CN116315171A

CN116315171A - Method for prolonging service life of battery cell, battery management system, battery pack and electric equipment

Info

Publication number: CN116315171A
Application number: CN202310132258.6A
Authority: CN
Inventors: 蔡阳声
Original assignee: Xiamen Xinneng'an Technology Co ltd
Current assignee: Xiamen Xinneng'an Technology Co ltd
Priority date: 2023-02-17
Filing date: 2023-02-17
Publication date: 2023-06-23

Abstract

The application discloses a method for prolonging service life of a battery cell, a battery management system, a battery pack and electric equipment. Relates to the technical field of batteries. The method for prolonging the service life of the battery cell comprises the following steps: receiving the health state value and the delivery time of the battery cell; and controlling the upper voltage of the battery cell to be less than or equal to the first voltage threshold in response to the health status value being less than or equal to the first capacity threshold, or in response to the factory time being greater than or equal to the first time threshold. Through the mode, the service life of the battery cell can be prolonged.

Description

Method for prolonging service life of battery cell, battery management system, battery pack and electric equipment

Technical Field

The application relates to the technical field of batteries, in particular to a method for prolonging service life of a battery cell, a battery management system, a battery pack and electric equipment.

Background

The lithium iron manganese phosphate (LFMP) system is a new lithium battery system currently in the industry and has a higher energy density than the traditional lithium iron phosphate system, so the lithium iron manganese phosphate (LFMP) system is also a new system which is recently paid close attention.

Wherein the higher energy density of the lithium iron phosphate system compared to the lithium iron phosphate system is mainly derived from Mn ²⁺ /Mn ³⁺ Phase change reaction of (a).

Disclosure of Invention

The application aims to provide a method for prolonging service life of a battery cell, a battery management system, a battery pack and electric equipment, and the service life of the battery cell can be prolonged.

To achieve the above object, in a first aspect, the present application provides a method for prolonging a lifetime of a battery cell, including: receiving the health state value and the delivery time of the battery cell; and controlling the upper voltage of the battery cell to be less than or equal to the first voltage threshold in response to the health status value being less than or equal to the first capacity threshold, or in response to the factory time being greater than or equal to the first time threshold.

And when the health state value or the delivery time of the battery cell meets a certain condition, limiting the upper limit voltage of the battery cell. The probability of disproportionation reaction of Mn ions can be reduced, so that the dissolved Mn ions are reduced, the gas production risk of the battery cell is further reduced, and the service life of the battery cell is prolonged.

In an alternative mode, the battery cell adopts lithium manganese iron phosphate as cathode material, and the method further comprises: the first capacity threshold, the first time threshold, and the first voltage threshold are determined based on a first metering ratio of manganese ions in lithium iron manganese phosphate. Wherein the first metering ratio is a ratio between the number of manganese ions and the sum of the number of manganese ions and the number of iron ions.

In an alternative manner, the first capacity threshold, the first time threshold, and the first voltage threshold are determined based on a first metering ratio of manganese ions in lithium manganese phosphate, and at least any of the following conditions is satisfied: (i) The first capacity threshold exhibits a positive correlation with the first metering ratio. (ii) The first time threshold exhibits a negative correlation with the first metric. (iii) The first voltage threshold exhibits a positive correlation with the first metering ratio.

In an alternative manner, determining the first capacity threshold, the first time threshold, and the first voltage threshold based on the first metering ratio of manganese ions in the lithium manganese iron phosphate includes: determining a first capacity threshold based on a first metering ratio, a preset metering ratio and a first preset capacity threshold, wherein the preset metering ratio is a ratio between the number of manganese ions in preset lithium iron manganese phosphate and the sum of the number of manganese ions and the number of iron ions, and the first preset capacity threshold is a preset first capacity threshold; and/or determining a first time threshold based on the first metering ratio, the preset metering ratio and a first preset time threshold, wherein the preset metering ratio is the ratio of the number of manganese ions in the preset lithium iron manganese phosphate to the sum of the number of manganese ions and the number of iron ions, and the first preset time threshold is the preset first time threshold; and/or determining a first voltage threshold based on the first metering ratio, a preset metering ratio and a first preset voltage threshold, wherein the preset metering ratio is a ratio between the number of manganese ions in the preset lithium iron manganese phosphate and the sum of the number of manganese ions and the number of iron ions, and the first preset voltage threshold is the preset first voltage threshold.

In an alternative, the first predetermined voltage threshold is Fe in the cell ²⁺ Conversion to Fe by phase transition reaction ³⁺ Voltage at that time.

In an alternative, the first preset capacity threshold is 70%, the first preset time threshold is 5 years, and the first preset voltage threshold is 3.4V when the preset metering ratio is 0.7.

In an alternative manner, determining the first capacity threshold based on the first metering ratio, the preset metering ratio, and the first preset capacity threshold includes: if the first metering ratio is larger than the preset metering ratio, determining that the first capacity threshold is equal to a second preset capacity threshold, wherein the second preset capacity threshold is a preset first capacity threshold, and 1 is larger than the second preset capacity threshold and larger than the first preset capacity threshold; if the first metering ratio is smaller than or equal to the preset metering ratio, the first capacity threshold value is determined to be equal to the first preset capacity threshold value.

In an alternative, if the first preset capacity threshold is 70%, the second preset capacity threshold is 80%.

In an alternative manner, determining the first time threshold based on the first metering ratio, the preset metering ratio, and the first preset time threshold includes: determining a first time length threshold as: t=k1- (Y1-K2) 10. Wherein t is a first time threshold, K1 is a first preset time threshold, K2 is a preset metering ratio, and Y1 is a first metering ratio.

In an alternative manner, determining the first voltage threshold based on the first metering ratio, the preset metering ratio, and the first preset voltage threshold includes: determining a first voltage threshold as: v1=k3+ (Y2-K4). Wherein V1 is a first voltage threshold, K3 is a first preset voltage threshold, Y2 is a first metering ratio, and K4 is a preset metering ratio.

In a second aspect, the present application provides a battery management system comprising: at least one processor and a memory communicatively coupled to the at least one processor, the memory storing instructions executable by the at least one processor to enable the at least one processor to perform the method of the first aspect.

In a third aspect, the present application provides a battery pack comprising: the battery and the battery management system in the second aspect. The battery includes at least one cell.

In a fourth aspect, the present application provides a powered device comprising a load and a battery pack of the third aspect. The battery pack is used for supplying power to the load.

In a fifth aspect, the present application provides a non-transitory computer-readable storage medium storing computer-executable instructions that, when executed by a processor, cause the processor to perform the method of the first aspect.

The beneficial effects of this application are: the method for prolonging the service life of the battery cell realizes that the upper limit voltage of the battery cell is limited when the health state value or the delivery time of the battery cell meets certain conditions. Aiming at the fact that the battery system is a lithium iron manganese phosphate system, the probability of disproportionation reaction of Mn ions can be reduced by limiting the upper limit voltage of the battery cell, so that dissolved Mn ions are reduced, the risk of generating gas by the battery cell is reduced, and the service life of the battery cell is prolonged.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which the figures of the drawings are not to be taken in a limiting sense, unless otherwise indicated.

Fig. 1 is a schematic structural view of a battery pack according to an embodiment of the present disclosure;

FIG. 2 is a flow chart of a method for extending the lifetime of a battery cell according to an embodiment of the present application;

FIG. 3 is a flow chart of a method for extending the life of a battery cell when the battery cell uses lithium iron manganese phosphate as the cathode material according to an embodiment of the present application;

FIG. 4 is a schematic diagram of an open circuit voltage of a battery cell in a full SOC according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of an implementation of step 31 shown in FIG. 3 provided in an example of the present application;

FIG. 6 is a schematic diagram of an implementation of step 51 shown in FIG. 5 provided in an example of the present application;

FIG. 7 is a schematic diagram of an implementation of step 52 shown in FIG. 5 provided in an example of the present application;

FIG. 8 is a schematic diagram of an implementation of step 53 shown in FIG. 5 provided in an example of the present application;

fig. 9 is a schematic structural diagram of an electric device according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be described in detail below with reference to the accompanying drawings in the embodiments of the present application. The following examples are illustrative and not limiting, are intended to provide a basic understanding of the present application, and are not intended to identify key or critical elements of the application or to delineate the scope of the protection.

It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present therebetween.

In addition, technical features which are described below and which are involved in the various embodiments of the present application may be combined with each other without constituting a conflict.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a battery pack 1000 according to an embodiment of the present disclosure. The battery pack 1000 includes the battery management system 100 and the battery 200. The elements can be connected through a bus or directly.

The battery 200 is used to store and provide electrical energy. The battery 200 includes at least one cell 202 (only one shown). When the battery 200 includes more than two cells 202, each cell 202 may be connected in series, in parallel, or in a hybrid of series and parallel. In some embodiments, battery 200 is a rechargeable battery. For example, the battery 200 may be a lead-acid battery, a nickel-cadmium battery, a nickel-hydrogen battery, a lithium ion battery, a lithium polymer battery, a lithium iron phosphate battery, or the like. The battery 200 may be repeatedly charged in a recyclable manner.

In some embodiments, the cell 202 has a lithium iron manganese phosphate (LFMP) material as the cathode host material. The cell 202 includes a positive electrode sheet, a negative electrode sheet, an isolating film, and an electrolyte.

In this embodiment, the preparation process of the positive electrode sheet is as follows: lithium iron manganese phosphate (LFMP), conductive carbon black (Super P) and polyvinylidene fluoride (PVDF) are mixed according to the weight ratio of 97.5:1.0:1.5, N-methyl pyrrolidone (NMP) is added as a solvent, and the mixture is prepared into slurry with the solid content of 0.75, and the slurry is uniformly stirred. Uniformly coating the slurry on aluminum foil with the thickness of 12 mu m, wherein the weight of positive electrode active substance on the pole piece is 180g/m ² . Drying at 90 ℃ to finish the single-sided coating of the positive electrode plate, and then finishing the coating of the other side by the same method. After the coating was completed, the positive electrode active material layer of the pole piece was cold-pressed to 4.1g/cm ³ And then auxiliary processes such as tab welding, gummed paper and the like are carried out to complete the whole preparation process of the double-sided coated positive plate.

The preparation process of the negative electrode plate comprises the following steps: mixing negative electrode active material Graphite (Graphite), conductive carbon black (Super P) and Styrene Butadiene Rubber (SBR) according to the weight ratio of 96:1.5:2.5, and adding deionized water (H) ₂ O) was used as a solvent, and the slurry was prepared to have a solid content of 0.7, and stirred uniformly. Uniformly coating the slurry on a copper foil with the thickness of 8 mu m, wherein the weight of negative electrode active substances on a pole piece is 95g/m ² . Drying at 110 ℃ to finish the single-sided coating of the negative electrode plate of the electrode plate, and then finishing the coating of the other side by the same method. After the coating was completed, the negative electrode active material layer of the pole piece was cold-pressed to 1.7g/cm ³ Is a compact density of (a). And then auxiliary processes such as tab welding and gummed paper pasting are carried out, so that all preparation processes of the double-sided coated negative electrode plate are completed.

The preparation process of the electrolyte is as follows: in a dry argon atmosphere, the organic solvents Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in mass ratio EC: EMC: dec=30:50:20, and then lithium salt lithium hexafluorophosphate (LiPF) was added to the organic solvent ₆ ) Dissolving and mixing uniformly to obtain the electrolyte with the lithium salt concentration of 1.15M.

The preparation process of the cell 202 is as follows: polyethylene (PE) with thickness of 15 μm is selected as a base film of the isolating film and is coated with a ceramic coating (2 μm) and a polymer coating (2.5 mg/1540.25 mm) ² ) And fixing the prepared positive pole piece and isolating film on a structure formed by the negative pole piece, and stacking and winding the positive pole piece and the isolating film into a bare cell according to the sequence. After top sealing and side sealing, the battery cell is injected with liquid, and the battery cell after the injection is formed (for example, the battery cell is charged to 3.3V by 0.02C constant current and then charged to 3.6V by 0.1C constant current), so that the active substance of the battery cell is activated, and finally the battery cell 202 is obtained.

It should be noted that the foregoing illustrates only one preparation process of the battery cell 202, and in other embodiments, the preparation may be performed in other manners, which is not limited herein.

The battery management system (Battery Management System, BMS) 100 is used for detecting, managing, and/or protecting the battery 200, etc. In some embodiments, the BMS100 is configured to obtain a State of Health (SOH) value and a factory time of the battery 202.

The SOH of the battery cell 202 may be a ratio of a performance parameter to a nominal parameter of the battery cell 202 after a period of use, where the SOH of the new battery cell is 100% and the SOH of the completely scrapped battery cell is 0%. The internal resistance of the cell 202 has a certain relationship with SOH. The lower the SOH, the greater the internal resistance of the cell 202. In some embodiments, the BMS100 can collect data such as voltage, current, temperature, etc. of the battery cell 202, and indirectly calculate the internal resistance value of the battery cell 202 according to the data, and then calculate SOH according to the relationship between SOH and the internal resistance of the battery cell 202.

Of course, in other embodiments, other calculation methods may be used to obtain SOH. For example, the BMS100 employs a mechanism modeling of electrochemical reactions occurring inside the battery cell 202, i.e., modeling specific physical and chemical reactions inside the battery cell 202 during charge and discharge, and estimating SOH of the battery cell 202 on the basis of an electrochemical model.

The factory time of the battery cell 202 may also be the date of manufacture of the battery cell 202. In some embodiments, the BMS100 can directly read the factory time of the battery cells 202 from the production data of the battery cells 202.

The battery management system 100 includes at least one processor 104 and a memory 102, where the memory 102 may be built in the battery management system 100, or may be external to the battery management system 100, and the memory 102 may be a remote memory, and connected to the battery management system 100 through a network.

The memory 102 is used as a non-volatile computer-readable storage medium for storing non-volatile software programs, non-volatile computer-executable programs, and modules. The memory 102 may include a storage program area that may store an operating system, at least one application program required for functions, and a storage data area; the storage data area may store data created according to the use of the terminal, etc. In addition, memory 102 may include high-speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 102 may optionally include memory located remotely from processor 104, which may be connected to the terminal via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

The processor 104 performs various functions of the terminal and processes the data by running or executing software programs and/or modules stored in the memory 102 and invoking the data stored in the memory 102, thereby performing overall monitoring of the terminal, such as implementing the method of extending the lifetime of the battery cells in any of the embodiments of the present application.

The number of processors 104 may be one or more, one processor 104 being illustrated in fig. 1. The processor 104 and the memory 102 may be connected by a bus or other means. The processor 104 may include a Central Processing Unit (CPU), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a controller, a Field Programmable Gate Array (FPGA) device, or the like. The processor 104 may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

Referring to fig. 2, fig. 2 is a flowchart of a method for prolonging the lifetime of a battery cell according to an embodiment of the present application. As shown in fig. 2, the method for prolonging the service life of the battery cell comprises the following steps:

step 21: and receiving the health state value and the delivery time of the battery cell.

Step 22: and controlling the upper voltage of the battery cell to be less than or equal to the first voltage threshold in response to the health status value being less than or equal to the first capacity threshold, or in response to the factory time being greater than or equal to the first time threshold.

The first capacity threshold is a preset capacity threshold, which may be set according to an actual application situation, which is not specifically limited in the embodiment of the present application. When the health state value of the battery core is smaller than or equal to the first capacity threshold value, the corresponding battery core is subjected to multiple charge and discharge processes, and the current rated capacity of the battery core is smaller than the initial rated capacity of the battery core. And, the smaller the first capacity threshold is set, the more the corresponding battery cell has completed the charging and discharging process, the smaller the current rated capacity of the battery cell. In this case, by limiting the upper limit voltage of the battery cell, the risk of gas generation due to an excessively high voltage of the battery cell can be reduced. The upper limit voltage is the maximum voltage of the battery cell for charging and discharging. That is, when it is determined that the voltage of the battery cell is charged to be equal to the upper limit voltage, the charging of the battery cell should be stopped to reduce the risk of abnormal gas production of the battery cell, thereby prolonging the service life of the battery cell.

The first time threshold is a preset capacity threshold, which can be set according to practical application conditions, and the embodiment of the application is not particularly limited. When the factory time of the battery cell is greater than or equal to the first time threshold, the battery cell may be in a rest state, and/or a use state. The static state means that the battery cell does not perform a charging and discharging process, but the current rated capacity of the battery cell is smaller than the initial rated capacity of the battery cell due to self-discharging of the battery cell; the usage state refers to that the battery cell has been subjected to an overcharging process and/or a discharging process, and the current rated capacity of the battery cell is also caused to be smaller than the initial rated capacity of the battery cell. And, the larger the first time threshold is set, the smaller the current rated capacity of the corresponding battery cell. At this time, by limiting the upper limit voltage of the battery cell, the risk of gas generation caused by the excessively high voltage of the battery cell can be reduced, so as to prolong the service life of the battery cell.

The first voltage threshold is a preset voltage threshold, which may be set according to practical application conditions, which is not specifically limited in the embodiments of the present application. The first voltage threshold is the maximum value of the upper limit voltage, and the smaller the first voltage threshold is set, the smaller the maximum value of the upper limit voltage, and the lower the risk of gas generation caused by the over-high voltage of the battery cell.

In one embodiment, as shown in fig. 3, when the battery cell uses lithium manganese iron phosphate as the cathode material, the method for prolonging the service life of the battery cell further comprises the following steps:

step 31: a first capacity threshold, a first time threshold, and a first voltage threshold are determined based on a first metering ratio of manganese ions in lithium iron manganese phosphate.

Wherein the first metering ratio is a ratio between the number of manganese ions and the sum of the number of manganese ions and the number of iron ions.

In this embodiment, for a cell in which the cathode chemistry system is an LFMP system, the LFMP system has Mn present ²⁺ /Mn ³⁺ Phase change reaction of (a). The phase change reaction can cause the stability of the material to be poor, and the disproportionation reaction of Mn ions can be deteriorated under the high-voltage condition, so that the Mn ions dissolved out by the disproportionation reaction attack the cell anode and cause the cell gas production risk, and further the service life of the cell is influenced.

LFMP material is used as LiMn _0.7 Fe _0.3 PO ₄ As an example. Referring to FIG. 4, the reference to FIG. 4 is an exemplary illustration of LiMn _0.7 Fe _0.3 PO ₄ The system is used as yinSchematic of open circuit voltage (Open circuit voltage, OCV) of a cell of a pole material at full State of Charge (SOC). The SOC is the ratio of the remaining capacity to the battery capacity, and is commonly expressed as a percentage. The SOC ranges from 0 to 100%, and indicates that the battery is completely discharged when soc=0 and that the battery is completely charged when soc=100%. Full SOC refers to SOC from 0-100%. OCV refers to the potential difference between the poles of a cell when the cell is not discharging.

As shown in fig. 4, the abscissa is SOC and the ordinate is OCV. Curve L1 is LiMn _0.7 Fe _0.3 PO ₄ OCV curve of battery cell of system as cathode material under full SOC. Mn at an OCV of about 3.9V ²⁺ Conversion to Mn by phase transition reaction ³⁺ . Mn when the voltage of the battery cell is greater than or equal to 3.9V ²⁺ /Mn ³⁺ Mn is easy to dissolve out due to disproportionation effect, mn attacks SEI (solid electrolyte interface film) to cause side reaction of anode and electrolyte to produce gas, and further the service life of the battery cell is shortened. It can be seen that the cell gassing is related to the Mn ions in the LFMP system.

Second, another phase change reaction occurs in the LFMP system. With continued reference to FIG. 4, when the OCV is about 3.4V, the corresponding Fe ²⁺ Conversion to Fe by phase transition reaction ³⁺ . The phase change reaction occurs with a corresponding OCV less than Mn ²⁺ Conversion to Mn by phase transition reaction ³⁺ The corresponding OCV occurs. Based on this, fe can be ²⁺ Conversion to Fe by phase transition reaction ³⁺ The corresponding OCV is used as the basis for controlling the upper limit voltage of the battery cell to more effectively reduce Mn ²⁺ Conversion to Mn by phase transition reaction ³⁺ Thereby reducing the risk of gas generation caused by the attack of dissolved Mn ions on the anode of the battery cell and being beneficial to prolonging the service life of the battery cell.

In conclusion, the cell generates gas production and is related to Mn ions and Fe ions in LFMP. Based on the first metering ratio, namely the ratio between the number of Mn ions and the sum of the number of Mn ions and the number of Fe ions, whether the battery cell generates production gas or not can be accurately judged. Furthermore, the first capacity threshold, the first time threshold and the first voltage threshold are determined based on the first metering ratio, so that the upper limit voltage of the battery cell can be controlled within a proper range, and the battery cell can be kept to have higher charge and discharge voltage on the basis of reducing the risk of generating gas by the battery cell.

In this embodiment, if the LFMP material is LiMn _0.7 Fe _0.3 PO ₄ The metering ratio for the number of Mn ions is 0.7 and the metering ratio for the number of Fe ions is 0.3, so the ratio between the number of Mn ions and the sum of the number of Mn ions and Fe ions is 0.7/(0.3+0.7) =0.7, i.e., the first metering ratio is 0.7.

In one embodiment, the first capacity threshold, the first time threshold, and the first voltage threshold are determined in step 31 based on the first measurement ratio of manganese ions in lithium manganese phosphate, and at least one of the following three conditions is satisfied: the first condition is that the first capacity threshold exhibits a positive correlation with the first metering ratio. The second condition is that the first time threshold and the first metering ratio show a negative correlation. The third condition is that the first voltage threshold exhibits a positive correlation with the first metering ratio.

In LFMP materials, the ratio of Mn ions to Fe ions has a large impact on the stability of the material. The method is characterized in that in different LFMP systems, the ratio of Mn ions to Fe ions is different, and the gas production resistance of each LFMP system is also different. The higher the Mn ion proportion, namely the higher the Mn ion content, the weaker the gas production resistance of the LFMP system, and the more easily the battery cell generates gas; conversely, the lower the Mn ion proportion, i.e. the lower the Mn ion content, the stronger the gas production resistance of the LFMP system, and the more difficult the cell is to produce gas.

If the battery cell is more prone to generate gas, the upper limit voltage of the battery cell should be limited earlier, and the first capacity threshold value should be set to be larger or the first time threshold value should be set to be smaller correspondingly, so that the risk of generating gas of the battery cell is reduced. Conversely, if the more difficult it is to generate gas, the later the upper voltage of the cell should be limited, the smaller the first capacity threshold should be set or the larger the first time threshold should be set.

Next, in this embodiment, the ratio of the size of the first metering ratio to the Mn ion is taken as an example. The larger the first metering ratio is, the higher the proportion of Mn ions is; the smaller the first metering ratio, the lower the proportion of Mn ions. In other embodiments, other parameters may be used corresponding to the ratio of Mn ions, which is not particularly limited in the embodiments of the present application. For example, in some embodiments, the ratio of the number of Mn ions to the number of Fe ions (denoted as the second metering ratio) is used as a parameter corresponding to the ratio of Mn ions. Wherein the larger the second metering ratio is, the higher the proportion of Mn ions is; the smaller the second metering ratio, the lower the proportion of Mn ions.

In summary, the larger the first metering ratio is, the higher the Mn ion content is, the more easily the battery cell is producing gas, and the larger the first capacity threshold value is set or the smaller the first time threshold value is set correspondingly; the smaller the first metering ratio, the lower the Mn ion content, the more difficult the cell is to produce gas, and the smaller the first capacity threshold should be set or the larger the first time threshold should be set. That is, the first capacity threshold and the first metering ratio exhibit a positive correlation, and the first time threshold and the first metering ratio exhibit a negative correlation.

In another embodiment, as shown in fig. 5, the process of determining the first capacity threshold, the first time threshold and the first voltage threshold in step 31 based on the first metering ratio of manganese ions in the lithium iron manganese phosphate includes the following steps:

step 51: the first capacity threshold is determined based on the first metering ratio, the preset metering ratio, and the first preset capacity threshold.

The preset metering ratio is the ratio of the number of manganese ions in the preset lithium iron manganese phosphate to the sum of the number of manganese ions and the number of iron ions, and is also the reference metering ratio.

For example, in one embodiment, LFMP material is LiMn _0.7 Fe _0.3 PO ₄ The parameters are used as references for setting the parameters in other LFMP materials. In this embodiment, the preset metering ratio is 0.7/(0.7+0.3) =0.7. At the same time, for LiMn _0.7 Fe _0.3 PO ₄ The cells used as cathode materials are tested or otherwise empirically determined to determine a first capacity threshold to be set for the cell, which may be a preset first capacity threshold, i.eIs a first preset capacity threshold. In some embodiments, for LiMn _0.7 Fe _0.3 PO ₄ As the cell of the cathode material, the first preset capacity threshold was set to 70%.

In practical application, when the LFMP material is selected to be LiMn-removed _0.7 Fe _0.3 PO ₄ When other materials are used, the first preset capacity threshold value can be correspondingly modified based on the difference between the first metering ratio of the actual LFMP material and the preset metering ratio so as to obtain the actual first capacity threshold value.

In some embodiments, as shown in fig. 6, the process of determining the first capacity threshold in step 51 based on the first metering ratio, the preset metering ratio, and the first preset capacity threshold includes the steps of:

step 61: if the first metering ratio is greater than the preset metering ratio, the first capacity threshold value is determined to be equal to the second preset capacity threshold value.

Step 62: if the first metering ratio is smaller than or equal to the preset metering ratio, the first capacity threshold value is determined to be equal to the first preset capacity threshold value.

The second preset capacity threshold is a preset first capacity threshold, and 1 is greater than the second preset capacity threshold and greater than the first preset capacity threshold.

Specifically, when the first metering ratio of the LFMP material actually used is greater than the preset metering ratio, it may be determined that the content of Mn ions in the LFMP material actually used is higher relative to the content of Mn ions in the reference LFMP material. Compared with the reference LFMP material, when the actually adopted LFMP material is used as the cathode material of the battery cell, the capability of gas generation resistance is weaker, the gas generation of the battery cell is easier to cause, and the upper limit voltage of the battery cell is limited earlier. At this time, the upper limit voltage of the battery cell can be limited earlier by increasing the first capacity threshold. The method specifically includes limiting the first capacity threshold to be equal to a second preset capacity threshold, wherein the second preset capacity threshold is greater than the first preset capacity threshold so as to improve the first capacity threshold. Therefore, the health state value of the battery cell when the upper limit voltage of the battery cell is limited is improved, and the risk of gas production of the battery cell can be reduced.

When the first metering ratio of the LFMP material actually used is less than or equal to the preset metering ratio, it may be determined that the content of Mn ions in the LFMP material actually used is the same as or lower than the content of Mn ions in the reference LFMP material. Compared with the reference LFMP material, when the LFMP material is actually used as the cathode material of the battery cell, the resistance to gas generation is close to or stronger. At this time, the first capacity threshold may be set equal to the first preset capacity threshold. On one hand, the effect of reducing the gas production risk of the battery cell can be achieved; on the other hand, the utilization rate of the electric quantity of the electric core can be improved without improving the health state value of the electric core when the upper limit voltage of the electric core is limited.

The reference LFMP material (also preset LFMP material) is LiMn _0.7 Fe _0.3 PO ₄ And the corresponding preset metering ratio is 0.7, the first preset capacity threshold value is 70%, and the second preset capacity threshold value is 80% for example.

In one embodiment, the first meter ratio of LFMP material actually used is greater than 0.7, and the first capacity threshold set by this example is determined to be equal to 80%. That is, when the state of health value of the battery cell is less than or equal to 80%, the upper limit voltage of the battery cell needs to be limited. The health state value of the battery cell when the upper limit voltage of the battery cell is limited is improved, and the risk of gas production of the battery cell can be reduced.

In another embodiment, the first meter ratio of LFMP material actually used is less than or equal to 0.7, and then it is determined that the first capacity threshold set by this example should be greater than or equal to 70%. That is, when the state of health value of the battery cell is less than or equal to 70%, the upper limit voltage of the battery cell needs to be limited. At this time, the upper limit voltage of the battery cell is not limited in the period of 70% -80% in the health state of the battery cell, and the battery cell can still be charged and discharged with rated voltage, so that the utilization rate of the electric quantity of the battery cell can be improved.

Step 52: the first time threshold is determined based on the first metering ratio, the preset metering ratio, and the first preset time threshold.

The first preset time threshold is a preset first time threshold.

Likewise, in LFMThe P material is LiMn _0.7 Fe _0.3 PO ₄ The parameters are used as references for setting the parameters in other LFMP materials. In this embodiment, the preset metering ratio is 0.7. And determine by LiMn _0.7 Fe _0.3 PO ₄ The first capacity threshold value is correspondingly set when the battery core is used as the cathode material, so that the first capacity threshold value can be used as a preset first time threshold value, namely a first preset time threshold value. In some embodiments, for LiMn _0.7 Fe _0.3 PO ₄ As the battery cell of the cathode material, the corresponding set first capacity threshold is 5 years, i.e. the first preset time threshold is set to 5 years.

In practical application, when the LFMP material is selected to be LiMn-removed _0.7 Fe _0.3 PO ₄ When other materials are used, the first preset time threshold value can be correspondingly modified based on the difference between the first metering ratio of the actual LFMP material and the preset metering ratio so as to obtain the actual first time threshold value.

In some embodiments, as shown in fig. 7, one way of correspondingly modifying the first preset time threshold to obtain an actual first time threshold is illustrated in fig. 7, based on a difference between the actual first and preset metering ratios of LFMP material. Specifically, the process of determining the first time threshold in step 52 based on the first metering ratio, the preset metering ratio and the first preset time threshold includes the following steps:

step 71: determining a first time length threshold as: t=k1- (Y1-K2) 10.

Wherein t is a first time threshold, K1 is a first preset time threshold, K2 is a preset metering ratio, and Y1 is a first metering ratio.

In this embodiment, the time difference to be adjusted is 10 times the difference between the first metering ratio and the preset metering ratio. The time difference is a difference between a first time length threshold value corresponding to the case that the LFMP material is actually used as the cell of the cathode material and a first time length threshold value corresponding to the case that the reference LFMP material is used as the cell of the cathode material.

Based on the standardLFMP material of (C) is LiMn _0.7 Fe _0.3 PO ₄ An example is described. The preset metering ratio K2 is 0.7. And by LiMn _0.7 Fe _0.3 PO ₄ The first time period threshold value set correspondingly when the material is used as the battery core of the cathode material is 5 years, namely the first preset time period threshold value K1=5 years. The first time length threshold value set correspondingly when the LFMP material actually used is used as the cell of the cathode material is: 5- (Y1-0.7) x 10.

For example, in one embodiment, the LFMP material actually used is LiMn _0.6 Fe _0.4 PO ₄ The first metering ratio Y1 is 0.6/(0.6+0.4) =0.6, and at this time, the first time length threshold value set correspondingly when the LFMP material actually used is used as the cell of the cathode material is: 5- (0.6-0.7) 10=6 years. Then, for the battery cell, when the delivery time of the battery cell is longer than 6 years, the upper limit voltage of the battery cell is controlled to be smaller than or equal to the first voltage threshold value, so that the risk of abnormal gas production of the battery cell can be reduced.

Step 53: the first voltage threshold is determined based on the first metering ratio, the preset metering ratio, and the first preset voltage threshold.

The first preset voltage threshold is a preset first voltage threshold.

Similarly, LFMP material is LiMn _0.7 Fe _0.3 PO ₄ The parameters are used as references for setting the parameters in other LFMP materials. In this embodiment, the preset metering ratio is 0.7. And determine by LiMn _0.7 Fe _0.3 PO ₄ The first voltage threshold value is correspondingly set when the battery core is used as the cathode material, so that the first voltage threshold value can be used as a preset first voltage threshold value, namely a first preset voltage threshold value.

In some embodiments, for a cell in which LFMP material is the cathode material, the first preset voltage threshold is set to Fe in the cell ²⁺ Conversion to Fe by phase transition reaction ³⁺ Voltage at that time. As shown in FIG. 4, fe ²⁺ Conversion to Fe by phase transition reaction ³⁺ Voltage at less than Mn ²⁺ Conversion to Mn by phase transition reaction ³⁺ At a voltage of a first presetSetting a voltage threshold value as Fe in the battery cell ²⁺ Conversion to Fe by phase transition reaction ³⁺ At a voltage of less than Mn ²⁺ Conversion to Mn by phase transition reaction ³⁺ Voltage at time Mn ²⁺ Conversion to Mn by phase transition reaction ³⁺ The probability of (2) is smaller, the dissolved Mn ions are reduced, the gas production risk of the battery cell is reduced, and the service life of the battery cell is prolonged.

In other embodiments, the compositions are directed to LiMn _0.7 Fe _0.3 PO ₄ As for the cell as the cathode material, as shown in fig. 4, fe in the cell ²⁺ Conversion to Fe by phase transition reaction ³⁺ The voltage is approximately 3.4V, and the first preset voltage threshold may be set to 3.4V. In practical application, when the LFMP material is selected to be LiMn-removed _0.7 Fe _0.3 PO ₄ And when the material is the other material, correspondingly modifying the first preset time threshold based on the difference between the first metering ratio and the preset metering ratio of the actual LFMP material so as to obtain the actual first time threshold.

In an embodiment, referring to fig. 8, fig. 8 illustrates one way how the first preset voltage threshold is modified correspondingly to obtain an actual first voltage threshold based on a difference between the actual first metering ratio of LFMP material and the preset metering ratio. Specifically, the process of determining the first voltage threshold in step 53 based on the first metering ratio, the preset metering ratio and the first preset voltage threshold includes the following steps:

step 81: determining a first voltage threshold as: v1=k3+ (Y2-K4).

Wherein V1 is a first voltage threshold, K3 is a first preset voltage threshold, Y2 is a first metering ratio, and K4 is a preset metering ratio.

In this embodiment, the difference between the first metering ratio and the preset metering ratio is used as the voltage difference to be adjusted. The voltage difference is a difference between a first voltage threshold value corresponding to the case where the LFMP material actually used is used as the cell of the cathode material and a first voltage threshold value corresponding to the case where the reference LFMP material is used as the cell of the cathode material.

The LFMP material based on standard is LiMn _0.7 Fe _0.3 PO ₄ An example is described. The preset metering ratio K4 is 0.7. And by LiMn _0.7 Fe _0.3 PO ₄ The first voltage threshold value corresponding to the case where the material is used as the cell of the cathode material is 3.4V, that is, the first preset voltage threshold value k3=3.4v. The first voltage threshold value set correspondingly when the LFMP material actually used is used as the cell of the cathode material is: 3.4+ (Y2-0.7).

For example, in one embodiment, the LFMP material actually used is LiMn _0.8 Fe _0.2 PO ₄ The first metering ratio Y1 is 0.8/(0.8+0.2) =0.8, and at this time, the first voltage threshold value set correspondingly when the LFMP material actually used is used as the cell of the cathode material is: 3.4+ (0.8-0.7) =3.5V.

Further, in combination with the above description of the embodiments, the present invention is directed to LiMn _0.7 Fe _0.3 PO ₄ As the cell of the cathode material, the first preset capacity threshold is set to 70%, and the second preset capacity threshold is set to 80% as an example. Since the first metering ratio of the LFMP material actually used is 0.8 to be greater than the preset metering ratio of 0.7, the first capacity threshold value correspondingly set when the LFMP material actually used is used as the cell of the cathode material is 80%.

The contents of the above embodiments are again combined to target LiMn _0.7 Fe _0.3 PO ₄ As the cell of the cathode material, the preset metering ratio K2 is 0.7, and the corresponding first preset duration threshold is 5 years. Since the first metering ratio of the LFMP material actually used is 0.8, the first time length threshold value correspondingly set when the LFMP material actually used is used as the cell of the cathode material is 5- (0.8-0.7) ×10=4 years.

In conclusion, for LiMn _0.8 Fe _0.2 PO ₄ As for the battery core of the cathode material, when the health state value of the battery core is smaller than or equal to 80%, or the delivery time of the battery core is larger than or equal to 4 years, the upper limit voltage of the battery core is controlled to be smaller than or equal to 3.5V, so that the risk of abnormal gas production of the battery core can be reduced.

Referring to table 1 below, the results of testing a plurality of cells (prepared by the above-mentioned examples, and with the first measurement ratio changed correspondingly from example 1 to example 10) in practical application are shown in table 1.

TABLE 1

As shown in table 1, with comparative example 1 as a reference example for comparison, tests were performed by setting corresponding first capacity threshold, first time threshold and first voltage threshold in examples 1 to 10 to determine whether the method for prolonging the lifetime of the battery cell provided in the examples of the present application is effective. In comparative example 1 and examples 1 to 10, the cathode materials of the cells used in the test were LFMP materials. The test result can be used for observing whether the battery cell swells or not through naked eyes, and the thickness of the battery cell can be tested through tools such as a vernier caliper and the like so as to estimate the volume of the battery cell.

In comparative example 1, the first metering ratio of Mn ions in LFMP material in the cell cathode material used was 0.7, and the method for prolonging the life of the cell provided in the examples of the present application was not performed, the test result was that the Mn was as follows ²⁺ /Mn ³⁺ The phase change reaction of (c) causes deterioration of the stability of the material and deterioration under high voltage conditions, followed by disproportionation of Mn ions. Further, mn ions eluted by the disproportionation reaction attack the battery anode and cause gas generation. Also, the cell volume expansion of about 10% was determined by visual observation or measurement evaluation, and it was also determined that the cell used for the test was generating gas in comparative example 1.

In example 1, the same first metering ratio of 0.7 as in comparative example 1 was maintained. Example 1 differs from comparative example 1 in that the method of extending the life of the battery cells provided in the examples of the present application was performed. From the above examples, it can be seen that for LiMn _0.7 Fe _0.3 PO ₄ As a cell of the cathode material, the first capacity threshold may be set to 70%, the first time threshold may be set to 5 years, and the first voltage threshold may be set to 3.4V. While example 1 test was performedThe battery cell further improves the first capacity threshold on the basis of keeping the first time threshold and the first voltage threshold, namely when the first metering ratio is 0.7, the risk of gas production of the battery cell can be well reduced by improving the first capacity threshold to 80% or setting the first time threshold to 5 years and setting the first voltage threshold to 3.4V, and the battery cell does not produce gas at the moment and does not expand in volume.

In example 2, the same first metering ratio of 0.7 as in comparative example 1 was maintained. Example 2 also performs the method of extending the life of a battery provided in the examples of the present application. From the above examples, it can be seen that for LiMn _0.7 Fe _0.3 PO ₄ As a cell of the cathode material, the first capacity threshold may be set to 70%, the first time threshold may be set to 5 years, and the first voltage threshold may be set to 3.4V. While the cell used in the test of example 2 was reduced by the first capacity threshold on the basis of maintaining the first time threshold and the first voltage threshold, i.e., at a first metering ratio of 0.7, the cell produced gas at about 7% volume expansion due to the first capacity threshold being set to 60%.

In example 3, the same first metering ratio of 0.7 as in comparative example 1 was maintained. Example 3 the method of extending the life of a battery cell provided in the examples of the present application was also performed. From the above examples, it can be seen that for LiMn _0.7 Fe _0.3 PO ₄ As a cell of the cathode material, the first capacity threshold may be set to 70%, the first time threshold may be set to 5 years, and the first voltage threshold may be set to 3.4V. The battery cell used in the test of embodiment 3 shortens the first time threshold on the basis of maintaining the first capacity threshold and the first voltage threshold, so as to limit the upper voltage of the battery cell in advance, and further reduce the risk of gas production of the battery cell. Therefore, when the first metering ratio is 0.7, the first capacity threshold is set to 70% or the first time threshold is set to 4 years, and the first voltage threshold is set to 3.4V, so that the battery cell does not generate gas, and the risk of gas generation of the battery cell can be well reduced.

In example 4, the same first metering ratio of 0.7 as in comparative example 1 was maintained. Example 4 the prolonged electrical supply provided in the examples of the present application is also performedMethod of core life. From the above examples, it can be seen that for LiMn _0.7 Fe _0.3 PO ₄ As a cell of the cathode material, the first capacity threshold may be set to 70%, the first time threshold may be set to 5 years, and the first voltage threshold may be set to 3.4V. While the cell used in the test of example 4 extended the first time threshold on the basis of maintaining the first capacity threshold and the first voltage threshold to delay the upper voltage limit of the cell, the risk of cell gassing increased. Therefore, at a first metering ratio of 0.7, the cell is gassing and volume expanding by about 8% by setting the first capacity threshold to 70% or the first time threshold to 5 years and the first voltage threshold to 3.4V.

In example 5, the same first metering ratio of 0.7 as in comparative example 1 was maintained. Example 5 the method of extending the life of a battery cell provided in the examples of the present application was also performed. From the above examples, it can be seen that for LiMn _0.7 Fe _0.3 PO ₄ As a cell of the cathode material, the first capacity threshold may be set to 70%, the first time threshold may be set to 5 years, and the first voltage threshold may be set to 3.4V. While the cell used in the test of example 5 increased the first voltage threshold on the basis of maintaining the first capacity threshold and the first time threshold to increase the upper voltage limiting the cell, the risk of cell gassing increased. Therefore, at a first metering ratio of 0.7, the cell is gassing and volume expanding by about 10% by setting the first capacity threshold to 70% or the first time threshold to 5 years and the first voltage threshold to 3.6V.

In example 6, the same first metering ratio of 0.7 as in comparative example 1 was maintained. Example 6 also performs the method of extending the life of a battery provided in the examples of the present application. From the above examples, it can be seen that for LiMn _0.7 Fe _0.3 PO ₄ As a cell of the cathode material, the first capacity threshold may be set to 70%, the first time threshold may be set to 5 years, and the first voltage threshold may be set to 3.4V. While example 6 the cell used in the test reduced the first voltage threshold to reduce the upper voltage limit of the limiting cell based on maintaining the first capacity threshold and the first time threshold, furtherAnd the risk of gas production of the battery cell is reduced. Therefore, when the first metering ratio is 0.7, the first capacity threshold is set to 70% or the first time threshold is set to 5 years, and the first voltage threshold is set to 3.2V, so that the battery cell does not generate gas, and the risk of gas generation of the battery cell can be well reduced.

In example 7, the first metering ratio was changed to 0.8 with respect to comparative example 1. Example 7 also performs the method of extending the life of a battery provided by the examples of this application. From the above examples, it can be seen that for LiMn _0.8 Fe _0.2 PO ₄ As a cell of the cathode material, the first capacity threshold may be set to 80%, the first time threshold may be set to 4 years, and the first voltage threshold may be set to 3.5V. While the cell used in the test of example 7 reduced the first voltage threshold on the basis of maintaining the first capacity threshold and the first time threshold, so as to reduce the upper voltage limit of the cell and further reduce the risk of cell gassing. Therefore, when the first metering ratio is 0.8, the risk of gas production of the battery cell can be well reduced by setting the first capacity threshold to 80% or setting the first time threshold to 4 years and setting the first voltage threshold to 3.3V, and the battery cell does not produce gas at this time and does not expand in volume.

In example 8, the first metering ratio was changed to 0.8 with respect to comparative example 1. Example 8 the method of extending the life of a battery cell provided in the examples of the present application was also performed. From the above examples, it can be seen that for LiMn _0.8 Fe _0.2 PO ₄ As a cell of the cathode material, the first capacity threshold may be set to 80%, the first time threshold may be set to 4 years, and the first voltage threshold may be set to 3.5V. While the cell used in the test of example 8 was beneficial to reducing the risk of cell gassing by reducing the first voltage threshold to reduce the upper voltage limit of the cell while the first time threshold was maintained at the first capacity threshold, the increase in the risk of cell gassing was increased. If the first capacity threshold is set to 70% or the first time threshold is set to 5 years and the first voltage threshold is set to 3.4V at a first metering ratio of 0.8, the cell produces gas with a volume expansion of about 8%.

In example 9, the first metering ratio was changed to 0.6 with respect to comparative example 1. Example 9 also performs the method of extending the life of a battery provided in the examples of the present application. From the above examples, it can be seen that for LiMn _0.6 Fe _0.4 PO ₄ As a cell of the cathode material, the first capacity threshold may be set to 70%, the first time threshold may be set to 6 years, and the first voltage threshold may be set to 3.3V. While the cell used in the test of example 9 reduced the first voltage threshold on the basis of maintaining the first capacity threshold and the first time threshold to reduce the upper voltage limit of the limiting cell, further reducing the risk of cell gassing. Therefore, when the first metering ratio is 0.6, the first capacity threshold is set to 70% or the first time threshold is set to 6 years, and the first voltage threshold is set to 3.3V, so that the battery cell does not generate gas, and the risk of gas generation of the battery cell can be well reduced.

In example 10, the first metering ratio was changed to 0.6 with respect to comparative example 1. Embodiment 10 also performs the method of extending the life of a battery provided by embodiments of the present application. From the above examples, it can be seen that for LiMn _0.6 Fe _0.4 PO ₄ As a cell of the cathode material, the first capacity threshold may be set to 70%, the first time threshold may be set to 6 years, and the first voltage threshold may be set to 3.3V. On the one hand, the battery cell adopted in the test of the embodiment 10 shortens the first time threshold to limit the upper limit voltage of the battery cell in advance on the basis of keeping the first capacity threshold, so that the risk of gas production of the battery cell can be further reduced; on the other hand, the first voltage threshold is reduced, so that the upper limit voltage of the limiting battery cell is reduced, and the risk of gas generation of the battery cell can be further reduced. Therefore, when the first metering ratio is 0.6, the first capacity threshold is set to 70% or the first time threshold is set to 5 years, and the first voltage threshold is set to 3.4V, so that the battery cell does not generate gas, and the risk of gas generation of the battery cell can be well reduced.

In summary, the method for prolonging the service life of the battery cell provided by the embodiment of the application can be applied to battery cells with different first metering ratios. And when the first metering ratio of the LFMP material in the battery core is determined, parameters such as a first capacity threshold, a first time threshold, a first voltage threshold and the like are adjusted, so that the risk of generating gas by the battery core can be reduced, and the service life of the battery core is prolonged. The first capacity threshold and the risk of generating gas are in negative correlation, the first time threshold and the risk of generating gas are in positive correlation, and the first voltage threshold and the risk of generating gas are in positive correlation.

The embodiment of the application also provides electric equipment, as shown in fig. 9, the electric equipment 1 comprises a battery pack 1000 and a load 2000. The load 2000 may be an electrical device in the electrical consumer 1.

The powered device 1 may be any suitable device that requires power from the battery pack 1000, such as an unmanned aerial vehicle, an energy storage product, an electric tool, a two-wheeled vehicle, etc.

Embodiments also provide a non-transitory computer readable storage medium storing computer executable instructions that, when executed by a processor, cause a process to perform a method in any of the embodiments of the present application.

Embodiments of the present application also provide a computer program product comprising a computer program stored on a computer readable storage medium, the computer program comprising program instructions which, when executed by a computer, cause the computer to perform the method of any of the embodiments of the present application.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; the technical features of the above embodiments or in the different embodiments may also be combined under the idea of the present application, the steps may be implemented in any order, and there are many other variations of the different aspects of the present application as described above, which are not provided in details for the sake of brevity; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of extending the life of a battery cell comprising:

receiving the health state value and the delivery time of the battery cell;

and controlling the upper voltage of the battery cell to be smaller than or equal to a first voltage threshold in response to the health state value being smaller than or equal to a first capacity threshold or in response to the factory time being larger than or equal to a first time threshold.

2. The method of claim 1, wherein the cell employs lithium iron manganese phosphate as a cathode material, the method further comprising:

determining the first capacity threshold, the first time threshold, and the first voltage threshold based on a first metering ratio of manganese ions in the lithium iron manganese phosphate;

wherein the first metering ratio is a ratio between the number of manganese ions and a sum of the number of manganese ions and iron ions.

3. The method of claim 2, wherein the determining the first capacity threshold, the first time threshold, and the first voltage threshold based on a first metering ratio of manganese ions in the lithium iron manganese phosphate satisfies at least any one of:

(i) The first capacity threshold and the first metering ratio show positive correlation;

(ii) The first time threshold and the first metering ratio show a negative correlation;

(iii) The first voltage threshold exhibits a positive correlation with the first metering ratio.

4. The method of claim 2, wherein the determining the first capacity threshold, the first time threshold, and the first voltage threshold based on a first metering ratio of manganese ions in the lithium iron manganese phosphate comprises:

determining a first capacity threshold based on the first metering ratio, a preset metering ratio and a first preset capacity threshold, wherein the preset metering ratio is a ratio between the number of manganese ions in preset lithium iron manganese phosphate and the sum of the number of manganese ions and the number of iron ions, and the first preset capacity threshold is a preset first capacity threshold; and/or the number of the groups of groups,

determining a first time threshold based on the first metering ratio, a preset metering ratio and a first preset time threshold, wherein the preset metering ratio is a ratio between the number of manganese ions in preset lithium iron manganese phosphate and the sum of the number of manganese ions and the number of iron ions, and the first preset time threshold is a preset first time threshold; and/or the number of the groups of groups,

determining a first voltage threshold based on the first metering ratio, a preset metering ratio and a first preset voltage threshold, wherein the preset metering ratio is a ratio between the number of manganese ions in preset lithium iron manganese phosphate and the sum of the number of manganese ions and the number of iron ions, and the first preset voltage threshold is a preset first voltage threshold.

5. The method of claim 4, wherein the first predetermined voltage threshold is Fe in the cell ²⁺ Conversion to Fe by phase transition reaction ³⁺ Voltage at that time.

6. The method of claim 4, wherein the first preset capacity threshold is 70%, the first preset time threshold is 5 years, and the first preset voltage threshold is 3.4V when the preset metering ratio is 0.7.

7. The method of any of claims 4-6, wherein the determining the first capacity threshold based on the first metering ratio, the preset metering ratio, and a first preset capacity threshold comprises:

if the first metering ratio is larger than the preset metering ratio, determining that the first capacity threshold is equal to a second preset capacity threshold, wherein the second preset capacity threshold is a preset first capacity threshold, and 1 is larger than the second preset capacity threshold and larger than the first preset capacity threshold;

and if the first metering ratio is smaller than or equal to the preset metering ratio, determining that the first capacity threshold is equal to the first preset capacity threshold.

8. The method of claim 7, wherein the second preset capacity threshold is 80% if the first preset capacity threshold is 70%.

9. The method of any of claims 4-6, wherein the determining the first time threshold based on the first metric, the preset metric, and a first preset time threshold comprises:

determining the first time length threshold is: t=k1- (Y1-K2) ×10, where t is the first time length threshold, K1 is the first preset time threshold, K2 is the preset metering ratio, and Y1 is the first metering ratio.

10. The method of any of claims 4-6, wherein the determining the first voltage threshold based on the first metering ratio, the preset metering ratio, and a first preset voltage threshold comprises:

determining the first voltage threshold as: v1=k3+ (Y2-K4), where V1 is the first voltage threshold, K3 is the first preset voltage threshold, Y2 is the first metering ratio, and K4 is the preset metering ratio.

11. A battery management system, comprising:

at least one processor and a memory communicatively coupled to the at least one processor, the memory storing instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-10.

12. A battery pack comprising a battery and the battery management system of claim 11, the battery comprising at least one cell.

13. A powered device comprising a load and the battery pack of claim 12 for powering the load.

14. A non-transitory computer readable storage medium storing computer executable instructions which, when executed by a processor, cause the processor to perform the method of any of claims 1-10.