Battery, charging method thereof, battery management system and electric device

Abstract

A battery, a battery charging method, a battery management system and a power consumption device can improve the charging performance of the battery. The battery comprises at least one battery cell and a battery management system. The positive active material of the battery cell comprises LiMPO4, wherein M comprises Mn and Fe. The battery management system is configured to control the battery to be charged based on a first charging current to heat the battery during the charging process when the SOC of the battery is less than or equal to a preset SOC threshold, and control the battery to be charged based on a second charging current when the SOC of the battery is greater than the SOC threshold, wherein the first charging current is greater than the second charging current.

Description

[0001] This application claims priority to PCT application filed on April 27, 2023, with application number PCT / CN2023 / 091302, entitled “Charging method, apparatus, electronic device and computer-readable storage medium”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, and in particular to a battery, a charging method thereof, a battery management system, and an electrical device thereof. Background Technology

[0003] With the development of the times, electric vehicles have huge market prospects due to their advantages such as high environmental friendliness, low noise, and low operating costs. They can also effectively promote energy conservation and emission reduction, which is beneficial to social development and progress.

[0004] For electric vehicles, battery technology is a crucial factor in their development. Therefore, improving battery charging performance has become an urgent problem to be solved. Summary of the Invention

[0005] This application provides a battery and its charging method, a battery management system, and an electrical device, which can improve the charging performance of the battery.

[0006] In a first aspect, a battery is provided, comprising at least one battery cell and a battery management system, wherein the positive electrode active material of the battery cell comprises LiMPO4, wherein M comprises Mn and Fe elements; the battery management system is configured to: control the battery to charge based on a first charging current for at least a portion of a time when the state of charge (SOC) of the battery is less than or equal to a preset SOC threshold, so as to heat the battery during the charging process; and control the battery to charge based on a second charging current for at least a portion of a time when the SOC of the battery is greater than the SOC threshold, wherein the first charging current is greater than the second charging current.

[0007] The battery in this application uses LiMPO4 material as its positive electrode active material, where M includes Mn and Fe elements, which has advantages such as high energy density and large capacity. However, when LiMPO4 material is used as the positive electrode active material of the battery, it sequentially experiences the charging plateau corresponding to Fe and the charging plateau corresponding to Mn elements during the charging process. In the charging plateau stage corresponding to Mn elements, the delithiation depth of the positive electrode active material is relatively low, making it difficult for the battery capacity to be fully utilized. Therefore, when the battery's SOC is less than or equal to a preset SOC threshold, the battery management system controls the battery to charge based on a larger first charging current, increasing the battery temperature during the charging process until the battery's SOC exceeds the SOC threshold, at which point the battery is controlled to charge based on a conventional second charging current. In this way, when entering the charging plateau stage corresponding to Mn elements, the battery has a suitable temperature, which can increase the delithiation depth of the positive electrode active material LiMPO4, thereby increasing the battery's charging capacity and improving the battery's charging performance.

[0008] In some possible implementations, the first charging current is configured to decrease based on the increase of the battery's state of charge (SOC).

[0009] In this implementation, as the battery's SOC increases, the battery's charging capacity, such as its maximum allowable charging current, gradually decreases. In order to reduce lithium plating and other issues caused by the charging current exceeding the battery's maximum allowable charging current during the charging process, the first charging current needs to be adjusted in real time as the battery's SOC increases during the charging process.

[0010] In some possible implementations, the range less than or equal to the SOC threshold includes multiple SOC intervals, each corresponding to a multiple current value of the first charging current. Specifically, the battery management system is used to: determine a target current value corresponding to the target SOC interval based on the correspondence between the multiple SOC intervals and the multiple current values, and the target SOC interval in which the battery's SOC is located; and, when the battery's SOC is within the target SOC interval, control the battery to charge based on the target current value.

[0011] In this implementation, multiple SOC intervals are set before the battery's SOC reaches the SOC threshold. Each SOC interval corresponds to a different current value of the first charging current. The battery management system determines the corresponding current value to charge the battery based on the SOC interval in which the current SOC is located. This effectively reduces lithium plating and other issues caused by the charging current exceeding the battery's maximum allowable charging current.

[0012] In some possible implementations, the length of the SOC interval is between 3% and 10%.

[0013] In this implementation, the smaller the length of the SOC interval, the larger the current value corresponding to the maximum SOC value within each SOC interval, and the greater the temperature rise of the battery. On the other hand, the larger the length of the SOC interval, the lower the control complexity of the battery management system. Therefore, setting the length of the SOC interval between 3% and 10% can meet the temperature rise requirements of the battery without increasing the control complexity of the battery management system.

[0014] In some possible implementations, the current value corresponding to each of the plurality of SOC intervals is less than or equal to the maximum allowable charging current of the battery corresponding to the largest SOC value in each SOC interval.

[0015] In this implementation, as the SOC of the battery increases, the maximum allowable charging current of the battery gradually decreases. In order to reduce lithium plating and other issues caused by the charging current exceeding the maximum allowable charging current of the battery during the charging process, the current value of the first charging current corresponding to each SOC interval should be less than or equal to the maximum allowable charging current of the battery corresponding to the largest SOC value in that SOC interval.

[0016] In some possible implementations, the SOC threshold is determined based on the molar percentage of iron in the iron-manganese element of the positive electrode active material. For example, the SOC threshold is the product of the SOC of the battery in a fully charged state and the molar percentage.

[0017] In this implementation, the SOC threshold can be determined based on the molar ratio of iron in the iron-manganese element of the positive electrode active material. This ensures that the battery has a suitable temperature when it reaches the charging platform corresponding to the Mn element, which can effectively improve the charging performance of the battery and reduce unnecessary power consumption.

[0018] In some possible implementations, the second charging current is a constant current. That is, after the SOC exceeds the SOC threshold, the battery is charged using a constant current charging method, which has advantages such as high charging efficiency, easy precise control, and reduced battery damage caused by overcharging or fast charging, thereby extending battery life.

[0019] In some possible implementations, the capacity of the battery cell is between 100Ah and 300Ah, or between 130Ah and 250Ah. Since larger capacity battery cells generate more heat, a higher temperature at which the battery reaches its State of Charge (SOC) threshold is more conducive to maximizing the capacity of the battery cell.

[0020] In some possible implementations, the positive electrode active material includes at least one of the following materials:

[0021] LiMn1-yFeyPO4, where y is any value in the range of 0.001 to 0.5;

[0022] Li1+tMn1-cFecP1-zRzO4, where t is any value in the range of -0.100 to 0.100, c is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, and R includes one or more elements selected from B, S, Si and N;

[0023] Li1+wCmMn1-uFeuP1-aRaO4-nDn, wherein C includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W, R includes one or more elements selected from B, S, Si and N, D includes one or more elements selected from S, F, Cl and Br, w is any value in the range of -0.100 to 0.100, u is any value in the range of 0.001 to 0.500, a is any value in the range of 0.001 to 0.100, n is any value in the range of 0.001 to 0.1, and m is any value in the range of 0.9 to 1.1.

[0024] In a second aspect, a method for charging a battery is provided, the battery comprising at least one battery cell, the positive electrode active material of the battery cell comprising LiMPO4, wherein M comprises Mn and Fe elements, the charging method comprising: controlling the battery to charge based on a first charging current for at least a portion of a time when the state of charge (SOC) of the battery is less than or equal to a preset SOC threshold, thereby heating the battery during the charging process; and controlling the battery to charge based on a second charging current for at least a portion of a time when the SOC of the battery is greater than the SOC threshold, wherein the first charging current is greater than the second charging current.

[0025] In some possible implementations, the first charging current is configured to decrease based on the increase of the battery's state of charge (SOC).

[0026] In some possible implementations, the range less than or equal to the SOC threshold includes multiple SOC intervals, each corresponding to a multiple current value of the first charging current. The charging method further includes: determining a target current value corresponding to the target SOC interval based on the correspondence between the multiple SOC intervals and the multiple current values, and the target SOC interval in which the battery's SOC is located; controlling the battery to charge based on the first charging current includes: controlling the battery to charge based on the target current value when the battery's SOC is within the target SOC interval.

[0027] In some possible implementations, the length of the SOC interval is between 3% and 10%.

[0028] In some possible implementations, the current value corresponding to each of the plurality of SOC intervals is less than or equal to the maximum allowable charging current of the battery corresponding to the largest SOC value in each SOC interval.

[0029] In some possible implementations, the SOC threshold is determined based on the molar percentage of iron in the iron-manganese element of the positive electrode active material. For example, the SOC threshold is the product of the SOC of the battery in a fully charged state and the molar percentage.

[0030] In some possible implementations, the second charging current is a constant current.

[0031] In some possible implementations, the capacity of the battery cell is between 100Ah and 300Ah, or between 130Ah and 250Ah.

[0032] In some possible implementations, the positive electrode active material includes at least one of the following materials:

[0033] LiMn 1-y Fe y PO4, where y is any value in the range of 0.001 to 0.5;

[0034] Li 1+t Mn 1-c Fe c P 1-z R z O4, where t is any value in the range of -0.100 to 0.100, c is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, and R includes one or more elements selected from B, S, Si and N;

[0035] Li 1+w C m Mn 1-u Fe u P 1-a R a O 4-n D nWherein, C includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; R includes one or more elements selected from B, S, Si and N; D includes one or more elements selected from S, F, Cl and Br; w is any value in the range of -0.100 to 0.100; u is any value in the range of 0.001 to 0.500; a is any value in the range of 0.001 to 0.100; n is any value in the range of 0.001 to 0.1; and m is any value in the range of 0.9 to 1.1.

[0036] Thirdly, a battery management system is provided for performing a charging method for a battery as described in the first aspect or any possible implementation thereof, the battery comprising at least one battery cell, the positive electrode active material of the battery cell comprising LiMPO4, wherein M comprises Mn and Fe elements.

[0037] Fourthly, an electrical device is provided, comprising the battery described in the first aspect or any possible implementation thereof.

[0038] Fifthly, a charging device is provided, including a processor and a memory, the memory for storing a computer program, and the processor for calling and running the computer program stored in the memory to perform the method described in the second aspect or any possible implementation thereof.

[0039] A sixth aspect provides a computer-readable storage medium for storing a computer program that, when executed by a computing device, causes the computing device to implement the method according to the second aspect or any implementation thereof. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0041] Figure 1 This is a schematic block diagram of a charging system that may be applied in the embodiments of this application.

[0042] Figure 2 This is a schematic block diagram of a battery according to an embodiment of this application.

[0043] Figure 3 This is a schematic flowchart of a battery charging method according to an embodiment of this application.

[0044] Figure 4yes Figure 3 The flowchart illustrates one possible implementation of the battery charging method shown.

[0045] Figure 5 This is a schematic diagram of an electrical device according to an embodiment of this application. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy. "Vertical" is not strictly vertical, but within the allowable tolerance range. "Parallel" is not strictly parallel, but within the allowable tolerance range.

[0048] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0049] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0050] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, in this application, the character " / " indicates that the preceding and following related objects have an "or" relationship.

[0051] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0052] A battery typically refers to a single physical module comprising one or more individual battery cells to provide higher voltage and capacity. For example, the battery can be a battery module, where multiple battery cells are arranged and fixed to form a battery module; or, for another example, the battery can be a battery pack, which includes individual battery cells and a housing, with the individual battery cells or battery modules housed within the housing.

[0053] The technical solutions described in the embodiments of this application are applicable to various battery-powered devices, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, electric vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0054] It should be understood that the technical solutions described in the embodiments of this application are not limited to the devices described above, but can also be applied to all devices that use batteries. However, for the sake of brevity, the following embodiments are all illustrated using electric vehicles as examples.

[0055] Figure 1 An architectural diagram of a charging system 100 applicable to an embodiment of this application is shown. Figure 1 As shown, the charging system 100 includes a charging device 110 and a battery 120. Optionally, the battery 120 may be a battery in an electrical device, such as a battery in a vehicle, or a battery in other application scenarios.

[0056] Optionally, the battery 120 includes a battery cell 121 and a battery management system (BMS) 122. The BMS 122 is used to monitor the status of the battery cell 121, and to intelligently manage and maintain the battery cell 121, reducing the probability of overcharging and over-discharging of the battery 120.

[0057] The charging device 110 is used to replenish the electrical energy of the battery cells 121 in the battery 120 and / or control the discharge of the battery cells 121. For example, the charging and discharging device 110 can be a regular charging pile, a supercharging pile, a charging pile supporting vehicle-to-grid (V2G) mode, a charger, or other charging devices used to charge and / or discharge the battery. This application does not limit the specific type or application scenario of the charging device 110.

[0058] Optionally, such as Figure 1 As shown, the charging / discharging device 110 is connected to the battery cell 121 via a wire 150 and to the BMS 122 via a communication line 140. The communication line 140 is used to enable information exchange between the charging device 110 and the BMS 122. As an example, the communication line 140 may include, but is not limited to, a controller area network (CAN) communication bus or a daisy chain communication bus.

[0059] Optionally, in addition to communicating with the BMS 122 via the communication line 140, the charging device 110 can also communicate with the BMS 122 via a wireless network. This application embodiment does not specifically limit the type of wired or wireless communication between the charging device 110 and the BMS 122.

[0060] like Figure 2 As shown, this application embodiment provides a battery 120, including at least one battery cell 121 and a battery management system 122. The positive electrode active material of the battery cell 121 is lithium manganese iron phosphate, hereinafter also referred to as LiMPO4, where M includes Mn and Fe elements. The battery management system 122 is used for:

[0061] During at least a portion of the time when the SOC of battery 120 is less than or equal to a preset SOC threshold, battery 120 is controlled to charge based on a first charging current to heat battery 120 during the charging process; and,

[0062] During at least a portion of the time when the SOC of battery 120 is greater than the SOC threshold, battery 120 is controlled to charge based on a second charging current, wherein the first charging current is greater than the second charging current.

[0063] Here, the battery management system 122 can be, for example, a Figure 1 The BMS 122 shown can also be other control modules that can be used to control the charging current of the battery 120.

[0064] Battery 120 includes at least one battery cell 121. The positive electrode active material of battery cell 121 is LiMPO4 material, where M in LiMPO4 material may include Mn and Fe elements. Compared with traditional batteries using LiFePO4 material as the positive electrode active material, battery 120 using LiMPO4 material as the positive electrode active material has a higher voltage platform and its energy density can be about 15% higher than that of batteries using LiFePO4 material. It has advantages such as high energy density and large capacity, as well as lower cost and higher safety.

[0065] However, when LiMPO4 is used as the positive electrode active material of battery 120, the charging process of battery 120 will successively experience the charging platform corresponding to Fe and the charging platform corresponding to Mn. In the charging platform stage corresponding to Mn, the delithiation depth of the positive electrode active material is low, which makes it difficult for the capacity of battery 120 to be fully utilized. In addition, the delithiation speed of the positive electrode active material is slow, which makes the charging rate of the battery low, thus affecting the charging performance of battery 120 and reducing the user experience.

[0066] Therefore, in this embodiment, when the battery's SOC is less than or equal to a preset SOC threshold, the battery management system 122 controls the battery to charge using a larger first charging current. When the first charging current passes through the battery 120, the battery 120 generates heat due to its internal resistance, thus increasing the battery temperature during charging. This continues until the battery's SOC exceeds the SOC threshold, at which point the battery is then charged using a conventional second charging current, which is less than the first charging current. This ensures that the battery 120 has a suitable temperature when entering the charging platform stage corresponding to the Mn element. This temperature helps to increase the delithiation depth of the positive electrode active material LiMPO4, thereby increasing the capacity of the battery 120. The suitable temperature also helps to increase the diffusion rate and delithiation rate of lithium ions, which is beneficial for shortening the charging time of the battery 120 and easily meeting the requirements of fast charging. Therefore, to a certain extent, this solves the problems of insufficient capacity utilization and slow charging speed caused by using LiMPO4 as the positive electrode active material of the battery 120.

[0067] It is understood that, in the embodiments of this application, the charging platform refers, for example, to the stage in which the electrochemical reaction reaches equilibrium during the charging process. Within the charging platform, the battery potential fluctuates less with the state of charge (SOC), or in other words, the battery potential remains relatively stable within the charging platform.

[0068] In this embodiment, the battery 120 can be charged based on the first charging current for all periods when the SOC is less than or equal to a preset SOC threshold, so as to heat the battery 120 through the first charging current; or, the battery 120 can be charged based on the first charging current for some periods when the SOC is less than or equal to the SOC threshold, so as to heat the battery 120 through the first charging current.

[0069] For example, when the State of Charge (SOC) is less than or equal to the SOC threshold, the battery 120 can be controlled to be charged based on a first charging current to heat the battery 120, and the battery 120 can also be controlled to be charged based on a third charging current. Optionally, the third charging current is less than the first charging current and greater than or equal to the second charging current. That is, the battery 120 can be heated using the first charging current during certain periods when the SOC is less than or equal to the SOC threshold, and charged using the third charging current during other periods, in order to reduce the damage to the battery 120 caused by prolonged high-current charging.

[0070] Optionally, during at least a portion of the stages when the SOC of battery 120 is less than or equal to the SOC threshold, external heating may be applied to battery 120, and the external heating may at least partially overlap with the charging process of battery 120. For example, during the charging process of battery 120 based on the aforementioned third charging current, external heating may be used to heat battery 120 simultaneously.

[0071] In this embodiment, the battery 120 can be controlled to charge based on the second charging current for all periods when the SOC is greater than the preset SOC threshold; or, the battery 120 can be controlled to charge based on the second charging current for some periods when the SOC is greater than the SOC threshold.

[0072] For example, when the State of Charge (SOC) is greater than the SOC threshold, the battery 120 can be controlled to be charged based on a second charging current, and the battery 120 can also be controlled to be charged based on a fourth charging current. Optionally, the fourth charging current is less than or equal to the first charging current, but greater than the second charging current. The fourth charging current can, for example, be used to heat the battery 120. That is, if the temperature of the battery 120 drops after charging it for a period of time based on the second charging current when the SOC is greater than the SOC threshold, the charging can be switched to the fourth charging current to raise the temperature of the battery 120 again.

[0073] Of course, at least during a portion of the period when the SOC is greater than the SOC threshold, the battery 120 may also be externally heated, and the external heating process may at least partially overlap with the charging process of the battery 120. For example, if the temperature of the battery 120 decreases after charging the battery 120 for a period of time based on the second charging current when the SOC is greater than the SOC threshold, the battery 120 may also be heated by external heating.

[0074] In this embodiment, external heating refers to heating the battery 120 by a heating device outside the battery 120. The heating device may be, for example, a heating film, an active heating device such as a positive temperature coefficient (PTC) heating element or a high volgate heater (HVH), or a passive heating device such as a heat pump. The temperature of the battery 120 is increased by heat transfer between the heating device and the battery 120.

[0075] The state of charge (SOC) of battery 120 is used to characterize the remaining capacity of battery 120, for example, it can be expressed as the proportion of the remaining capacity of battery 120 to its total capacity. As an example, when detecting the SOC of battery 120, the open circuit voltage (OCV) of battery 120 can be detected, and based on a pre-set curve representing the relationship between the voltage and SOC of battery 120, namely the SOC-OCV curve, the SOC corresponding to the currently detected OCV can be found.

[0076] For battery 120 using LiMPO4 as the positive electrode active material, the charging process sequentially passes through the charging platform corresponding to Fe and the charging platform corresponding to Mn. Since the direct current resistance (DCR) of battery 120 within the Mn charging platform is 1.5-2 times that within the Fe charging platform, lithium ions are difficult to release from the battery 120 after reaching the Mn charging platform. When the state of charge (SOC) of battery 120 is greater than the SOC threshold, it has already passed through the Fe charging platform and entered the Mn charging platform. Because the temperature of battery 120 has already increased during the initial charging current, this facilitates lithium removal from the positive electrode active material within the Mn charging platform stage, thereby improving the charging performance of battery 120.

[0077] As mentioned above, during the charging process of battery 120, it sequentially experiences the charging platform corresponding to Fe and the charging platform corresponding to Mn, and the problem of low delithiation depth occurs at the charging platform corresponding to Mn. Therefore, in some embodiments, the SOC threshold can be determined based on the molar percentage f of Fe in the iron-manganese element of the positive electrode active material.

[0078] For example, the first SOC threshold can be the product between the SOC of battery 120 in a fully charged state and the molar percentage f of Fe element in iron and manganese elements.

[0079] In the case of LiMPO4 material, M includes Mn and Fe. The molar percentage f of Fe in the iron-manganese element is equal to the ratio between the molar content of Fe and the total molar content of Fe and Mn.

[0080] It is understandable that the State of Charge (SOC) of battery 120 in a fully charged state is usually equal to 1. However, as battery 120 degrades during use, its SOC in a fully charged state may gradually decrease, thus falling below 1. To determine the SOC threshold, the actual SOC of battery 120 in a fully charged state needs to be used. This actual SOC is multiplied by the molar percentage (f) of Fe in the iron-manganese mixture to obtain the SOC threshold.

[0081] Where 0 < f < 1, and optionally, 0.01 ≤ f ≤ 0.6.

[0082] The proportion of Fe in iron and manganese can be less than the proportion of Mn. For example, f can be between 0.001 and 0.5, such as f equal to 0.001, 0.002, 0.003, 0.004, 0.005, 0.007, 0.008, 0.009, 0.01, 0.02, 0.05, 0.07, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.49, 0.5, etc.

[0083] The proportion of Fe in iron and manganese can be slightly greater than that of Mn. For example, f can be between 0.5 and 0.6, such as f equal to 0.51, 0.52, 0.55, 0.57, 0.58, 0.59, 0.6, etc.

[0084] For example, assuming f = 0.3, the ratio of Fe to Mn elements in the LiMPO4 material is 3:7, and the SOC threshold can be 30% of the SOC of battery 120 in a fully charged state. When the SOC of battery 120 is less than 30%, the first charging current is used to charge battery 120. During the charging process, the temperature of battery 120 is increased. When battery 120 is charged to 30% of its SOC in a fully charged state, it indicates that it has passed the charging plateau corresponding to Fe and is about to enter the charging plateau corresponding to Mn. At this time, since the temperature of battery 120 has been increased, the charging performance of battery 120 in the charging plateau corresponding to Mn can be improved.

[0085] For example, assuming f = 0.4, the ratio of Fe to Mn in the LiMPO4 material is 4:6. Therefore, the first SOC threshold can be 40% of the SOC of battery 120 in a fully charged state. When the SOC of battery 120 is less than 40%, the first charging current is used to charge battery 120. During the charging process, the temperature of battery 120 is simultaneously increased. When battery 120 is charged to 40% of its fully charged state SOC, it indicates that it has passed the charging plateau corresponding to Fe and is about to enter the charging plateau corresponding to Mn. At this point, since the temperature of battery 120 has already increased, the charging performance of battery 120 within the charging plateau corresponding to Mn can be improved.

[0086] It is understandable that during the charging process of battery 120 based on the first charging current, when the first charging current passes through battery 120, battery 120 can generate heat due to its own internal resistance, so as to achieve self-heating of battery 120 and thus increase its temperature.

[0087] As the state of charge (SOC) of the battery increases, the charging capacity of battery 120 gradually decreases. To reduce lithium plating and other issues caused by the charging current exceeding the maximum allowable charging current of battery 120 during charging, the first charging current needs to be adjusted in real time according to the increase in the SOC of battery 120 during charging. Therefore, in some embodiments, the first charging current can be configured to decrease based on the increase in the battery's SOC.

[0088] In some embodiments, the range less than or equal to the SOC threshold includes multiple SOC intervals, each corresponding to a multiple current value of the first charging current. The battery management system 122 can determine a target current value corresponding to the target SOC interval based on the correspondence between the multiple SOC intervals and the multiple current values, as well as the target SOC interval where the battery 120's SOC is located, and charge the battery 120 using the target current value when the battery 120's SOC is within the target SOC interval.

[0089] In other words, during the charging process, the SOC of battery 120 gradually increases, and the value of the first charging current needs to be adjusted every time it passes through a SOC interval. The battery management system 122 can determine the corresponding current value based on the SOC interval in which the current SOC is located and the correspondence between the SOC interval and the current value, so that the value of the first charging current matches the current SOC of battery 120, thereby reducing lithium plating and other issues caused by the charging current exceeding the maximum allowable charging current of battery 120.

[0090] In some embodiments, the current value of the first charging current corresponding to each SOC interval is less than or equal to the maximum charging current allowed by the battery 120 corresponding to the largest SOC value within that SOC interval.

[0091] The maximum allowable charging current of battery 120 is related to the material and other characteristics of battery 120. For example, the maximum charging current is related to the electrolyte and graphite of battery 120.

[0092] It is understood that in the embodiments of this application, the current value of the first charging current corresponding to each SOC interval can be either the magnitude of the first charging current or the range of the first charging current. That is, a corresponding current magnitude can be set for each SOC interval, or a corresponding current range can be set for each SOC interval. Typically, the magnitude of the charging current can be expressed by the charging rate, for example, the charging rate is equal to the ratio of the charging current to the rated capacity.

[0093] During the charging process, before the SOC of battery 120 reaches the SOC threshold, for each SOC range reached by battery 120, the current magnitude or current range of the first charging current needs to be adjusted to the current magnitude or current range corresponding to that SOC range, and battery 120 is charged based on the current magnitude or current range.

[0094] The shorter the length of the SOC interval, the larger the current value corresponding to the maximum SOC value in each SOC interval, and the greater the temperature rise of the battery 120. On the other hand, the longer the SOC interval, the lower the control complexity of the battery management system 122. Therefore, in some embodiments, the length of the SOC interval can be set between 3% and 10%, which can meet the temperature rise requirements of the battery 120 without increasing the control complexity of the battery management system 122.

[0095] In some embodiments, the range of the first charging current is determined based on the maximum allowable charging current of the battery 120 when the state of charge (SOC) of the battery 120 is at the SOC threshold and the maximum allowable charging current of the battery 120 when the SOC of the battery 120 is 0. For example, the range of the first charging current includes 0.36C to 4.92C; further, optionally, the range of the first charging current includes 0.40C to 4.2C.

[0096] As an example, assuming a SOC threshold of 45% and a SOC interval length of 5%, the correspondence between the first charging current and the SOC interval is shown in Table 1. When the SOC of battery 120 is less than or equal to 45%, the first charging current is used to charge battery 120, and the charging rate of the first charging current corresponding to each SOC interval is different. After the SOC of battery 120 reaches 45%, a second charging current is used to charge battery 120, and the second charging current is less than the first charging current. Table 1 provides three possible correspondences between the first charging current and the SOC interval, namely the currents described in Examples 1, 2, and 3.

[0097] Table 1

[0098]

[0099]

[0100] As can be seen, as the SOC increases, the battery management system 122 adjusts the first charging current at each SOC range to reduce the first charging current accordingly, thereby reducing the probability that the charging current exceeds the maximum charging current allowed by the battery 120, reducing the probability of lithium plating in the battery 120, and extending the life of the battery 120.

[0101] Taking Example 1 as an example, when the SOC of battery 120 is between 0% and 5%, it is charged at a charging rate of 4.1C; when the SOC of battery 120 is between 5% and 10%, it is charged at a charging rate of 3.53C; when the SOC of battery 120 is between 10% and 15%, it is charged at a charging rate of 2.95C; when the SOC of battery 120 is between 15% and 20%, it is charged at a charging rate of 2.50C; and when the SOC of battery 120 is between 20% and 25%, it is charged at a charging rate of 2.05C. The battery 120 is charged at a rate of 1.79C when its SOC is between 25% and 30%; at a rate of 1.54C when its SOC is between 30% and 35%; at a rate of 1.18C when its SOC is between 35% and 40%; at a rate of 1.09C when its SOC is between 40% and 45%; and at a rate of 0.33C when its SOC exceeds 45%.

[0102] For example, as shown in Table 2, regarding the correspondence between the first charging current and the SOC interval, assuming the SOC threshold is 45% and the length of the SOC interval is 5%, as shown in Table 2, when the SOC of battery 120 is less than or equal to 45%, the first charging current is used to charge battery 120, and the charging rate range of the first charging current corresponding to each SOC interval is different. After the SOC of battery 120 reaches 45%, a second charging current is used to charge battery 120, and the second charging current is less than the first charging current. Table 2 provides two possible correspondences between the first charging current and the SOC interval, namely Example 1 and Example 2.

[0103] Table 2

[0104]

[0105]

[0106] As the State of Charge (SOC) increases, the battery management system 122 adjusts the first charging current at each SOC range to reduce the first charging current accordingly. The first charging current can be any charging rate within the charging rate range corresponding to the SOC range, thereby reducing the probability that the charging current exceeds the maximum allowable charging current of the battery 120, reducing the probability of lithium plating in the battery 120, and extending the life of the battery 120.

[0107] Taking Example 1 as an example, when the SOC of battery 120 is between 0% and 5%, it is charged at a charging rate ranging from 1.37C to 4.92C; when the SOC of battery 120 is between 5% and 10%, it is charged at a charging rate ranging from 1.18C to 4.23C; when the SOC of battery 120 is between 10% and 15%, it is charged at a charging rate ranging from 0.98C to 3.54C; when the SOC of battery 120 is between 15% and 20%, it is charged at a charging rate ranging from 0.83C to 3.00C; and when the SOC of battery 120 is between 20% and 25%, it is charged at a charging rate ranging from 0.68C to 2.46C. Battery 120 is charged at the following rates: when the SOC of battery 120 is between 25% and 30%, it is charged at a rate between 0.60C and 2.15C; when the SOC of battery 120 is between 30% and 35%, it is charged at a rate between 0.51C and 1.84C; when the SOC of battery 120 is between 35% and 40%, it is charged at a rate between 0.39C and 1.42C; when the SOC of battery 120 is between 40% and 45%, it is charged at a rate between 0.36C and 1.31C; and when the SOC of battery 120 exceeds 45%, it is charged at a rate of 0.33C.

[0108] It is understood that the battery management system 122 can select any one of the charging rate ranges corresponding to each SOC interval as the current magnitude for charging the battery 120. For example, it can randomly select a current magnitude within this range, or select a current magnitude based on a preset rule.

[0109] The ranges described in the embodiments of this application all include the endpoint values ​​of the range. For example, the range [a, b] refers to a range that is greater than or equal to a and less than or equal to b.

[0110] In some embodiments, as shown in Tables 1 and 2 above, the second charging current can be a constant current, for example, between 0.3C and 1.0C; further, optionally, the second charging current can be between 0.33C and 0.8C, with 0.33C being used as an example below. That is, after the SOC of battery 120 is greater than the SOC threshold, constant current charging is used to charge battery 120, which has advantages such as high charging efficiency, easy precise control, and reduced damage to battery 120 caused by overcharging or fast charging, thereby extending the battery 120's lifespan.

[0111] Of course, after the SOC of battery 120 is greater than the SOC threshold, constant voltage charging can also be used to charge battery 120. In this case, the second charging current is not constant, but gradually decreases.

[0112] Alternatively, after the SOC of battery 120 exceeds the SOC threshold, a constant second charging current can be used to charge battery 120 at a constant current, and then a constant voltage can be used to charge battery 120 at a constant voltage to eliminate polarization.

[0113] This application does not limit the charging method used after the SOC of battery 120 exceeds the SOC threshold.

[0114] During the charging process of battery 120 using the first charging current, heat is generated by the internal resistance of battery 120 itself. Larger capacity battery cells 121 generate more heat, and the higher the temperature of battery 120 when it reaches the SOC threshold, the more beneficial it is for the battery cells 121 to achieve their full capacity. Therefore, the charging scheme of this application embodiment is more suitable for large capacity batteries 120. For example, in some embodiments, the capacity of battery cells 121 in battery 120 is between 100Ah and 300Ah; further, optionally, the capacity of battery cells 121 can be between 130Ah and 250Ah.

[0115] The capacity of battery 120 was tested under different first charging currents, as shown in Tables 3 and 4. The negative electrode of battery 120 used in the tests was made of graphite, including at least one of soft carbon, hard carbon, artificial graphite, and natural graphite. The graphite content of the negative electrode was 96.7%, the binder content was 1.5%, and the negative electrode coating weight was 0.163 mg / 1540 mm². 2 The porosity is 27%, the negative electrode coating thickness is 0.216 mm, and the negative electrode compaction density is 1.65 g / cm³. 3 .

[0116] The electrolyte of battery cell 121 is selected from one or more organic carbonate esters such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate, which are electronically insulating and ion-conducting, and include one or more lithium salts such as LiPF6, LiBF4, LiBOB, LiAsF6, Li(CF3SO2)2N, LiCF3SO3, and LiClO4 as solutes.

[0117] The separator of the battery cell 121 is selected from one or more of the following materials: electrochemically stable and chemically stable polyethylene, polypropylene, non-woven fabric, and polyfiber.

[0118] In the fabrication of the positive electrode sheet of battery cell 121, the active material LiMPO4, conductive carbon black Super-P, and binder PVDF are thoroughly mixed in an NMP solvent system at a weight ratio of 97:1:2, and then coated onto Al foil, with the coating weight controlled at 360 g / m². 2 The cathode electrode is obtained by drying, cold pressing, slitting, and cutting.

[0119] In the fabrication of the negative electrode sheet of battery cell 121, graphite, conductive carbon black Super-P, and binder SBR are thoroughly mixed in an H2O solvent system at a weight ratio of 97.4:0.8:1.8, and then coated onto Cu foil, with the coating weight controlled at 0.163 mg / 1540 mm. 2 The anode electrode is obtained by drying, cold pressing, slitting, and cutting.

[0120] In manufacturing battery cell 121, a three-layer porous polymer film of PE / PP / PE is used as the separator. The positive electrode, separator, and negative electrode are wound sequentially, with the separator positioned between the positive and negative electrodes to provide isolation. The winding process also controls the misalignment between the positive and negative electrodes, and between the electrodes and the separator. This results in a bare cell, or electrode assembly. The electrode assembly is then welded to the top cover of battery cell 121 using tabs, completing the casing, baking, electrolyte injection, and formation processes to obtain a qualified battery cell 121. This battery cell 121 can be used as the battery 120 to be tested; that is, taking battery 120 as an example where it consists of only one battery cell 121.

[0121] Taking a SOC threshold of 45% and a SOC interval length of 5% as an example, as shown in Table 3, in the comparative example, a second charging current, such as 0.33C, is always used to charge battery 120 at a constant current. In Examples 1, 2, and 3, when the SOC of battery 120 is less than or equal to 45%, the first charging current is used to charge battery 120. When the SOC is greater than 45%, the second charging current, such as 0.33C, is used to charge battery 120. Note that the value of the first charging current corresponding to each SOC interval is different in Examples 1, 2, and 3.

[0122] Table 3

[0123]

[0124]

[0125] In Examples 1, 2, and 3, the first charging current decreases as the State of Charge (SOC) range increases. When the SOC reaches 45%, a second charging current of 0.33C is used to charge battery 120. The first charging current is always greater than 0.33C. In the comparative example, a second charging current of, for example, 0.33C, is always used to perform constant current charging on battery 120.

[0126] The comparative examples, Example 1, Example 2 and Example 3 were all tested on battery 120 under the same conditions in the following manner.

[0127] During the testing of battery 120, firstly, battery 120 is placed at an ambient temperature of, for example, 25°C for a period of time to acclimatize. After the temperature of battery 120 reaches 25°C, battery 120 is charged to a full charge state with a specific current. Then, it is left at that temperature for a certain period of time to acclimatize until the temperature of battery 120 reaches 25°C. Then, battery 120 is discharged at a constant current with a specific current until the cutoff voltage of battery 120 is reached. The capacity of the constant current discharge is taken as the rated capacity of battery 120.

[0128] Next, the battery 120 is placed at an ambient temperature, e.g., 25°C, for a period of time to acclimatize. After the temperature of the battery 120 reaches 25°C, it is charged to full charge using a specific current. Then, it is left at that temperature for a certain period of time to acclimatize until the temperature of the battery 120 reaches 25°C. The rated capacity of the battery 120 is divided into several equal parts, and then the battery 120 is discharged at a constant current using a specific current to each equal part of the capacity. Between two adjacent discharges, the battery 120 is left to rest for a certain period of time, e.g., more than 30 minutes. The final voltage value of the battery 120 after each rest is recorded. This process is repeated until the battery 120 is completely discharged.

[0129] In an environment of 25°C, battery 120 is first discharged at a discharge rate of 0.1C until its voltage equals 2.0V, denoted as 0% SOC. Battery 120 is then charged using the currents corresponding to the comparative examples, Examples 1, 2, and 3 shown in Table 3. During charging, the temperature and SOC of each battery cell 121 are collected. Charging is stopped when battery 120 reaches a cutoff voltage, for example, 4.1V; the capacity obtained at this point is the battery's charging capacity. After the temperature of battery 120 returns to 25°C, it is discharged using a current of 0.33C until its voltage equals 2.0V, yielding the discharge capacity of battery 120.

[0130] As shown in Table 4, in the comparative example, when battery 120 is charged at 0.33C to a SOC of 45%, the temperature of battery 120 can reach 28.0℃; in Example 1, the first charging current decreases as the SOC range increases, and when battery 120 is charged to a SOC of 45% using the first charging current, the temperature of battery 120 can reach 40.0℃; in Example 2, the first charging current decreases as the SOC range increases, and when battery 120 is charged to a SOC of 45% using the first charging current, the temperature of battery 120 can reach 35.5℃; in Example 3, the first charging current decreases as the SOC range increases, and when battery 120 is charged to a SOC of 45% using the first charging current, the temperature of battery 120 can reach 30.4℃.

[0131] Table 4

[0132]

[0133]

[0134] Therefore, when the first charging current is used to charge the battery 120 in Examples 1, 2 and 3, the temperature of the battery 120 is greater than 28°C in the comparative example when the SOC of the battery 120 reaches 45%. When the SOC of the battery 120 is less than or equal to 45%, the first charging current can effectively increase the temperature of the battery 120.

[0135] Furthermore, in Examples 1, 2, and 3, the first charging current corresponding to the same SOC range gradually decreases. Correspondingly, when the SOC of battery 120 is 45%, the temperature of battery 120 gradually decreases. Therefore, the larger the first charging current, the faster the temperature of battery 120 rises.

[0136] Furthermore, as shown in Table 4, the higher the SOC of battery 120 is at 45%, the higher its temperature, meaning the higher the temperature of battery 120 during charging after the SOC exceeds 45%, and the greater its charging and discharging capacity. In Examples 1, 2, and 3, the temperature reached by battery 120 at 45% SOC gradually decreases, resulting in a gradual decrease in both its charging and discharging capacity.

[0137] After reaching 45%, battery 120 reaches the charging platform corresponding to the Mn element in the LiMPO4 material. The delithiation rate of the positive electrode active material slows down in the charging platform stage corresponding to the Mn element. However, by increasing the temperature of battery 120 in this stage, it is beneficial to the delithiation of lithium ions and to the capacity utilization of battery 120.

[0138] This application also provides a charging method 200 for charging the battery 120. Method 200 can be executed, for example, by a battery management system 122. For example, as... Figure 3 As shown, method 200 includes some or all of the following steps.

[0139] In step 210, during at least a portion of the time when the SOC of the battery 120 is less than or equal to a preset SOC threshold, the battery 120 is controlled to charge based on a first charging current in order to heat the battery 120 during the charging process.

[0140] In step 220, during at least a portion of the time when the SOC of the battery 120 is greater than the SOC threshold, the battery 120 is controlled to charge based on a second charging current, wherein the first charging current is greater than the second charging current.

[0141] In some embodiments, the first charging current is configured to decrease based on an increase in the state of charge (SOC) of the battery 120.

[0142] In some embodiments, the range less than or equal to the SOC threshold includes multiple SOC intervals, each of which corresponds to a multiple current value of the first charging current. The charging method further includes: determining a target current value corresponding to the target SOC interval based on the correspondence between the multiple SOC intervals and the multiple current values, and the target SOC interval where the SOC of the battery 120 is located; wherein, in step 210, controlling the battery 120 to charge based on the first charging current includes: controlling the battery 120 to charge based on the target current value when the SOC of the battery 120 is located in the target SOC interval.

[0143] In some embodiments, the length of the SOC interval is between 3% and 10%.

[0144] In some embodiments, the current value corresponding to each of the plurality of SOC intervals is less than or equal to the maximum allowable charging current of the battery 120 corresponding to the largest SOC value in each SOC interval.

[0145] In some embodiments, the SOC threshold is determined based on the molar percentage of iron in the iron-manganese element of the positive electrode active material. For example, the SOC threshold is the product of the SOC of battery 120 in a fully charged state and the molar percentage.

[0146] In some embodiments, the second charging current is a constant current.

[0147] In some embodiments, the capacity of a single battery cell 120 is between 100 Ah and 300 Ah, or between 130 Ah and 250 Ah.

[0148] It is understood that the specific details of charging method 200 can be referred to in the aforementioned description of battery 120, and will not be repeated here for the sake of brevity.

[0149] In this embodiment, during the charging process of the battery management system 122, the battery management system 122 can send a charging command to the charging device 110. This charging command can carry information about the first charging current updated each time, instructing the charging device 110 to change the charging current. After receiving the charging command, the charging device 110 changes the magnitude of the charging current input to the battery 120, thereby regulating the charging current of the battery 120.

[0150] For example, such as Figure 4 The flowchart illustrates one possible implementation of the charging method 200. In step 201, the battery management system 122 obtains the SOC of the battery 120.

[0151] In step 202, when the SOC of battery 120 is less than or equal to a preset SOC threshold, the battery management system 122 sends a first charging command to the charging device 110.

[0152] The first charging command carries information about the first charging current.

[0153] In step 203, the charging device 110 receives the first charging command.

[0154] In step 204, the charging device 110 charges the battery 120 based on the first charging current according to the first charging command.

[0155] In step 205, if the SOC of battery 120 is greater than a preset SOC threshold, the battery management system 122 sends a second charging command to the charging device 110.

[0156] The second charging command carries information about the second charging current.

[0157] In step 206, the charging device 110 receives the second charging command.

[0158] In step 207, the charging device 110 charges the battery 120 based on the second charging current according to the second charging command.

[0159] Since the first charging currents corresponding to multiple SOCs are different, when the SOC is less than or equal to the preset SOC threshold, the first charging command needs to be updated every time the SOC of battery 120 passes through a SOC interval. The updated first charging command carries information about the first charging current corresponding to the SOC interval in which the current SOC is located. Figure 4 The example shown only covers a single SOC range, with the corresponding first charging command carrying the current value for that SOC range.

[0160] As can be seen from the above description, in this embodiment, when the SOC of battery 120 is less than or equal to a preset SOC threshold, the battery management system 122 controls battery 120 to charge based on a larger first charging current, increasing the temperature of battery 120 during charging until the SOC of battery 120 exceeds the SOC threshold. Then, the system controls battery 120 to charge based on a conventional second charging current. This SOC threshold can be determined based on the molar ratio of iron in the iron-manganese element of the positive electrode active material of battery 120. Thus, when entering the charging platform stage corresponding to Mn, the battery has a suitable temperature, which can increase the delithiation depth of the positive electrode active material LiMPO4, thereby increasing the battery's charging capacity and improving its charging performance. The range less than or equal to the SOC threshold includes multiple SOC intervals, each corresponding to a different current value of the first charging current. The battery management system 122 determines the target current value corresponding to the target SOC range based on the correspondence between multiple SOC ranges and multiple current values, as well as the target SOC range in which the battery 120's SOC is located. When the battery 120's SOC is within the target SOC range, the system controls the battery 120 to charge based on the corresponding target current value. Therefore, it can effectively reduce lithium plating and other issues caused by the charging current exceeding the maximum allowable charging current of the battery 120 during the charging process.

[0161] The embodiments of this application can be applied to various types of batteries, especially battery 120 which uses LiMPO4 material as the positive electrode active material, wherein M in LiMPO4 material may include Mn and Fe elements. The LiMPO4 material will be described in detail below.

[0162] As one way to realize LiMPO4 materials, LiMPO4 can be of the chemical formula LiMn 1-y Fe y Compounds of PO4, where y is any value in the range of 0.001 to 0.5.

[0163] With compound LiMn 0.80 Fe 0.20 Taking PO4 as an example, for the compound LiMn 0.80 Fe 0.20 The preparation method of PO4 will be described. This preparation method may include, for example, the following steps.

[0164] In step S1, Fe-doped manganese oxalate is prepared.

[0165] For example, 919.4 g of manganese carbonate and 231.7 g of ferrous carbonate can be added to a mixer and mixed thoroughly for 6 hours. The resulting mixture is then transferred to a reaction vessel, 5 L of deionized water and 1260.6 g of oxalic acid dihydrate are added, and the mixture is heated to 80°C and stirred thoroughly at 500 rpm for 6 hours to ensure homogeneity, until the reaction is terminated and no bubbles are generated, resulting in an Fe-doped manganese oxalate suspension. The suspension is then filtered, dried at 120°C, and milled to obtain ferric manganese oxalate particles with a particle size of 100 nm.

[0166] In step S2, LiMn is prepared. 0.80 Fe 0.20 PO4.

[0167] For example, the manganese iron oxalate (in C2O4Mn) prepared in step S1 can be taken. 0.80 Fe 0.20 1791.4 g (based on 2H₂O), 369.4 g of lithium carbonate, and 1150.1 g of ammonium dihydrogen phosphate were added to 20 L of deionized water and stirred thoroughly. The mixture was then uniformly mixed and reacted at 80 °C for 10 hours to obtain a slurry. This slurry was then transferred to a spray dryer for spray drying and granulation, and dried at 250 °C to obtain a powder. Under a protective atmosphere, such as 90% nitrogen and 10% hydrogen, the powder was sintered in a roller kiln at 700 °C for 4 hours.

[0168] As another way to realize LiMPO4 materials, LiMPO4 can be chemically formulated as Li 1+t Mn 1-c Fec P 1-z R z Compounds of O4, wherein t is any value in the range of -0.100 to 0.100, c is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, and R includes one or more elements selected from B, S, Si and N.

[0169] The values ​​of t, c, and z are configured to maintain the overall electroneutrality of the compound. Optionally, the ratio of c to 1-c can be from 1:10 to 1:1, and more preferably from 1:4 to 1:1, where c represents the sum of the stoichiometric coefficients of the Fe dopant elements at the Mn sites. Optionally, the ratio of z to 1-z can be from 1:9 to 1:999, and more preferably from 1:499 to 1:249, where z represents the sum of the stoichiometric coefficients of the R dopant elements at the P sites.

[0170] For example, compound Li 1+t Mn 1-c Fe c P 1-z R z The preparation method of O4 may include the following steps.

[0171] In step S1, the manganese source, iron source, and acid are dissolved and stirred in a solvent to generate a suspension of manganese salt doped with Fe. The suspension is filtered and the filter cake is dried to obtain manganese salt doped with Fe.

[0172] In step S2, the lithium source, phosphorus source, source of element R, solvent, and manganese salt doped with element Fe obtained from step S1 are added to the reaction vessel, ground and mixed to obtain a slurry.

[0173] In step S3, the slurry obtained in step S2 is transferred to a spray drying equipment for spray drying and granulation to obtain granules.

[0174] In step S4, the particles obtained in step S3 are sintered to obtain the positive electrode active material.

[0175] The manganese source is, for example, a manganese-containing substance that can be used to prepare lithium manganese phosphate, including but not limited to one or a combination of elemental manganese, manganese dioxide, manganese phosphate, manganese oxalate, and manganese carbonate. The iron source is, for example, at least one selected from elemental iron, its oxides, phosphates, oxalates, carbonates, and sulfates. The acid is, for example, one or more selected from hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and organic acids, such as oxalic acid. The source of element R is, for example, at least one selected from sulfates, borates, nitrates, and silicates of element R.

[0176] With compound Li 1.001 Mn0.999 Fe 0.001 P 0.999 Si 0.001 Taking O4 as an example, its preparation methods may include:

[0177] In step S1, Fe-doped manganese oxalate is prepared.

[0178] For example, 1148.2 g of manganese carbonate and 1.2 g of ferrous carbonate were added to a mixer and mixed thoroughly for 6 hours. The resulting mixture was then transferred to a reaction vessel, and 5 L of deionized water and 1260.6 g of oxalic acid dihydrate were added. The mixture was heated to 80°C and stirred thoroughly at 500 rpm for 6 hours to ensure homogeneity, until the reaction was terminated and no bubbles were generated, resulting in an Fe-doped manganese oxalate suspension. The suspension was then filtered, dried at 120°C, and milled to obtain ferric manganese oxalate particles with a particle size of 100 nm.

[0179] Step S2: Preparation of Li 1.001 Mn 0.999 Fe 0.001 P 0.999 Si 0.001 O4.

[0180] Take the manganese iron oxalate (in C2O4Mn) prepared in step S1 0.999 Fe 0.001 1789.6g (based on 2H₂O), 369.8g lithium carbonate, 1148.9g ammonium dihydrogen phosphate, and 0.8g silicic acid were added to 20L of deionized water and stirred thoroughly. The mixture was then uniformly mixed and reacted at 80°C for 10 hours to obtain a slurry. This slurry was then transferred to a spray dryer for spray drying and granulation at 250°C to obtain a powder. The powder was then sintered in a roller kiln at 700°C for 4 hours under a protective atmosphere, such as 90% nitrogen and 10% hydrogen.

[0181] As another way to realize LiMPO4 materials, LiMPO4 can be chemically formulated as Li 1+w C m Mn 1-u Fe u P 1-a R a O 4- n D nThe compound, wherein C includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; R includes one or more elements selected from B, S, Si, and N; D includes one or more elements selected from S, F, Cl, and Br; w is any value in the range of -0.100 to 0.100; u is any value in the range of 0.001 to 0.500; a is any value in the range of 0.001 to 0.100; n is any value in the range of 0.001 to 0.1; and m is any value in the range of 0.9 to 1.1.

[0182] Similarly, the values ​​of w, u, a, and m mentioned above are configured to keep the entire compound electrically neutral.

[0183] For example, compound Li 1+w C m Mn 1-u Fe u P 1-a R a O 4-n D n The preparation method may include the following steps.

[0184] In step S1, the manganese source, iron source, and acid are dissolved and stirred in a solvent to generate a suspension of manganese salt doped with Fe. The suspension is filtered and the filter cake is dried to obtain manganese salt doped with Fe.

[0185] In step S2, the lithium source, phosphorus source, source of element C, source of element R and source of element D, solvent, and manganese salt doped with element Fe obtained from step S1 are added to the reaction vessel, ground and mixed to obtain a slurry.

[0186] In step S3, the slurry obtained in step S2 is transferred to a spray drying equipment for spray drying and granulation to obtain granules.

[0187] In step S4, the particles obtained in step S3 are sintered to obtain the positive electrode active material.

[0188] The source of element C is selected from at least one of elemental C, its oxide, phosphate, oxalate, carbonate, and sulfate. The source of manganese is, for example, a manganese-containing substance that can be used to prepare lithium manganese phosphate, including but not limited to elemental manganese, manganese dioxide, manganese phosphate, manganese oxalate, manganese carbonate, or a combination thereof. The source of iron is selected from at least one of elemental iron, its oxide, phosphate, oxalate, carbonate, and sulfate. The source of acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and organic acids, for example, oxalic acid. The source of element R is selected from at least one of elemental R's sulfate, borate, nitrate, and silicate. The source of element D is selected from at least one of elemental D and its ammonium salt.

[0189] For positive electrode active materials, Li may be present. 1+w C m Mn 1-u Fe u P 1-a R a O 4-n D nIn this case, the value of x is affected by the valence states of Fe and R, as well as the values ​​of y and z, to ensure the overall system is electrically neutral. If the value of x is too small, the lithium content of the entire system will decrease, affecting the specific capacity of the material. The value of y limits the total amount of all doping elements. If y is too small, i.e., the doping amount is too low, the doping elements will not play a role. If y exceeds 0.5, the Mn content in the system will be low, affecting the voltage plateau of the material. The R element is doped at the P position. Since PO tetrahedra are relatively stable, and a large z value will affect the stability of the material, the value of a is limited to 0.001 to 0.100. More specifically, w is any value in the range of -0.100 to 0.100, u is any value in the range of 0.001 to 0.500, a is any value in the range of 0.001 to 0.100, n is any value in the range of 0.001 to 0.1, and m is any value in the range of 0.9 to 1.1. For example, 1+x is selected from the range of 0.9 to 1.1, such as 0.97, 0.977, 0.984, 0.988, 0.99, 0.991, 0.992, 0.993, 0.994, 0.995, 0.996, 0.997, 0.998, 1.01; x is selected from the range of 0.001 to 0.1, such as 0.001, 0.005; and y is selected from the range of 0.001 to 0.5, such as 0.001. The values ​​are 0.005, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.34, 0.345, 0.349, 0.35, and 0.4, where z is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, and 0.1, and n is selected from the range of 0.001 to 0.1, for example, 0.001, 0.005, 0.08, and 0.1, and the positive electrode active material is electrically neutral.

[0190] Unless otherwise stated, in the above chemical formulas, when a doping site contains two or more elements, the limitations on the numerical ranges of w, u, a, or m are not only limitations on the stoichiometric coefficient of each element serving as that site, but also limitations on the sum of the stoichiometric coefficients of all elements serving as that site. For example, in a site with the chemical formula Li 1+w Mn 1- u Fe u P 1-a R aIn the case of O4 compounds, if R consists of two or more elements R1, R2, ..., Rn, the stoichiometric coefficients z1, z2, ..., zn of each element must fall within the numerical range of z defined in this application, and the sum of z1, z2, ..., zn must also fall within this numerical range. Similarly, for the case where C consists of two or more elements, the limitation on the numerical range of the stoichiometric coefficients of C has the same meaning.

[0191] This application also provides a battery management system 122 for performing a charging method 200 for the battery 120 described in any of the above embodiments. The battery 120 includes at least one battery cell 121, and the positive electrode active material of the battery cell 121 includes LiMPO4, wherein M includes Mn and Fe elements.

[0192] This application also provides an electrical device, including the battery 120 described in any of the above embodiments, the battery 120 being used to provide power to the electrical device.

[0193] The electrical equipment can be, for example, mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, electric vehicles, ships, and spacecraft, such as airplanes, rockets, space shuttles, and spacecraft.

[0194] As an example, such as Figure 5 The diagram shown is a structural schematic of a vehicle 1 according to one embodiment of this application. Vehicle 1 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A motor 30, a controller 20, and a battery 120 can be installed inside vehicle 1. The controller 20 controls the battery 120 to supply power to the motor 30. For example, the battery 120 can be installed at the bottom, front, or rear of vehicle 1. The battery 120 can be used to power vehicle 1. For example, the battery 120 can serve as the operating power source for vehicle 1, for example, for the electrical system of vehicle 1, such as for the power requirements of vehicle 1's starting, navigation, and operation. In another embodiment of this application, the battery 120 can not only serve as the operating power source for vehicle 1, but also as the driving power source for vehicle 1, replacing or partially replacing gasoline or natural gas to provide driving power for vehicle 1.

[0195] This application also provides a computer-readable storage medium for storing a computer program that, when executed by a computing device, causes the computing device to implement the method performed by the battery management system 122 in any of the above embodiments. Optionally, the computer program may be the computer program in the battery management system 122 described above.

[0196] It should be noted that, without conflict, the various embodiments and / or technical features described in this application can be arbitrarily combined with each other, and the resulting technical solutions should also fall within the protection scope of this application.

[0197] In the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0198] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0199] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and 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 through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0200] 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.

[0201] The various implementation methods described in this specification can be implemented individually or in combination, and the embodiments of this application are not limited in this respect.

[0202] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery, characterized in that, include: At least one battery cell, wherein the positive electrode active material of the battery cell comprises LiMPO4, wherein M comprises Mn and Fe elements; and, Battery management system, used for: During at least a portion of the time when the SOC of the battery is less than or equal to a preset SOC threshold, the battery is controlled to be charged based on a first charging current in order to heat the battery during the charging process. as well as, During at least a portion of the time when the SOC of the battery is greater than the SOC threshold, the battery is controlled to be charged based on a second charging current, wherein the first charging current is greater than the second charging current. The SOC threshold is determined based on the molar percentage of iron in the iron-manganese element of the positive electrode active material. The molar percentage of iron is equal to the ratio between the molar content of iron and a first content, where the first content is the total molar content of iron and manganese.

2. The battery according to claim 1, characterized in that, The first charging current is configured to decrease based on the increase of the battery's state of charge (SOC).

3. The battery according to claim 1 or 2, characterized in that, The range less than or equal to the SOC threshold includes multiple SOC intervals, each corresponding to a different current value of the first charging current. The battery management system is specifically used for... Based on the correspondence between the multiple SOC intervals and the multiple current values, and the target SOC interval in which the battery's SOC is located, determine the target current value corresponding to the target SOC interval; When the battery's SOC is within the target SOC range, the battery is controlled to charge based on the target current value.

4. The battery according to claim 3, characterized in that, The length of the SOC interval is between 3% and 10%.

5. The battery according to claim 3, characterized in that, The current value corresponding to each of the plurality of SOC intervals is less than or equal to the maximum allowable charging current of the battery corresponding to the largest SOC value in each SOC interval.

6. The battery according to claim 1 or 2, characterized in that, The SOC threshold is the product of the SOC of the battery in a fully charged state and the molar percentage.

7. The battery according to claim 1 or 2, characterized in that, The second charging current is a constant current.

8. The battery according to claim 1 or 2, characterized in that, The capacity of the individual battery cells is between 100Ah and 300Ah.

9. The battery according to claim 1 or 2, characterized in that, The positive electrode active material includes at least one of the following materials: LiMn 1-y Fe y PO4, where y is any value in the range of 0.001 to 0.5; Li 1+t Mn 1-c Fe c P 1-z R z O4, where t is any value in the range of -0.100 to 0.100, c is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, and R includes one or more elements selected from B, S, Si and N; Li 1+w C m Mn 1-u Fe u P 1-a R a O 4-n D n Wherein, C includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; R includes one or more elements selected from B, S, Si and N; D includes one or more elements selected from S, F, Cl and Br; w is any value in the range of -0.100 to 0.100; u is any value in the range of 0.001 to 0.500; a is any value in the range of 0.001 to 0.100; n is any value in the range of 0.001 to 0.1; and m is any value in the range of 0.9 to 1.

1.

10. A method for charging a battery, characterized in that, The battery includes at least one battery cell, the positive electrode active material of the battery cell includes LiMPO4, wherein M includes Mn and Fe elements, and the charging method includes: During at least a portion of the time when the SOC of the battery is less than or equal to a preset SOC threshold, the battery is controlled to be charged based on a first charging current in order to heat the battery during the charging process. During at least a portion of the time when the SOC of the battery is greater than the SOC threshold, the battery is controlled to be charged based on a second charging current, wherein the first charging current is greater than the second charging current. The SOC threshold is determined based on the molar percentage of iron in the iron-manganese element of the positive electrode active material. The molar percentage of iron is equal to the ratio between the molar content of iron and a first content, where the first content is the total molar content of iron and manganese.

11. The charging method according to claim 10, characterized in that, The first charging current is configured to decrease based on the increase of the battery's state of charge (SOC).

12. The charging method according to claim 10 or 11, characterized in that, The range less than or equal to the SOC threshold includes multiple SOC intervals, each corresponding to a multiple current value of the first charging current. The charging method further includes: Based on the correspondence between the multiple SOC intervals and the multiple current values, and the target SOC interval in which the battery's SOC is located, determine the target current value corresponding to the target SOC interval; The control of charging the battery based on the first charging current includes: When the battery's SOC is within the target SOC range, the battery is controlled to charge based on the target current value.

13. The charging method according to claim 12, characterized in that, The length of the SOC interval is between 3% and 10%.

14. The charging method according to claim 12, characterized in that, The current value corresponding to each of the plurality of SOC intervals is less than or equal to the maximum allowable charging current of the battery corresponding to the largest SOC value in each SOC interval.

15. The charging method according to claim 10 or 11, characterized in that, The SOC threshold is the product of the SOC of the battery in a fully charged state and the molar percentage.

16. The charging method according to claim 10 or 11, characterized in that, The second charging current is a constant current.

17. The charging method according to claim 10 or 11, characterized in that, The capacity of the individual battery cells is between 100Ah and 300Ah.

18. The charging method according to claim 10 or 11, characterized in that, The positive electrode active material includes at least one of the following materials: LiMn 1-y Fe y PO4, where y is any value in the range of 0.001 to 0.5; Li 1+t Mn 1-c Fe c P 1-z R z O4, where t is any value in the range of -0.100 to 0.100, c is any value in the range of 0.001 to 0.500, z is any value in the range of 0.001 to 0.100, and R includes one or more elements selected from B, S, Si and N; Li 1+w C m Mn 1-u Fe u P 1-a R a O 4-n D n Wherein, C includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo and W; R includes one or more elements selected from B, S, Si and N; D includes one or more elements selected from S, F, Cl and Br; w is any value in the range of -0.100 to 0.100; u is any value in the range of 0.001 to 0.500; a is any value in the range of 0.001 to 0.100; n is any value in the range of 0.001 to 0.1; and m is any value in the range of 0.9 to 1.

1.

19. A battery management system, characterized in that, A method for performing a charging of a battery according to any one of claims 10 to 18, the battery comprising at least one battery cell, the positive electrode active material of the battery cell comprising LiMPO4, wherein M comprises Mn and Fe elements.

20. An electrical appliance, characterized in that, Includes the battery according to any one of claims 1 to 9.

21. A computer-readable storage medium, characterized in that, Used to store a computer program, which, when executed by a computing device, causes the computing device to implement the charging method of the battery according to any one of claims 10 to 18.

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