Battery control method, controller, battery pack and electric device

Abstract

Embodiments of the present application provide a battery control method, a controller, a battery pack and a power consumption device. The method comprises: when the temperature of the battery is lower than a first temperature, controlling the battery to perform self-heating, and the heating current of the self-heating satisfies: wherein the ratio of the peak value to the valley value of the current value of the heating current is denoted as, and the initial state of charge of the self-heating of the battery is denoted as SOC. On the basis of improving the heating efficiency of the self-heating, the risk of lithium precipitation is reduced, the retention rate of the battery capacity is improved, the fast charging time is shortened, and the battery life is improved.

Description

Technical Field

[0001] This application relates to the field of batteries, and more particularly to a battery control method, controller, battery pack, and electrical device. Background Technology

[0002] Fast charging of lithium-ion batteries at low temperatures can lead to battery life degradation. The core mechanism is that during fast charging, the lithium-ion concentration at the negative electrode interface increases sharply, significantly increasing interfacial polarization. This causes lithium metal to deposit on the negative electrode, exacerbating interfacial contact failure and creating a high-resistance interfacial layer that hinders lithium-ion transport. This impedes the lithium-ion insertion / extraction process, reducing the amount of usable active material in the lithium-ion battery and resulting in rapid capacity decay and low capacity retention.

[0003] To alleviate the aforementioned problems, related technologies employ self-heating with heating current. By increasing the current rate, the cell temperature is accelerated to a higher level before charging, thereby enhancing lithium-ion transport kinetics, suppressing lithium plating, and improving battery life. However, using heating current for self-heating in these technologies carries the risk of increased lithium plating risk or reduced heating efficiency.

[0004] Therefore, there is an urgent need for a battery control method that, while meeting the heating efficiency requirements of self-heating, reduces the risk of lithium plating and maintains a high capacity retention rate to ensure a long battery life. Summary of the Invention

[0005] This application provides a battery control method, controller, battery pack, and electrical device to reduce the risk of lithium plating while maintaining high capacity retention and long battery life, while ensuring self-heating efficiency.

[0006] In a first aspect, embodiments of this application provide a battery control method, the method comprising:

[0007] When the battery temperature is lower than a first temperature, the battery is controlled to self-heat, and the heating current for self-heating satisfies: ;

[0008] The ratio of the peak value to the valley value of the heating current is denoted as . The initial state of charge of the battery during self-heating is denoted as SOC.

[0009] In one possible implementation, .

[0010] In one possible implementation, the frequency of the heating current is denoted as f, and the unit is Hz. .

[0011] In one possible implementation, the first temperature is greater than or equal to -30°C and less than or equal to 20°C.

[0012] In one possible implementation, the bifacial areal density of the positive electrode of the battery is denoted as σ1, with units of g / m³. 2 300 1000; and / or, the double-sided areal density of the negative electrode of the battery is denoted as σ2, in g / m³. 2 130 460.

[0013] In one possible implementation, the waveform of the heating current includes at least one of the following: sine wave, square wave, trapezoidal wave, and triangular wave.

[0014] In one possible implementation, the mass percentage of the binder in the battery is denoted as ω. .

[0015] In one possible implementation, the mass percentage of the conductive agent is denoted as . 0 3 .

[0016] In one possible implementation, the compaction density of the positive electrode of the battery is denoted as γ1, with units of g / cm³. 3 2.2 3; and / or, the compaction density of the negative electrode of the battery is denoted as γ2, in g / cm³. 3 1.4 2.

[0017] In one possible implementation, the battery is charged using a charging current when it self-heats to a second temperature.

[0018] Secondly, embodiments of this application provide a battery control method applied to an electric vehicle, the electric vehicle having a charging interface and a battery, the method comprising:

[0019] When the charging interface is connected to an external charging device and the battery temperature is lower than a first temperature, the battery is controlled to self-heat, and the self-heating current satisfies: ;

[0020] The ratio of the peak value to the valley value of the heating current is denoted as . The initial state of charge of the battery during self-heating is denoted as SOC.

[0021] Thirdly, embodiments of this application provide a battery control method applied to a charging device, the method comprising:

[0022] When the charging device is connected to an external electrical device, and the temperature of the battery of the external electrical device is lower than a first temperature, the battery is controlled to self-heat, and the heating current of the self-heating satisfies: ;

[0023] The ratio of the peak value to the valley value of the heating current is denoted as . The initial state of charge of the battery during self-heating is denoted as SOC.

[0024] Fourthly, embodiments of this application provide a controller, including: a memory and a processor;

[0025] The memory stores computer-executed instructions;

[0026] The processor executes computer execution instructions stored in the memory, causing the processor to perform any one of the methods described in the first to third aspects above.

[0027] Fifthly, embodiments of this application provide a battery pack, the battery pack including a battery and a controller as described in the fourth aspect above.

[0028] Sixthly, embodiments of this application provide an electrical device, including a battery pack as described in the fifth aspect above, or a controller as described in the fourth aspect above.

[0029] In a seventh aspect, embodiments of this application provide a battery pack, including a battery;

[0030] When the battery temperature is below a first temperature, it self-heats, and the heating current for self-heating satisfies the following: ;

[0031] The ratio of the peak value to the valley value of the heating current is denoted as . The initial state of charge of the battery during self-heating is denoted as SOC.

[0032] The battery control method, controller, battery pack, and electrical device provided in this application embodiment control the battery to self-heat when the battery temperature is lower than a first temperature. The ratio of the peak value to the valley value of the heating current is denoted as... The initial state of charge of the battery during self-heating is denoted as SOC. .

[0033] At lower SOCs, the battery's lithium insertion capacity increases and the risk of lithium plating decreases. However, lower SOCs also increase the risk of over-discharge gas generation, reducing battery capacity retention. By appropriately increasing the peak-to-valley ratio, a higher asymmetric waveform can accelerate heating while simultaneously increasing the overall SOC, thus reducing the risk of over-discharge gas generation. Conversely, at higher SOCs, the risk of lithium plating during low-temperature self-heating significantly increases. By appropriately reducing the peak-to-valley ratio, the lithium insertion / extraction process on the negative electrode surface can be precisely controlled. A smaller peak-to-valley ratio provides a buffer time for lithium ions to return from the negative electrode to the electrolyte, greatly reducing the risk of lithium plating and improving battery cycle life.

[0034] Therefore, in this embodiment of the application, when the battery temperature is lower than the first temperature, the ratio of the peak value to the valley value of the heating current is controlled to satisfy: The ratio of the peak to the valley value of the heating current is controlled by the battery's state of charge (SOC). This approach ensures a balance between lithium plating risk and gas generation risk, thereby reducing lithium plating risk, improving battery capacity retention, reducing gas generation risk, and improving battery heating efficiency. While maintaining a constant lithium plating risk level, the ratio of peak to trough values ​​is appropriately increased to reduce gas generation and improve self-heating efficiency. Based on the battery control method implemented in this application, the lithium plating risk is reduced, battery capacity retention is improved, fast charging time is shortened, and battery life is extended, all while improving self-heating efficiency. Attached Figure Description

[0035] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0036] Figure 1 A schematic flowchart illustrating the battery control method provided in an embodiment of this application;

[0037] Figure 2 A waveform diagram of the heating current provided in the embodiments of this application. Figure 1 ;

[0038] Figure 3 A waveform diagram of the heating current provided in the embodiments of this application. Figure 2 ;

[0039] Figure 4 A waveform diagram of the heating current provided in the embodiments of this application. Figure 3 ;

[0040] Figure 5 A waveform diagram of the heating current provided in the embodiments of this application. Figure 4 ;

[0041] Figure 6A schematic diagram of the controller provided in this application.

[0042] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0043] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0044] Lithium-ion batteries are widely used in electric vehicles, energy storage systems, and consumer electronics due to their high energy density, long cycle life, and low self-discharge rate. However, current technologies face the problem of rapid capacity decay during lithium-ion battery charging caused by increased polarization.

[0045] To alleviate the aforementioned problems, related technologies employ self-heating with heating current. By increasing the current rate, the cell temperature is accelerated to a higher level before charging, thereby enhancing lithium-ion transport kinetics, suppressing lithium plating, and improving battery life. However, using heating current for self-heating in these technologies carries the risk of increased lithium plating risk or reduced heating efficiency.

[0046] Therefore, there is an urgent need for a battery control method that can reduce the risk of lithium plating and maintain a high capacity retention rate of the battery by controlling the value of the heating current, thereby ensuring the battery has a long lifespan while meeting the heating efficiency requirements of self-heating.

[0047] Therefore, this application proposes a battery control method that controls the battery to self-heat when the battery temperature is lower than a first temperature, and limits the peak / valley ratio of the heating current based on the battery's SOC.

[0048] At lower SOCs, the battery's lithium insertion capacity increases and the risk of lithium plating decreases. However, lower SOCs also increase the risk of over-discharge gas generation, reducing battery capacity retention. By appropriately increasing the peak-to-valley ratio, a higher asymmetric waveform can accelerate heating while simultaneously increasing the overall SOC, thus reducing the risk of over-discharge gas generation. Conversely, at higher SOCs, the risk of lithium plating during low-temperature self-heating significantly increases. By appropriately reducing the peak-to-valley ratio, the lithium insertion / extraction process on the negative electrode surface can be precisely controlled. A smaller peak-to-valley ratio provides a buffer time for lithium ions to return from the negative electrode to the electrolyte, greatly reducing the risk of lithium plating and improving battery cycle life.

[0049] Therefore, in this embodiment of the application, when the battery temperature is lower than the first temperature, the ratio of the peak value to the valley value of the heating current is controlled to satisfy: The ratio of the peak to the valley value of the heating current is controlled by the battery's state of charge (SOC). This approach ensures a balance between lithium plating risk and gas generation risk, thereby reducing lithium plating risk, improving battery capacity retention, reducing gas generation risk, and improving battery heating efficiency. While maintaining a constant lithium plating risk level, the ratio of peak to trough values ​​is appropriately increased to reduce gas generation and improve self-heating efficiency. Based on the battery control method implemented in this application, the lithium plating risk is reduced, battery capacity retention is improved, fast charging time is shortened, and battery life is extended, all while improving self-heating efficiency.

[0050] The battery control method of this application embodiment can be applied to any battery charging scenario, such as charging scenarios for electric vehicles and energy storage systems. The battery control method of this application embodiment can be applied to both fast charging and non-fast charging scenarios. In both fast charging and non-fast charging scenarios, any charging strategy (constant current charging, stepped charging, etc.) can be adopted.

[0051] The positive electrode active material used in the battery of this application includes, but is not limited to, at least one of lithium iron phosphate (LiFePO4), NCM ternary positive electrode material, lithium manganese oxide (LiMn2O4), and lithium-rich manganese-based materials, and the negative electrode active material includes at least one of graphite, silicon, silicon-carbon, and lithium titanate.

[0052] The executing entity in this application embodiment can be the battery management system (BMS) of the battery, or any controller or control device outside the battery management system that can control the charging current. For example, the executing entity can be the control module on the side of the device where the battery is located (e.g., electrical equipment, electrical appliance, etc.). The electrical appliance mentioned here can be, for example, an electric vehicle or other electric vehicle. The following embodiment uses the BMS as the executing entity for illustration.

[0053] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0054] Figure 1 This is a schematic flowchart illustrating the battery control method provided in an embodiment of this application. Figure 1 As shown, the method includes:

[0055] S101. When the battery temperature is lower than a first temperature, control the battery to self-heat. The self-heating current satisfies: The ratio of the peak value to the valley value of the heating current is denoted as ; The initial state of charge of a battery that is self-heating is denoted as SOC.

[0056] The first temperature is the threshold temperature at which the battery begins to self-heat. When the battery temperature is below the first temperature, it indicates that the battery is in a low-temperature environment and needs to self-heat.

[0057] The heating current is the current applied during the battery's self-heating process. The heating current is used to raise the battery temperature. The heating current is an alternating current (AC) current, and its value changes periodically over time. For example, the heating current's current rating can be 1C, 2C, 3C, 4C, 5C, 6C, 7C, 8C, or any combination thereof.

[0058] The state of charge (SOC) of a battery indicates the percentage of its remaining capacity. For example, an SOC of 30% means that the battery has 30% of its rated capacity remaining. When a battery pack contains multiple batteries, the SOC of each battery is the same as the SOC of the entire battery pack.

[0059] The peak and trough values ​​of the battery's heating current are the ratio of the current values ​​during the charging and discharging phases, used to characterize the asymmetry of the current waveform. Asymmetric waveform self-heating refers to self-heating by alternating current or pulsed current with asymmetrical positive and negative current amplitudes, durations, or frequencies. When a battery pack contains multiple batteries, the battery's heating current is the same as the battery pack's heating current.

[0060] Figure 2 A waveform diagram of the heating current provided in the embodiments of this application. Figure 1 .like Figure 2 As shown, taking the waveform of the heating current as a sine wave as an example, where i C i is the peak value of the heating current. D This represents the valley value of the heating current. Figure 2 Chinese A To tC During the charging phase, t C To t D This is the discharge phase. The waveforms of the charging and discharging phases are symmetrical. The value is 1, and it is adjusted. This allows the heating current waveform to be asymmetrical. It should be understood that during the self-heating process in the embodiments of this application, Not equal to 1, the battery is self-heated by a heating current based on an asymmetric waveform.

[0061] At low temperatures, the charge-discharge performance of lithium-ion batteries deteriorates, lithium-ion transport kinetics decrease, and lithium plating easily occurs on the negative electrode surface. The lithium dendrites produced by lithium plating react with the electrolyte in the battery, consuming active lithium and electrolyte, leading to lithium loss and consequently battery capacity decay. Heating the lithium-ion battery with a heating current to raise its temperature before charging can enhance lithium-ion transport kinetics, thereby suppressing lithium plating and improving battery life.

[0062] The inventors discovered that at lower battery SOC (State of Charge), the battery's lithium intercalation capability increases and the risk of lithium plating decreases, but the risk of gas generation increases, reducing the battery's capacity retention rate. Therefore, appropriately increasing the peak-to-valley ratio allows for faster heating and reduced gas generation through a higher asymmetric waveform. In summary, the peak-to-valley ratio of the heating current is controlled by adjusting the battery's SOC. This allows for rapid temperature rise while suppressing lithium plating, thus improving battery safety.

[0063] Therefore, in the embodiments of this application, according to Based on the battery's SOC, the ratio of the peak to the valley value of the heating current is limited. It dynamically adapts to batteries with different SOCs.

[0064] The ratio of peak to valley values ​​of the heating current dynamically adjusted based on the battery's SOC. On the one hand, it can improve heating efficiency, reduce the risk of gas generation, maintain the battery's fast charging capability, and keep the battery's fast charging time stable. On the other hand, it can suppress the risk of lithium plating, thereby reducing battery polarization, improving the battery capacity retention rate, and extending battery life.

[0065] The battery control method provided in this application controls the battery to self-heat when the battery temperature is lower than a first temperature. The ratio of the peak value to the valley value of the heating current is denoted as... The initial state of charge of a battery that self-heats is denoted as SOC. .

[0066] At lower SOCs, the battery's lithium insertion capacity increases and the risk of lithium plating decreases. However, lower SOCs also increase the risk of over-discharge gas generation, reducing battery capacity retention. By appropriately increasing the peak-to-valley ratio, a higher asymmetric waveform can accelerate heating while simultaneously increasing the overall SOC, thus reducing the risk of over-discharge gas generation. Conversely, at higher SOCs, the risk of lithium plating during low-temperature self-heating significantly increases. By appropriately reducing the peak-to-valley ratio, the lithium insertion / extraction process on the negative electrode surface can be precisely controlled. A smaller peak-to-valley ratio provides a buffer time for lithium ions to return from the negative electrode to the electrolyte, greatly reducing the risk of lithium plating and improving battery cycle life.

[0067] Therefore, in this embodiment of the application, when the battery temperature is lower than the first temperature, the ratio of the peak value to the valley value of the heating current is controlled to satisfy: The ratio of the peak to the valley value of the heating current is controlled by the battery's state of charge (SOC). This approach ensures a balance between lithium plating risk and gas generation risk, thereby reducing lithium plating risk, improving battery capacity retention, reducing gas generation risk, and improving battery heating efficiency. While maintaining a constant lithium plating risk level, the ratio of peak to trough values ​​is appropriately increased to reduce gas generation and improve self-heating efficiency. Based on the battery control method implemented in this application, the lithium plating risk is reduced, battery capacity retention is improved, fast charging time is shortened, and battery life is extended, all while improving self-heating efficiency.

[0068] Optionally, when the battery self-heats to the second temperature, the BMS can charge the battery using the charging current.

[0069] The charging current can be the current value of the battery under fast charging or non-fast charging. For example, the charging current ratio can be 0.1C, 1C, 2C, 3C, 4C, 5C, 6C, 7C, 8C, 10C, 15C, or any range thereof. The charging current is used to provide charging energy to the battery.

[0070] The second temperature is the battery temperature threshold at the end of self-heating. For example, the second temperature is within a range of 15°C, 18°C, 20°C, 25°C, 30°C, or any combination thereof. The second temperature is greater than or equal to the first temperature.

[0071] For example, taking a second temperature of 20°C as an example, when the battery is at 5°C, the BMS can apply a heating current to the battery to heat it. The ratio of the peak value to the valley value of the heating current is greater than 0 and less than or equal to 0. The heating current is applied until the battery temperature reaches 20°C. Then, the BMS stops applying the heating current and begins applying a charging current to charge the battery. For example, the BMS can apply a 3C charging current for fast charging.

[0072] The method of this application embodiment, when the battery is heated to a second temperature based on the heating current, charges the battery with the charging current. By heating the battery cell to a higher temperature before charging, the battery in the current state is charged. Compared with charging the battery before heating, the lithium-ion transport dynamics during the charging process can be enhanced, the charging efficiency can be improved, the charging time can be shortened, and lithium plating can be suppressed, thereby improving the battery capacity retention rate.

[0073] The following describes an embodiment of the present application in which the battery is controlled to self-heat when the battery temperature is lower than a first temperature.

[0074] Optionally, the first temperature is greater than or equal to -30°C and less than or equal to 20°C.

[0075] Optionally, the first temperature can be -30, -25, -20, -15, -10, -5, 0, 5, 10, 15, 20, or any combination of the above values.

[0076] For example, if the first temperature is greater than or equal to -30°C and less than or equal to 20°C, the BMS can obtain the battery temperature. If the battery temperature is lower than the first temperature, the BMS can obtain the battery's SOC (State of Charge). The system determines the ratio of the peak to the trough of the heating current to control the battery's self-heating. Once the battery has self-heated to a second temperature, it is charged using the charging current. If the battery temperature exceeds 20°C, the charging current is used to charge the battery. For example, the BMS can apply a 3C charging current for fast charging.

[0077] For example, when the battery is a battery pack, the BMS can obtain the temperature of any cell in the battery, or the average temperature of multiple cells, to obtain the battery temperature.

[0078] For example, if the battery is a battery pack and multiple sensors are installed inside the battery pack, the BMS can obtain the lowest temperature among the multiple temperatures measured by the multiple sensors to obtain the temperature of the battery.

[0079] For example, when the battery is a single cell, the BMS can obtain the temperature of the cell near the negative terminal post on the negative side of the cell to obtain the battery temperature.

[0080] Because the electrolyte may solidify when the battery temperature is below -30°C, the battery cannot function properly and cannot be heated by applying a heating current. When the battery temperature is above 20°C, the lithium ion diffusion rate and electrolyte conductivity are both at a good level, the risk of lithium plating is low, and no heating current is needed. Therefore, in this embodiment, the first temperature is greater than or equal to -30°C and less than or equal to 20°C.

[0081] When the battery temperature is greater than or equal to -30℃ and less than or equal to 20℃, the electrolyte viscosity increases significantly, increasing ion migration resistance. This prevents lithium ions from being promptly inserted into the negative electrode during charging, easily leading to lithium plating. Furthermore, this results in a substantial decrease in battery charge / discharge efficiency, reduced power performance, and prolonged charging time. Therefore, when the battery temperature is greater than or equal to -30℃ and less than or equal to 20℃, controlling the battery to self-heat and utilizing the internal resistance heat generation mechanism to achieve rapid temperature rise before charging can more effectively enhance lithium-ion transport kinetics, suppress lithium plating, and improve battery life.

[0082] Optionally, the waveform of the heating current includes at least one of the following: sine wave, square wave, trapezoidal wave, and triangular wave.

[0083] For example, the heating current value includes a first value and a second value. The heating current value rises from the initial value to the first value, then falls from the first value to the second value, and then rises from the second value back to the initial value.

[0084] For example, during the period when the battery is heated using a heating current, the first value corresponding to the heating current is i. C The second value is i D The heating current is determined by the initial value i. A Rise to the first value i C Then from the first value i C Decrease to the second value i D Then from the second value i D Rise to the initial value i A For example, the waveform of the heating current may exhibit a symmetrical or asymmetrical pattern, with the current rising first and then falling. The first value i C It is the peak value of the heating current, the second value i D It is the valley value of the heating current.

[0085] like Figure 2 As shown, the waveform of the heating current can be a sine wave, where the heating current rises from an initial value of 0 to a first value i. C Then from the first value i C Decrease to the second value i D Then from the second value i DIt rises to the initial value of 0. Where t... A To t C During the charging phase, t C To t D This is the discharge stage.

[0086] The battery is heated by a sinusoidal heating current. The continuous and smooth characteristics of the sinusoidal wave can reduce the impact of sudden current changes on the battery interior, reduce polarization effects, avoid local overheating or overcooling, and improve the uniformity of battery temperature distribution.

[0087] Figure 3 A waveform diagram of the heating current provided in the embodiments of this application. Figure 2 .like Figure 3 As shown, the waveform of the heating current can be a square wave.

[0088] The battery is heated by a square wave heating current. The pulsed high current of the square wave can instantly generate a large amount of Joule heat, which accelerates the overall temperature rise and increases the heating rate.

[0089] Figure 4 A waveform diagram of the heating current provided in the embodiments of this application. Figure 3 .like Figure 4 As shown, the waveform of the heating current can be a trapezoidal wave.

[0090] The battery is heated by a trapezoidal wave heating current. The trapezoidal wave generates heat rapidly in the early stage, and the thermal shock is reduced in the later stage by the ramp current, thus balancing the heating rate and the uniformity of temperature distribution.

[0091] Figure 5 A waveform diagram of the heating current provided in the embodiments of this application. Figure 4 .like Figure 5 As shown, the waveform of the heating current can be a triangular wave.

[0092] The battery is heated by a triangular wave heating current. The current amplitude of the triangular wave changes linearly, which can realize heating regulation and achieve high-precision heating through linear temperature control.

[0093] It should be understood that Figures 2-5 The waveform of the heating current shown is a symmetrical waveform. The ratio of the peak value to the valley value of the heating current is denoted as [value missing]. This allows it to be adjusted to an asymmetrical waveform.

[0094] The method in this application embodiment uses a heating current waveform that includes at least one of a sine wave, a square wave, a trapezoidal wave, and a triangular wave. By providing heating currents with multiple waveforms to heat the battery, the heating efficiency can be optimized based on the characteristics of different waveforms.

[0095] Optionally, the frequency of the heating current is denoted as f, and the unit is Hertz (Hz). .

[0096] Optionally, the frequency f of the heating current can be 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 50, or any combination thereof.

[0097] For example, when the battery temperature is below a first temperature, the BMS can obtain the battery's SOC and determine the ratio of the peak to the trough of the heating current value. The frequency f of the heating current is obtained, where the frequency f is greater than or equal to 1 Hz and less than or equal to 50 Hz. The ratio of the peak value to the valley value of the current is used. A heating current with frequency f is used to self-heat the battery. Once the battery has self-heated to a second temperature, a charging current is used to charge the battery.

[0098] Since the frequency f of the heating current is greater than or equal to 1, it ensures that the heating current based on this frequency can quickly generate sufficient Joule heat inside the battery, achieving a rapid temperature rise. If the frequency f of the heating current is less than or equal to 10, it prevents overheating caused by the Joule heat generated by the heating current based on this frequency, which could damage the battery. Therefore, based on... The heating current is used to heat the battery, which can achieve rapid temperature rise and improve heating efficiency while ensuring battery safety. When there are multiple batteries in the battery pack, the frequency of the battery's heating current is the same as the frequency of the battery pack's heating current.

[0099] The following describes an embodiment in which the battery is charged using a charging current when the battery self-heats to a second temperature.

[0100] Optionally, the charging current can be a constant current. When the battery self-heats to a second temperature, the BMS uses a constant current to charge the battery.

[0101] Optionally, the charging current can be a curved waveform. A corresponding charging current value is set for each charging stage, and charging is performed based on the charging current corresponding to each charging stage.

[0102] For example, the charging current used by the BMS can be a dynamically changing current. The charging current can be related to the charging duration. For instance, the charging current used during charging period t1 is linearly related to the charging duration, and the heating current can be expressed as I1(t1).

[0103] It should be understood that the charging current used during a charging period can be related to the charging duration. The charging current used during a charging period... With charging time The relationship is based on function representation, and the embodiments of this application do not limit the function form.

[0104] For example, With time The functional form can be expressed as , can also be expressed as Where a, b, A, B, C, and D can be positive real constants, negative real constants, or 0, and can be determined based on the battery's state of charge. Taking the battery's state of charge under constant current charging as an example... =0, This is the current value of the charging current.

[0105] Taking the charging state of a battery under fast charging as an example, the relationship between the charging current and the charging time during the charging period can be determined based on the preset relationship between the charging current and the charging time under the fast charging state of the battery. That is, the relationship between the charging current and the charging time under the fast charging state of the battery is determined as the relationship between the charging current and the charging time during the charging period in this embodiment of the application.

[0106] The method of this application embodiment involves heating the battery to a second temperature using a heating current, and then charging the battery using a charging current. Since the battery temperature is heated to the second temperature, charging the battery in its current state, compared to charging the battery before heating, enhances lithium-ion transport kinetics during charging, improves charging efficiency, shortens charging time, suppresses lithium plating, and improves battery capacity retention.

[0107] The parameters of the battery will now be described when the charging control is performed using the method of the embodiments of this application.

[0108] In the above embodiments, when the battery temperature is lower than a first temperature, the BMS can control the battery to self-heat and obtain the battery's SOC, controlling the heating current to meet the requirements. .

[0109] Preferably, Optionally, It can be 1, 3.5, 6, 8.5, 11, 13.5, 16, 18.5, 21, 23.5, 26, 28.5, 30, or any combination of the above values.

[0110] In the above embodiments, when the battery's SOC is low, the cell's lithium intercalation capability increases, the risk of lithium plating decreases, and the risk of gas generation increases. Appropriately increasing the peak-to-valley ratio helps to achieve higher [specific performance]. The asymmetric waveform accelerates heating and reduces gas production. However, when the battery's SOC is high, the risk of gas production is low, and only the risk of lithium plating needs to be considered when implementing self-heating. Therefore, for... The battery, according to The battery is controlled to self-heat, thereby effectively reducing the risk of gas generation and improving heating efficiency while minimizing the risk of lithium plating.

[0111] For example, when the battery temperature is below a first temperature, the BMS can obtain the battery's SOC. If the battery's SOC is greater than or equal to 1 and less than or equal to 30, then according to... The ratio of the peak value to the valley value of the heating current. Based on this Heat the battery.

[0112] In this embodiment of the application, for The battery is controlled to self-heat; the ratio of the peak value to the valley value of the heating current is denoted as... The initial state of charge of a battery that self-heats is denoted as SOC. When the battery's SOC is low, the ratio of the peak to the valley value of the heating current is dynamically adjusted based on the battery's SOC. This method can reduce the risk of gas generation and improve battery heating efficiency when the risk of lithium plating is low. Based on the battery control method implemented in this application, the risk of lithium plating is reduced, the battery capacity retention rate is improved, the fast charging time is shortened, and the battery life is extended, while improving the self-heating efficiency.

[0113] Optionally, the mass percentage of the battery binder is denoted as ω. .

[0114] Optionally, the mass percentage of the binder in the battery can be 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination of the above values.

[0115] The mass percentage of the binder in a battery refers to the proportion of the binder in the electrode slurry by mass, which affects the coverage of active sites and charge transfer resistance. Binders include at least one of carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE).

[0116] For example, the mass percentage of the binder in the negative electrode sheet can be measured by thermogravimetric analysis. For instance, an inert atmosphere of nitrogen (N2) or argon (Ar) is used to study the pyrolysis behavior of the material in an oxygen-free environment. The temperature is raised from room temperature to ~120°C and held constant to remove physically adsorbed water, and the mass loss m1 is recorded. The temperature is then further increased to 500-800°C in the inert atmosphere, depending on the type of binder; the mass loss m2 at this stage is mainly due to the pyrolysis and volatilization of the binder. Under an inert atmosphere, the mass percentage of the binder is obtained using the formula: Binder mass percentage ≈ m2 / initial sample mass × 100%.

[0117] In the method of this application embodiment, when the binder mass percentage is greater than or equal to 0.5%, it can ensure that the electrode maintains structural integrity during heating, prevents active material from falling off, and reduces capacity decay. When the binder mass percentage is less than or equal to 5%, it avoids excessively high binder mass percentages that could encapsulate the active material and conductive agent, hindering lithium-ion transport. The battery can achieve a balance between electrode structure stability and lithium plating risk, and improve the reliability of heating and charging the battery.

[0118] Optionally, the double-sided areal density of the positive electrode of the battery is denoted as σ1, with units of g / m³. 2 300 1000; and / or, the areal density of the negative electrode of the battery is denoted as σ², in g / m³. 2 130 460.

[0119] For example, the bifacial density σ1 of the positive electrode of the battery can be 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, or any combination of the above values.

[0120] For example, the areal density σ2 of the negative electrode of the battery can be 130, 135, 140, 145, 150, 160, 170, 180, 190, 200, 250, 300, 350, 400, 430, 460, or any combination thereof.

[0121] The areal density of the positive electrode of a battery refers to the total mass of active material coated per unit area on both sides of the positive electrode plate. The areal density of the negative electrode of a battery refers to the total mass of active material coated per unit area on both sides of the negative electrode plate.

[0122] Optionally, the areal density of the battery can be obtained based on battery disassembly. For example, the battery is disassembled in a dew point room or glove box, separating the positive and negative electrodes and the separator. Electrode samples of known area are cut. The total weight of the sample is accurately weighed. The binder and conductive agent are washed away with a specific solvent, leaving the active material, which is then dried and weighed. The areal density is obtained by calculating the ratio of the weight of the active material to the sample area. Simultaneously, coating thickness, compaction density, etc., can be calculated. Specific solvents include N-methyl-2-pyrrolidone (NMP).

[0123] In the method of this application embodiment, the double-sided areal density of the positive electrode of the battery is greater than or equal to 300 g / m². 2 And / or, the areal density of the negative electrode of the battery is greater than or equal to 130 g / m². 2 This approach allows for increased energy density while maintaining a constant battery volume, and enhanced structural stability can reduce the rate of capacity decay and improve capacity retention. The bifacial areal density of the battery's positive electrode is less than or equal to 1000 g / m³, and / or the bifacial areal density of the battery's negative electrode is less than or equal to 1000 g / m³. 2 By controlling the surface density of the positive electrode, the low internal resistance of the battery can be maintained, thereby improving the battery's heating and charging efficiency. (Through 300...) 1000, and / or 130 A 460-cell battery can achieve a balance between improving battery heating and charging efficiency, as well as improving battery capacity retention.

[0124] Optionally, the mass percentage of the conductive agent in the battery is denoted as . 0 3 .

[0125] Optionally, the mass percentage of the conductive agent in the battery It can be 0, 0.25%, 0.5%, 0.85%, 1%, 1.25%, 1.5%, 1.85%, 2%, 2.25%, 2.5%, 2.75%, 3%, or any combination of the above values.

[0126] The mass percentage of the conductive agent in a battery refers to the percentage of the conductive agent's mass relative to the total mass of the mixture of electrode active materials and the conductive agent. This mass percentage can be the mass percentage of the positive electrode or the negative electrode. Conductive agents can include at least one of carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, and graphene.

[0127] Optionally, the mass percentage of the conductive agent can be obtained by disassembling the battery. Specifically, the binder is dissolved and washed away using N-methyl-2-pyrrolidone solvent to separate the active material and the conductive agent. The active material is then removed by high-temperature calcination or acid dissolution to obtain the pure conductive agent, which is then accurately weighed. The mass percentage of the conductive agent is obtained by dividing the mass of the pure conductive agent by the total mass of the coating, based on the total mass of the electrode coating.

[0128] The conductive agent forms an interconnected three-dimensional network in the battery electrodes, which helps to conduct electrons. The mass percentage of the conductive agent in the battery is less than or equal to 3%. This avoids the problem that excessive conductive agent content may lead to increased slurry viscosity, cracking, and powdering during coating, thus improving the structural stability of the battery and consequently enhancing the reliability and stability of battery heating and charging.

[0129] Optionally, the compaction density of the positive electrode of the battery is denoted as γ1, with units of g / cm³. 3 2.2 3; The compaction density of the negative electrode of the battery is denoted as γ2, with units of g / cm³. 3 1.4 2.

[0130] Optionally, the compaction density γ1 of the positive electrode of the battery can be 2.2, 2.25, 2.3, 2.35, 2.4, 2.45, 2.5, 2.55, 2.6, 2.7, 2.8, 2.9, 2.95, 3, or any combination thereof.

[0131] Optionally, the compaction density γ2 of the negative electrode of the battery can be 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.95, 2, or any combination thereof.

[0132] The compacted density of a battery's positive electrode refers to the mass per unit volume of the positive electrode material after it has been compacted under a specific pressure. The compacted density of a battery's negative electrode refers to the mass per unit volume of the negative electrode material after it has been compacted under a specific pressure.

[0133] For lithium-ion batteries, increasing the compaction density can increase the content of active material per unit volume, thereby improving the battery's energy density and capacity. Furthermore, the reduced volume of electrode materials during cycling can improve ion and electron transport efficiency, enhancing battery heating and charging efficiency. However, over-voltage of the electrode sheets can lead to reduced battery capacity and increased internal resistance. Therefore, based on 2.2... 3, 1.4 The battery, while ensuring sufficient capacity, achieves a balance between improving heating and charging efficiency, and enhancing capacity retention.

[0134] Optionally, the lithium salt in the battery electrolyte includes at least one of lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI), and the concentration of the electrolyte is 0.7-1.3 mol / L. The solvent includes at least one of ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl acetate (EA), and the conductivity of the electrolyte is 5-20 mS / cm.

[0135] Optionally, the concentration of the electrolyte can be 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, or any combination of the above values.

[0136] Optionally, the conductivity of the electrolyte can be 5, 5.5, 6, 6.5, 7, 8, 8.5, 9, 10, 11, 12, 12.5, 13, 14, 15, 16, 17, 17.5, 18, 18.5, 19, 19.5, 20, or any combination thereof.

[0137] For example, the electrolyte conductivity can be measured using a conductivity meter. Take an appropriate amount of the electrolyte to be tested into a clean, dry sample cell. Immerse the electrode in the electrolyte, agitating it to remove air bubbles and ensuring the platinum sheet is completely submerged. Place the sample cell in a preheated bath and let it stand for 10-15 minutes to allow the sample temperature to match the bath temperature. Select the correct measurement mode on the conductivity meter and read the solution temperature using the instrument. The solution temperature is measured using an external temperature probe. Wait for the reading to stabilize; the stabilization time is typically a few seconds to tens of seconds. Record the stable conductivity value and the corresponding temperature.

[0138] Electrolyte concentration is determined using ion chromatography to measure the concentration of anions, thereby indirectly determining the lithium salt concentration. For example, the concentrations of anions PF6⁻ and FSI⁻.

[0139] When the electrolyte concentration is too low, the number of lithium ions is insufficient, leading to a decrease in ion migration rate and an increase in internal resistance. Rapid charging and discharging are required during self-heating to generate Joule heat; low-concentration electrolytes cannot meet the ion conduction requirements under high current densities, thus failing to meet self-heating needs. Increasing the electrolyte concentration can shorten heating time and improve heating efficiency. Conversely, when the electrolyte concentration is too high, the intermolecular forces of the solvent increase, leading to increased viscosity and thus increased ion migration resistance and internal resistance, reducing self-heating efficiency. Therefore, an electrolyte concentration of 0.7-1.3 mol / L can improve heating efficiency while still meeting self-heating requirements.

[0140] The self-heating process relies on the rapid migration of lithium ions in the electrolyte to generate Joule heat. If the conductivity is too low, ion migration is hindered, increasing internal resistance and preventing the second temperature from being reached quickly enough. Therefore, increasing the electrolyte concentration can shorten the heating time and improve heating efficiency. If the conductivity is too high, the electrolyte viscosity increases, leading to increased resistance to ion migration and internal resistance, thus reducing self-heating efficiency. Therefore, a conductivity of 5-20 mS / cm is sufficient to improve heating efficiency while meeting the self-heating requirements.

[0141] Optionally, the base film layer of the battery includes at least one of polyethylene (PE), polypropylene (PP), cellulose, polyester film (PET), polyimide (PI), nonwoven fabric and electrospun separator, with a thickness of 2-22 μm.

[0142] Optionally, the thickness of the base film layer of the battery can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, or any combination thereof.

[0143] A thinner base film can improve ion transport efficiency and reduce internal resistance, thereby increasing heating efficiency. However, it also results in insufficient physical protection, decreased thermal stability, and an increased risk of thermal runaway, thus reducing battery life. Therefore, a base film thickness of 2-22µm can ensure safety through moderate physical protection and thermal stability, while maintaining low internal resistance to improve heating efficiency.

[0144] Optionally, the functional layer material on the base film includes at least one of alumina, aramid, polyimide (PI), metal organic framework (MOF), magnesium oxide, and magnesium hydroxide, with a coating thickness of 0.3-8 μm.

[0145] Optionally, the coating thickness of the functional layer material on the base film can be 0.3, 0.8, 1.3, 1.8, 2.3, 2.8, 3.3, 3.8, 4.3, 4.8, 5.3, 5.8, 6.3, 6.8, 7.3, 7.8, 8, or any combination thereof.

[0146] While a thinner coating reduces ion transport resistance and improves heating efficiency, uneven coating coverage can lead to localized thermal inhomogeneity, potentially causing cycle life degradation. A thicker coating enhances thermal stability but significantly increases internal resistance due to prolonged ion migration paths. Therefore, a coating thickness of 0.3-8 μm is ideal, as it balances thermal stability with maintaining low internal resistance to improve heating efficiency.

[0147] Optionally, the coating adhesive layer on the base membrane includes at least one of polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polyolefins, hydroxyethyl methacrylate, acrylic acid, butyl acrylate, isooctyl acrylate, and butyl oleate, with a coating thickness of 0.2-5 μm and a membrane porosity of 25%-60%.

[0148] Optionally, the coating thickness of the adhesive layer on the base film can be 0.2, 0.7, 1.2, 1.7, 2.2, 2.7, 3.2, 3.7, 4.2, 4.7, 5, or any combination thereof.

[0149] Optionally, the porosity of the membrane can be 25, 27.5, 30, 32.5, 35, 37.5, 40, 42.5, 45, 47.5, 50, 52.5, 55, 57.5, 60, or any combination thereof.

[0150] During battery self-heating, a lower coating thickness can reduce ion transport interface resistance and improve heating efficiency, but insufficient adhesion may lead to electrode-base film interface peeling, resulting in cycle life degradation. A higher coating thickness can improve battery structural stability, but excessive coating thickness increases ion migration path length, leading to increased internal resistance and reduced heating efficiency. Therefore, a coating thickness of 25%-60% is used to improve heating efficiency while enhancing battery structural stability and reducing cycle life degradation.

[0151] Optionally, when the battery pack contains multiple batteries, the battery parameters included in this application embodiment, such as the mass percentage of the battery binder, the mass percentage of the battery conductive agent, the compaction density of the battery's positive electrode, the compaction density of the battery's negative electrode, the double-sided areal density of the battery's positive electrode, the double-sided areal density of the battery's negative electrode, the conductivity of the battery's electrolyte, the concentration of the battery's electrolyte, the thickness of the battery's base film layer, the coating thickness of the functional layer material on the battery's base film, the coating thickness of the adhesive layer on the base film, and the porosity of the separator, can be obtained based on the average value of the parameters of multiple batteries. Taking the mass percentage of the battery binder as an example, the mass percentage of the battery binder can be measured for three batteries randomly selected, and the average value of the mass percentage of the battery binder measured for the three batteries can be calculated as the mass percentage of the battery binder in this application embodiment.

[0152] The battery control method of this application will be further described below based on experimental data.

[0153] In this embodiment, liquid lithium-ion batteries of different systems are used as the experimental subjects. Different self-heating strategies are used to heat and charge the batteries, and the heat generation efficiency and lifespan decay of the experimental subjects are compared.

[0154] Example 1:

[0155] The experimental subject was a cathode material made primarily of lithium iron phosphate. The coating also included 1.2% PVDF binder and 1% single-walled carbon nanotubes. After mixing, the mixture was coated onto a 13µm carbon-coated aluminum foil. After coating and compaction, the double-sided areal density of the cathode was 350 g / m². 2 The compacted density is 2.71 g / cm³. 3 The negative electrode is made of graphite, and the coating includes a 2.5% CMC and SBR mixed binder, which is coated on an 8µm copper foil. The areal density of the compacted electrode is 161 g / m³. 2 The compacted density is 1.57 g / cm³. 3 The separator is a coated separator with a porosity of 25%, a separator thickness of 7µm, and a separator coating thickness of 0.3µm. The positive electrode, separator, negative electrode, separator, and positive electrode are stacked sequentially, and after baking, liquid injection, formation, and capacity testing are performed to obtain a single cell with a capacity of 108Ah.

[0156] The following self-heating test was conducted on the above experimental subjects:

[0157] 1) Battery pretreatment: Charge the battery to 0.8% SOC at room temperature.

[0158] 2) Low-temperature standing: Place the pretreated battery in a test chamber that has been cooled to -10℃ and stand for at least 24 hours to ensure that the cell temperature is fully balanced with the ambient temperature, i.e., the temperature difference is ≤2℃.

[0159] 3) Equipment and instrument preparation: A high-precision battery testing system is adopted, which can be programmed and output high-frequency, high-precision bidirectional pulse current, and simultaneously acquire voltage and current data at high frequency.

[0160] Self-heating program editing: Program positive and negative pulse current values ​​before testing, positive current... 10.8C, negative current For 10C, the ratio The value is 1.08, and the duty cycle is 50%. The duty cycle characterizes the time ratio of the positive pulse current to the negative pulse current; duty cycle = positive pulse current time / one charge / discharge cycle time. 100%.

[0161] 4) Perform self-heating test: Record the lowest temperature of the cell before startup as the starting temperature. Simulate an asymmetric self-heating program command through the test system to trigger the battery's self-heating function. Perform asymmetric sinusoidal AC self-heating at a self-heating frequency of 1 Hz until the target temperature of 25℃ is reached. Record the cell voltage, current, battery SOC, and temperature in real time. Record the highest and lowest temperature points.

[0162] 5) Performance evaluation: Calculate the average temperature rise rate (°C / min) to evaluate the heat generation efficiency; let it stand for a period of time to ensure that the battery temperature recovers to -10°C, repeat the above test, and cycle 200 times to evaluate the impact on battery life.

[0163] For example, the battery capacity retention rate is calculated as follows:

[0164] Based on the cell capacity of Q0 before the test (the cell capacity Q0 can also be the nominal capacity of the cell), a cyclic test was performed using the self-heating test procedure described above, for 200 cycles. After 200 cycles, a Reference Performance Test (RPT) was performed on the battery at a 1 / 3C rate, and the calibrated capacity was Q200. The capacity retention rate after the 200th cycle was Q200 / Q0×100%.

[0165] The experimental subjects in Examples 2-17 and Comparative Examples 1-10 were prepared in the same way as those in Example 1. The positive and negative electrode mixing ratios in Examples 18-21 and Comparative Examples 11-14 were different. Specifically, the positive electrode coating consisted of 2.1% PVDF binder and 1.8% single-walled carbon nanotubes; the negative electrode consisted of 3.7% CMC and SBR mixed binder.

[0166] Each embodiment or comparative example follows the self-heating test procedure of Example 1 to test the battery. The difference lies in that the starting state of charge (SOC), the frequency f of the heating current, and the ratio of the peak to the valley value of the heating current are denoted as follows: They are different. Specifically, the valley value of the heating current... The temperature is fixed at 10°C, and the ratio of the peak value to the valley value of the heating current is denoted as: The difference lies in the peak value of the heating current. different.

[0167] Specifically, the ratio of the peak value to the valley value of the heating current in Comparative Examples 1-14 is denoted as... In In addition; the SOC of Comparative Examples 1, 2, 9-11, and 14 was at In addition; the frequency f of the heating current in Comparative Examples 2, 4, 6, 8, 10, and 14 is at In addition.

[0168] Examples 22-38 and Comparative Examples 15-24 used ternary liquid lithium-ion batteries as their experimental subjects. The positive electrode used ternary NCM as the main material. The ternary material, 1.4% conductive agent (carbon nanotubes, CNTs), and 2.2% binder (PVDF) were mixed at high speed in an N-methylpyrrolidone solvent to form a uniform slurry. This slurry was then uniformly coated onto an aluminum foil current collector. The electrode was compacted using a roller press, achieving a compaction density and areal density of 2.71 g / cm³. 3 With 350g / m 2 The negative electrode uses graphite. Graphite, 2.8% conductive agent (carbon black SP), and 4.4% binder (CMC / SBR system) are mixed at high speed in deionized water in a specific ratio to form a uniform slurry. The areal density of the coated and rolled electrode is 161 g / m³. 2 The compacted density is 1.57 g / cm³. 3 The positive and negative electrodes (separated by a separator) are stacked and assembled into a battery cell. After baking, the cell undergoes processes such as electrolyte injection, formation, and capacity testing to obtain a single battery cell with a capacity of 127 Ah. The mixing ratio of the positive and negative electrodes in Examples 39-42 differs from that in Comparative Examples 25-28. Specifically, the positive electrode coating ratio is 2.1% conductive agent (CNT) and 1.8% binder (PVDF); the negative electrode auxiliary material ratio is 1.7% conductive agent (SP) and 3.7% binder (CMC / SBR system).

[0169] Each embodiment or comparative example was tested with the battery according to the self-heating test procedure of Example 1. The difference was that the peak value to valley value of the heating start-up SOC, self-heating frequency, and heating current were recorded as follows: different.

[0170] Specifically, the ratio of the peak value to the valley value of the heating current in Comparative Examples 15-28 is denoted as... In In addition; the SOC of comparative examples 15, 16, 23-25, and 28 was at In addition; the frequency f of the heating current in Comparative Examples 16, 18, 20, 22, 24, and 28 is at In addition.

[0171] Specific parameters and data are shown in Table 1:

[0172] Table 1

[0173]

[0174]

[0175] The capacity retention rate of a battery determines its remaining lifespan. A higher capacity retention rate indicates a longer remaining lifespan. For example, a capacity retention rate of over 95% after 200 cycles indicates a longer remaining lifespan. The above experiment uses the capacity retention rate after 200 cycles as the basis for analysis. A higher capacity retention rate after 200 cycles indicates less damage to the battery from the corresponding charging method and a longer battery lifespan; conversely, a lower capacity retention rate indicates that the charging method accelerates battery aging and shortens battery lifespan. The following analysis is based on the battery capacity retention rate:

[0176] The ratio of the peak to the valley value of the heating current for the battery The analysis of heating efficiency and battery capacity retention is as follows:

[0177] The data from Examples 1-21 are the ratios of the peak to the trough values ​​of the heating current. satisfy In this case, data from testing a first type of battery based on the battery control method of the embodiments of this application is used. This is combined with the ratio of the peak value to the valley value of the heating current in Comparative Examples 1-14. In In cases other than those described above, data from battery tests show that the battery control method based on the embodiments of this application charges the battery effectively. Under these conditions, it achieves higher heating efficiency and battery capacity retention.

[0178] The data from Examples 22-42 are the ratios of the peak to the trough values ​​of the heating current. satisfy In this case, data from testing a second type of battery based on the battery control method of the embodiments of this application is used. This is combined with the ratio of the peak to the valley value of the heating current in Comparative Examples 15-28. In In cases other than those described above, data from battery tests show that the battery control method based on the embodiments of this application charges the battery effectively. Under these conditions, it achieves higher heating efficiency and battery capacity retention.

[0179] The heating efficiency and battery capacity retention are analyzed for the heating current frequency f, as follows:

[0180] The data from Examples 1-15 and Examples 18-21 are based on the heating current frequency f satisfying... In this case, data from testing a first type of battery based on the battery control method of the embodiments of this application is used. Combining Comparative Examples 2, 4, 6, 8, 10, and 14, the frequency f of the heating current is at... In cases other than those described above, data from battery tests show that the battery control method based on the embodiments of this application charges the battery effectively. Under these conditions, it achieves higher heating efficiency and battery capacity retention.

[0181] The data from Examples 22-36 and Examples 39-41 are based on the heating current frequency f satisfying... In this case, data from testing a second type of battery based on the battery control method of the embodiments of this application is presented. Combining Comparative Examples 16, 18, 20, 22, 24, and 28, the frequency f of the heating current is at... In cases other than those described above, data from battery tests show that the battery control method based on the embodiments of this application charges the battery effectively. Under these conditions, it achieves higher heating efficiency and battery capacity retention.

[0182] The following analysis examines the temperature rise efficiency and battery capacity retention rate at the state of charge (SOC) starting from battery self-heating:

[0183] The data from Examples 4-12, 16, 17, and 19-21 are based on the battery's initial SOC meeting the requirements at the start of heating. In this case, the battery control method according to the embodiments of this application was used to test the first type of battery. Combined with Comparative Examples 1, 2, 9-11, and 14, the battery's initial heating SOC was at... In cases other than those described above, data from battery tests show that the battery control method based on the embodiments of this application charges the battery effectively. Under these conditions, it achieves higher heating efficiency and battery capacity retention.

[0184] The data from Examples 25-33, 37, 38, and 40-42 are based on the battery's initial SOC meeting the requirements at the start of heating. In this case, data from testing a second type of battery based on the battery control method of the embodiments of this application is used. Combined with Comparative Examples 15, 16, 23-25, and 28, the battery's initial heating SOC is at... In cases other than those described above, data from battery tests show that the battery control method based on the embodiments of this application charges the battery effectively. Under these conditions, it achieves higher heating efficiency and battery capacity retention.

[0185] This application also provides a charging current control method for an electric vehicle, the electric vehicle having a charging interface and a battery, comprising: when the charging interface is connected to an external charging device and the battery temperature is lower than a first temperature, controlling the battery to self-heat, wherein the self-heating heating current satisfies: The ratio of the peak value to the valley value of the heating current is denoted as ; The initial state of charge of a battery that is self-heating is denoted as SOC.

[0186] The battery control method for electric vehicles provided in this application, when the charging interface is connected to an external charging device and the battery temperature is lower than a first temperature, controls the battery to self-heat. The ratio of the peak value to the valley value of the heating current is denoted as... The initial state of charge of a battery that self-heats is denoted as SOC. .

[0187] At lower SOCs, the battery's lithium insertion capacity increases and the risk of lithium plating decreases. However, lower SOCs also increase the risk of over-discharge gas generation, reducing battery capacity retention. By appropriately increasing the peak-to-valley ratio, a higher asymmetric waveform can accelerate heating while simultaneously increasing the overall SOC, thus reducing the risk of over-discharge gas generation. Conversely, at higher SOCs, the risk of lithium plating during low-temperature self-heating significantly increases. By appropriately reducing the peak-to-valley ratio, the lithium insertion / extraction process on the negative electrode surface can be precisely controlled. A smaller peak-to-valley ratio provides a buffer time for lithium ions to return from the negative electrode to the electrolyte, greatly reducing the risk of lithium plating and improving battery cycle life.

[0188] Therefore, in this embodiment of the application, when the battery temperature is lower than the first temperature, the ratio of the peak value to the valley value of the heating current is controlled to satisfy: The ratio of the peak to the valley value of the heating current is controlled by the battery's state of charge (SOC). This approach ensures a balance between lithium plating risk and gas generation risk, thereby reducing lithium plating risk, improving battery capacity retention, reducing gas generation risk, and improving battery heating efficiency. While maintaining a constant lithium plating risk level, the ratio of peak to trough values ​​is appropriately increased to reduce gas generation and improve self-heating efficiency. Based on the battery control method implemented in this application, the lithium plating risk is reduced, battery capacity retention is improved, fast charging time is shortened, and the battery life of electric vehicles is extended, all while improving self-heating efficiency.

[0189] This application also provides a battery control method applied to a charging device, comprising: when the charging device is connected to an external electrical device and the temperature of the battery of the external electrical device is lower than a first temperature, controlling the battery to self-heat, wherein the self-heating heating current satisfies: The ratio of the peak value to the valley value of the heating current is denoted as ; The initial state of charge of a battery that is self-heating is denoted as SOC.

[0190] The battery control method for charging devices provided in this application involves controlling the battery to self-heat when the charging device is connected to an external electrical device and the temperature of the external electrical device's battery is lower than a first temperature. The ratio of the peak value to the valley value of the heating current is denoted as... The initial state of charge of a battery that self-heats is denoted as SOC. .

[0191] At lower SOCs, the battery's lithium insertion capacity increases and the risk of lithium plating decreases. However, lower SOCs also increase the risk of over-discharge gas generation, reducing battery capacity retention. By appropriately increasing the peak-to-valley ratio, a higher asymmetric waveform can accelerate heating while simultaneously increasing the overall SOC, thus reducing the risk of over-discharge gas generation. Conversely, at higher SOCs, the risk of lithium plating during low-temperature self-heating significantly increases. By appropriately reducing the peak-to-valley ratio, the lithium insertion / extraction process on the negative electrode surface can be precisely controlled. A smaller peak-to-valley ratio provides a buffer time for lithium ions to return from the negative electrode to the electrolyte, greatly reducing the risk of lithium plating and improving battery cycle life.

[0192] Therefore, in this embodiment of the application, when the battery temperature is lower than the first temperature, the ratio of the peak value to the valley value of the heating current is controlled to satisfy: The ratio of the peak to the valley value of the heating current is controlled by the battery's state of charge (SOC). This approach ensures a balance between lithium plating risk and gas generation risk, thereby reducing lithium plating risk, improving battery capacity retention, reducing gas generation risk, and improving battery heating efficiency. While maintaining a constant lithium plating risk level, the ratio of peak to trough values ​​is appropriately increased to reduce gas generation and improve self-heating efficiency. Based on the battery control method implemented in this application, the lithium plating risk is reduced, battery capacity retention is improved, fast charging time is shortened, and the battery life of external electrical devices is extended, all while improving self-heating efficiency.

[0193] This application also provides a battery control device that can control the battery to self-heat when the battery temperature is lower than a first temperature; wherein, the ratio of the peak value to the valley value of the heating current is denoted as... The initial state of charge of a battery that self-heats is denoted as SOC. When the battery self-heats to a second temperature, it is charged using a charging current. This battery control device includes, but is not limited to, electric vehicle charging stations, wireless chargers, power banks, charging cabinets, and energy storage cabinets.

[0194] The battery control device provided in this application embodiment controls the ratio of the peak value to the valley value of the heating current to satisfy the following when the battery temperature is lower than a first temperature: The ratio of the peak to the valley value of the heating current is controlled by the battery's state of charge (SOC). This approach ensures a balance between lithium plating risk and gas generation risk, thereby reducing lithium plating risk, improving battery capacity retention, reducing gas generation risk, and improving battery heating efficiency. While maintaining a constant lithium plating risk level, the ratio of peak to trough values ​​is appropriately increased to reduce gas generation and improve self-heating efficiency. Based on the battery control method implemented in this application, the lithium plating risk is reduced, battery capacity retention is improved, fast charging time is shortened, and battery life is extended, all while improving self-heating efficiency.

[0195] This application provides a battery pack including a battery; the battery self-heats when its temperature is below a first temperature, and the self-heating current satisfies the following: The ratio of the peak value to the valley value of the heating current is denoted as ; The initial state of charge of a battery that is self-heating is denoted as SOC.

[0196] Figure 6 This is a schematic diagram of the controller provided in this application. Figure 6 As shown, the controller 600 provided in this embodiment includes at least one processor 601 and a memory 602. Optionally, the controller 600 further includes a communication component 603. The processor 601, memory 602, and communication component 603 are connected via a bus.

[0197] In a specific implementation, at least one processor 601 executes computer execution instructions stored in memory 602, causing at least one processor 601 to perform the above-described method.

[0198] The specific implementation process of processor 601 can be found in the above method embodiments, and its implementation principle and technical effect are similar, so it will not be repeated here. In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly manifested as execution by a hardware processor, or execution by a combination of hardware and software modules in the processor.

[0199] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0200] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0201] This application provides a battery management system, which includes the controller or battery control device described in the above embodiments.

[0202] This application provides a battery pack including a battery and a controller as described in the above embodiments.

[0203] This application provides an electrical device, including the battery pack of the above embodiments, or the controller of the above embodiments.

[0204] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0205] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0206] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0207] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0208] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0209] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0210] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0211] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0212] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0213] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A battery control method characterized by, The method includes: when the temperature of the battery is lower than the first temperature, controlling the battery to perform self-heating, a heating current of the self-heating satisfying: ; When the battery self-heats to the second temperature, the battery is charged using a charging current; The ratio of the peak value to the valley value of the current during the charging and discharging phases of the heating current is denoted as: The initial state of charge of the battery during self-heating is denoted as SOC. The first temperature is greater than or equal to -30°C and less than or equal to 20°C; the heating current is controlled by the state of charge (SOC) of the battery. .

2. The method of claim 1, wherein, The frequency of the heating current is denoted by f, in Hz, .

3. The method of claim 1, wherein, The double-sided area density of the positive electrode of the battery is denoted as σ1, with the unit of g / m 2 , 300 1000; and / or the double-sided area density of the negative electrode of the battery is denoted as σ2, with the unit of g / m 2 , 130 460; And / or, the compaction density of the positive electrode of the battery is denoted as γ1, with units of g / cm³. 3 2.2 3; and / or, the compaction density of the negative electrode of the battery is denoted as γ2, in g / cm³. 3 1.4 2.

4. The method according to any one of claims 1 to 3, characterized in that, The waveform of the heating current includes at least one of the following: sine wave, square wave, trapezoidal wave, and triangular wave.

5. The method according to any one of claims 1 to 3, characterized in that, The mass percentage of the binder of the battery is denoted as ω, .

6. The method according to any one of claims 1 to 3, characterized in that, The mass ratio of the conductive agent of the battery is denoted as ,0 3 .

7. A battery control method characterized by, Applied to an electric vehicle having a charging interface and a battery, the method includes: In a case where the charging interface is connected with the external charging device and the temperature of the battery is lower than the first temperature, the battery is controlled to perform self-heating, and a heating current of the self-heating satisfies: ; When the battery self-heats to the second temperature, the battery is charged using a charging current; Wherein, the ratio of the peak value and the valley value of the current value of the charging stage and the discharging stage of the heating current is recorded as ; the initial state of charge of the self-heating of the battery is recorded as SOC; ; the first temperature is greater than or equal to -30℃ and less than or equal to 20℃; the heating current is controlled by the SOC of the battery .

8. A battery control method characterized by, Applied to a charging device, the method includes: In the charging device is connected with the external power device, and the temperature of the battery of the external power device is lower than the first temperature, the battery is controlled to perform self-heating, and the heating current of the self-heating satisfies: ; When the battery self-heats to the second temperature, the battery is charged using a charging current; Wherein, the ratio of the peak value and the valley value of the current value of the charging stage and the discharging stage of the heating current is recorded as ; the initial state of charge of the self-heating of the battery is recorded as SOC; ; the first temperature is greater than or equal to -30℃ and less than or equal to 20℃; the heating current is controlled by the SOC of the battery .

9. A controller characterized by comprising: include: Memory, processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any one of claims 1-8.

10. A battery pack, characterized by, Includes a battery, and a controller as described in claim 9.

11. An electrical device, characterized by This includes the battery pack as described in claim 10, or the controller as described in claim 9.

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