module; The first type of battery cell and the second type of battery cell satisfy the following relationship: 1.01×C 1 / C 2 ≤N 2 ≤1.25, and C 1 <C 2 , Among them, N 2 is the charging battery balance rate of the second type of battery; C 1 and C 2 They are the capacities of the first type of battery cell and the second type of battery cell respectively.

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