Secondary battery charging method, secondary battery charging apparatus, charging device, and computer storage medium
Patent Information
- Application Number
- ES2022764288T
- Authority / Receiving Office
- ES · ES
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2021-10-29
- Filing Date
- 2022-04-27
- Publication Date
- 2026-09-14
- Estimated Expiration
- 2042-04-27
Smart Images
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Abstract
Description
Secondary battery charging method, secondary battery charging apparatus, charging device, and computer storage medium The present application claims priority to Chinese Patent Application No. 202111277631.4 entitled "CHARGING METHOD FOR SECONDARY BATTERY, CHARGING APPARATUS FOR SECONDARY BATTERY, CHARGING DEVICE, AND COMPUTER STORAGE MEDIUM" filed on October 29, 2021. Technical field This application relates to the technical field of batteries, and specifically to a charging method for a secondary battery, a charging apparatus for a secondary battery, a charging device, and a computer storage medium. Background of the technique In recent years, with the application and promotion of secondary batteries in industries such as various electronic products and new energy vehicles, their energy density has attracted increasing attention. A charging method for a secondary battery according to the preamble of claim 1 is known from CN 113258147 A, and further charging methods for secondary batteries are disclosed in CN 107221650 B and CN 105655554 A. However, in a first charging process of a secondary battery, a solid electrolyte interface (SEI) inevitably forms on the surface of a negative electrode active material, resulting in irreversible consumption of active ions. This makes it difficult to eliminate the irreversible capacity loss of the secondary battery and poses challenges for improving its energy density. Summary of the invention The examples in this application provide a method for a secondary battery, an apparatus for a secondary battery, a device, a computer storage medium, which can add lithium to the secondary battery in a cycling process. In one aspect, an example in this application provides a charging method for a secondary battery, the secondary battery comprising a lithium additive material. The method includes: acquiring a first health state (SOH1) of the secondary battery when the secondary battery is at a predetermined charging node; activating the lithium additive material when SOH1 is less than or equal to a first threshold for adding lithium to the secondary battery; performing a first charging process on the secondary battery; determining a second health state (SOH2) of the secondary battery based on a working parameter of the secondary battery in the first charging process; and charging the secondary battery when SOH2 is greater than a second threshold. The above technical solution detects the state of health (SOH) of the secondary battery when the secondary battery is in the preset charging node, subsequently adds lithium to the secondary battery when the SOH is low, and performs a normal charge-discharge cycle when the active lithium content of the secondary battery after the subsequent addition of lithium reaches the standard, thereby determining the loss of active lithium of the secondary battery in time, effectively adding active lithium, prolonging the cycle life of the secondary battery, and improving the energy density of the secondary battery.Furthermore, in the example of the present application, lithium is subsequently added to the secondary battery, thereby avoiding a number of problems such as the phase transition of the material on the surface of the material of the positive and negative electrode sheets, the increase in current resistance (DCR) and the generation of gas due to the decomposition of the electrolyte solution, and improving the cycle performance and rate performance of the secondary battery. In some possible examples, the method also includes: determining that the secondary battery is at a next charging node of the preset charging node when SOH2 is less than or equal to the second threshold; and activating the lithium addition material to add lithium to the secondary battery. According to the above technical solution, when the effect of adding lithium does not meet the operating requirements of the secondary battery, lithium is added again to the secondary battery, thereby maintaining the active lithium content in the secondary battery within a relatively high range, prolonging the cycle life of the secondary battery and improving the energy density of the secondary battery.In some possible examples, the activation of the lithium addition material to add lithium to the secondary battery includes: setting an overcharge protection voltage as the lithium addition voltage, where the lithium addition voltage is a charge cutoff voltage corresponding to a charge node where the secondary battery is located; charging the secondary battery to the lithium addition voltage at a first preset constant current rate; charging the secondary battery to a first preset charge cutoff voltage at a constant voltage of the lithium addition voltage; and discharging the second battery to a first preset cutoff voltage at a second preset constant current rate. The activation of the lithium addition material is implemented using the above approach, thereby avoiding the reduction of the electrochemical performance of the secondary battery, while adding active lithium for the secondary battery. In some possible examples, after establishing the overcharge protection voltage as the lithium addition voltage, the method further includes: heating the secondary battery to a first temperature. Before performing the first charging process on the secondary battery, the method further includes: monitoring the temperature of the secondary battery as a second temperature. According to the above technical solution, the secondary battery is heated before the addition of lithium and cycled at a low temperature before the addition of lithium, thereby reducing the capacity loss caused by battery polarization in the lithium addition process, releasing more active lithium from the lithium addition material and accelerating the rate of lithium addition. In some possible examples, the first temperature is from 25°C to 60°C, and the second temperature is from 20°C to 30°C. The first and second temperatures are controlled within an appropriate range, thereby further improving the lithium addition efficiency and ensuring the electrochemical performance of the secondary battery. The first charging process includes: discharging the second battery to a second preset cutoff voltage at a third preset constant current rate; charging the secondary battery to the first cutoff voltage at a fourth preset constant current rate; charging the secondary battery to the second preset cutoff voltage at a constant voltage of the first cutoff voltage; and discharging the second battery to the second cutoff voltage at the third preset constant current rate. In the previous technical solution, performing the first charging process on the secondary battery can facilitate the acquisition of charging parameters of the secondary battery, thus determining the effect of adding lithium. In some possible examples, the first rate is from 0.1 C to 1 C. In some possible examples, the first rate is from 0.1 C to 0.5 C. The first rate within an appropriate range can completely and uniformly disintercalate active lithium from an electrode material, and can increase the lithium reservoir in the negative electrode. In some possible examples, charging the secondary battery when SOH2 is greater than the second threshold includes: cyclically running the following stages on the secondary battery when SOH2 is greater than the second threshold until a preset stop condition is met: charging the secondary battery to the first cutoff voltage at the fourth preset constant current rate; charging the secondary battery to the second preset charge cutoff current at the constant voltage of the first cutoff voltage; and discharging the second battery to the second cutoff voltage at the third preset constant current rate, where the preset stop condition includes: the number of times the secondary battery is discharged to the second cutoff voltage reaches a preset number of times threshold, or the secondary battery is at the preset charging node. In the previous technical solution, the normal charge-discharge cycle can be performed when the active lithium content is sufficient, thus guaranteeing the cycle performance of the secondary battery. In some possible examples, the method further includes: establishing N load nodes and a plurality of first thresholds such that there is a one-to-one correspondence between each of the load nodes and the plurality of first thresholds based on the number of cycles and a cycle capacity of the secondary battery, where N2; establishing a plurality of second thresholds such that there is a one-to-one correspondence between the N load nodes and the plurality of second thresholds; and establishing a plurality of load cutoff voltages such that there is a one-to-one correspondence between the N load nodes and the plurality of load cutoff voltages, based on the second threshold. In the previous technical solution, the health status of the secondary battery can be monitored at each charging node, thus adding active lithium in a timely manner and also guaranteeing the energy density and cycle life of the battery. In some possible examples, the load cutoff voltage is from 4.4V to 4.8V. When the load cutoff voltage is within the above appropriate range, the lithium addition material can be better activated for lithium addition. In some possible examples, the lithium addition material has a molecular formula of Li1+xMyOz, where element M is selected from at least one of Ni or Co and at least one of Mn, Mo, Ru or Ti; where 0.05x0.5.0.10 <y0, 95, and 2z<4; y una proporción másica w del material de adición de litio satisface: 0w0, 35 respecto a la masa total de una lámina de electrodo positivo en la batería secundaria. The composition and content of the lithium additive material within the above appropriate range can further extend the cycle life of the secondary battery and ensure the energy density of the secondary battery. In some possible examples, a first coulombic efficiency e of the lithium addition material satisfies: 0, 2e0, 9. The first coulombic efficiency within the above appropriate range can reduce the irreversible capacity loss of the secondary battery during the first charge-discharge, thereby improving the cycle performance and energy density of the secondary battery. In some possible examples, in the secondary battery, a CB ratio of a charge capacity of a negative electrode active material to a charge capacity of a positive electrode active material satisfies 1, 05C.B.1, 15. Controlling the CB ratio of the charge capacity of the negative electrode active material to the charge capacity of the positive electrode active material within an appropriate range can improve the energy density of the secondary battery and reduce the manufacturing costs of the secondary battery, while ensuring the cycle performance of the secondary battery. In some possible examples, the secondary battery has a gas-permeable top cover. The secondary battery, which has a gas-permeable top cover, can immediately discharge the gas generated during lithium addition and secondary battery cycling processes, thus avoiding potential safety hazards such as battery expansion. In a second aspect, the present application provides a system comprising a charging apparatus and a secondary battery, the secondary battery comprising a lithium additive material.The device includes: an acquisition module configured to acquire a first health state SOH1 of the secondary battery when the secondary battery is in a preset charging node; a processing module configured to activate the lithium addition material when SOH1 is less than or equal to a first threshold for adding lithium to the secondary battery; a first charging module configured to perform a first charging process on the secondary battery; a first determination module configured to determine a second health state SOH2 of the secondary battery based on a working parameter of the secondary battery in the first charging process; and a second charging module, configured to charge the secondary battery when SOH2 is greater than a second threshold. In a third aspect, the present application provides a loading device. The device includes: a processor and a memory that stores computer program instructions; wherein the processor, when executing the computer program instructions, implements the loading method provided in any example in the first aspect of the present application. In a fourth aspect, the present application provides a computer storage medium, wherein the computer storage medium stores computer program instructions, and the computer program instructions, when executed by a processor, implement the loading method provided in any example in the first aspect of the present application. Description of drawings To more clearly describe the technical solutions in the examples provided in this application, the accompanying drawings to be used in the examples are briefly presented below. For those skilled in the art, other drawings based on these drawings can also be obtained without any further creative work. Fig. 1 is a schematic flowchart of a loading method provided in an example in this application; Fig. 2 is a schematic structural diagram of a loading apparatus provided in another example in this application; Figure 3 is a schematic structural diagram of a loading device provided in another example in this application; and Fig. 4 is a cycle capacity retention rate test diagram at 25°C of a secondary battery in Example 7 and Comparative Example 3 of this application. Detailed description The following are detailed examples of the technical solutions in this application, with reference to the accompanying drawings. These examples are used simply to illustrate the technical solutions in this application more clearly and are therefore intended only as examples and may not be used to limit the scope of protection of the attached claims. Unless otherwise defined, all technical and scientific terms used herein have the same meanings commonly understood by those skilled in the technical field of this application. The terms used herein are intended only to describe specific examples and are not intended to limit the scope of this application. The terms "comprises" and "has" and any variations thereof in the specification and claims of this application and the brief description of the drawings are intended to cover a non-exclusive inclusion. In the description of the examples in this application, the technical terms "first," "second," etc., are used only to distinguish different objects and cannot be understood to indicate or imply relative importance or implicitly indicate the number, specific order, or primary-secondary relationship of the technical features stated. In the description of the examples in this application, "a plurality of" means two or more, unless explicitly and specifically defined otherwise. The "examples" mentioned herein mean that particular features or feature structures described with reference to the examples may be included in at least one example in this application. The expression appearing in various parts of the specification does not always refer to the same example, nor to separate or alternative examples that are mutually exclusive with other examples. It is understood explicitly and implicitly by those skilled in the art that the examples described herein may be combined with other examples. In the description of the examples in this application, "and / or" is simply an association relationship used to describe associated objects, indicating that three relationships are possible. For example, A and / or B indicates that there are three cases: A alone, A and B together, and B alone. Furthermore, the " / " character in this document generally signifies that the associated objects before and after it are in an "or" relationship. In the description of the examples in this application, "a plurality of" refers to two or more (including two). Similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces). In the description of the examples in this application, the orientation or position relationship indicated by the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "top", "bottom", "front", "back", "left", "right", "vertical", "horizontal", "above", "below", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or position relationship shown in the accompanying drawings and is intended to facilitate the description of the examples in this application and simplify the description only, rather than indicate or imply that the device or element referred to must have a specific orientation or must be constructed or operated in a particular orientation and, therefore, should not be interpreted as limitations of the examples in this application. In the description of the examples in this application, unless expressly specified and limited otherwise, the technical terms "assemble," "join," "connect," "fix," etc., are to be understood in a broad sense, including a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection, an indirect connection through an intermediate means, an internal connection of two elements, or an interaction between two elements. For those skilled in the art, the specific meanings of the foregoing terms in the examples in this application may be determined on a case-by-case basis. To meet the requirements for high energy density in secondary batteries, the active lithium content can be increased using lithium addition technology to compensate for the loss of active lithium in the secondary battery during the initial charging process. Currently, the main lithium addition process with a high level of technical maturity involves directly adding lithium strip or lithium powder to the negative electrode or adding a lithium-rich material (such as lithium-rich transition metal oxides) to the positive electrode foil to increase the amount of active lithium. During the battery's chemical formation or initial charging process, this active lithium is disintercalated from the lithium-rich material to compensate for the loss of active lithium caused by the formation of the SEI film on the negative electrode active material. The inventor has discovered through research that, because the materials are pre-lithited before the battery's chemical formation, or because lithium is added to the secondary battery during the initial charging and chemical formation process, a significant amount of lithium-rich material is disintercalated from the active lithium during the first cycle. This necessitates an excess of negative electrode active material to provide intercalation sites for the active lithium. Furthermore, due to low coulombic efficiency, this excess negative electrode active material cannot participate in the lithium disintercalation process in subsequent cycles, thereby reducing the secondary battery's energy density to some extent.Furthermore, high-voltage charging is typically required to add lithium to the secondary battery during chemistry or the initial battery charge, leading to several problems, including phase transition on the surface of the positive and negative electrode plates, gas generation due to electrolyte decomposition, and a high DCR (Discharge Current Ratio). These problems also tend to worsen with increasing cycle counts. In order to solve the related technical problems, the inventor has found after thorough reflection that the addition of lithium during the secondary battery cycling process can largely compensate for the shortcomings of the lithium addition technology. Based on this, the examples in this application provide a charging method for a secondary battery, a charging apparatus for a secondary battery, a charging device, and a computer storage medium. The charging method for a secondary battery provided in one example in this application is presented first below. Figure 1 shows a schematic flow diagram of a charging method for a secondary battery provided in an example in this application, where the secondary battery comprises a lithium addition material. In the secondary battery, the lithium addition material may be a positive electrode lithium addition material to be added to a positive electrode sheet. As shown in Figure 1, the charging method for a secondary battery may specifically include the following steps (from S110 to S150). S110: Acquire a first SOH1 health state of a secondary battery when the secondary battery is in a preset charging node. S120: Activate a lithium addition material when SOH1 is less than or equal to a first threshold for adding lithium to the secondary battery. S130: perform a first charging process on the secondary battery. S140: Determine a second health state SOH2 of the secondary battery based on a working parameter of the secondary battery in the first charging process. S150: Charge the secondary battery when SOH2 is greater than a second threshold In stage S110, the preset charging node can be any charging node among at least two charging nodes arranged based on experimental data, such as cycle life or capacity fading of the secondary battery. Specifically, the preset charging node can be a time-based node or a cycle-number node where greater active lithium loss is predicted based on the aforementioned experimental data. SOH1 can represent the remaining battery life (SOH) of the secondary battery at a given time and has a widely understood meaning in the field. Specifically, SOH can also be defined in terms of cycle life or capacity fade. In stage S120, the first threshold can be a preset State of Hydrogen (SOH) used to measure the degree of active lithium loss in the secondary battery. When SOH1 is less than or equal to the first threshold, the secondary battery can be considered to be in a state where active lithium needs to be added. In this case, the lithium addition material can be activated to add lithium to the secondary battery. The lithium addition material can be activated by different means. For example, the lithium addition material can be activated by increasing the charging voltage or charging rate, or by increasing the temperature, or it can be activated by charging and discharging at a certain voltage or rate. Alternatively, when SOH1 is less than or equal to the first threshold, a warning signal can be sent to the user to alert them that the secondary battery is in a state where active lithium needs to be added. In stage S130, the first charging process can be to charge and discharge the secondary battery based on parameters of a normal charge-discharge cycle. In stages S140 and S150, SOH2 can represent the remaining battery life SOH after adding lithium to the secondary battery, and has a similar meaning to SOH1. The second threshold can be a preset SOH used to measure whether the active lithium content of the secondary battery meets a standard. When SOH2 is greater than the second threshold, it can be considered that, after the lithium addition, the lost active lithium has been fully added to the secondary battery and the active lithium content in the secondary battery can meet operating requirements. In this case, the lithium addition can be considered complete, and normal charge-discharge cycling can be performed on the secondary battery. In the example of the present application, the SOH of the secondary battery is detected when the secondary battery is in the preset charging node, lithium is subsequently added to the secondary battery when the SOH is low, and the normal charge-discharge cycle is performed when the active lithium content of the secondary battery after the subsequent addition of lithium reaches the standard, thus determining the loss of active lithium of the secondary battery in time, effectively adding active lithium, prolonging the cycle life of the secondary battery, and improving the energy density of the secondary battery.Furthermore, in the example of the present application, lithium is subsequently added to the secondary battery, thereby avoiding a number of problems such as the phase transition of the material on the surface of the material of the positive and negative electrode sheets, the increase in DCR current resistance and the generation of gas due to the decomposition of the electrolyte solution, and improving the cycle performance and rate performance of the secondary battery. In some examples, the method may also include: determining that the secondary battery is at a next charging node of the preset charging node when SOH2 is less than or equal to the second threshold; and activating the lithium addition material to add lithium to the secondary battery. When SOH2 is less than or equal to the second threshold, it can be considered that, after adding lithium to the secondary battery, the active lithium content still does not meet the operating requirements of the secondary battery. In this case, the secondary battery can be moved to the next charging node and receive another lithium addition. This allows us to determine whether the state of the secondary battery can meet the operating requirements based on its active lithium content after lithium addition. If the state of the secondary battery cannot meet the operating requirements, more lithium is added. This way, the active lithium content in the secondary battery can be maintained within a high range, thus extending its cycle life and improving its energy density. In some examples, the activation of the lithium addition material to add lithium to the secondary battery specifically includes: establishing an overcharge protection voltage as the lithium addition voltage, where the lithium addition voltage is a charge cutoff voltage corresponding to a charge node where the secondary battery is located; charging the secondary battery to the lithium addition voltage at a first preset constant current rate; charging the secondary battery to a first preset charge cutoff voltage at a constant voltage of the lithium addition voltage; and discharging the second battery to a first preset cutoff voltage at a second preset constant current rate. The overcharge protection voltage can be understood as a maximum charging voltage set to ensure the safe operation of the secondary battery. When the charging voltage exceeds the overcharge protection voltage, the charging circuit is disconnected. The lithium addition voltage can be understood as the charge cutoff voltage required to activate the lithium addition material. The magnitude of the charge cutoff voltage can be determined based on the charging node, and it is generally higher than the charge cutoff voltage during the normal charge-discharge cycle of the secondary battery. For example, the charge cutoff voltage might be 4.4 V to 4.8 V, 4.4 V to 4.7 V, or 4.5 V to 4.7 V. Maintaining the charge cutoff voltage within an appropriate range ensures both safety and high lithium addition efficiency in the lithium addition process. When the secondary battery is at different charging nodes, the charging cutoff voltages can be the same or they can be different. For example, the charging cutoff voltages at the charging nodes can increase with the number of charging cycles at those nodes. This is equivalent to dividing the high-voltage charging process for adding lithium into multiple subsequent lithium addition processes, allowing the electrode material time and space to dampen, release surface tension, and re-establish its structure. This can improve the stability of the surface structure of the positive and negative electrode sheets, thereby enhancing the electrochemical performance of the secondary battery, such as initial capacity and first coulombic efficiency. The first and second rates can be preset small charging and discharging rates. These rates can be the same or different. For example, the first and second rates can be selected independently from 0.1 C to 1 C, or from 0.1 C to 0.5 C. Specifically, the first and second rates can be 0.1 C, 0.2 C, 0.33 C, 0.5 C, or 1 C.In the process of activating the lithium addition material to add lithium to the secondary battery, controlling the charge-discharge rate within an appropriate and small range can cause the active lithium to disintercalate completely and uniformly from the electrode material, thereby reducing the migration of transition metal and the degree of phase transition on the surface of the material, increasing the lithium reserve in the negative electrode, adding more active lithium, and further improving the energy density and cycle performance of the secondary battery. The first charge cutoff voltage can be a charge cutoff current based on the properties of the electrode material and the lithium additive material in the secondary battery, and can be, for example, 0.05 C, 0.04 C, or 0.02 C. The first charge cutoff voltage can be the charge cutoff voltage in the normal cycle. In this example, charging is done at a small rate and high voltage, and discharging is done at a small rate, thereby activating the lithium addition material, adding lithium to the secondary battery, avoiding problems such as phase transition of the material on the surface of the positive and negative electrode sheets, gas generation due to decomposition of the electrolyte solution, and increased DCR, while simultaneously adding active lithium and ensuring that the secondary battery has high energy density, long cycle life, good cycle performance and rate performance. In some examples, after establishing the overcharge protection voltage as the lithium addition voltage, the method may also include: heating the secondary battery to a first temperature. Before performing the first charging process on the secondary battery, the method may also include: monitoring the temperature of the secondary battery as a second temperature. The first temperature can be 25°C to 60°C, 30°C to 55°C, 35°C to 50°C, or 40°C to 45°C. Specifically, the first temperature can be 25°C, 35°C, 45°C, or 55°C. The second temperature can be, for example, 20°C to 30°C, during the normal charge-discharge cycle of the secondary battery. It is easily understood that the second temperature can be lower than the first temperature. Maintaining the first temperature within an appropriate range can reduce capacity loss caused by battery polarization during the lithium addition process, release more active lithium from the lithium addition material, and accelerate the lithium addition rate. Maintaining the second temperature within an appropriate range can ensure the cycle performance and discharge rate of the secondary battery. In this example, before activating the lithium addition material to add lithium to the secondary battery, the temperature of the secondary battery is increased. This reduces the capacity loss caused by battery polarization during the lithium addition process, releasing more active lithium from the lithium addition material and accelerating the lithium addition rate. This improves the lithium addition efficiency, thereby enhancing the energy density and cycle performance of the secondary battery. In some examples, the first charging process may include: discharging the second battery to a second preset cutoff voltage at a third preset constant current rate; charging the secondary battery to the first cutoff voltage at a fourth preset constant current rate; charging the secondary battery to the second preset cutoff voltage at a constant voltage of the first cutoff voltage; and discharging the second battery to the second cutoff voltage at the third preset constant current rate. In the first charging process, the secondary battery can operate at the charge-discharge rate and charge-discharge cutoff voltage of the normal cycling process. The third rate can be from 0.2C to 1C. The second cutoff voltage can be the cutoff voltage corresponding to the normal cycling process of the secondary battery. The fourth rate can be from 0.2C to 1C. The second charge cutoff current can be a charge cutoff current corresponding to the normal cycling process of the secondary battery, and specifically the second charge cutoff current can be from 0C to 0.05C. In this example, the secondary battery operates at the charge-discharge rate and charge-discharge cutoff voltage during normal cycling after lithium addition. Therefore, the State of Hydrogen (SOH) of the secondary battery during normal cycling can be determined based on the secondary battery's operating parameters during the initial charging process. This allows us to determine whether the active lithium content in the secondary battery after lithium addition can meet operating requirements and further simplifies the determination of the secondary battery's lithium addition process. In some examples, charging the secondary battery when SOH2 is greater than the second threshold may include: cyclically executing the following stages on the secondary battery when SOH2 is greater than the second threshold until a preset stop condition is met: charging the secondary battery to the first cutoff voltage at the fourth preset constant current rate; charging the secondary battery to the second preset charge cutoff current at the constant voltage of the first cutoff voltage; and discharging the second battery to the second cutoff voltage at the third preset constant current rate. The preset stop condition may include: the secondary battery being discharged a number of times to the second cutoff voltage reaching a preset threshold, or the secondary battery being at the preset charging node. In this example, when the active lithium content in the secondary battery can meet the working requirements after the addition of lithium, the normal charge-discharge cycle can be carried out until the service life of the secondary battery has ended, or until it is necessary to add active lithium to the secondary battery, so that the secondary battery can quickly return to a normal working state after the amount of lithium added reaches a standard, thereby ensuring the cycle performance of the secondary battery. In some examples, the method may further include: establishing N load nodes and a plurality of first thresholds such that there is a one-to-one correspondence between each of the load nodes and the plurality of first thresholds based on the number of cycles and a cycle capacity of the secondary battery, where N2; establishing a plurality of second thresholds such that there is a one-to-one correspondence between the N load nodes and the plurality of second thresholds; and establishing a plurality of load cutoff voltages such that there is a one-to-one correspondence between the N load nodes and the plurality of load cutoff voltages, based on the second threshold. The N charging nodes can be any charging node between at least two charging nodes arranged based on experimental data, such as cycle life or capacity fading of the secondary battery. Specifically, the charging node can be a time node or a cycle-number node where a greater loss of active lithium is predicted based on the aforementioned experimental data. It is easily understood that, among the N charging nodes, each charging node corresponds to a different cycle time or number of cycles, and also to different first and second thresholds. As the cycle time or number of cycles increases, the first and second thresholds may gradually decrease corresponding to the charging node. Similarly, as the cycle time or number of cycles increases, the voltage required to activate the lithium additive material will change accordingly.Specifically, a charge cutoff voltage corresponding to each charge node can be set based on the active lithium content to be achieved at different charge nodes of the secondary battery, for example the second threshold. In this example, two or more charging nodes can be preset, and the health status of the secondary battery can be monitored at each charging node, thereby adding active lithium in a timely manner and also ensuring the energy density and cycle life of the battery. In some examples, the lithium addition material may have a molecular formula of Li1+xMyOz, where element M can be selected from at least one of Ni or Co and at least one of Mn, Mo, Ru or Ti, where 0.05x0.5, optionally 0.1x0.3, and more specifically 0.15x0.25; 0.10 <y0, 95, opcionalmente 0, 55y0, 90, y más específicamente 0, 65y0, 85; y 2z4, opcionalmente 2z3, y más específicamente 2z2, 5. A mass ratio w of the lithium addition material can satisfy: 0w0.35 with respect to the total mass of the positive electrode sheet in the secondary battery. Optionally, 0w0.25, 0.02w0.15 or 0.03w0.10. The lithium additive material in this example can be added to the positive electrode plate of the secondary battery. The lithium additive material has an appropriate active lithium content and activation voltage, and can be activated during the battery cycling process, thereby adding active lithium to the secondary battery. Furthermore, the inventor discovered that adding too little lithium additive material reduces the cycle life enhancement effect of the secondary battery to some extent, while adding too much will reduce the energy density of the secondary battery.The mass proportion of the lithium addition material in the positive electrode sheet within the above appropriate range can achieve both a long cycle life and a high energy density of the secondary battery, thereby further extending the cycle life of the secondary battery and ensuring the energy density of the secondary battery. In some examples, the first coulombic efficiency e of the lithium addition material can satisfy: 0.20e0.90, optionally 0.30e0.80, 0.40e0.75, 0.40e0.65 or 0.50e0.65. In this example, the first coulombic efficiency of the lithium additive material can be controlled by various means. For instance, the first coulombic efficiency can be regulated by adjusting the composition, crystalline phase, and preparation process of the lithium additive material, as well as the porosity of the lithium additive material particles. Any approach that keeps the first coulombic efficiency of the lithium additive material within the specified range is acceptable. This is not limited in the present application. This approach can reduce the irreversible capacity loss of the secondary battery during the first charge / discharge cycle, thereby improving the cycle performance and energy density of the secondary battery. By controlling the composition, mass ratio, and first coulombic efficiency of the lithium addition material, the lithium reserve in the positive electrode relative to the negative electrode can satisfy: 0.01 lithium reserve 0.99, 0.05 lithium reserve 0.60, and 0.09 lithium reserve 0.3, thereby significantly improving the effect of enhancing the service life of the secondary battery and ensuring the energy density of the secondary battery. In some examples, in the secondary battery, a CB ratio of a charge capacity of a negative electrode active material to a charge capacity of a positive electrode active material may satisfy: 1, 05C.B.1, 15, 1, 1C.B.1, 15 or 1, 1C.B.1, 13. In prelithiation technology for lithium addition, considering that the activation of the lithium-rich phase in the lithium addition material during the first charge and the charging of the positive electrode active material over a wider range leads to greater charging capacity, the excess negative electrode active material is used to balance the positive electrode capacity. This excess negative electrode active material cannot be used in subsequent cycling processes, thus decreasing the energy density. The present application adds lithium by post-addition and can make full use of lithium deintercalation sites in the negative electrode active material corresponding to a hidden depth of discharge (DOD), such as the lithium deintercalation sites of the negative electrode active material corresponding to 0 to 5% or 95 to 100% DOD, when lithium is added in the cycling process.Furthermore, with the gradual increase in active lithium loss during cycling, the active material of the negative electrode can provide a large number of lithium disintercalation sites. Therefore, the content of the negative electrode active material can be designed based on the normal cycling capacity, and consequently, it is not necessary to increase the amount of electrolyte solution used. For example, the first cycle capacity of the positive electrode over a cycle voltage range is defined as Q, the first cycle capacity of the positive electrode over a lithium addition voltage range is defined as R, and the first specific cycle capacity of the negative electrode is defined as P. In pre-lithiation technology for lithium addition, when designing a secondary battery, the first required cycle capacity of the negative electrode is CB*(Q+R). The negative electrode is designed based on the normal cycle capacity, and the first required cycle capacity of the negative electrode is CB*Q. When the two designs have the same CB value, the present embodiment can save the amount of negative electrode active material used by CB*R / P. In this example, controlling the CB ratio (the charge capacity of the negative electrode active material relative to the charge capacity of the positive electrode active material) within an appropriate range in the secondary battery can improve the secondary battery's energy density and reduce its manufacturing costs, while ensuring its cycle performance. In some examples, the secondary battery may have a gas-permeable top cover. The secondary battery, which has a gas-permeable top cover, can immediately discharge the gas generated during lithium addition and secondary battery cycling processes, thus avoiding potential safety hazards such as battery expansion. Based on the same inventive concept, an example in this application further provides a charging apparatus 200 for a secondary battery. The secondary battery includes a lithium additive material. The description will be provided specifically with reference to Fig. 2. As shown in Fig. 2, the loading apparatus 200 may include an acquisition module 201, a processing module 202, a first loading module 203, a first determination module 204, and a second loading module 205. The acquisition module 201 is configured to acquire a first SOH1 health state of the secondary battery when the secondary battery is in a preset charging node. Processing module 202 is configured to activate lithium addition material when SOH1 is less than or equal to a first threshold for adding lithium to the secondary battery. The first charging module 203 is configured to perform an initial charging process on the secondary battery. The first determination module 204 is configured to determine a second health status (SOH2) of the secondary battery based on a working parameter of the secondary battery during the initial charging process. The second charging module 205 is configured to charge the secondary battery when SOH2 is greater than a second threshold. In some examples, the charging device 200 may also include: a second determination module configured to determine that the secondary battery is at a subsequent charging node of the preset charging node when SOH2 is less than or equal to the second threshold. Processing method 202 is further configured to activate the lithium addition material to add lithium to the secondary battery. In some examples, the processing module 202 may specifically include: an adjustment submodule configured to set an overload protection voltage as the lithium add voltage, where the lithium add voltage is a charge cutoff voltage corresponding to a charge node where the secondary battery is located; a first constant current charge submodule configured to charge the secondary battery to the lithium add voltage at a first preset constant current rate; a first constant voltage charge submodule configured to charge the secondary battery to a first preset charge cutoff voltage at a constant voltage of the lithium add voltage; and a first constant current discharge submodule configured to discharge the second battery to a first preset cutoff voltage at a second preset constant current rate. In some examples, the 202 processing module may also include: a heating submodule configured to heat the secondary battery to a first temperature; and a control submodule configured to control a temperature of the secondary battery as a second temperature. In some examples, the first temperature might be from 25°C to 60°C, from 30°C to 55°C, from 35°C to 50°C, or from 40°C to 45°C. The second temperature might be from 20°C to 30°C. In some examples, the first 203 charging module may specifically include: a second constant current discharge submodule configured to discharge the second battery to a second preset cutoff voltage at a third preset constant current rate; a second constant current charging submodule configured to charge the secondary battery to the first cutoff voltage at a fourth preset constant current rate; a second constant voltage charging submodule configured to charge the secondary battery to the second preset cutoff voltage at a constant voltage of the first cutoff voltage; and a third constant current discharge submodule configured to discharge the second battery to the second cutoff voltage at the third preset constant current rate. In some examples, the first rate is from 0.1 C to 1 C. In some examples, the first rate is from 0.1 C to 0.5 C. In some examples, the second charging module may specifically include: a processing submodule configured to cyclically execute the following stages on the secondary battery when SOH2 exceeds the second threshold until a preset stop condition is met: charging the secondary battery to the first cutoff voltage at a fourth preset constant current rate; charging the secondary battery to the second preset cutoff voltage at a constant voltage of the first cutoff voltage; and discharging the second battery to the second cutoff voltage at the third preset constant current rate. The preset stop condition may include: the number of times the secondary battery is discharged to the second cutoff voltage reaches a preset threshold, or the secondary battery is at the preset charging node. In some possible examples, the charging apparatus 200 may further include: a first adjustment module configured to establish N charging nodes and a plurality of first thresholds such that there is a one-to-one correspondence between each of the charging nodes and the plurality of first thresholds based on the number of cycles and a cycle capacity of the secondary battery, where N2; a second adjustment module configured to establish a plurality of second thresholds such that there is a one-to-one correspondence between the N charging nodes and the plurality of second thresholds; and a third adjustment module configured to establish a plurality of charge cutoff voltages such that there is a one-to-one correspondence between the N charging nodes and the plurality of charge cutoff voltages, based on the second threshold. In some examples, the load cutoff voltage can be from 4.4V to 4.8V, from 4.4V to 4.7V, or from 4.5V to 4.7V. In some examples, the lithium addition material may have a molecular formula of Li1+xMyOz, where element M can be selected from at least one of Ni or Co and one or more of Mn, Mo, Ru or Ti, where 0.05x0.5, optionally 0.1x0.3, and more specifically 0.15x0.25; 0.10 <y0, 95, opcionalmente 0, 55y0, 90, y más específicamente 0, 65y0, 85; y 2z4, opcionalmente 2z3, y más específicamente 2z2, 5. A mass ratio w of the lithium addition material can satisfy: 0w0.35 with respect to the total mass of the positive electrode sheet in the secondary battery. Optionally, 0w0.25, 0.02w0.15 or 0.03w0.10. In some examples, the first coulombic efficiency e of the lithium addition material can satisfy: 0.20e0.90, optionally 0.30e0.80, 0.40e0.75, 0.40e0.65 or 0.50e0.65. In some examples, in the secondary battery, a CB ratio of a charge capacity of a negative electrode active material to a charge capacity of a positive electrode active material may satisfy: 1, 05C.B.1, 15, 1, 1C.B.1, 15 or 1, 1C.B.1, 13. In some examples, the secondary battery may have a gas-permeable top cover. Therefore, the State of Hydrogen (SOH) of the secondary battery can be detected when the secondary battery is in the preset charging node. Lithium can be subsequently added to the secondary battery when the SOH is low, and the normal charge-discharge cycle can be performed when the active lithium content of the secondary battery, after the subsequent addition of lithium, reaches the standard. This determines the loss of active lithium in the secondary battery in a timely manner, effectively adding active lithium, prolonging the cycle life of the secondary battery, and improving the energy density of the secondary battery.Furthermore, in the example of the present application, lithium is subsequently added to the secondary battery, thereby avoiding a number of problems such as the phase transition of the material on the surface of the material of the positive and negative electrode sheets, the increase in DCR current resistance and the generation of gas due to the decomposition of the electrolyte solution, and improving the cycle performance and rate performance of the secondary battery. Based on the same inventive concept, an example in the present application further provides a charging device, which will be described in detail specifically with reference to Fig. 3. As shown in Fig. 3, the loading device may include a processor 301 and a memory 302 that stores computer program instructions. Specifically, the 301 processor may include a central processing unit (CPU), or an application-specific integrated circuit (ASIC), or one or more integrated circuits that may be configured to implement examples of the present application. Memory 302 can include mass storage for data or instructions. For example, and without limitation, memory 302 can include a hard disk drive (HDD), a floppy disk drive, flash memory, an optical disc, a magneto-optical disc, a magnetic tape, or a universal serial bus (USB) drive, or a combination of two or more of the above. Memory 302 can include removable or non-removable (or fixed) media, as applicable. Memory 302 can be internal or external to an integrated disaster recovery gateway device, as applicable. In one specific example, memory 302 is non-volatile solid-state memory. Memory may include read-only memory (ROM), random-access memory (RAM), a disk storage device, an optical storage device, a flash memory device, or an electrical, optical, or other physical / tangible memory device. Therefore, memory usually includes one or more tangible (non-transient) computer-readable storage media (e.g., memory devices) encoded with software that includes computer-executable instructions, and the software, when executed (e.g., by one or more processors), is operative to perform the operations described with reference to the method in any aspect of this disclosure. Processor 301 reads and executes computer program instructions stored in memory 302 to implement any of the loading methods from the previous examples. As an example, the charging device may also include a communication interface 303 and a bus 310. As shown in Fig. 3, the processor 301, memory 302, and communication interface 303 communicate with each other via bus 310. The 303 communication interface is primarily configured to implement communication between the modules, appliances, units and / or devices of the examples in this application. The 310 bus includes hardware, software, or both, and couples the components of the online data flow measurement device. For example, and without limitation, the bus may include an Accelerated Graphics Port (AGP) or other graphics buses, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an InfiniBand interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, an Advanced Technology Serial Transport (SATA) bus, a Video Electronics Standards Association (VLB) local bus, or other appropriate buses, or a combination of two or more of the above. The 310 bus may include one or more buses, as applicable.Although the examples in this application describe and illustrate a specific bus, this application contemplates any appropriate bus or interconnection. The loading device can execute a method to recognize a multi-level dialogue intent in the examples in this application, thereby implementing the loading method and loading delivery described with reference to Fig. 1 and Fig. 2. An example of the present application further provides a computer-readable storage medium that stores computer program instructions, wherein the computer program instructions, when executed by a processor, implement the method of the example shown in Fig. 1 provided in the present application. The functional blocks shown in the preceding structural block diagrams can be implemented as hardware, software, firmware, or a combination thereof. When the functional blocks are implemented as hardware, the hardware may be, for example, an electronic circuit, an application-specific integrated circuit (ASIC), appropriate firmware, a plug-in module, or a function card. When the functional blocks are implemented as software, the elements of this application are programs or code segments used to perform the required tasks. The programs or code segments may be stored on a machine-readable medium or transmitted over a transmission medium or communication link by means of a data signal carried on a carrier wave. "Machine-readable medium" may include any medium capable of storing or transmitting information.Examples of machine-readable media include an electronic circuit, a semiconductor memory device, a read-only memory (ROM), flash memory, an erasable ROM (EROM), a floppy disk, a CD-ROM, an optical disc, a hard drive, fiber optic media, a radio frequency (RF) link, and the like. Code segments can be downloaded over a computer network, such as the Internet or an intranet. It should also be noted that the illustrative examples referenced in this application describe methods or systems based on a series of steps or devices. However, this application is not limited to the order of the steps mentioned above; that is, the steps may be executed in the order mentioned in the examples or in a different order, or several steps may be executed concurrently. Examples The following are examples from this application. The examples described below are illustrative and used simply to explain this application, and should not be interpreted as limiting it. Where no specific technique or condition is specified in an example, a technique or condition described in the literature on the technique or in the product manual shall prevail. Reagents or instruments used without manufacturer indication are conventional, commercially available products. Examples 1-17 Preparation of a positive electrode sheet A positive electrode active material (LiNi0.5Co0.2Mn0.3O2), a lithium addition material, a polyvinylidene fluoride (PVDF) binder, and a Super P conductive agent were dissolved in N-methylpyrrolidone (NMP) in a mass ratio of 80:10:5:5 and thoroughly mixed. The surface of an aluminum foil was then coated with the solution, dried, and cold-pressed to obtain the positive electrode foil. Preparation of a negative electrode foil A negative electrode active material, styrene-butadiene rubber (SBR), and a conductive agent, Super P, were dissolved in deionized water at a mass ratio of 90:5:5 and thoroughly mixed. The surface of a copper foil was then coated with the solution, dried, and cold-pressed to obtain the negative electrode foil. Preparing a secondary battery The resulting positive electrode sheet and negative electrode sheet were rolled, hot-pressed, injected with liquid, and encapsulated to obtain a secondary lithium-ion battery. Chemical formation of the secondary battery The secondary battery was charged to 3.0 V at a constant current at a rate of 0.1 C, and then charged to 3.75 V at a constant current at a rate of 0.2 C. Secondary battery cycle The following cycle was performed on the secondary battery under normal conditions at 25°C: charge to 4.40 V at a constant current of 1 C, charge to 0.05 C at a constant voltage, and discharge to 2.5 V at a constant current of 0.2 C. Addition of lithium to the secondary battery The second secondary battery in Example 5 was provided with 1 charging node, the secondary batteries in Examples 6 and 7 were provided with 2 charging nodes, and the secondary batteries in the remaining examples were provided with 3 charging nodes. A first node was one in which, when the secondary battery had undergone 500 cycles, a corresponding first threshold was 93% SOH, a corresponding second threshold was 98% SOH, and a corresponding charge cutoff voltage was Vc1; a second node was one in which, when the secondary battery had undergone 1,000 cycles, a corresponding first threshold was 88% SOH, a corresponding second threshold was 93% SOH, and a corresponding charge cutoff voltage was Vc2; and a third node was one in which, when the secondary battery had undergone 1,000 cycles, a corresponding first threshold was 88% SOH, a corresponding second threshold was 93% SOH, and a corresponding charge cutoff voltage was Vc2.After 500 cycles, the first corresponding threshold was 83% SOH, the second corresponding threshold was 85% SOH, and the corresponding charge cutoff voltage was Vc3. When the secondary battery reached a charging node, the lithium addition process was activated to add lithium to the secondary battery. Table 1 shows the first rate, first temperature, and first cutoff voltage for the lithium addition process. The first charge cutoff current was 0.05 C, and the second rate was 0.2 C. If the SOH of the secondary battery after lithium addition was less than the second corresponding threshold, the secondary battery proceeded directly to the next charging node for lithium addition. Comparative Example 1 The preparation of the positive electrode sheet, the preparation of the negative electrode sheet, the preparation of the secondary battery, and the chemical formation of the secondary battery were the same as in Examples 1 to 17, except that: the lithium addition material was not added, and in the preparation of the positive electrode sheet, the mass ratio of the positive electrode active material, PVDF, and Super P conductive agent was 90:5:5. Secondary battery cycle The following cycle was performed at 25 °C: charge to 4.40 V at a constant current of 1 C, charge to 0.05 C at a constant voltage, and discharge to 2.5 V at a constant current of 0.2 C. Comparative Example 2 The preparation of the positive electrode sheet, the preparation of the negative electrode sheet, the preparation of the secondary battery, and the chemical formation of the secondary battery were the same as in Examples 1 to 17. Addition of lithium to the secondary battery Once the chemical formation process was complete, the secondary battery was further charged to 4.7 V at a constant current rate of 0.2 C, then charged to a constant voltage at a cutoff current of 0.05 C; and then discharged to 2.5 V at a constant current of 0.33 C. Secondary battery cycle The following cycle was performed at 25 °C: charge to 4.40 V at a constant current of 1 C, charge to 0.05 C at a constant voltage, and discharge to 2.5 V at a constant current of 0.2 C. Comparative Example 3 The preparation of the positive electrode sheet, the preparation of the negative electrode sheet, the preparation of the secondary battery, and the chemical formation of the secondary battery were the same as in Examples 1 to 17. Addition of lithium to the secondary battery Once the chemical formation process was completed, the secondary battery was further charged to 4.5 V at a constant current at a rate of 0.2 C, then charged to a constant voltage at a cutoff current of 0.05 C; and then discharged to 2.5 V at a constant current of 0.33 C. Secondary battery cycle The following cycle was performed at 25 °C: charge to 4.40 V at a constant current of 1 C, charge to 0.05 C at a constant voltage, and discharge to 2.5 V at a constant current of 0.2 C. The specific parameters are shown in Table 1. Proof (1) Test of a secondary battery capacity retention rate At 25 °C, the secondary battery was charged to 4.4 V at a constant current of 1 C and then charged to 0.05 C at a constant voltage, with the charge capacity at that point reported as the first cycle charge capacity. The secondary battery was then discharged to 2.5 V at a constant current of 0.2 C and allowed to stand for 5 minutes, constituting a cyclic charge-discharge process. The discharge capacity at that point was reported as the first cycle discharge capacity. The secondary battery was subjected to a cyclic charge-discharge test using the above approach. A discharge capacity was reported after each cycle, and the capacity retention rate of the cycled secondary battery to the Nth cycle was defined as a percentage value of the Nth cycle discharge capacity divided by the first cycle discharge capacity. The results of the Example 7 test and the Comparative Example 3 test are shown in Fig. 4. (2) Test of a cycle life of the secondary battery At 25°C, the secondary battery was charged to an upper cutoff voltage of 4.4 V at a constant current of 1 C and then charged at 0.05 C at a constant voltage. The charge capacity at this point was reported as the first cycle charge capacity. The secondary battery was then discharged to 2.5 V at a constant current of 0.2 C and allowed to stand for 5 minutes, constituting a cyclic charge-discharge process. The discharge capacity at this point was reported as the first cycle discharge capacity. The secondary battery was subjected to a cyclic charge-discharge test using the above approach. A discharge capacity was reported after each cycle until the secondary battery's discharge capacity faded to 80% of the first cycle discharge capacity, and the number of cycles at this point was used as the cycle life of the secondary battery. (3) Test of a first coulombic efficiency e of the lithium addition material The lithium addition material, a polyvinylidene fluoride (PVDF) binder, and a Super P conductive agent were dissolved in N-methylpyrrolidone (NMP) at a mass ratio of 90:5:5 and thoroughly mixed. The surface of an aluminum foil was then coated with the solution, dried, and cold-pressed to obtain the positive electrode foil. A negative electrode active material, styrene-butadiene rubber (SBR), and a Super P conductive agent were dissolved in deionized water at a mass ratio of 90:5:5 and thoroughly mixed. The surface of a copper foil was then coated with the solution, dried, and cold-pressed to obtain the negative electrode foil. The previous positive electrode sheet and the previous negative electrode sheet were assembled to form a secondary battery. At 25 °C, the secondary battery was charged to 4.7 V at a constant current at a rate of 0.1 C and then charged to 0.05 C at a constant voltage, and the charge capacity at that time was reported as a first cycle charge capacity C0; the secondary battery was discharged to 2.5 V at a constant current of 0.1 C, and a discharge capacity at that time was reported as a first cycle discharge capacity D0; and the first coulombic efficiency e of the lithium addition material was D0 / C0. (4) Lithium reserve test method The lithium reserve is a proportion of the lithium content in the negative electrode active material relative to all elements. The dried negative electrode foil was heat-treated in an oven at a specific temperature for a certain time (e.g., 400 °C, 2 h), and optionally a region of the heat-treated negative electrode foil was selected to sample the negative electrode active material (sampling optionally by scraping powder with a blade). The sample of negative electrode active material was dissolved in concentrated nitric acid, and the solution was then diluted to prepare a 500 µg / ml solution. The diluted solution was tested using an inductively coupled plasma optical emission spectrometer (ICP-OES) according to a standard ICP test procedure. The test results are detailed in Table 1. As can be seen from the previous test results, in Examples 1 to 24, by post-addition of lithium using the charging method provided in this application, the cycle life is improved to some extent. In Comparative Example 2 and Example 5, lithium was added only once at the same lithium addition voltage, and the only difference was that in Comparative Example 2, the lithium addition material was activated after chemical formation of the secondary battery, while in Example 5, lithium was added later in the cycling process. However, the secondary battery in Example 5 has a significantly longer cycle life than the secondary battery in Comparative Example 2. Furthermore, the type of lithium addition material, the first coulombic efficiency (e), the mass ratio (w) of the lithium addition material, the first temperature, the first rate, and the CBThese are also important factors that affect the cycle life of the secondary battery.
Claims
1. A charging method for a secondary battery, the secondary battery comprising a lithium additive material, the method comprising: acquiring a first health state SOH1 of the secondary battery when the secondary battery is at a preset charging node; activating the lithium additive material when SOH1 is less than or equal to a first threshold for adding lithium to the secondary battery; performing a first charging process on the secondary battery; determining a second health state SOH2 of the secondary battery based on a working parameter of the secondary battery in the first charging process; and charging the secondary battery when SOH2 is greater than a second threshold.characterized in that the first charging process comprises: discharging the secondary battery to a second preset cutoff voltage at a third preset constant current rate; charging the secondary battery to the first cutoff voltage at a fourth preset constant current rate; charging the secondary battery to a second preset charge cutoff voltage at a constant voltage of the first cutoff voltage; and discharging the second battery to the second cutoff voltage at the third preset constant current rate.
2. The method according to claim 1, wherein the method further comprises: determining that the secondary battery is at a subsequent charging node from the preset charging node when SOH2 is less than or equal to the second threshold; and activating the lithium addition material to add lithium to the secondary battery.
3. The method according to claim 1 or 2,wherein the activation of the lithium addition material for adding lithium to the secondary battery comprises: establishing an overcharge protection voltage as the lithium addition voltage, where the lithium addition voltage is a charge cutoff voltage corresponding to a charge node where the secondary battery is located; charging the secondary battery to the lithium addition voltage at a first preset constant current rate; charging the secondary battery to a first preset charge cutoff voltage at a constant voltage of the lithium addition voltage; and discharging the second battery to a first preset cutoff voltage at a second preset constant current rate, optionally after establishing the overcharge protection voltage as the lithium addition voltage, the method further comprises: heating the secondary battery to a first temperature,and before performing the first charging process on the secondary battery, the method further comprises: monitoring a temperature of the secondary battery as a second temperature, and optionally the first temperature is from 25°C to 60°C, and the second temperature is from 20°C to 30°C.
4. The method according to claim 3, wherein the first rate is from 0.1°C to 1°C, and optionally the first rate is from 0.1°C to 0.5°C.
5. The method according to any one of claims 1 to 4,wherein the charging of the secondary battery when SOH2 is greater than the second threshold comprises: cyclically executing the following stages on the secondary battery when SOH2 is greater than the second threshold until a preset stop condition is satisfied: charging the secondary battery to the first cutoff voltage at a fourth preset constant current rate; charging the secondary battery to a second preset charge cutoff voltage at a constant voltage of the first cutoff voltage; and discharging the second battery to the second cutoff voltage at the third preset constant current rate, wherein the preset stop condition includes: a number of times the secondary battery is discharged to the second cutoff voltage reaches a preset threshold number of times, or the secondary battery is at the preset charging node.
6. The method according to any one of claims 1 to 5,wherein the method further comprises: establishing N charging nodes and a plurality of first thresholds such that there is a one-to-one correspondence between each of the charging nodes and the plurality of first thresholds based on a number of cycles and a cycle capacity of the secondary battery, wherein N ≥ 2; establishing a plurality of second thresholds such that there is a one-to-one correspondence between the N charging nodes and the plurality of second thresholds; and establishing a plurality of charge cutoff voltages such that there is a one-to-one correspondence between the N charging nodes and the plurality of charge cutoff voltages based on the second threshold.
7. The method according to any one of claims 3 to 5, wherein the charge cutoff voltage is from 4.4 V to 4.8 V.
8. The method according to any one of claims 1 to 7, wherein the lithium addition material has a molecular formula of Li1+xMyOz,where element M is selected from at least one of Ni or Co and at least one of Mn, Mo, Ru or Ti, where 0, 05x0, 5, 0, 10 <y0, 95, y 2z<4; y una proporción másica w del material de adición de litio satisface: 0w0, 35 respecto a la masa total de una lámina de electrodo positivo en la batería secundaria.
9. El método según una cualquiera de las reivindicaciones 1 a 8, en donde una primera eficiencia coulómbica e del material de adición de litio satisface: 0, 2e0, 9.
10. El método según una cualquiera de las reivindicaciones 1 a 9, en donde, en la batería secundaria, una relación C. B. de una capacidad de carga de un material activo de electrodo negativo respecto un capacidad de carga de un material activo de electrodo positivo satisface 1, 05C.B.1, 15.
11. El método según una cualquiera de las reivindicaciones 1 a 10, en donde la batería secundaria tiene una cubierta superior permeable a gases.
12. Un sistema que comprende un aparato de carga (200) y una batería secundaria,the secondary battery comprising a lithium additive material, the apparatus comprising: an acquisition module (201) configured to acquire a first health state SOH1 of the secondary battery when the secondary battery is in a preset charging node; a processing module (202) configured to activate the lithium additive material when SOH1 is less than or equal to a first threshold for adding lithium to the secondary battery; a first charging module (203) configured to perform a first charging process on the secondary battery,comprising said first charging process discharging the secondary battery to a second preset cutoff voltage at a third preset constant current rate; charging the secondary battery to the first cutoff voltage at a fourth preset constant current rate; charging the secondary battery to a second preset charging cutoff voltage at a constant voltage of the first cutoff voltage; and discharging the second battery to the second cutoff voltage at the third preset constant current rate; a first determination module (204) configured to determine a second SOH2 health state of the secondary battery based on a working parameter of the secondary battery in the first charging process; and a second charging module (205) configured to charge the secondary battery when the SOH2 is greater than a second threshold.
13. A charging device,comprising: a processor (301) and a memory (302) that stores computer program instructions; wherein the processor (301), when executing the computer program instructions, implements the loading method according to any one of claims 1 to 11.
14. A computer storage medium that stores computer program instructions therein, wherein the computer program instructions, when executed by a processor (301), implement the loading method according to any one of claims 1 to 11.