Control method for improving battery capacity consistency, battery and readable medium

Abstract

The invention relates to a control method for improving battery capacity consistency, a battery and a readable medium. The method comprises the following steps: forming a to-be-formed battery, sequentially charging the to-be-formed battery through constant currents in different nominal capacity ranges, and standing the battery after each time of charging; and carrying out capacity grading on the formed battery, charging the battery based on constant current and constant voltage, and sequentially discharging the battery through constant current with different nominal capacities. In the formation process, the battery is charged in sequence through constant currents in different nominal capacity ranges, in the capacity grading process, after charging is conducted based on constant currents and constant voltages, the battery is discharged in sequence through the constant currents in different nominal capacities, charging and discharging are conducted based on the currents in different nominal capacities in the whole process, safety is higher, and the capacity grading effect is better. The formation of a compact SEI film is facilitated, the consistency of the battery capacity is improved, and the technical problem that the battery safety cannot be met and the consistency of the battery capacity cannot be improved when charging and discharging are carried out through small current or large current is solved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular to a control method for improving battery capacity consistency, a battery, and a readable medium. Background Art

[0002] Lithium-ion batteries, with their unique advantages such as high energy density, long cycle life and no memory effect, play a vital role in various fields, especially in the field of power storage. Lithium-ion batteries are responsible for balancing the load of the power grid, improving the quality of electricity and providing stable power output for renewable energy systems.

[0003] At present, the energy density of lithium-ion batteries has approached the theoretical limit, and the cycle life has been significantly extended. As a result, new requirements have been placed on the production efficiency and quality control of lithium-ion batteries. In practical applications, when multiple independent cells are integrated into a battery module through conductive elements in series or in parallel, they have to face the challenge of cell consistency. Cell inconsistency mainly includes inconsistencies in battery capacity, internal resistance, and open circuit voltage. These performance inconsistencies will gradually increase during the use cycle, specifically manifested as capacity loss, life loss, and increased internal resistance. Among them, the consistency of battery capacity depends on the stability of the solid electrolyte interface membrane (SEI). The existing technology uses a small current formation during the battery charging and discharging process, which is not conducive to the formation of a dense SEI membrane; while the use of a large current formation will produce excessive lithium ions, resulting in excessive battery temperature and a large safety hazard. It can be seen that the existing technology, whether it is formed by a small current or a large current, cannot meet the requirements of improving the consistency of lithium ion capacity while being safe and reliable. Summary of the invention

[0004] The present application provides a control method for improving battery capacity consistency, a battery and a readable medium to solve the above-mentioned technical problem that battery charging and discharging by a single small current or a large current cannot meet the requirements of battery safety and reliability while improving battery capacity consistency.

[0005] According to the first aspect of the embodiments of the present application, the present application provides a control method for improving the consistency of battery capacity, the method comprising: forming a battery to be formed, charging the battery to be formed in sequence by constant currents in different nominal capacity ranges, and leaving the battery to rest after each charging; dividing the capacity of the formed battery, charging the battery based on constant current and constant voltage, and then discharging the battery in sequence by constant currents in different nominal capacities.

[0006] Optionally, the battery to be formed is formed, and the battery to be formed is charged in sequence by constant currents in different nominal capacity ranges, and the battery is left to rest after each charging, including: charging the battery to be formed for the first time by a constant current in the first nominal capacity range; after the battery after the first charging is left to rest, charging the battery for the second time by a constant current in the first nominal capacity range; after the battery after the second charging is left to rest, charging the battery for the third time by a constant current in the second nominal capacity range, wherein the first nominal capacity range is smaller than the second nominal capacity range; and leaving the battery to rest after the third charging.

[0007] Optionally, the charging time corresponding to the first battery charging is 5 to 10 minutes, and the rest time of the first battery charging and the second battery charging is 5 to 10 minutes.

[0008] Optionally, the standing time after the third battery charging is 48 to 72 hours, and the temperature corresponding to the standing process is 40 to 50° C.

[0009] Optionally, the capacity of the formed battery is divided, and after the battery is charged based on constant current and constant voltage, the battery is discharged in sequence by constant currents of different nominal capacities, including: charging the formed battery by constant current and constant voltage; discharging the battery for the first time by a first constant current after constant current and constant voltage charging; discharging the battery for the second time by a second constant current after the first constant current charging; discharging the battery for the third time by a third constant current after the second constant current charging; discharging the battery for the fourth time by a fourth constant current after the third constant current charging, wherein the nominal capacities of the first constant current, the second constant current, the third constant current and the fourth constant current decrease in sequence.

[0010] Optionally, charging the formed battery by constant current and constant voltage includes: charging the formed battery to 3.65V by constant current and constant voltage of 0.5C, with a cut-off voltage of 0.05C.

[0011] Optionally, the nominal capacity of the first constant current is 0.5C, the nominal capacity of the second constant current is 0.2C, the nominal capacity of the third constant current is 0.05C, the nominal capacity of the fourth constant current is 0.01C, the discharge voltages of the first battery discharge, the second battery discharge and the third battery discharge are 2.5V, and the discharge voltage of the fourth battery discharge is 2.0V.

[0012] Optionally, the positive electrode slurry of the battery includes lithium iron phosphate, the current collector of the positive electrode of the battery includes aluminum foil, the negative electrode slurry of the battery includes graphite, and the current collector of the negative electrode of the battery includes copper foil.

[0013] According to a second aspect of an embodiment of the present application, the present application provides a lithium iron phosphate battery, which is obtained by processing a control method for improving battery capacity consistency based on the first aspect described above.

[0014] According to a third aspect of an embodiment of the present application, the present application provides a computer-readable storage medium having a non-volatile program code executable by a processor, wherein the program code enables the processor to execute a control method for improving battery capacity consistency as described in the first aspect above.

[0015] The above technical solution provided by the embodiment of the present application has the following advantages compared with the related art:

[0016] In the process of forming the battery to be formed, the battery is charged in sequence by constant currents of different nominal capacity ranges, and the battery is left to stand after each charge. In the process of battery capacity division, the battery is first charged based on constant current and constant voltage, and then the battery is discharged in sequence by constant currents of different nominal capacities. The above whole process is based on charging and discharging of currents of different nominal capacities, which is not only safer, but also more conducive to forming a dense SEI film relative to a single current charging and discharging method, thereby improving the consistency of battery capacity. The higher the consistency of the capacity of each battery, the more conducive to extending the service life of the battery module to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] Figure 1 A schematic flow chart of a control method for improving battery capacity consistency provided according to an embodiment of the present application;

[0020] Figure 2 A schematic diagram of a lithium-ion battery process according to an embodiment of the present application;

[0021] Figure 3 A schematic diagram of the process of step S1 according to an embodiment of the present application;

[0022] Figure 4 A schematic diagram of the process of step S2 provided according to an embodiment of the present application;

[0023] Figure 5 A schematic diagram comparing the capacity ratios of the embodiments and comparative examples provided according to the embodiments of the present application;

[0024] Figure 6 A schematic diagram of an optional electronic device structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0026] In order to solve the above problems, in this embodiment, a control method for improving the consistency of battery capacity is provided, which can be applied to a hardware environment composed of a terminal and a server. The server is connected to the terminal through a network, and can be used to provide services for the terminal or a client installed on the terminal. A database can be set on the server or independently of the server to provide data storage services for the server. A control method for improving the consistency of battery capacity in an embodiment of the present application can be executed by a server, or by a terminal, or by both a server and a terminal.

[0027] It should be noted that the above-mentioned network may include but is not limited to at least one of the following: wired network, wireless network. The above-mentioned wired network may include but is not limited to at least one of the following: wide area network, metropolitan area network, local area network, and the above-mentioned wireless network may include but is not limited to at least one of the following: the above-mentioned wireless connection method may include but is not limited to 4G / 5G connection, WiFi (Wireless-Fidelity) connection, Bluetooth connection, WiMAX (Worldwide Interoperability for Microwave Access) connection, Zigbee (low-power LAN protocol, also known as Zifeng protocol) connection, UWB (ultrawideband) connection and other wireless connection methods currently known or to be developed in the future. The above-mentioned terminal may include but is not limited to PC, mobile phone, tablet computer, desktop computer, etc.

[0028] Figure 1 A flow chart of a control method for improving battery capacity consistency provided in an embodiment of the present application. Figure 1 As shown, the method comprises the following steps:

[0029] S1. Forming the battery to be formed, charging the battery to be formed in sequence by constant currents in different nominal capacity ranges, and leaving the battery to stand after each charging.

[0030] In this embodiment, a control method for improving battery capacity consistency provided by the present application can be applicable to different types of battery formation and capacity division processes, including lithium-ion batteries, sodium-ion batteries, nickel-metal hydride batteries, lead-acid batteries, etc. The present application uses lithium-ion batteries for illustration, and the lithium-ion batteries can be energy storage lithium-ion square shell batteries, which can reduce the cost of assembling energy storage battery modules.

[0031] Combination Figure 2 As shown, Figure 2 A flow chart of a battery process provided by an embodiment of the present invention. Figure 2 In the process, before the battery is formed, the positive and negative electrodes of the battery need to be stirred, coated, rolled and filmed in sequence, and then wound, hot pressed, assembled, welded, baked, injected and aged in sequence to obtain the battery to be formed, and then the battery is formed. After the formation, the battery can be aged and sealed, and finally the battery capacity is divided. Among them, the formation is an important step in the production process of lithium-ion batteries. The purpose is to activate the active substances inside the battery and stabilize the performance of the battery. Specifically, it includes activating the electrolyte, forming the SEI film and controlling the parameters. Among them, different parameters will have different effects on the formation of the SEI film and the performance of the battery. The parameters include charging current, charging voltage and charging time.

[0032] In this embodiment, before formation, the battery after injection can be placed at a high temperature of 40 to 50°C for 24 hours. During the formation process, the battery to be formed is charged in sequence by using constant currents of different nominal capacity ranges, and the duration of each charging can be different. Among them, through constant current charging, the magnitude of the current can be controlled so that the active substances inside the battery gradually participate in the electrochemical reaction, which is conducive to the stable formation of the SEI film and avoids the battery from generating excessive heat and gas, thereby reducing safety risks. Constant current charging with different nominal capacity ranges can simulate the charging process of the battery under different usage conditions, which helps to promote the formation of the SEI film more comprehensively.

[0033] As a possible implementation method, the battery can be charged with a constant current three times during the formation process, and the nominal capacity of each constant current charge can be different, for example, the current can be increased sequentially; or the first two times can be charged with a constant current with a smaller nominal capacity, and the third time can be charged with a constant current with a larger nominal capacity than the first two times, so as to achieve the purpose of cross-charging of large and small currents. For the method of using a smaller current for the first two charges and increasing the current for the third time, by charging with a smaller current at the beginning of the charge, the small current charging can reduce the lithium ion concentration gradient on the electrode surface and reduce the uneven deposition of lithium ions, thereby avoiding the situation where the SEI film is too thick in some areas and too thin in other areas, and helps the SEI film to form uniformly and slowly on the negative electrode surface. Then, by charging with a larger current relative to the first two times, the electrochemical reaction is more intense, which helps the inorganic components in the SEI film to better combine with the organic components to form a more solid and dense structure, which can promote the compactness of the inside of the SEI film, and finally achieve the purpose of forming a denser SEI film and improving the consistency of battery capacity. In addition, charging with a relatively small current first can provide a stable environment for the formation of the SEI film, and then charging with a relatively large current can promote the densification of the SEI film, avoiding the risk of excessive thickening and rupture, and improving the safety of the battery.

[0034] Furthermore, during the formation process, the battery is left to stand after each charge, and the length of the standing time can be different or the same. Standing can give the chemical substances inside the battery enough time to reach a state of equilibrium, further promoting the improvement and stability of the SEI film. During the standing process, the electrolyte in the battery can fully infiltrate the positive and negative electrode materials of the battery, which helps to form a denser and more stable SEI film on the surface of the electrode. And during the standing process, the temperature and pressure inside the battery will gradually stabilize, which helps to reduce safety risks. At the same time, standing can also allow the gas generated inside the battery to be gradually released, further reducing safety hazards.

[0035] S2. The formed batteries are divided into different capacities, and after charging the batteries based on constant current and constant voltage, the batteries are discharged in sequence through constant currents of different nominal capacities.

[0036] In this embodiment, the battery can be divided into different capacities after formation, and the battery capacity and internal resistance and other parameters can be determined by charging and discharging the battery. This process helps to screen out batteries with excellent performance, and to grade the batteries according to their excellent performance, so that they can be better applied to different scenarios and needs in the future. First, the battery will be charged through a constant current and constant voltage; then, the battery will be discharged once based on a constant current of different nominal capacities to determine the battery capacity.

[0037] As a possible implementation method, this embodiment sequentially discharges the battery using four constant currents with different nominal capacities, that is, four battery discharge tests are performed, wherein the constant current size of the latter discharge can be lower than the constant current size of the previous discharge, and the discharge voltage each time can be different or the same. Through four constant current discharges of different sizes, the discharge of the battery in different usage scenarios can be simulated, which helps to comprehensively evaluate the performance of the battery under different load conditions, including discharge capacity, discharge efficiency, discharge platform, etc. In addition, since the discharge current of the battery changes in actual use, the use of four constant current discharge test methods of different sizes can provide performance data closer to the actual use situation, which helps to more accurately evaluate the performance of the battery. Furthermore, some batteries may perform well at low rate discharge, but the performance decreases significantly at high rate discharge. Through four constant current discharge tests of different sizes, it is easier to screen out battery cells with stable performance to match battery cells with consistent performance, significantly improving the overall consistency of the battery. And gradually reducing the discharge current, the chemical reaction rate inside the battery will also decrease, which helps to reduce the heat and stress generated by the battery during the discharge process, thereby reducing the risk of internal damage to the battery and improving the safety of the battery.

[0038] In an embodiment of the present invention, when the battery to be formed is formed, the battery is charged in sequence by constant currents in different nominal capacity ranges, and the battery is left to stand after each charging; in the battery capacity division process, the battery is first charged based on constant current and constant voltage, and then the battery is discharged in sequence by constant currents with different nominal capacities. The above-mentioned whole process is based on charging and discharging with currents of different nominal capacities to simulate the charging process of the battery under different usage conditions. Compared with a single current charging and discharging method, it is more conducive to forming a dense SEI film, thereby improving the consistency of the battery capacity. The higher the consistency of the capacity of each battery is, the more conducive it is to extending the service life of the battery module to a certain extent.

[0039] In an optional embodiment, in combination Figure 3 As shown, Figure 3 The specific flow chart of step S1 provided in this embodiment. Step S1 specifically includes:

[0040] S11, performing a first battery charging on the battery to be formed by using a constant current within the first nominal capacity range;

[0041] S12, after the battery is left to rest after the first charge, charging the battery for the second time using a constant current within the first nominal capacity range;

[0042] S13, after the battery after the second charging is left to stand, charging the battery for the third time using a constant current in the second nominal capacity range, wherein the first nominal capacity range is smaller than the second nominal capacity range;

[0043] S14, leaving the battery after the third charge to rest.

[0044] Among them, the first nominal capacity range and the second nominal capacity range are used to indicate the current range applicable to the constant current, and the second nominal capacity range is larger than the first nominal capacity range. In this embodiment, the first nominal capacity range is 0.05-0.1C, and the second nominal capacity range is 0.15-0.2C. At the initial stage of battery charging, a smaller current in the first nominal capacity range is used for the first and second battery charging. After each charging, the battery can be left to stand for the same length of time. Small current charging can reduce the lithium ion concentration gradient on the electrode surface and reduce the uneven deposition of lithium ions, thereby avoiding the situation where the SEI film is too thick in some areas and too thin in other areas, which helps the SEI film to form evenly and slowly on the negative electrode surface.

[0045] Furthermore, after the SEI film is slowly formed through the first and second charging, the third battery charging can be continued with a larger current in the second nominal capacity range relative to the first two times, which can make the electrochemical reaction more intense, help the inorganic components and organic components in the SEI film to better combine, form a more solid and dense structure, promote the densification of the SEI film, and ultimately achieve the purpose of forming a denser SEI film and improving the consistency of battery capacity. In addition, charging with a relatively small current first can provide a stable environment for the formation of the SEI film, and then charging with a relatively large current can promote the densification of the SEI film, and can also avoid the risk of excessive thickening and rupture, thereby improving the safety of the battery.

[0046] In this embodiment, the formation process includes three battery charges. First, a relatively small current is used for the first and second battery charges at the initial stage of battery charging, which helps the SEI film to form evenly and slowly on the surface of the negative electrode; then, the constant current is increased during the third charge, which can accelerate the electrochemical reaction on the basis of the slow formation of the SEI film, help the inorganic components and organic components in the SEI film to better combine, promote the densification of the SEI film, and help improve the battery capacity consistency; in addition, standing after each charge is conducive to the electrolyte in the battery to fully infiltrate the positive and negative electrode materials of the battery, forming a denser and more stable SEI film on the electrode surface, and during the standing process, the temperature and pressure inside the battery will gradually stabilize, which helps to reduce safety risks.

[0047] In an optional embodiment, the charging time corresponding to the first battery charging is 5 to 10 minutes, the standing time of the first battery charging and the second battery charging is 5 to 10 minutes, the standing time after the third battery charging is 48 to 72 hours, and the temperature corresponding to the standing process is 40 to 50°C.

[0048] In this embodiment, the length of the charging time directly affects the formation process of the SEI film. Too long a charging time may cause the SEI film to be too thick, increase the internal resistance of the battery, and reduce the battery performance; while too short a charging time may cause the SEI film to be incompletely formed, affecting the cycle life and safety of the battery.

[0049] In this embodiment, during the formation process, the first battery charging can be performed at a constant current of 0.05 to 0.1 C for 5 to 10 minutes; after standing for 5 to 10 minutes, the second battery charging is performed at a constant current of 0.05 to 0.1 C for 0.5 to 1 hour; after standing for 5 to 10 minutes, the third battery charging is performed at a constant current of 0.15 to 0.2 C for 1 to 2.0 hours, and then the battery after the third battery charging is placed in a high temperature of 40 to 50° C. and allowed to stand for 48 to 72 hours.

[0050] In this embodiment, precise control of the charging time helps to form a stable and uniform SEI film. By precisely controlling the standing time, it is beneficial for the electrolyte in the battery to fully infiltrate the positive and negative electrode materials of the battery, forming a denser and more stable SEI film on the electrode surface. By increasing the standing time of the third charge and controlling the high temperature required for the standing process, under a high temperature environment, a longer standing time helps the electrolyte to better penetrate into the pores of the electrode material, thereby increasing the contact area and reaction activity between the electrolyte and the electrode. At the same time, high temperature can promote the uniform formation of the SEI film, making it more stable and improving the cycle life and safety of the battery. By first charging with a small current and then switching to a relatively larger current for charging, it helps the SEI film to form evenly and slowly on the surface of the negative electrode, and then accelerate the electrochemical reaction, promote the densification inside the SEI film, and improve the consistency of the battery capacity.

[0051] In an optional embodiment, in combination Figure 4 As shown, Figure 4 The specific flow chart of step S4 provided in this embodiment. Step S4 specifically includes:

[0052] S41, charging the formed battery by constant current and constant voltage;

[0053] S42, performing a first battery discharge on the battery after constant current and constant voltage charging by using a first constant current;

[0054] S43, performing a second battery discharge on the battery charged by the first constant current by using a second constant current;

[0055] S44, performing a third battery discharge on the battery charged by the second constant current by using a third constant current;

[0056] S45, performing a fourth battery discharge on the battery charged by the third constant current through a fourth constant current, wherein the nominal capacities of the first constant current, the second constant current, the third constant current and the fourth constant current are reduced in sequence.

[0057] In this embodiment, during the battery capacity division process, the battery is first charged by constant current and constant voltage so that the battery reaches a preset value, and the cut-off voltage can be set at the same time, wherein the nominal capacity of the constant voltage and constant current charging is higher than the maximum value of the second nominal capacity range, that is, after the constant current charging of 0.15 to 0.2C, it continues to be charged by a higher constant current and constant voltage. Constant current and constant voltage charging includes two stages. When in the constant current charging stage: before the battery voltage reaches the set value, a constant current is used for charging, which can ensure the stability of the current during the charging process and avoid the adverse effects of current fluctuations on the battery. When in the constant voltage charging stage: after the battery voltage reaches the set value, the charging mode is changed to constant voltage charging. At this time, the charging current will gradually decrease, but the voltage remains unchanged. The constant voltage charging stage can ensure that the battery is supplemented with a smaller current when it is close to a full charge state to avoid overcharging.

[0058] As a possible implementation, constant current and constant voltage charging includes: charging the formed battery to 3.65V by 0.5C constant current and constant voltage, with a cut-off voltage of 0.05C.

[0059] In this embodiment, the battery is charged to a set value of 3.65V through a 0.5C constant current and constant voltage, and the cut-off voltage is set to 0.05C. In the 0.5C constant current charging stage, the battery is charged with a constant current, which helps the active substances inside the battery to fully react and ensure that the battery can absorb enough electrical energy. In the constant voltage charging stage: when the battery voltage reaches 3.65V, the charging mode is switched to constant voltage charging. At this time, 0.5C is gradually reduced to a cut-off voltage of 0.05C, ensuring that the battery can continue to be charged with a smaller current after reaching the specified voltage to compensate for the self-discharge and other minor losses inside the battery, so that the battery reaches a more saturated state.

[0060] Furthermore, after completing the constant voltage and constant current charging, multiple discharge tests are performed, and the present embodiment includes four discharge tests, wherein, when the battery is discharged for the first time, the discharge is performed based on the first constant current until the set value required for the first discharge is reached; when the battery is discharged for the second time, the discharge is performed based on the second constant current until the set value required for the second discharge is reached; when the battery is discharged for the third time, the discharge is performed based on the third constant current until the set value required for the third discharge is reached; when the battery is discharged for the fourth time, the discharge is performed based on the fourth constant current until the set value required for the fourth discharge is reached. The set value required for each discharge may be the same or different, and may be specifically set based on demand. The nominal capacities of the first constant current, the second constant current, the third constant current, and the fourth constant current are reduced in sequence to meet different test requirements and facilitate the distinction of batteries with different performances.

[0061] As a possible implementation manner, the nominal capacity of the first constant current is 0.5C, the nominal capacity of the second constant current is 0.2C, the nominal capacity of the third constant current is 0.05C, the nominal capacity of the fourth constant current is 0.01C, the discharge voltages of the first battery discharge, the second battery discharge and the third battery discharge are 2.5V, and the discharge voltage of the fourth battery discharge is 2.0V.

[0062] In this embodiment, the battery is discharged to 2.5V by 0.5C constant current, discharged to 2.5V by 0.2C constant current, discharged to 2.5V by 0.05C constant current, and discharged to 2.0V by 0.01C constant current in sequence, which can simulate the use of the battery under different load conditions, so as to comprehensively evaluate the performance of the battery at different discharge rates, and more easily distinguish between batteries with excellent performance and batteries with poor performance.

[0063] In this embodiment, the above-mentioned charging by constant current and constant voltage can ensure the stability of the current during the charging process when the set value is not reached, and ensure that the battery voltage is supplemented with a smaller current after reaching the set value to avoid overcharging. Through the constant current discharge with a gradually decreasing value, the use of the battery under different load conditions can be simulated, so as to comprehensively evaluate the performance of the battery at different discharge rates, and it is easier to distinguish between batteries with excellent performance and batteries with poor performance. When assembling the battery, the batteries with similar performance are selected through the capacity test for pairing, which is conducive to improving the consistency and reliability of the battery pack. In addition, by gradually reducing the discharge current, the energy loss and chemical loss of the battery during the discharge process can be reduced, thereby extending the service life of the battery.

[0064] In an optional embodiment, the positive electrode slurry of the battery includes lithium iron phosphate, the current collector of the positive electrode of the battery includes aluminum foil, the negative electrode slurry of the battery includes graphite, and the current collector of the negative electrode of the battery includes copper foil.

[0065] Among them, in order to better promote the full formation of lithium-ion batteries, the positive electrode slurry in the lithium-ion battery may include lithium iron phosphate, and of course, it may also include one or more of lithium cobalt oxide, lithium manganese oxide or nickel cobalt manganese oxide. The negative electrode slurry in the lithium-ion battery may include graphite, and may also include a conductive agent, a binder, etc. The current collector of the positive electrode of the lithium-ion battery includes aluminum foil, and the aluminum foil includes smooth aluminum foil and pre-coated aluminum foil; the current collector of the negative electrode of the lithium-ion battery may include copper foil, and the copper foil includes smooth copper foil and pre-coated copper foil. Of course, the current collector of the positive electrode of the battery may also include aluminum foil, and the current collector of the negative electrode of the battery may also include copper foil, which is not limited here.

[0066] In this embodiment, by adding lithium iron phosphate to the positive electrode slurry of the battery, using aluminum foil as the current collector of the positive electrode of the battery, adding graphite to the negative electrode slurry of the battery, and using copper foil as the current collector of the negative electrode of the battery, the formation process can be made more complete, the gas production in the subsequent use process is greatly reduced, and the high temperature cycle performance is better.

[0067] The present application is further described in detail below in conjunction with specific embodiments, which include a comparative example and two embodiments provided based on the present application of a control method for improving battery capacity consistency, and the raw materials used in the comparative example and the two embodiments are consistent. It should be understood that these embodiments cannot be construed as limiting the scope of protection claimed in the present application.

[0068] Wherein, the formation step of the comparative example comprises:

[0069] 1) After the lithium-ion battery was placed at 40-50°C for 24 hours after injection, it was charged at a constant current of 0.1C for 7 minutes; 2) After placing it for 10 minutes, it was charged at a constant current of 0.18C for 0.6 hours; 3) After placing it for another 10 minutes, it was charged at a constant current of 0.18C for 11 minutes; 4) After placing it for another 10 minutes, it was charged at a constant current of 0.18C for 25 minutes; 5) It was placed at high temperature for 48-72 hours.

[0070] The comparative volume fractionation steps include:

[0071] 1) 0.5C constant current constant voltage charging to 3.65V, cut-off voltage 0.05C; 2) 0.5C constant current discharge to 2.5V; 3) 0.2C constant current discharge to 2.5V; 4) 0.05C constant current discharge to 2.5V; 5) 0.01C constant current discharge to 2.0V.

[0072] The formation steps of embodiment 1 include:

[0073] 1) Take the lithium battery that has been placed at high temperature for 24 hours after injection, and charge it at a constant current of 0.05-0.1C for 7 minutes; 2) After placing it for 10 minutes, charge it at a constant current of 0.05-0.1C for 0.8 hours; 3) After placing it for another 10 minutes, charge it at a constant current of 0.15-0.2C for 1.5 hours; 4) Place it at high temperature for 48-72 hours.

[0074] The capacity division step of the first embodiment includes:

[0075] 0.5C constant current and constant voltage charging to 3.65V, cut-off voltage 0.05C; 0.5C constant current discharge to 2.5V; 0.2C constant current discharge to 2.5V; 0.05C constant current discharge to 2.5V; 0.01C constant current discharge to 2.0V.

[0076] The formation steps of the second embodiment include:

[0077] 1) Take the lithium battery that has been placed at high temperature for 24 hours after injection, and charge it at a constant current of 0.05-0.1C for 7 minutes; 2) After placing it for 10 minutes, charge it at a constant current of 0.05-0.1C for 0.5 hours; 3) After placing it for another 10 minutes, charge it at a constant current of 0.15-0.2C for 1 hour; 4) Place it at high temperature for 48-72 hours.

[0078] The capacity division step of the second embodiment includes:

[0079] 1) 0.5C constant current constant voltage charging to 3.65V, cut-off voltage 0.05C; 2) 0.5C constant current discharge to 2.5V; 3) 0.2C constant current discharge to 2.5V; 4) 0.05C constant current discharge to 2.5V; 5) 0.01C constant current discharge to 2.0V.

[0080] like Figure 5 As shown, Figure 5 A schematic diagram comparing the capacity ratios of the embodiments and comparative examples provided in the embodiments of the present invention. Figure 5 The sample size, sample proportion and corresponding capacity level are analyzed. The comparative formation process adopts the same constant current for charging. The formation processes of Example 1 and Example 2 are charged based on constant currents of different sizes, but Example 2 increases the charging time relative to Example 1. Among them, the battery level after the comparative treatment is more between A5 and A8, among which A6 and A7 account for a relatively larger proportion; the battery level after the treatment based on Example 1 is between A5 and A7, and A7 accounts for the largest proportion; the battery level after the treatment based on Example 2 is between A7 and A9, and A7 accounts for the largest proportion.

[0081] Further, from Figure 5It can be seen that, for battery capacity, the parts of Example 1 and Example 2 that account for the largest proportion of capacity levels are much higher than those of the comparative example, which is more conducive to ensuring that batteries with similar or identical capacity levels have a high degree of battery capacity consistency; while the battery capacity in the comparative example is distributed from A2 to A9, and the capacity consistency is poor. By comparing the test data, it can be seen that the battery is charged and discharged using a control method for improving battery capacity consistency provided by the present application, and the process combines cross-charging and discharging of large and small currents, which can effectively improve the consistency of square shell battery capacity. High consistency can extend the service life of the battery module to a certain extent.

[0082] According to another aspect of an embodiment of the present application, a lithium iron phosphate battery is provided, wherein the lithium iron phosphate battery is processed based on a control method for improving battery capacity consistency described in any of the above embodiments.

[0083] In the present embodiment, based on the above-mentioned control method for improving the consistency of battery capacity, the lithium iron phosphate battery is processed, during the formation process of the battery to be formed, the battery is charged in sequence by constant currents of different nominal capacity ranges, and the battery is left to stand after each charging; and in the battery capacity division process, the battery is first charged based on constant current and constant voltage, and then the battery is discharged in sequence by constant currents of different nominal capacities. The above-mentioned whole process is based on charging and discharging of currents of different nominal capacities, which is more conducive to forming a dense SEI film than a single current charging and discharging method, thereby improving the consistency of the battery capacity. The higher the consistency of the capacity of each battery, the higher the consistency and stability of the battery module when forming a battery module, which is more conducive to extending the service life of the battery module to a certain extent.

[0084] According to a control method for improving battery capacity consistency provided in each of the above embodiments, based on the same inventive concept, a device for realizing a lithium-ion battery process is also provided in this embodiment, the device comprising a formation device and a capacity division device, wherein the formation device is used to form a battery to be formed, and the battery to be formed is sequentially charged by a constant current in different nominal capacity ranges, and the battery is left to stand after each charging; the capacity division device is used to divide the capacity of the formed battery, and after charging the battery based on a constant current and constant voltage, the battery is sequentially discharged by a constant current of different nominal capacities.

[0085] It should be noted that the above-mentioned formation equipment and capacity division equipment may include modules or units for executing various specific steps, which are used to implement the method steps of a control method for improving battery capacity consistency provided in the above-mentioned embodiment, and will not be repeated here.

[0086] According to another aspect of the embodiments of the present application, the present application provides an electronic device, such as Figure 6As shown, it includes a memory 601, a processor 603, a communication interface 605 and a communication bus 607. The memory 601 stores a computer program that can be run on the processor 603. The memory 601 and the processor 603 communicate through the communication interface 605 and the communication bus 607. When the processor 603 executes the computer program, the steps of the above-mentioned control method for improving the consistency of battery capacity are implemented.

[0087] The memory and processor in the above electronic device communicate via a communication bus and a communication interface. The communication bus may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus may be divided into an address bus, a data bus, a control bus, etc.

[0088] The above-mentioned memory may include random access memory, non-volatile memory, storage device located far away from the above-mentioned processor, etc. The processor may be a general-purpose processor, including a central processing unit, a network processor, etc.; it may also be a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component.

[0089] According to another aspect of the embodiments of the present application, a computer program product or a computer program is provided, the computer program product or the computer program includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the steps of any of the above embodiments.

[0090] Optionally, in an embodiment of the present application, a computer-readable storage medium is configured to store a program code for the processor to perform the following steps: S1, forming a battery to be formed, charging the battery to be formed in sequence by a constant current in different nominal capacity ranges, and leaving the battery to rest after each charging; S2, dividing the capacity of the formed battery, charging the battery based on a constant current and constant voltage, and then discharging the battery in sequence by a constant current of different nominal capacities.

[0091] Optionally, the specific examples in this embodiment can refer to the examples described in the above embodiments, and this embodiment will not be repeated here. And when the embodiments of this application are specifically implemented, they can refer to the above embodiments and have corresponding technical effects.

[0092] It is understood that the embodiments described herein may be implemented in hardware, software, firmware, middleware, microcode, or a combination thereof. For hardware implementation, the processing unit may be implemented in one or more application specific integrated circuits (ASIC), digital signal processors (DSP), digital signal processing devices (DSPD), programmable logic devices (PLD), field programmable gate arrays (FPGA), general purpose processors, controllers, microcontrollers, microprocessors, other electronic units for performing the functions described in the present application, or a combination thereof.

[0093] For software implementation, the technology described herein can be implemented by a unit that performs the functions described herein. The software code can be stored in a memory and executed by a processor. The memory can be implemented in the processor or outside the processor.

[0094] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0095] In the embodiments provided in the present application, it should be understood that the disclosed control device for improving battery capacity consistency and a control method for improving battery capacity consistency can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the modules is only a logical function division, and there may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point, 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. The unit described as a separate component may or may not be physically separated, and the component displayed as a unit may or may not be a physical unit, that is, it may be located in one place, or it may be distributed on multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit.

[0096] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-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 the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of a control method for improving battery capacity consistency described in each embodiment of the present application.

[0097] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0098] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A control method for improving battery capacity consistency, characterized in that: Methods include: Forming the battery to be formed, charging the battery to be formed in sequence by constant currents in different nominal capacity ranges, and leaving the battery to stand after each charging; The formed batteries are divided into different capacities, and after charging the batteries based on constant current and constant voltage, the batteries are discharged in sequence using constant currents of different nominal capacities.

2. A control method for improving battery capacity consistency according to claim 1, characterized in that: The battery to be formed is formed, the battery to be formed is charged sequentially by constant currents in different nominal capacity ranges, and the battery is left to stand after each charging, including: Performing a first battery charging on the battery to be formed by a constant current within the first nominal capacity range; After the battery is left to rest after the first charge, the battery is charged for a second time using a constant current within the first nominal capacity range; After the battery after the second charging is left to stand, charging the battery for the third time with a constant current in the second nominal capacity range, wherein the first nominal capacity range is smaller than the second nominal capacity range; After the third charge, the battery is left to rest.

3. A control method for improving battery capacity consistency according to claim 2, characterized in that: The charging time corresponding to the first battery charging is 5 to 10 minutes, and the standing time of the first battery charging and the second battery charging is 5 to 10 minutes.

4. A control method for improving battery capacity consistency according to claim 2, characterized in that: The standing time after the third battery charging is 48 to 72 hours, and the temperature during the standing process is 40 to 50° C.

5. A control method for improving battery capacity consistency according to claim 1, characterized in that: The method of dividing the capacity of the formed battery, charging the battery based on constant current and constant voltage, and then discharging the battery in sequence through constant currents of different nominal capacities includes: The formed battery is charged by constant current and constant voltage; Discharging the battery for the first time after constant current and constant voltage charging by using a first constant current; Discharging the battery charged by the first constant current for a second time by using a second constant current; Discharging the battery charged by the second constant current for a third time by using a third constant current; The battery charged by the third constant current is discharged for a fourth time by using a fourth constant current, wherein the nominal capacities of the first constant current, the second constant current, the third constant current and the fourth constant current are reduced in sequence.

6. A control method for improving battery capacity consistency according to claim 5, characterized in that: The method of charging the formed battery by constant current and constant voltage includes: charging the formed battery to 3.65V by constant current and constant voltage of 0.5C, and the cut-off voltage is 0.05C.

7. A control method for improving battery capacity consistency according to claim 5, characterized in that: The nominal capacity of the first constant current is 0.5C, the nominal capacity of the second constant current is 0.2C, the nominal capacity of the third constant current is 0.05C, the nominal capacity of the fourth constant current is 0.01C, the discharge voltages of the first battery discharge, the second battery discharge and the third battery discharge are 2.5V, and the discharge voltage of the fourth battery discharge is 2.0V.

8. A control method for improving battery capacity consistency according to any one of claims 1 to 7, characterized in that: The positive electrode slurry of the battery includes lithium iron phosphate, the current collector of the positive electrode of the battery includes aluminum foil, the negative electrode slurry of the battery includes graphite, and the current collector of the negative electrode of the battery includes copper foil.

9. A lithium iron phosphate battery, characterized in that: The lithium iron phosphate battery is obtained based on a control method for improving battery capacity consistency according to any one of claims 1 to 8.

10. A computer-readable storage medium having a processor-executable non-volatile program code, characterized in that: The program code enables the processor to execute the control method for improving battery capacity consistency as described in any one of claims 1 to 8.

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