Method for restoring activity of lithium-ion battery and lithium-ion battery

Abstract

The present application provides a method for recovering the activity of a lithium-ion battery, a lithium-ion battery, a charging device, a battery management system, a vehicle, and a related readable storage medium, which belong to the field of batteries. The method includes recovering the activity by applying an activation voltage according to the battery health status value of the lithium-ion battery. The method achieves the effects of reducing costs, simplifying the preparation process, improving the first coulomb efficiency of the battery, and no capacity decay during use while ensuring high energy density, and prolonging the life of the battery.

Description

Technical Field

[0001] The present application relates to the field of batteries, and more specifically to a method for recovering the activity of a lithium-ion battery and a lithium-ion battery using the method, as well as a battery module, a control circuit, a battery management system, a vehicle and related readable storage media that contain or use a lithium-ion battery. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density, long cycle life and no memory effect, so they are widely used in consumer electronic products. In recent years, with the continuous development of electric vehicles and energy storage systems, the market requirements for various battery performance have been continuously improved. For example, during the first charging process of the battery, the components in the electrolyte will be reduced and decomposed on the surface of the negative electrode material to form a solid electrolyte interface film (SEI), whose main components include lithium carbonate, lithium fluoride and alkyl lithium carbonate. This process will consume a part of the lithium ions released from the positive electrode material, resulting in the loss of active lithium and the reduction of the first coulomb efficiency. When using high-capacity alloy negative electrodes (silicon, germanium, tin) and transition metal oxides and other materials, the consumption of active lithium caused by the above factors will be further aggravated.

[0003] Therefore, people are eager to develop a new technology that can replenish and restore the lithium ions lost during the initial charging process and the subsequent charging and discharging processes of lithium-ion batteries and the reduced battery activity in a very convenient and inexpensive way, so that the initial coulombic efficiency of lithium-ion batteries can be significantly improved and the effective life can be significantly extended. During this effective life, the various performance of the battery - such as energy density, charging and discharging performance, etc. - can be effectively maintained or restored without significant attenuation. Summary of the invention

[0004] As described above, the present application has developed a technology for restoring the activity of batteries, especially lithium-ion batteries. By carefully designing the process parameters during the initial charging and use of the battery, the performance of the battery after the initial charging and the overall effective service life are significantly improved.

[0005] A first aspect of the present application provides a method for restoring the activity of a battery, such as a lithium-ion battery, the method comprising: obtaining a battery health status value of the battery during a charging process; when the battery health status value is less than or equal to a preset threshold, applying an activation voltage to the battery so that lithium ions contained in a lithium supplement in the battery are released into an electrolyte, wherein the activation voltage is higher than a normal charging voltage of the battery; when the battery health status value rises to a value greater than or equal to a second preset threshold, restoring from the activation voltage to a normal charging voltage.

[0006] According to one embodiment of the first aspect of the present application, the lithium supplement is contained in the positive electrode of the battery.

[0007] According to another embodiment of the first aspect of the present application, the battery health status value is selected from at least one of the following parameters: battery capacity, remaining capacity, energy density, power density, electromotive force, open circuit voltage, operating voltage, discharge termination voltage and operating current.

[0008] According to another embodiment of the first aspect of the present application, the battery health status value is the real-time capacity C of the battery. 实 The battery exhibits an initial capacity C0 in the initial charge-discharge cycle, and the threshold is C0×80%. 实 When the temperature drops to less than or equal to C0×80%, an activation voltage is applied to the battery.

[0009] According to another embodiment of the first aspect of the present application, after the initial charge-discharge cycle, the activation voltage is not applied, and the subsequent 2nd to Nth charge-discharge operations are directly performed, wherein N is an integer from 2 to 500,000, and the 2nd to Nth charge-discharge operations are performed using the normal charging voltage. During the 2nd to Nth charge-discharge operations, the real-time capacity C 实 Gradually decreases, whenever C 实 When the activation voltage V is applied to the battery, the 活 To perform activity recovery, when the battery health status value increases to be greater than or equal to a second preset threshold, the activation voltage is restored to a normal charging voltage to continue the charge-discharge operation.

[0010] According to another embodiment of the first aspect of the present application, an activation voltage V is applied to the battery. 活 The activity recovery operation is performed more than once. Starting from the second time, the activation voltage used for each activity recovery is increased relative to the activation voltage of the previous activity recovery. The amplitude of each activation voltage increase is fixed or the amplitude changes each time.

[0011] According to another embodiment of the first aspect of the present application, an activation voltage V is applied to the battery. 活 The activity recovery operation is performed more than once, and starting from the second time, the activation voltage used in each activity recovery is increased by ≥0.1 V relative to the activation voltage of the previous activity recovery.

[0012] According to another embodiment of the first aspect of the present application, the operations of applying the normal charging voltage and the activation voltage are performed using the same charging device.

[0013] The second aspect of the present application provides a lithium-ion secondary battery, which contains a lithium supplement. The lithium-ion secondary battery performs charge-discharge operations at a normal charging voltage, and the lithium supplement can restore the activity of the battery at an activation voltage, and the activation voltage is higher than the normal charging voltage.

[0014] A third aspect of the present application provides a battery management system, the battery management system comprising:

[0015] Interconnected monitoring unit, charging unit and control unit;

[0016] The monitoring unit is used to monitor one or more health status values ​​of the lithium-ion battery;

[0017] The charging unit can apply a normal charging voltage or an activation voltage to the battery, wherein the normal charging voltage is lower than the activation voltage;

[0018] The control unit generates a charging signal or an activation signal according to the health status value measured by the monitoring unit;

[0019] When the charging unit receives a charging signal, a normal charging voltage is applied to the battery; when the charging unit receives an activation signal, an activation voltage is applied to the battery.

[0020] The fourth aspect of the present application provides a readable storage medium for storing a computer program, wherein the computer program is used to execute the battery activation method of the present application. According to an embodiment of the fourth aspect of the present application, the computer program is a battery management system (BMS) program.

[0021] In the embodiments of the present application, through optimized and refined process design, simple and inexpensive technical means are used to continuously compensate and restore the lithium ion loss and battery performance degradation that occur during the initial charging and subsequent charging and discharging of the lithium ion battery. This solves the various problems that have long existed in the prior art lithium ion secondary batteries and are difficult to overcome, such as complex structure, high cost, severe lithium ion loss, coulombic efficiency after initial charging that is seriously lower than the theoretical value, many side reactions, short battery life, and rapid degradation of various battery properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart according to an implementation method of the present application;

[0023] Figure 2 is a flow chart according to another embodiment of the present application;

[0024] Figure 3 is a schematic diagram of a battery management system according to an embodiment of the present application;

[0025] Figure 4 is a schematic diagram of an embodiment of a secondary battery of the present application;

[0026] Figure 5 yes Figure 4 An exploded view of a secondary battery is shown.

[0027] In the specific implementation section below, the design details of the lithium-ion battery activity recovery method designed in the present application, the related lithium-ion battery, the charging device for implementing the method, and the battery module, battery pack and electrical device containing the battery are described. DETAILED DESCRIPTION

[0028] "Scope" disclosed herein is defined in the form of lower limit and upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The scope defined in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a particular parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0029] In this application, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution.

[0030] In this application, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0031] In the present application, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0032] In this application, unless otherwise specified, the terms "include" and "comprising" mentioned herein may be open-ended or closed-ended. For example, the terms "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0033] In the description of this article, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number itself, and “several” in “one or several” means two or more technical solutions.

[0034] In the description herein, unless otherwise specified, the term "and / or" is inclusive. For example, the phrase "A and / or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A and / or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0035] The battery activation method and battery control system (BMS) developed in the present application are applicable to various types of secondary batteries (also known as rechargeable batteries), preferably to lithium-ion secondary batteries.

[0036] Secondary battery

[0037] According to one embodiment of the present application, a lithium-ion secondary battery is provided, which includes a positive electrode, a negative electrode, a separator, an electrolyte, etc. During the battery charging and discharging process, active ions are embedded and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays the role of conducting ions between the positive electrode plate and the negative electrode plate. The present application specifically designs the positive electrode material in the secondary battery, and specially designs detailed battery status detection and reactivation operation processes during the initial charging and subsequent charging and discharging processes, thereby realizing a lithium-ion battery with high energy density, no capacity decay, and long service life.

[0038] Positive electrode

[0039] In the secondary battery of the present application, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector and including a positive electrode active material and a lithium supplement agent. For example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is provided on any one or both of the two opposite surfaces of the positive electrode current collector. In the secondary battery of the present application, the positive electrode current collector may be a metal foil or a composite current collector. For example, the metal foil may be an aluminum foil, and the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material on a polymer material substrate.

[0040] According to an embodiment of the present application, the lithium supplement agent contains compound L, and the molecular formula of compound L is Li x Ni a Cu 1-a-b M b O2, where 1 ≤ x ≤ 2, 0 < a < 1, 0 ≤ b < 0.1, and M is selected from one or more of Zn, Sn, Mg, Fe, and Mn.

[0041] In one embodiment of the present application, 0 < a < 1 in the molecular formula of compound L. In another embodiment of the present application, 0.1 ≤ a ≤ 0.9 in the molecular formula of compound L. Optionally, 0.2 ≤ a ≤ 0.6, and further optionally, 0.2 ≤ a ≤ 0.4. In another embodiment of the present application, for compound L, a is 0.1, 0.2, 0.3, 0.4, 0.5, or 0.6.

[0042] In one embodiment of the present application, 0 ≤ b < 0.1 in the molecular formula of compound L. In another embodiment of the present application, 0 ≤ b ≤ 0.05 in the molecular formula of compound L. In another embodiment of the present application, for compound L, b = 0 or 0.05. In another embodiment of the present application, regarding compound L, b = 0.05.

[0043] In the present application, when the relative molar ratios of Ni element to Cu element in compound L, a, and (1 - a - b) are within the above ranges, it is beneficial to synthesize compound L with higher crystallinity at a lower temperature, effectively reducing the production cost; at the same time, it can also ensure that the lithium supplement agent containing it has a higher specific capacity and charge-discharge plateau, which is beneficial to improving the energy density of the lithium secondary battery.

[0044] In one embodiment of the present application, compound L, for example, includes but is not limited to, Li2Ni 0.1 Cu 0.9 O2, Li2Ni 0.2 Cu 0.8 O2, Li2Ni0.3 Cu 0.7 O2、Li2Ni 0.4 Cu 0.6 O2、Li2Ni 0.5 Cu 0.5 O2、Li2Ni 0.6 Cu 0.4 O2、Li2Ni 0.7 Cu 0.3 O2、Li2Ni 0.8 Cu 0.2 O2、Li2Ni 0.9 Cu 0.1 O2, or Li2Ni 0.4 Cu 0.55 Mg 0.05 O2.

[0045] According to a preferred embodiment of the present application, based on the total weight of the positive electrode film layer, the content of the lithium supplement in the positive electrode film layer is 0.1-50% by weight.

[0046] According to one embodiment of the present application, the lithium supplement agent and the positive electrode active material are uniformly distributed in the entire positive electrode film layer. According to another embodiment of the present application, the outer surface of the lithium supplement agent is optionally partially or completely covered by one or more external coating layers.

[0047] In some embodiments, the positive electrode film layer may also optionally include a binder, a conductive agent, etc. In one embodiment of the present application, the positive electrode may be prepared by the following method: the components for preparing the positive electrode, such as the positive electrode active material, the lithium supplement, the conductive agent, the binder and any other components are dispersed in a solvent to form a uniform positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, a positive electrode sheet can be obtained.

[0048] Negative electrode

[0049] The secondary battery of the present application includes a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer contains a negative electrode active material, for example, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material can be selected from one or more of elemental silicon, silicon oxide, and silicon-carbon composite. The tin-based material can be selected from one or more of elemental tin, tin oxide compounds, and tin alloys.

[0050] In the secondary battery of the present application, in addition to the negative electrode active material, the negative electrode membrane also contains an optional binder, an optional conductive agent and other optional auxiliary agents, which are usually formed by coating and drying the negative electrode slurry. The negative electrode slurry coating is usually formed by dispersing the negative electrode active material and the optional conductive agent and binder in a solvent and stirring them evenly. The solvent can be N-methylpyrrolidone (NMP) or deionized water.

[0051] As an example, the conductive agent may include one or more of superconducting carbon, carbon black (eg, acetylene black, Ketjen black), carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0052] In addition, in the secondary battery of the present application, the negative electrode plate does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode plate of the present application may also include a conductive primer layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the first negative electrode film layer and disposed on the surface of the negative electrode current collector. In some other embodiments, the negative electrode plate of the present application may also include a covering protective layer covering the surface of the second negative electrode film layer.

[0053] In the secondary battery of the present application, the negative electrode current collector may be a metal foil or a composite current collector.

[0054] Electrolytes

[0055] The electrolyte plays the role of conducting ions between the positive electrode plate and the negative electrode plate. The electrolyte can be selected from at least one of a solid electrolyte and a liquid electrolyte (i.e., an electrolyte). In some embodiments, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent. In one embodiment of the present application, the content of the solvent is 60-99% by weight based on the total weight of the electrolyte. In one embodiment of the present application, the content of the electrolyte is 1-40% by weight based on the total weight of the electrolyte.

[0056] Isolation film

[0057] In one embodiment of the present application, the secondary battery further includes a separator, which separates the anode side of the secondary battery from the cathode side, and provides selective permeation or blocking for substances of different types, sizes and charges in the system. For example, the separator can insulate electrons, physically isolate the positive and negative active substances of the secondary battery, prevent internal short circuits and form an electric field in a certain direction, and allow ions in the battery to pass through the separator and move between the positive and negative electrodes. In one embodiment of the present application, the material used to prepare the separator may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer can be the same or different.

[0058] Cells and secondary batteries

[0059] In one embodiment of the present application, the positive electrode sheet, the negative electrode sheet and the separator can be made into an electrode assembly / bare cell by a winding process or a lamination process.

[0060] In one embodiment of the present application, the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte. In some embodiments, the outer package of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. In other embodiments, the outer package of the secondary battery may be a soft package, such as a bag-type soft package.

[0061] The shape of the secondary battery of the present application can be cylindrical, square or any other shape. Figure 4 The secondary battery 5 is a square structure as an example. Figure 5 Shows Figure 4 The exploded view of the secondary battery 5 is shown in FIG. 5 . 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. The bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity. The cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation film can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly is encapsulated in the receiving cavity, and the electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more.

[0062] According to various embodiments of the present application, a method for recovering the activity of a lithium-ion battery is provided, the method comprising: obtaining a battery health status value of the lithium-ion battery during a charging process; when the battery health status value is less than or equal to a first preset threshold value, applying an activation voltage to the lithium-ion battery so that lithium ions at a lithium supplement contained in the battery are released into an electrolyte, wherein the activation voltage is higher than a normal charging voltage of the lithium-ion battery; when the battery health status value rises to be greater than or equal to a second preset threshold value, recovering from the activation voltage to a normal charging voltage.

[0063] In order to solve the problem of lithium loss in lithium-ion batteries due to side reactions during the first charge, in order to improve the first coulombic efficiency of lithium ions and obtain long-life lithium-ion batteries, it is necessary to over-supply active lithium to prepare for the consumption of side reactions during the cycle storage process. In previous scientific research results, pre-lithiation of the positive or negative electrode and providing excess lithium ion reserves in the battery is a way to improve the first coulombic efficiency and extend the battery life. However, there are various defects in the specific operation. For example, for pre-lithiation of the negative electrode, the most common method is to use metallic lithium powder or lithium belt to pre-lithiate the negative electrode material, thereby providing sufficient active lithium for the consumption of the SEI film during the first charge. However, this method has high cost, complex preparation process, poor practicality, and is not conducive to large-scale commercial applications. At the same time, the great disadvantage of negative electrode lithium supplementation is that lithium powder is directly coated on the graphite surface, so the graphite must be excessive to prevent lithium precipitation, that is, the discharge balance (cell balance) of graphite during discharge needs to be much greater than the cell balance during charging. The consequence is that the amount of graphite used is much greater than the amount of graphite used in non-lithium supplemented batteries. After capacity decay, a large amount of graphite will be redundant, which will not only reduce energy density, but also increase costs, greatly reducing the electrical performance and economic dimensions. Another very important point is that the above-mentioned side reactions that consume lithium ions continue during normal use of the battery. The above-mentioned negative electrode lithium supplementation technology cannot achieve continuous lithium supplementation for the battery (maintaining battery activity for a long time), nor can it achieve the purpose of maintaining battery activity at a high level for a long time.

[0064] The idea of ​​replenishing lithium in the positive electrode is similarly to include a lithium replenisher (lithium-rich material) in the positive electrode to provide excess lithium ions in the system during the first charge to at least partially offset the lithium ion consumption caused by the above-mentioned side reactions. However, the problem is that this approach also cannot maintain the activity of the battery for a long time.

[0065] The method developed in the present application successfully solves all the above problems. In the method of the present application, lithium ions are pre-stored in the positive electrode in the form of a lithium supplement. The lithium supplement releases a portion of lithium ions into the electrolyte under the action of the initial charging voltage during the initial charging process, effectively replenishing the lithium ions in the electrolyte lost due to side reactions during the initial charging process. At the same time, a considerable portion of lithium ions are still preserved in the lithium supplement in the positive electrode, avoiding the problem of lithium precipitation or excessive graphite content on the negative electrode, effectively maintaining high energy density, and saving costs. At the same time, the method of the present application effectively stores lithium ions in the lithium supplement in the positive electrode, avoiding the rapid loss of stored lithium ions, monitoring the health of the battery during normal charging and discharging, and performing efficient and controlled lithium ion supplementation when necessary, so that the activity of the battery can be restored, thereby maintaining the lithium ion content and activity of the battery for a long time.

[0066] Figure 1 is a flow chart of a method for restoring battery activity according to one embodiment of the present application, such as Figure 1 As shown, the battery activity recovery method in this embodiment may include steps S110 to S150.

[0067] S110, charging the battery.

[0068] The charging can be performed using an independent conventional charging device or a charging device integrated into a battery management system (BMS). The charging process is to ensure that the battery has the power required for normal operation.

[0069] S120, obtaining a battery health status value.

[0070] The monitoring device in the BMS is used to measure one or more health status values ​​of the battery, such as battery capacity, remaining capacity, energy density, power density, electromotive force, open circuit voltage, operating voltage, discharge end voltage and operating current. The health status value can be measured at a specific time, or it can be the integral result or average value of a series of values ​​measured within a specific time period.

[0071] S130, when the health status value of the battery is less than or equal to a first preset threshold, applying an activation voltage to the battery.

[0072] The first preset threshold here can be flexibly designed as needed, for example, it can be a specific proportion of an initial health value after the battery is charged for the first time, such as 70%-90% or 80-85% of the initial health value. The first preset threshold can be input into the control unit of the BMS, and the control unit of the BMS issues an instruction to the charging unit based on the signal about the health value sent by the monitoring unit to apply an activation voltage to the battery. The activation voltage is higher than the normal charging voltage during the normal charging and discharging process of the battery, so that the lithium supplement in the positive electrode of the battery is activated, and the lithium ions are released into the electrolyte of the battery, so that the battery is restored to activity.

[0073] S140, when the battery health status value increases to be greater than or equal to a second preset threshold, stop applying the activation voltage.

[0074] The second preset threshold here can be flexibly designed as needed, for example, it can be a specific proportion of an initial health value after the battery is charged for the first time, such as 90-110% or 95-105% of the initial health value. The second preset threshold can be input into the control unit of the BMS, and the control unit of the BMS issues an instruction to the charging unit based on the signal about the health value sent by the monitoring unit to stop applying the activation voltage to the battery. At this time, it is considered that the activity of the battery has been restored and can be used for subsequent normal operation, that is, charge-discharge operation under normal charging voltage.

[0075] S150, continue to perform normal charge-discharge cycle on the battery.

[0076] After the activation, the battery at least partially recovers its activity due to the replenishment of lithium ions, and the activity can be characterized by the above-mentioned health status value. The battery can then undergo normal charge-discharge cycles at normal charge and discharge voltages. For laboratory research, the battery can then use a BMS to perform conventional charge-discharge operations at normal charging voltages to detect its various properties. For practical situations, the battery is included in various electrical devices, such as electric vehicles, and undergoes charge-discharge cycles during daily use.

[0077] Optionally, the battery processed by the method of the present application is a secondary battery, preferably a secondary lithium-ion battery.

[0078] Figure 2 A schematic flow chart of a method for restoring battery activity according to another embodiment of the present application is shown. Figure 2 As shown, the battery activity recovery method in this embodiment may include steps S210 to S270.

[0079] S210, charging the battery for the first time.

[0080] In secondary batteries, especially secondary lithium-ion batteries, after the battery is manufactured, it is necessary to charge the newly manufactured battery for the first time. During this initial charging process, a portion of the lithium ions in the electrolyte inevitably undergo reduction decomposition on the surface of the negative electrode material to form a solid electrolyte interface film (SEI) and are lost. Optionally, the initial charging is performed at the voltage of a conventional charge and discharge cycle. Under this initial charging voltage, a portion of the lithium ions contained in the lithium supplement in the positive electrode of the battery are released into the electrolyte of the battery to supplement the lithium ions lost during the initial charging process.

[0081] S220, obtaining an initial health status value of the battery.

[0082] The present application considers obtaining the initial health state value of the battery during or after the first charging of the battery, and the initial health state value of the battery after the first charging can be used as an important reference factor for subsequently determining the first threshold value and the second threshold value. Optionally, the first threshold value can be a specific proportion of the initial health state value, such as 70-90%, or 80-85%, and the second threshold value can be a specific proportion of the initial health state value, such as 90-110%, or 95-105%.

[0083] S230, performing a normal charge-discharge cycle on the battery.

[0084] The battery that has undergone the initial charge performs normal charge and discharge operations under normal charge and discharge conditions, and the operation can be controlled using a BMS. According to some embodiments of the present application, the charging voltage of the normal charge and discharge operation can be equal to the initial charge voltage described herein, or can be higher or lower than the initial charge voltage. During the normal charge and discharge process, lithium ions will still be gradually lost, which will cause the battery activity to decrease, and the activity decrease can be represented by one or more health status values.

[0085] In the present application, the process conditions used in the normal charging and discharging process of the battery, such as the charging voltage, can be reasonably adjusted according to the positive electrode active material used in the battery, the type of lithium supplement in the positive electrode, the negative electrode active material, the electrolyte, the required battery performance, etc. For example, in one of the following embodiments, a charging voltage of 3.65V is used in the normal charging and discharging process, but it should be understood that the charging voltage that can be used in the method of the present application is not limited to this, but can be appropriately adjusted within a reasonable range according to actual conditions.

[0086] S240, obtaining a health status value of the battery.

[0087] During the normal charge-discharge process, the BMS is used to monitor one or more health status values ​​of the battery in a continuous or intermittent manner, for example, one or more health status values ​​of the battery are detected after each charging is completed, or one or more health status values ​​of the battery are detected during each charging process.

[0088] S250, determining whether the health status value is less than or equal to a first preset threshold.

[0089] As described above, the first threshold value can be determined according to the needs of the actual application of the battery or the industry standard, can be pre-input into the control unit of the BMS, or can be automatically generated by the control unit of the BMS according to the initial health status value obtained from the monitoring unit. During the normal charge and discharge process of the battery, the monitoring unit of the BMS obtains information on the battery health status value in a continuous or intermittent manner and transmits the information to the control unit. When the battery health status value is still greater than the first threshold, the battery continues to perform normal charge and discharge operations. When the battery health status value drops to equal to or below the first threshold, step S260 is performed.

[0090] S260, applying an activation voltage to the battery.

[0091] When the health status value of the battery drops to or below the first threshold, the control unit of the BMS issues an instruction to its charging unit, so that the charging unit applies an activation voltage to the battery. The activation voltage is higher than the normal charging voltage. Under the action of the activation voltage, a portion of the lithium ions stored in the lithium supplement in the positive electrode of the battery (the portion of the lithium ions that will not be released under the normal charge and discharge voltage) is at least partially released from the positive electrode to supplement the lithium ions lost in the electrolyte, so that the activity of the battery is restored.

[0092] S270, when the battery health status value increases to be greater than or equal to a second preset threshold, stop applying the activation voltage.

[0093] The increase of the battery health status value to greater than or equal to the second preset threshold value indicates that the lithium ions lost by the battery in the normal charge-discharge cycle have been sufficiently compensated. At this time, the activation voltage is released and the battery has recovered an activity close to, equal to, or even exceeding its initial state. At this time, the control unit sends an instruction to the charging unit to stop activation based on the information provided by the monitoring unit. According to some embodiments of the present application, the second threshold value can be a specific proportion of a certain health status value of the battery after the initial charge, such as 90%, 95%, 98%, 99%, 100%, 102%, 105% or 110% of a certain health status value of the battery after the initial charge.

[0094] The method of the present application may have some specific preferred embodiments. According to a preferred embodiment, the lithium supplement is contained in the positive electrode of the lithium-ion battery, so that it can be gradually and controlled to be released according to the activation conditions, so as to achieve the longest possible battery service life. According to another preferred embodiment, the battery health status value is selected from at least one of the following parameters: battery capacity, remaining capacity, energy density, power density, electromotive force, open circuit voltage, operating voltage, discharge termination voltage and operating current, so that the battery activity level (lithium ion content) can be flexibly selected to monitor and implement activation based on the differences of different products, different scales and different purposes. According to another preferred embodiment of the present application, the battery health status value is the real-time capacity C of the lithium-ion battery. 实 The lithium-ion battery exhibits an initial capacity C0 in the initial charge-discharge cycle, and the threshold value is C0×80%. 实 When the activation voltage drops to less than or equal to C0×80%, an activation voltage is applied to the lithium-ion battery. The capacity of a battery is a very important and widely used technical indicator, which is conducive to more accurately monitoring the battery activity level (lithium ion content) and implementing activation. According to another preferred embodiment of the present application, after the initial charge-discharge cycle, the activation voltage is not applied, and the subsequent 2nd to Nth charge-discharge operations are directly performed, wherein N is an integer from 2 to 500,000, and the 2nd to Nth charge-discharge operations are performed using the normal charging voltage. During the 2nd to Nth charge-discharge operations, the real-time capacity C 实 Gradually decreases, whenever C 实 When the activation voltage V is applied to the lithium-ion battery, the activation voltage V 活 When the battery health status value rises to a value greater than or equal to a second preset threshold, the activation voltage is restored to a normal charging voltage, and the charge-discharge operation is continued. The technical solution of the present application can achieve extremely excellent battery capacity stability and extremely long service life, and its service life can even be up to hundreds of thousands of cycles. According to another embodiment of the present application, an activation voltage V is applied to the lithium-ion battery. 活 The activity recovery operation is performed more than once. Starting from the second time, the activation voltage used for each activity recovery is increased relative to the activation voltage of the previous activity recovery. The amplitude of each activation voltage increase is fixed or the amplitude changes each time. By adopting this step-like multi-step activation operation mode, lithium ions can be replenished more accurately and economically, effectively avoiding the waste of lithium ions, and can effectively extend the battery life. It can also avoid the excessive presence of lithium ions in the battery system, which is of great significance for maintaining stable battery performance and inhibiting the occurrence of lithium ion side reactions. According to another preferred embodiment of the present application, an activation voltage V is applied to the lithium-ion battery.活 The activity recovery operation is performed more than once, and starting from the second time, the activation voltage used for each activity recovery is increased by ≥0.1 volt relative to the activation voltage of the previous activity recovery. This can refine the lithium ion replenishment, avoid the waste of lithium ions and extend the battery life, maintain the stability of battery performance and inhibit the occurrence of lithium ion side reactions. According to a preferred embodiment of the present application, the operation of applying the normal charging voltage and the activation voltage is performed using the same charging device, so that the battery lithium replenishment activation process can be carried out in a manner that is as convenient as possible.

[0095] Compared with the secondary battery and battery activation method recorded in the prior art, the most important improvement of the secondary battery and battery activation method of the present application is that the lithium ions in the lithium supplement can be regarded as divided into at least two parts, wherein the first part of the lithium ions escape from the lithium supplement during the initial charging process of the battery (the initial charging adopts a normal charging voltage, which is lower than the activation voltage) and enter the electrolyte. According to one embodiment of the present application, during the initial charging process using the normal charging voltage, part of the lithium ions in the positive electrode active material in the positive electrode also escape from the positive electrode and enter the electrolyte to compensate for the part of the lithium ions lost during the initial charging process. After the initial charging, the secondary battery then uses the normal charging voltage for a conventional charge-discharge cycle. With the charge-discharge cycle, one or more side reactions may occur in the secondary battery, such as some components in the electrolyte are reduced and decomposed at the surface of the negative electrode to form a solid electrolyte interface film (SEI) and cause the gradual loss of lithium ions in the electrolyte, thereby causing the overall performance of the secondary battery to gradually deteriorate. In some embodiments of the present application, at least one parameter of a secondary battery is selected to characterize the health state of the secondary battery. The selected parameter is called a "battery health state value", which can be selected from at least one of the following parameters: battery capacity, remaining capacity, energy density, power density, electromotive force, open circuit voltage, operating voltage, discharge termination voltage and operating current. The battery health state value of the secondary battery can be measured in a continuous or intermittent manner. For example, a sensor connected to the secondary battery can be used to continuously monitor the health state value of the secondary battery in a continuous manner. Or the health state value of the secondary battery can be monitored in an intermittent manner with one or more hours, days, weeks or months as intervals. Or more preferably, the health state value of the secondary battery is measured each time the secondary battery is charged. In this case, the measuring device for measuring the health state value can be set in a device (such as a vehicle) using the secondary battery, or in a charging device (such as a charging pile or charging station). The measuring device for detecting the health state value can be a monitoring unit in a BMS, which can be set in a vehicle or installed in a charging device.

[0096] According to a preferred embodiment of the present application, the real-time capacity C of the secondary battery is selected. 实 As the battery health status value, the lithium-ion battery exhibits an initial capacity C0 in the initial charge-discharge cycle, and a specific battery capacity threshold is selected, which is lower than the initial capacity C0. As the battery undergoes charge-discharge cycles, the real-time capacity C 实 Gradually decreases, when the secondary battery's C 实 When it drops to be equal to or lower than the first threshold, an activation voltage is applied to the secondary battery, and the activation voltage is higher than the normal charging voltage used in the conventional charge-discharge process. Under the action of the higher activation voltage, a portion of the remaining lithium ions in the lithium supplement agent detach from the lithium supplement agent and enter the electrolyte (electrolyte), compensating for the lithium ions lost in the battery, so that the performance of the secondary battery can be restored. This process is referred to as the battery activity recovery process in this application. According to one embodiment of the present application, the above-mentioned activity recovery operation can increase the health state value of the lithium ion secondary battery to be equal to or higher than the second threshold. As described above, the second threshold can be a specific proportion of a certain health state of the battery after the initial charge (i.e., the initial health state), such as 90%, 95%, 100%, 105%, 110%, etc. of the initial health state. According to a preferred embodiment of the present application, after the above-mentioned activity recovery operation, the performance of the secondary battery (for example, any one or more of the performances that can be used as the battery health status value) is restored to at least 97%, or at least 98%, or at least 99%, or at least 99.5%, or at least 99.9%, or 100% of the performance (for example, initial capacity C0) after the secondary battery is initially charged. In this article, the health status value after the primary activity recovery (for example, C 实 ) to the performance of the secondary battery after the initial charge (e.g., initial capacity C0) is called the activity recovery ratio. In some embodiments, according to the specific process parameters of activity recovery, the health status value (e.g., C0) after each activity recovery is 实) may even be higher than the performance (e.g., initial capacity C0) of the secondary battery after the initial charge, that is, the activity recovery ratio may be greater than 100%, for example, ≤101%, or ≤102%, or ≤103%, or ≤104%, or ≤105%, or ≤106%, or ≤107%, or ≤108%, or ≤110%. According to a preferred embodiment of the present application, the threshold value is 70%, or 72%, or 75%, or 78%, or 80%, or 82%, or 85%, or 88%, or 90%, or 92%, or 95% of a particularly selected state of health value after the secondary battery is initially charged. For example, when the battery capacity is selected as the state of health value, the threshold value may be 70%, or 72%, or 75%, or 78%, or 80%, or 82%, or 85%, or 88%, or 90%, or 92%, or 95% of the initial battery capacity C0 obtained after the secondary battery is initially charged.

[0097] According to some embodiments of the present application, after the first activity recovery described above, the battery continues to perform conventional charging and discharging operations, and detects its health status value in a continuous or intermittent manner. After its real-time health status value drops to the above threshold again, the secondary battery is applied with an Nth activation voltage to perform the Nth battery activity recovery, wherein N is an integer from 2 to 500,000, for example, 2, 3, 5, 6, 8, 10, 15, 20, 50, 80, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1200, 1500, 1800, 2000, 2200, 2500, 2800, 3000, 3200, 3500, 3800, 4000, 4500, 5000, etc. According to a preferred embodiment of the present application, the activation voltage V used in the Nth activity recovery operation is N Higher than the activation voltage V used in the N-1th activity recovery operation N-1 ; The V N and V N-1The voltage difference between them is preferably ≥0.1 volt. According to another preferred embodiment of the present application, starting from the second activity recovery operation, the activation voltage used for each activity recovery is increased by ≥0.1 volt relative to the activation voltage of the previous activity recovery. According to another embodiment of the present application, the activation voltage used for each activity recovery is increased by a fixed or variable amplitude relative to the activation voltage of the previous activity recovery. For example, the amplitude of the activation voltage increase can be any one of the following values, or can be within the numerical range obtained by combining any two of the following values ​​(in volts): 0.1, 0.11, 0.12, 0.15, 0.18, 0.20, 0.21, 0.22, 0.25, 0.28, 0.30, 0.31, 0.32, 0.35, 0.38 , 0.40, 0.45, 0.48, 0.50, 0.51, 0.52, 0.55, 0.58, 0.60, 0.61, 0.62, 0.65, 0.68, 0.70, 0.71, 0.72, 0.75, 0.78, 0.80, 0.81, 0.82, 0.85, 0.88, 0.90, 0.91, 0.92, 0.95, 0.98, 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5.

[0098] According to another embodiment of the present application, the activation voltage V used in the Nth activity recovery operation is N It can be equal to the activation voltage V used in the N-1th activity recovery operation. N-1 .

[0099] According to a specific embodiment of the present application, a lithium-ion secondary battery is specifically prepared, and the method of the present application is used to perform multiple activation operations on it to fully demonstrate the excellent technical effect achieved. The lithium supplement agent used in this specific embodiment is prepared by conventional spray drying / roasting, and the element composition in the lithium supplement agent is controlled by the ratio of the raw materials. The prepared lithium supplement agent has at least one of the following elemental compositions: Li2Ni 0.1 Cu 0.9 O2、Li2Ni 0.2 Cu 0.8 O2、Li2Ni 0.3 Cu 0.7 O2、Li2Ni 0.4 Cu 0.6 O2、Li2Ni 0.5 Cu 0.5 O2、Li2Ni 0.6 Cu 0.4 O2、Li2Ni 0.7 Cu 0.3 O2、Li2Ni 0.8Cu 0.2 O2、Li2Ni 0.9 Cu 0.1 O2, or Li2Ni 0.4 Cu 0.55 Mg 0.05 O2.

[0100] Using the lithium supplement described above, a secondary battery is prepared and subjected to charge and discharge cycles and activity recovery operations according to the following steps:

[0101] Preparation of positive electrode

[0102] The positive electrode active material lithium iron phosphate (LFP), the conductive agent acetylene black, the binder polyvinylidene fluoride PVDF and the above-mentioned lithium supplement agent are fully stirred and mixed in an appropriate amount of N-methylpyrrolidone (NMP) in a weight ratio of (0.98×97):(0.98×1):(0.98×2):10 to form a uniform positive electrode slurry, and the positive electrode slurry is coated on both surfaces of the positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode sheet is obtained. The surface density of the positive electrode film layer is 300mg / cm 2 , compacted density is 2.4g / cm 3 .

[0103] Preparation of negative electrode

[0104] The negative electrode active material artificial graphite, the conductive agent acetylene black, the binder styrene butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC-Na) were fully stirred and mixed in an appropriate amount of deionized water at a weight ratio of 96.5:0.7:1.8:1 to form a negative electrode slurry; the negative electrode slurry was coated on both surfaces of the negative electrode current collector copper foil, and dried and cold pressed to obtain a negative electrode sheet. The compaction density of the negative electrode sheet is 1.6g / cm 3 , surface density is 150mg / m 2 .

[0105] Isolation film

[0106] A PE / PP porous polymer film with a thickness of 16 μm was selected as the isolation membrane.

[0107] Preparation of electrolyte

[0108] Ethylene carbonate (EC), propylene carbonate (PC) and ethyl methyl carbonate (DEC) are uniformly mixed in a volume ratio of 1:1:1, and then electrolyte lithium salt LiBOB is dissolved in the above solvent to obtain an electrolyte, wherein the concentration of LiBOB is 1 mol / L.

[0109] Preparation of secondary batteries

[0110] The positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound in order to obtain an electrode assembly, which is then placed in an outer package, injected with electrolyte, and packaged to obtain a lithium-ion secondary battery.

[0111] The prepared lithium ion secondary battery was subjected to charge-discharge cycle and activity recovery (battery capacity recovery) operations in the following manner:

[0112] The battery is charged for the first time at room temperature, and the battery is charged to 3.65V at a constant current rate of 1C, and then charged to a current of 0.05C at a constant voltage; the charge specific capacity and discharge specific capacity of the battery after the first charge are measured, respectively as the "initial charge specific capacity" and "initial discharge specific capacity", and 80% of the above initial charge specific capacity (i.e., initial charge specific capacity × 80%) is selected as the preset threshold. Then the battery is subjected to a conventional charge and discharge cycle at room temperature using the following conditions: "The battery is charged at room temperature, and the battery is charged to 3.65V at a constant current rate of 1C, and then charged to a current of 0.05C at a constant voltage, and then discharged to 2.5V at a constant current of 1C", and during this charge and discharge cycle, the battery management system BMS (Battery Management System) is used to continuously monitor the charge specific capacity and discharge specific capacity of the secondary battery. Whenever the BMS system detects that the charge capacity of the secondary battery drops to the preset threshold value (i.e., the initial charge capacity × 80%), the secondary battery is charged at a constant current of 1C until the activation voltage, and then charged at a constant voltage to a current of 0.05C at the activation voltage, and then discharged at a constant current of 1C to 2.5V, and then the above-mentioned conventional charge and discharge process is performed at a charging voltage of 3.65V until the charge capacity of the secondary battery drops to the preset threshold value (i.e., the initial charge capacity × 80%) again, and the next activation voltage is applied, and the operation is performed until 50,000 normal charge and discharge cycles of 3.65V are performed. The information of each battery activity recovery operation is summarized in the table below.

[0113] It should be noted that in the above specific embodiments, for the purpose of illustration, a normal charging voltage of 3.65V is used for the secondary lithium-ion battery with lithium iron phosphate as the positive electrode active material, but the voltage can be adjusted according to the specific characteristics of the secondary battery. For example, for the secondary lithium-ion battery with lithium iron phosphate as the positive electrode active material, the charging voltage used can be 1.6-4.5V; for the secondary lithium-ion battery with nickel-cobalt-manganese ternary positive electrode active material, the charging voltage used can be 2.5-4.5V; for the secondary lithium-ion battery with lithium manganate as the positive electrode active material, the charging voltage used can be 2.8-4.6V. In addition, in addition to the type of positive electrode active material, the charging voltage may also need to be appropriately adjusted according to other factors, including the type of lithium supplement, the size of the positive electrode, the amount of positive electrode active material, the type of electrolyte, the amount of negative electrode active material, the type of negative electrode active material, the size of the negative electrode, the purpose of the battery and the required performance, etc. According to the above factors, the charging voltage used can be appropriately adjusted within the range of 1.5-4.6V.

[0114] The charge and discharge specific capacities shown in the table below were tested in the following manner:

[0115] Charge and discharge specific capacity test

[0116] At room temperature (25°C), charge the battery at a constant current of 1C to 3.65V, then charge at a constant voltage to a current of 0.05C, and record the charging capacity at this time, which is the charging capacity; then discharge at a constant current of 1C to 2.5V, and record the discharge capacity at this time, which is the discharge capacity.

[0117] Charge capacity (mAh / g) = charge capacity / positive electrode active material mass

[0118] Discharge specific capacity (mAh / g) = discharge capacity / mass of positive electrode active material

[0119] The charge capacity and discharge capacity listed in the table below are the charge capacity and discharge capacity measured immediately after the first conventional charge or the Nth activity recovery, respectively, where the charge capacity and discharge capacity after the first charge are the initial values ​​described above.

[0120] Table 1: Activity recovery operation and battery specific capacity of the secondary battery of the present invention

[0121]

[0122] From the experimental results shown in Table 1 above, it can be seen that the present invention achieves the following beneficial effects through the specially designed step-by-step activity recovery operation:

[0123] 1. During the initial charge, the active lithium ions consumed by the formation of the SEI film in the electrolyte can be effectively concentrated, thereby obtaining a high energy density battery after the initial charge;

[0124] 2. Compared with other existing long-life batteries with over-supplemented lithium in the prior art, the lithium-ion battery of the present application does not need to use excessive graphite, and the lithium is stored in the cathode, thereby achieving a higher energy density.

[0125] 3. Continuously detect the capacity loss in the subsequent charge-discharge cycle of the battery, and activate it at an appropriate time to effectively replenish the active lithium ions consumed by side reactions in the normal charge-discharge process, so that the battery can restore its initial capacity at least once, preferably multiple times, thereby obtaining a lithium-ion secondary battery whose cycle performance and storage performance do not decay for a long time (or the degree of decay is extremely small).

[0126] 4. Through post-battery testing and capacity activation, a post-maintenance mode for lithium-ion battery capacity recovery has been created, which improves user experience, extends battery life, and enhances product value.

[0127] Figure 3 A battery management system (BMS) S300 according to an embodiment of the present application is provided, which includes a monitoring unit S310, a control unit S320 and a charging unit S330, and Figure 3 A battery S340 is also shown, which is not a part of the BMS ( S300 ) but is a target object directly acted upon by the BMS.

[0128] Specifically, the battery management system S300 includes:

[0129] S310, monitoring unit.

[0130] The monitoring unit is connected to the battery S340 located outside the BMS through one or more (one or more) sensors to obtain one or more health status values ​​of the battery S340. And the monitoring unit S310 is connected to the control unit S320 to transmit the measured health status value to the control unit S320.

[0131] S320, control unit.

[0132] The control unit may be a processor of various sizes, which may include pre-installed engineering software and pre-input parameters, and may include information about the first threshold and the second threshold in the control unit S320 in a manually input or automatically generated manner, and may also include a variety of command information for automatically adjusting the normal charging voltage and one or more activation voltages output by the charging unit. The control unit is connected to the charging unit and can control the sending of command information to the charging unit according to the health status value measured by the monitoring unit, instructing the charging unit to apply a charging voltage or an activation voltage to the battery.

[0133] S330, charging unit.

[0134] The charging unit is connected to the positive electrode and the negative electrode of the battery, and applies a normal charging voltage or an activation voltage to the lithium-ion battery based on the instruction issued by the control unit S320.

[0135] Through the automated operation of the above-mentioned units, a more efficient and finely designed lithium replenishment process for the battery can be achieved, so that the battery is always kept in the most ideal active state and the battery life is extended to the maximum extent.

[0136] The BMS system of the present application can be arranged in a charging device as needed, such as in a charging station or a charging pile, or can be arranged in an electrical device using a secondary lithium-ion battery, such as in an electric vehicle.

[0137] Electrical Devices

[0138] In one embodiment of the present application, the electrical device of the present application includes at least one of the secondary battery, battery module, or battery pack of the present application, and the secondary battery, battery module, or battery pack can be used as a power source of the electrical device, and can also be used as an energy storage unit of the electrical device. The electrical device includes but is not limited to mobile digital devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0139] Another example of a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.

[0140] According to a preferred embodiment of the present application, the lithium-ion battery (secondary battery) of the present application is used in an electric vehicle or a hybrid vehicle, and a battery capacity monitoring device is provided in the vehicle to continuously or intermittently monitor the battery capacity status in the vehicle, and send a signal according to a preset value when a specific proportion (for example, more than 30%, or more than 40%, or more than 50%, or more than 60%, or more than 70%) of the battery capacity drops to a threshold value, to notify the user to go to a 4S shop to restore the battery activity.

[0141] According to another embodiment of the present application, a detection device is provided in a charging pile or charging station to monitor the capacity status of each battery in the vehicle simultaneously during each normal charging, and send out a signal when the battery capacity drops to a threshold value at a predetermined specific proportion (for example, more than 30%, or more than 40%, or more than 50%, or more than 60%, or more than 70%) according to a preset setting, to notify the user to go to a 4S shop to restore the battery activity.

[0142] According to another embodiment of the present application, a detection device is provided in a charging pile or a charging station, which monitors the capacity status of each battery in the vehicle simultaneously during each normal charging, and sends a signal to the consumer at the same time when the battery capacity drops to a threshold value at a specific proportion (for example, more than 30%, or more than 40%, or more than 50%, or more than 60%, or more than 70%) as preset, and the charging pile or charging station applies an activation voltage to the battery automatically or manually to restore the battery activity.

[0143] According to a preferred embodiment of the present application, the normal charging voltage used in the normal charging and discharging process is 1.6 to 4.5 volts, for example, 2.0-3.65 volts, and the activation voltage is higher than the normal charging voltage and ≤5.5 volts. According to some embodiments of the present application, the normal charging voltage used in the normal charging process is 1.6-4.5 volts, for example, any one of the following voltage values, or a voltage value range obtained by combining any two of the following values: 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5. According to some embodiments of the present application, the activation voltage is higher than the normal charging voltage and is ≤5.5 volts, for example, it can be 3.2 volts ≤ activation voltage ≤5.5 volts, or it can be 3.65 volts ≤ activation voltage ≤5.0 volts, for example, any one of the following voltage values, or it can be within the voltage value range obtained by combining any two of the following values: 3.2, 3.3, 3.4, 3.5, 3.6, 3.65, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5 volts.

[0144] According to a preferred embodiment of the present application, the voltage application for normal charging and discharging and activity recovery is performed by the same device (charging device, such as a charging pile or charging station). According to another preferred embodiment of the present application, the voltage application for normal charging and discharging and activity recovery is performed by different devices, such as using a charging pile or charging station for normal charging and discharging, while the activity recovery of the battery needs to be performed at a 4S store using special equipment.

[0145] An embodiment of the present application provides a method for restoring the activity of a secondary lithium-ion battery, the method comprising: obtaining a battery health status value of the battery during a charging process; when the battery health status value is less than or equal to a preset threshold, applying an activation voltage to the battery so that lithium ions contained in a lithium supplement in the battery are released into an electrolyte, wherein the activation voltage is higher than a normal charging voltage of the battery; when the battery health status value rises to a value greater than or equal to a second preset threshold, restoring from the activation voltage to a normal charging voltage.

[0146] Another embodiment of the present application provides a method for activating a battery. In this embodiment, after the initial charge-discharge cycle, the activation voltage is not applied, and the subsequent 2nd to Nth charge-discharge operations are directly performed, wherein N is an integer from 2 to 500,000, and the 2nd to Nth charge-discharge operations are performed using the normal charging voltage. During the 2nd to Nth charge-discharge operations, the real-time capacity C 实 Gradually decreases, whenever C 实 When the activation voltage V is applied to the battery, the 活 To restore activity, when the battery health status value rises to greater than or equal to the second preset threshold, the activation voltage is restored to the normal charging voltage, and the charge-discharge operation is continued. And the activation voltage V is applied to the battery 活 The activity recovery operation is performed more than once. Starting from the second time, the activation voltage used for each activity recovery is increased relative to the activation voltage of the previous activity recovery. The amplitude of each activation voltage increase is fixed or the amplitude changes each time.

[0147] Another embodiment of the present application provides a lithium-ion secondary battery, which contains a lithium supplement in its positive electrode, and the lithium supplement can restore the activity of the battery under an activation voltage.

[0148] Another embodiment of the present application provides a battery management system, which includes: a monitoring unit, a charging unit and a control unit that are interconnected; the monitoring unit is used to monitor one or more health status values ​​of the lithium-ion battery; the charging unit can apply a normal charging voltage or an activation voltage to the battery, and the normal charging voltage is lower than the activation voltage; the control unit generates a charging signal or an activation signal according to the health status value measured by the monitoring unit; when the charging unit receives a charging signal, the charging unit applies a normal charging voltage to the battery; when the charging unit receives an activation signal, the charging unit applies an activation voltage to the battery.

[0149] Another embodiment of the present application further provides a readable storage medium for storing a computer program, wherein the computer program is used to execute the above-mentioned battery activation method. For example, the computer program may be a battery management system (BMS) program for use with the battery management system (BMS) of the present application.

[0150] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application is described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. In addition, the present application also includes technical solutions obtained by combining the various technical features described above, and technical solutions obtained by combining the various embodiments and implementation methods described above, provided that these technical solutions are included in the scope defined in the claims of the present invention.

Claims

1. A method for restoring battery activity, the method comprising: Get the battery health status value of the battery during the charging process; When the battery health status value is less than or equal to a first preset threshold, applying an activation voltage to the battery so that lithium ions in the lithium supplement contained in the battery are released into the electrolyte, wherein the activation voltage is higher than a normal charging voltage of the battery; When the battery health status value increases to be greater than or equal to a second preset threshold, the activation voltage is stopped from being applied and the normal charge-discharge cycle continues.

2. The method according to claim 1, characterized in that The lithium supplement is contained in the positive electrode of the battery.

3. The method according to claim 1, characterized in that The battery health status value is selected from at least one of the following parameters: battery capacity, remaining capacity, energy density, power density, electromotive force, open circuit voltage, operating voltage, discharge termination voltage and operating current.

4. The method according to any one of claims 1 to 3, characterized in that The battery health status value is the real-time capacity C real of the battery. The battery exhibits an initial capacity C0 in the initial charge-discharge cycle. The threshold is C0×80%. When C real drops to less than or equal to C0×80%, an activation voltage is applied to the battery.

5. The method according to claim 4, characterized in that After the initial charge-discharge cycle, the activation voltage is not applied, and the subsequent 2nd to Nth charge-discharge operations are directly performed, wherein N is an integer from 2 to 500,000, and the 2nd to Nth charge-discharge operations are performed using the normal charging voltage. During the 2nd to Nth charge-discharge operations, the real-time capacity Creal of the battery gradually decreases. Whenever Creal is lower than C0×80%, an activation voltage Vactive is applied to the battery to recover the activity. When the battery health status value increases to greater than or equal to a second preset threshold, the activation voltage is restored to the normal charging voltage, and the charge-discharge operation is continued.

6. The method according to claim 5, characterized in that The operation of applying an activation voltage Vactive to the battery for activity recovery is performed more than once. Starting from the second time, the activation voltage used for each activity recovery is increased relative to the activation voltage of the previous activity recovery. The amplitude of each activation voltage increase is fixed or the amplitude changes each time.

7. The method according to claim 5, characterized in that The operation of applying activation voltage Vactive to the battery for activity recovery is performed more than once, and starting from the second time, the activation voltage used for each activity recovery is increased by ≥0.1 V relative to the activation voltage of the previous activity recovery.

8. The method according to claim 1, characterized in that The operations of applying the normal charging voltage and the activation voltage are performed using the same charging device.

9. A lithium-ion secondary battery, comprising a lithium supplement, wherein the lithium-ion secondary battery performs charge-discharge operations at a normal charging voltage, and the lithium supplement can restore the activity of the battery at an activation voltage so that lithium ions contained in the lithium supplement in the battery are released into an electrolyte, and the activation voltage is higher than the normal charging voltage.

10. A battery management system (BMS), comprising: Interconnected monitoring unit, charging unit and control unit; The monitoring unit is used to monitor one or more health status values ​​of the lithium-ion battery; The charging unit can apply a normal charging voltage or an activation voltage to the battery, wherein the normal charging voltage is lower than the activation voltage; The control unit generates a charging signal or an activation signal according to the health status value measured by the monitoring unit; When the charging unit receives the charging signal, a normal charging voltage is applied to the battery; When the charging unit receives the activation signal, an activation voltage is applied to the battery, so that lithium ions in the lithium supplement contained in the battery are released into the electrolyte.

11. A vehicle, characterized in that: It includes the battery management system as claimed in claim 10.

12. A readable storage medium for storing a computer program, wherein the computer program is used to execute the method for restoring battery activity according to any one of claims 1 to 8.

13. The readable storage medium according to claim 12, wherein: The computer program is a battery management system (BMS) program.

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