Method for evaluating state of health of battery

Abstract

A battery health state assessment method comprises the following steps: S1, acquiring a charging or discharging IC curve group under a first rate when a calibrated battery has a plurality of different positive electrode active material loss amounts, a plurality of different negative electrode active material loss amounts and a plurality of different detachable ion loss amounts; s2, establishing a first relational expression between the positive electrode active material loss amount, the negative electrode active material loss amount and the deintercalated ion loss amount of the calibrated battery and the corresponding first characteristic values; s3, acquiring an IC curve of the to-be-tested battery under a plurality of different second multiplying powers; s4, extracting a second characteristic value of the IC curve of the battery to be detected, and establishing a second relational expression between the second characteristic value and the multiplying power; s5, the positive electrode active material loss amount LACM, the negative electrode active material loss amount LAAM and the deintercalated ion loss amount LII of the battery to be detected under the first rate are obtained; and according to SOH = 100%-max (LII, LAAM, LACM), obtaining the SOH of the battery to be tested.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a method for assessing the health status of a battery. Background Technology

[0002] Batteries are crucial energy storage devices, widely used in electronic devices, energy storage power stations, and electric vehicles. Over time, batteries experience capacity degradation, increased internal resistance, material aging, and unexpected side reactions, leading to reduced safety and performance. The State of Health (SOH) is an indicator used to assess the degree of performance degradation after a period of use, helping to determine battery life and usage status. In a Battery Management System (BMS), SOH assessment is a vital function, directly impacting the accuracy of estimates for the battery's maximum charge / discharge power (SOP) and total available energy (SOE). This plays a significant role in helping users understand the actual battery usage and use the battery appropriately. Obtaining accurate SOH values ​​through proper SOH modeling is essential for safe battery use.

[0003] Currently, common methods for assessing battery state of harm (SOH) include direct discharge, empirical or semi-empirical methods, mechanism-based methods, and feature-based prediction methods. Direct discharge involves fully charging the battery and then discharging it at a certain rate to the cutoff voltage, calculating the SOH based on the ratio of the discharged capacity to its nominal capacity. However, this method requires offline testing, resulting in a long testing cycle, making it unsuitable for vehicle-wide applications. Empirical or semi-empirical methods obtain SOH prediction models by fitting experimental data. These models can achieve high accuracy for specific battery types but lack physical meaning. In actual vehicle operation, fluctuations and unpredictability in battery system operating conditions can lead to significant SOH estimation errors. Mechanism-based methods establish electrochemical models of battery aging based on side reactions, predicting batteries under almost all state conditions and operating modes. However, these models are complex, computationally intensive, and unsuitable for BMS applications. Feature-based prediction methods estimate SOH by establishing the relationship between measurable characteristic parameters during battery aging and SOH. Commonly used methods include internal resistance methods and incremental capacity analysis (ICA). Among them, the internal resistance method is difficult to estimate the battery's state of charge (SOH) in real time and has low estimation accuracy. The incremental capacity analysis method uses the correlation between the peak characteristics of the battery capacity increment curve at small rates and the battery state to achieve accurate SOH estimation. It is an in-situ non-destructive analysis method that does not require additional equipment and is simple to operate. However, since small-rate charging / discharging will lead to a relatively long test cycle, this method is not suitable for use under actual vehicle operating conditions. If it is to be applied to actual vehicle operating conditions, the situation of large-rate charging and discharging needs to be considered. Summary of the Invention

[0004] The purpose of this invention is to provide a method for assessing the health status of a battery. By establishing a relationship model between the peak characteristic value of the IC curve under low-rate charge / discharge conditions and the loss of positive electrode active material, negative electrode active material, and intercalation / deintercalation ions, and by establishing a relationship model between different charge / discharge rates and the peak characteristic value of the IC curve, the loss of positive electrode active material, negative electrode active material, and intercalation / deintercalation ions of the battery under high-rate charge / discharge conditions can be obtained, thereby enabling the determination of the SOH value of the battery under high-rate charge / discharge conditions.

[0005] This invention provides a method for assessing the health status of a battery, comprising the following steps:

[0006] S1. Provide a calibration battery and obtain IC curves of the calibration battery at a first rate when the calibration battery has multiple different positive electrode active material loss amounts, multiple different negative electrode active material loss amounts, and multiple different intercalation / deintercalation ion loss amounts.

[0007] S2. Extract the first feature value of each IC curve group of the calibration battery, and establish a first relationship between the loss of positive electrode active material, the loss of negative electrode active material and the loss of intercalation / deintercalation ions of the calibration battery and the corresponding first feature value; wherein, the first feature value includes the peak position, peak area and peak height of the IC curve in the IC curve group of the calibration battery.

[0008] S3. Charge or discharge the battery under test at multiple different second rates to obtain the IC curves of the battery under test at multiple different second rates.

[0009] S4. Extract the second feature values ​​of each IC curve of the battery under test at multiple different second rates, and establish a second relationship between the second feature values ​​and the rate; wherein, the second feature values ​​include the peak position, peak area and peak height of the peak on the IC curve of the battery under test;

[0010] S5. Substitute the first rate into the second relationship in step S4 to obtain the second characteristic value of the battery under test at the first rate; then substitute the second characteristic value of the battery under test at the first rate into the first relationship in step S2 to obtain the positive electrode active material loss LACM, negative electrode active material loss LAAM, and deintercalation / intercalation ion loss LII of the battery under test at the first rate.

[0011] The SOH of the battery under test is obtained according to the SOH calculation formula: SOH = 100% - max(LII, LAAM, LACM).

[0012] In one feasible manner, the first multiplier is less than or equal to 0.1C.

[0013] In one feasible manner, at least a portion of the multiple different second multipliers are greater than or equal to the first multiplier.

[0014] In one feasible manner, the difference between adjacent second multipliers is greater than or equal to 0.1C.

[0015] In one feasible approach, the number of the second multiplier is at least three.

[0016] In one feasible manner, the values ​​of the positive electrode active material loss, negative electrode active material loss, and deintercalation / intercalation ion loss of the calibrated battery are all greater than or equal to 0.

[0017] In one feasible implementation, step S1 specifically includes:

[0018] A calibration battery is provided, and the calibration battery is charged or discharged at a first rate to obtain the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state. Based on the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state, the OCV curve of the calibration battery in the initial state is obtained. The initial state is the state in which the loss of positive electrode active material, the loss of negative electrode active material, and the loss of intercalation / deintercalation ions of the calibration battery are all 0.

[0019] Multiple positive electrode active material loss values ​​greater than 0, multiple negative electrode active material loss values ​​greater than 0, and multiple deintercalation / intercalation ion loss values ​​greater than 0 are designed respectively. Based on the designed positive electrode active material loss values, negative electrode active material loss values, and deintercalation / intercalation ion loss values, the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state are proportionally shrunk and translated, thereby obtaining the positive electrode OCP curve and negative electrode OCP curve of the calibration battery under multiple positive electrode active material loss values ​​greater than 0, multiple negative electrode active material loss values ​​greater than 0, and multiple deintercalation / intercalation ion loss values ​​greater than 0, respectively. Then, the OCV curve of the calibration battery under multiple positive electrode active material loss values ​​greater than 0, multiple negative electrode active material loss values ​​greater than 0, and multiple deintercalation / intercalation ion loss values ​​greater than 0 are obtained respectively.

[0020] Based on the various OCV curves of the calibration battery, IC curve sets of the calibration battery under multiple different positive electrode active material loss amounts, multiple different negative electrode active material loss amounts, and multiple different intercalation / deintercalation ion loss amounts are obtained respectively.

[0021] In one possible implementation, in step S2 above, any one of the loss of positive electrode active material, loss of negative electrode active material, and loss of intercalation / deintercalation ions in the calibration battery corresponds to any one of the peak position, peak area, and peak height of the IC curve in the IC curve set of the calibration battery, and the loss of positive electrode active material, loss of negative electrode active material, and loss of intercalation / deintercalation ions in the calibration battery respectively correspond to different first characteristic values.

[0022] In one feasible manner, in step S2 above, one of the loss of positive and negative active materials in the calibration battery corresponds to the peak area of ​​the IC curve in the IC curve set of the calibration battery, and the other of the loss of positive and negative active materials in the calibration battery corresponds to the peak height of the IC curve in the IC curve set of the calibration battery; the loss of intercalation / deintercalation ions in the calibration battery corresponds to the peak position of the IC curve in the IC curve set of the calibration battery.

[0023] In one possible implementation, in step S2 above, the first characteristic value is the peak position, peak area, or peak height of different peaks in the IC curves of the IC curve set of the calibrated battery.

[0024] In one feasible approach, during step S2 above, when extracting the first feature value of the IC curve in the IC curve group of the calibration battery, the peak position of the first peak, the peak area of ​​the largest peak among the intermediate peaks, and the peak height of the last peak in the IC curve group of the calibration battery are selected respectively.

[0025] In one feasible approach, both the first relation and the second relation are linear relations.

[0026] The battery health status assessment method provided by this invention employs incremental capacity analysis. It establishes a first relationship between the three capacity losses (positive electrode active material loss, negative electrode active material loss, and intercalation / deintercalation ion loss) of a calibrated battery at a first rate and the first characteristic value of the peak of the corresponding IC curve in its IC curve set. It also establishes a second relationship between the second characteristic value of the IC curve of the battery under test and the rate. Then, the first rate is substituted into the second relationship to obtain the second characteristic value of the battery under test at the first rate. Finally, the second characteristic value of the battery under test at the first rate is substituted into the first relationship to obtain the positive electrode active material loss (LACM), negative electrode active material loss (LAAM), and intercalation / deintercalation ion loss (LII) of the battery under test at the first rate. The SOH of the battery under test is then calculated using the SOH calculation formula. The proposed method for assessing the state of health (SOH) of a battery under test not only comprehensively considers various capacity loss modes, improving the accuracy and expanding the applicability of the SOH assessment method, but also is not limited by the real-time rate of the battery. That is, this method can be used to estimate the SOH of the battery under test at both low and high rates. Therefore, it can conveniently, quickly, and reliably estimate the SOH of the battery under test at high rates, making it better applicable to real-world vehicle scenarios and solving the technical drawback of existing incremental capacity analysis methods that can only be used under a single low current. Attached Figure Description

[0027] Figure 1 This is a schematic diagram showing the correspondence between the positive electrode OCP curve, negative electrode OCP curve, full cell OCV curve, and full cell IC curve of the calibrated battery in an embodiment of the present invention.

[0028] Figure 2a This is a comparative schematic diagram of the full-cell OCV curve, positive electrode OCP curve, and negative electrode OCP curve of the calibrated battery under different positive electrode active material loss amounts in an embodiment of the present invention.

[0029] Figure 2b This is a schematic diagram comparing the IC curves of the calibrated battery under different losses of positive electrode active material in an embodiment of the present invention.

[0030] Figure 3a This is a comparative schematic diagram of the full-cell OCV curve, positive electrode OCP curve, and negative electrode OCP curve of the calibrated battery under different losses of negative electrode active materials in an embodiment of the present invention.

[0031] Figure 3b This is a schematic diagram comparing the IC curves of the calibrated battery under different loss amounts of negative electrode active material in an embodiment of the present invention.

[0032] Figure 4a This is a comparative schematic diagram of the full cell OCV curve, positive electrode OCP curve, and negative electrode OCP curve of the calibrated battery under different amounts of intercalation / deintercalation ion loss in an embodiment of the present invention.

[0033] Figure 4b This is a schematic diagram comparing the IC curves of the calibrated battery under different amounts of intercalation / deintercalation ion loss in an embodiment of the present invention.

[0034] Figure 5a This is a schematic diagram illustrating the relationship between the loss of positive electrode active material and the peak height in an embodiment of the present invention.

[0035] Figure 5b This is a schematic diagram showing the relationship between the loss of negative electrode active material and the peak area of ​​the calibrated battery in an embodiment of the present invention.

[0036] Figure 5c This is a schematic diagram illustrating the relationship between the amount of intercalation / deintercalation ions lost and the peak position in the calibrated battery according to an embodiment of the present invention.

[0037] Figure 6a This is a schematic diagram comparing the voltage-capacity curves of the battery under test at different charging rates in an embodiment of the present invention.

[0038] Figure 6b This is a schematic diagram comparing the IC curves of the battery under test at different charging rates in an embodiment of the present invention.

[0039] Figure 7a This is a schematic diagram illustrating the relationship between the peak position and the rate of the battery under test in an embodiment of the present invention.

[0040] Figure 7b This is a schematic diagram illustrating the relationship between the peak height and the rate of the battery under test in an embodiment of the present invention.

[0041] Figure 7c This is a schematic diagram illustrating the relationship between the peak area and the rate of the battery under test in an embodiment of the present invention.

[0042] Figure 8This is a comparative schematic diagram of the IC curves of lithium-ion battery A at different charging rates in Embodiment 1 of the present invention.

[0043] Figure 9 This is a comparative schematic diagram of the IC curves of lithium-ion battery B at different charging rates in Embodiment 2 of the present invention.

[0044] Figure 10a This is a schematic diagram showing the relationship between the peak position and the rate of lithium-ion battery B in Embodiment 2 of the present invention.

[0045] Figure 10b This is a schematic diagram showing the relationship between the peak height and the rate of lithium-ion battery B in Embodiment 2 of the present invention.

[0046] Figure 10c This is a schematic diagram showing the relationship between the peak area and the rate of lithium-ion battery B in Embodiment 2 of the present invention. Detailed Implementation

[0047] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0048] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0049] like Figures 1 to 7c As shown, this embodiment of the invention provides a method for assessing battery health status, including the following steps:

[0050] S1. Provide a calibration battery, and obtain sets of IC (incremental capacity) curves for charging or discharging at a first rate when the calibration battery has multiple different losses of positive electrode active material, multiple different losses of negative electrode active material, and multiple different losses of intercalation / deintercalation ions; each IC curve set of the calibration battery includes multiple IC curves (e.g., ... Figure 2b As shown, the IC curves of the calibration battery under multiple different positive electrode active material loss rates constitute the first set of IC curves; as... Figure 3b As shown, the IC curves of the calibration battery under multiple different losses of negative electrode active materials form the second set of IC curves; as... Figure 4bAs shown, the IC curves of the calibration battery at multiple different intercalation / deintercalation ion losses form the third IC curve group; wherein, the calibration battery is a battery with different positive electrode active material losses, different negative electrode active material losses, or different intercalation / deintercalation ion losses, wherein, when the calibration battery is in the BOL (begin of life) state, the positive electrode active material loss, negative electrode active material loss, and intercalation / deintercalation ion loss of the calibration battery are all 0; the positive electrode active material loss, negative electrode active material loss, and intercalation / deintercalation ion loss of the calibration battery are all percentages;

[0051] S2. Extract the first characteristic value of the IC curve in each IC curve group of the calibration battery under multiple different positive electrode active material loss amounts, multiple different negative electrode active material loss amounts, and multiple different intercalation / deintercalation ion loss amounts. Based on the correlation between the positive electrode active material loss amount, negative electrode active material loss amount, and intercalation / deintercalation ion loss amount of the calibration battery and each first characteristic value of the IC curve in the IC curve group (i.e., when the calibration battery experiences a certain type of capacity loss, a certain first characteristic value of the IC curve in the IC curve group of the calibration battery changes significantly, that is, the correlation between this type of capacity loss and this first characteristic value is relatively large, and the two can be correlated), establish a first relationship between the positive electrode active material loss amount, negative electrode active material loss amount, and intercalation / deintercalation ion loss amount of the calibration battery and the corresponding first characteristic value.

[0052] The first feature value includes the peak position, peak area and peak height of the IC curve in the IC curve set of the calibrated battery. That is, the first relationship includes the quantitative relationship between the capacity loss and peak position of the calibrated battery, the quantitative relationship between the capacity loss and peak area of ​​the calibrated battery, and the quantitative relationship between the capacity loss and peak height of the calibrated battery.

[0053] Wherein, any one of the positive electrode active material loss, negative electrode active material loss, and deintercalation / intercalation ion loss of the calibration battery corresponds to any one of the peak position, peak area, and peak height of the IC curve in the IC curve set of the calibration battery, and the positive electrode active material loss, negative electrode active material loss, and deintercalation / intercalation ion loss of the calibration battery respectively correspond to different first characteristic values ​​(i.e., one of the three of positive electrode active material loss, negative electrode active material loss, and deintercalation / intercalation ion loss corresponds to the peak position, another of the three of positive electrode active material loss, negative electrode active material loss, and deintercalation / intercalation ion loss corresponds to the peak area, and yet another of the three of positive electrode active material loss, negative electrode active material loss, and deintercalation / intercalation ion loss corresponds to the peak height);

[0054] S3. Charge or discharge the battery under test at multiple different second charging rates to obtain the IC curves of the battery under test at multiple different second charging rates; wherein, the battery under test is any battery whose battery health status needs to be measured, the battery under test and the calibration battery are the same type of battery (e.g., both are lithium-ion batteries or sodium-ion batteries), and the positive and negative electrode materials of the battery under test are the same as those of the calibration battery; the electrolytes of the battery under test and the calibration battery can be the same or different; preferably, the electrolytes of the battery under test and the calibration battery are the same. The IC curves of the battery under test at multiple different charging rates are as follows: Figure 6b As shown;

[0055] S4. Extract the second characteristic values ​​of each IC curve of the battery under test at multiple different second rate, and establish a second relationship between the second characteristic values ​​of the IC curve of the battery under test and the rate; wherein, the second characteristic values ​​include the peak position, peak area and peak height of the peak on the IC curve of the battery under test, that is, the second relationship includes the quantitative relationship between the peak position and the rate of the IC curve of the battery under test, the quantitative relationship between the peak area and the rate, and the quantitative relationship between the peak height and the rate; moreover, the characteristic values ​​of the peak position, peak area and peak height of the IC curve of the battery under test are the same as the peak position, peak area and peak height of the IC curve in the IC curve group of the calibration battery (that is, the peak position of the IC curve of the battery under test is the same as the peak position of the same peak on the IC curve in the IC curve group of the calibration battery, the peak area of ​​the IC curve of the battery under test is the same as the peak area of ​​the same peak on the IC curve in the IC curve group of the calibration battery, and the peak height of the IC curve of the battery under test is the same as the peak height of the same peak on the IC curve group of the calibration battery).

[0056] S5. Substitute the first rate into the second relationship in step S4 to obtain the second characteristic value of the battery under test at the first rate (specifically, substitute the first rate into the quantitative relationship between peak position and rate, the quantitative relationship between peak area and rate, and the quantitative relationship between peak height and rate, respectively, and then obtain the peak position, peak area and peak height of the battery under test at the first rate).

[0057] Then, the second characteristic values ​​of the battery under test at the first rate are substituted into the corresponding first relationships in step S2 to obtain the loss of active cathode material (LACM), loss of active anode material (LAAM), and loss of intercalation / deintercalation ions (LII) of the battery under test at the first rate. Specifically, the peak position, peak area, and peak height of the battery under test at the first rate are substituted into the corresponding quantitative relationship between capacity loss and peak position, peak area, and peak height to obtain the positive electrode active material loss LACM, negative electrode active material loss LAAM, and deintercalation / intercalation ion loss LII of the battery under test at the first rate. Among them, the positive electrode active material loss LACM, negative electrode active material loss LAAM, and deintercalation / intercalation ion loss LII of the battery under test are all percentages. Since the first relationship is obtained by charging or discharging the calibration battery at the first rate, the first rate needs to be substituted into each of the second relationships to obtain the second characteristic value of the battery under test at the first rate. Then, the second characteristic value of the battery under test at the first rate is substituted into the first relationship to obtain each loss amount of the battery under test at the first rate.

[0058] Substituting the loss of positive electrode active material LACM, negative electrode active material LAAM, and intercalation / deintercalation ion loss LII into the SOH calculation formula, the SOH of the battery under test is obtained according to the formula: SOH = 100% - max(LII, LAAM, LACM). Where max(LII, LAAM, LACM) represents the maximum of the three losses: LACM (positive electrode active material loss), LAAM (negative electrode active material loss), and LII (intercalation / deintercalation ion loss).

[0059] Specifically, the method for assessing the health status of the battery under test can be used for lithium-ion batteries, sodium-ion batteries, and other types of secondary batteries. When both the calibration battery and the battery under test are lithium-ion batteries, the deintercalable ion is lithium-ion; when both the calibration battery and the battery under test are sodium-ion batteries, the deintercalable ion is sodium-ion.

[0060] Specifically, the principle behind the SOH calculation formula is as follows: the battery capacity is essentially related to the reversible intercalation / deintercalation reaction of ions between the positive and negative electrodes, that is, to the number of ions undergoing reversible intercalation / deintercalation and the number of reversible intercalation / deintercalation sites. The number of intercalation / deintercalation ions is fixed at the initial design stage of the battery. When the loss of intercalation / deintercalation ions due to irreversible side reactions dominates, even if further loss of active materials occurs at the positive and negative electrodes, the reduction in the required reversible intercalation / deintercalation sites will not cause additional capacity loss because the number of reversible intercalation / deintercalation sites decreases (as the number of intercalation / deintercalation ions decreases, the corresponding number of required reversible intercalation / deintercalation sites also decreases). In other words, at this point, the capacity loss is determined by the loss of intercalation / deintercalation ions. When the loss of positive / negative electrode active materials due to changes in the positive / negative electrode structure is dominant, the capacity decreases due to the reduction in reversible insertion / extraction sites. Even if there is further loss of insertion / extraction ions, the reduction in the number of required insertion / extraction ions will not cause additional capacity loss because the number of required insertion / extraction ions decreases (the number of reversible insertion / extraction sites decreases, and the number of required insertion / extraction ions also decreases). In this case, the capacity is determined by the number of insertion / extraction sites, that is, the capacity loss is determined by the amount of positive / negative electrode active materials lost.

[0061] The IC curve of a battery reflects the structural characteristics of the positive and negative electrode materials. Since the battery capacity decay mainly comes from the loss of intercalation / deintercalation ions (LII), loss of negative electrode active material (LAAM), and loss of positive electrode active material (LACM), the characteristics of the IC curve are strongly correlated with the battery capacity decay, which is very important for studying the health status of the battery. By monitoring the peak position, peak area, and peak height of specific peaks in the IC curve, the capacity loss changes of the battery during its lifetime can be studied and used to estimate the state of energy loss (SOH).

[0062] The battery health status assessment method provided in this invention adopts incremental capacity analysis. It establishes a first relationship between the three capacity losses (positive electrode active material loss, negative electrode active material loss, and intercalation / deintercalation ion loss) of a calibrated battery at a first rate and the first characteristic value of the peak on the IC curve in the corresponding IC curve set. It also establishes a second relationship between the second characteristic value of the peak on the IC curve of the battery under test and the rate. Then, it substitutes the first rate into the second relationship to obtain the second characteristic value of the battery under test at the first rate. Finally, it substitutes the second characteristic value of the battery under test at the first rate into the first relationship to obtain the positive electrode active material loss (LACM), negative electrode active material loss (LAAM), and intercalation / deintercalation ion loss (LII) of the battery under test at the first rate. Finally, it calculates the SOH of the battery under test using the SOH calculation formula. The method for assessing the state of health (SOH) of the battery under test not only comprehensively considers various loss modes of capacity loss, improving the accuracy and expanding the applicability of the SOH assessment method, but also is not limited by the real-time rate of the battery (i.e., the charging or discharging rate of the battery under test during actual operation). In other words, this assessment method can be used to estimate the SOH of the battery under test at both low and high rates. Therefore, it can conveniently, quickly, and reliably estimate the SOH of the battery under test at high rates, making it better applicable to real-world scenarios such as vehicles. This solves the technical drawback of existing incremental capacity analysis methods that can only be used under a single low current.

[0063] Current incremental capacity analysis methods primarily estimate State of Harmony (SOH) under single low-current charge / discharge conditions, requiring actual charging / discharging of the battery with a small current. This neglects the need for high-rate charging / discharging in real-world vehicle applications. In contrast, this application only requires pre-establishing the aforementioned first and second relationships. In practical applications such as vehicle manufacturing, the SOH can be obtained simply by substituting the first rate into the corresponding relationship, without needing to use a low-current charge / discharge method.

[0064] In one implementation, the real-time rate is greater than or equal to the first rate. In another implementation, the first rate is a low rate, less than or equal to 0.1C, for example, 0.05C; the real-time rate is a high rate, greater than or equal to 1C. Since the first rate is a low rate, battery polarization caused by current can be ignored during charging and discharging under low rate conditions. Therefore, the first relationship between the loss of positive electrode active material, the loss of negative electrode active material, and the loss of intercalation / deintercalation ions in the calibrated battery and their corresponding first characteristic values ​​can be obtained more accurately. Thus, based on the first relationship of the calibrated battery under low rate charging and discharging conditions, and combined with the second relationship between the second characteristic value of the IC curve of the battery under test and the rate, the SOH of the battery under test under high rate charging and discharging conditions can be accurately obtained.

[0065] In one implementation, in step S3 above, at least some of the multiple different second rates are greater than or equal to the first rate. In another implementation, the difference between adjacent second rates is greater than or equal to 0.1C. In yet another implementation, all of the multiple different second rates are less than or equal to 1C. The number of second rates is at least three, preferably at least four (in this embodiment, four rate values ​​are selected: 0.05C, 0.33C, 0.5C, and 1C). This allows for a more accurate determination of the second characteristic value of the IC curve of the battery under test and the second relationship between the rate.

[0066] As one implementation method, the above-mentioned step S3 specifically includes:

[0067] The battery under test is discharged to the lower limit voltage, and then charged to its upper limit voltage at multiple different second rates. The capacity and voltage data of the battery under test during the charging process are obtained. The capacity and voltage data of the battery under test during the charging process are processed (i.e., the voltage is differentiated by the full capacity of the battery under test, and the differentiation formula is IC = dQ / dV) to obtain the IC curve of the battery under test at multiple different second rates.

[0068] Alternatively, the battery under test is charged to its upper limit voltage, and then discharged to its lower limit voltage at multiple different second-rate discharges. The capacity and voltage data of the battery under test during the discharge process are obtained, and the capacity and voltage data of the battery under test during the discharge process are processed to obtain the IC curves of the battery under test at multiple different second-rate discharges.

[0069] The lower limit voltage refers to the discharge termination voltage specified in the manufacturer's technical specifications (i.e., the lowest voltage value at which the battery should no longer discharge). The upper limit voltage (also known as the charging limit voltage) refers to the maximum voltage value of the battery when it transitions from constant current charging to constant voltage charging, as specified by the manufacturer; this voltage value is mainly used to protect the battery and prevent overcharging.

[0070] As one implementation method, the step of obtaining the IC curve set of the calibration battery under multiple different positive electrode active material loss amounts, multiple different negative electrode active material loss amounts, and multiple different intercalation / deintercalation ion loss amounts in step S1 specifically includes:

[0071] The positive electrode OCP (Open Circuit Potential) curves and negative electrode OCP curves of the calibration battery were obtained under multiple different positive electrode active material loss amounts, multiple different negative electrode active material loss amounts, and multiple different intercalation / deintercalation ion loss amounts, respectively.

[0072] Based on the OCP curves of each positive electrode and each negative electrode of the calibration battery, the OCV (Open Circuit Voltage) curves of the calibration battery under multiple different positive electrode active material loss amounts, multiple different negative electrode active material loss amounts, and multiple different intercalation / deintercalation ion loss amounts are obtained respectively.

[0073] Based on the various OCV curves of the calibration battery, IC curve sets of the calibration battery under multiple different positive electrode active material loss amounts, multiple different negative electrode active material loss amounts, and multiple different intercalation / deintercalation ion loss amounts are obtained respectively.

[0074] Specifically, the OCV (full cell voltage) of a battery can be determined by the open-circuit potential (OCP) of the battery's positive terminal. pos Subtract the battery's negative open-circuit potential (OCP) neg We obtain that OCV = OCP pos -OCP neg Therefore, after obtaining the positive and negative OCP curves of the battery, the OCV curve can be obtained; the positive and negative OCP curves can be obtained by charging / discharging the battery. After obtaining the OCV curve, the battery capacity of the entire battery is differentiated from the total voltage value in the OCV curve using the formula IC = dQ / dOCV, to obtain the IC value (in Ah / V) corresponding to each voltage value, and thus the IC curve (dQ / dV-V) is obtained.

[0075] In one implementation, the values ​​of the loss of positive electrode active material, the loss of negative electrode active material, and the loss of intercalation / deintercalation ions in the calibration battery are all greater than or equal to 0.

[0076] In one implementation, the loss amounts of multiple different positive electrode active materials, multiple different negative electrode active materials, and multiple different intercalation / deintercalation ion losses of the calibration battery each include 0 and multiple values ​​greater than 0. Step S1 specifically includes:

[0077] A calibration battery is provided, and the calibration battery is charged or discharged at a first rate to obtain the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state. Based on the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state, the OCV curve of the calibration battery in the initial state is obtained. Simultaneously, the positive electrode usage area and negative electrode usage area of ​​the calibration battery can be obtained through the positive electrode OCP curve, negative electrode OCP curve, and OCV curve of the calibration battery in the initial state. The initial state is the state in which the loss of positive electrode active material, the loss of negative electrode active material, and the loss of intercalation / deintercalation ions are all 0.

[0078] Multiple positive electrode active material loss values ​​greater than 0, multiple negative electrode active material loss values ​​greater than 0, and multiple deintercalation / intercalation ion loss values ​​greater than 0 are designed (the positive electrode active material loss value, negative electrode active material loss value, and deintercalation / intercalation ion loss value can be set according to the positive electrode and negative electrode usage areas). Simulation is used (i.e., computer software simulation, specifically by establishing the corresponding IC construction module in MATLAB software). Based on the designed positive electrode active material loss value, negative electrode active material loss value, and deintercalation / intercalation ion loss value... The positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state are proportionally shrunk and translated to obtain the positive electrode OCP curve and negative electrode OCP curve of the calibration battery under multiple positive electrode active material loss amounts greater than 0, multiple negative electrode active material loss amounts greater than 0, and multiple deintercalation / intercalation ion loss amounts greater than 0, respectively. Then, the OCV curve of the calibration battery under multiple positive electrode active material loss amounts greater than 0, multiple negative electrode active material loss amounts greater than 0, and multiple deintercalation / intercalation ion loss amounts greater than 0, respectively.

[0079] Based on the various OCV curves of the calibration battery, IC curve sets are obtained for the calibration battery under multiple different positive electrode active material loss amounts, multiple different negative electrode active material loss amounts, and multiple different intercalation / deintercalation ion loss amounts. That is, in this embodiment, each IC curve set obtained under multiple different positive electrode active material loss amounts, multiple different negative electrode active material loss amounts, and multiple different intercalation / deintercalation ion loss amounts includes the IC curve of the calibration battery in its initial state. Furthermore, the IC curve of the calibration battery in its initial state is obtained by actually charging and discharging the calibration battery, while the IC curves of the calibration battery under other loss states are constructed through simulation.

[0080] In one implementation, in step S1 above, the loss of multiple positive electrode active materials in the calibrated battery design increases sequentially, and the gradient of the increase in the loss of multiple positive electrode active materials (i.e., the difference between the loss of two adjacent positive electrode active materials) is 3%-30% (preferably 5%-15%). The loss of multiple negative electrode active materials in the calibrated battery design increases sequentially, and the gradient of the increase in the loss of multiple negative electrode active materials is 3%-30% (preferably 5%-15%). The loss of multiple intercalation / deintercalation ions in the calibrated battery design increases sequentially, and the gradient of the increase in the loss of multiple intercalation / deintercalation ions is 3%-30% (preferably 5%-15%).

[0081] In one implementation, both the first and second relationships are linear relationships (i.e., linear functions). That is, in step S2 above, the first relationships between the loss of positive electrode active material, the loss of negative electrode active material, and the loss of intercalation / deintercalation ions of the calibrated battery and the corresponding first characteristic values ​​are all linear relationships; in step S4 above, the second relationships between the peak position and the rate of the IC curve of the battery under test, the second relationships between the peak area and the rate, and the second relationships between the peak height and the rate are all linear relationships.

[0082] In one implementation, in steps S1 and S3 above, both the calibration battery and the battery under test are charged or discharged at a preset temperature, which is 20°C-28°C, for example, 25°C.

[0083] like Figure 1 As shown, in one implementation, the positive electrode OCP curve (SOC-V), negative electrode OCP curve (SOC-V), OCV curve (SOC-V), and IC curve (dQ / dV-V) of the calibration battery in the initial state (BOL state) are placed in the same coordinate system (e.g., Figure 1 , Figure 1 The vertical axis on the left represents the voltage values ​​of the positive OCP curve, OCV curve, and IC curve. Figure 1 The right-hand vertical axis represents the voltage value of the negative electrode OCP curve. The voltage range corresponding to the two valleys of any peak on the IC curve corresponds to the SOC range of the OCV curve. Furthermore, the SOC range of the OCV curve corresponds to the positive electrode usage area in the positive electrode OCP curve and the negative electrode usage area in the negative electrode OCP curve. The integral of the peak area in the IC curve represents the capacity, which is related to the length (i.e., capacity value) of the corresponding positive and negative electrode usage areas in the OCP curve. The peak position of the IC curve is related to the position of the positive and negative electrode plateaus in the OCP curve. Experiments have shown that the peak height of the IC curve is related to the slope of the OCP curve.

[0084] like Figures 1 to 4bAs shown, when the positive / negative electrode of the calibrated battery experiences losses, it is manifested as a contraction or shift in the positive / negative electrode OCP curve. Specifically, when the positive / negative electrode materials of the calibrated battery are materials with a plateau, the OCP curve shows a change in the length of the plateau; when the positive / negative electrode materials of the calibrated battery are materials without a plateau or with an indistinct plateau, the OCP curve shows a change in the slope of the curve. Materials without a plateau or with an indistinct plateau include lithium cobalt oxide, ternary materials, and soft carbon, while materials with a plateau include graphite, lithium titanate, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium manganese oxide, Na3V2(PO4)3, Na2Fe2(CN)6, and NaNi. 0.6 Fe 0.25 Mn 0.15 O2, etc.

[0085] Specifically, when the negative electrode of the calibrated battery is made of a material with a plateau, if the negative electrode of the calibrated battery experiences loss, the plateau length of the negative electrode OCP curve will change. That is, the length of the negative electrode's usable region and the position of the plateau will change, corresponding to changes in the peak area and peak position of the IC curve. When the negative electrode of the calibrated battery is made of a material without a plateau or with an indistinct plateau, if the negative electrode of the calibrated battery experiences loss, the slope of the negative electrode OCP curve will change, corresponding to changes in the peak height of the IC curve. Similarly, when the positive electrode of the calibrated battery is made of a material with a plateau, if the positive electrode of the calibrated battery experiences loss, the plateau length of the positive electrode OCP curve will change. That is, the length of the positive electrode's usable region and the position of the plateau will change, corresponding to changes in the peak area and peak position of the IC curve. When the positive electrode of the calibrated battery is made of a material without a plateau or with an indistinct plateau, if the positive electrode of the calibrated battery experiences loss, the slope of the positive electrode OCP curve will change, corresponding to changes in the peak height of the IC curve. When intercalation / deintercalation ions are lost, the plateau of the positive / negative electrode OCP curve shifts, resulting in a change in the usable region of the positive / negative electrode, and the corresponding peak position of the IC curve changes.

[0086] Because the loss of positive / negative electrode materials with a plateau will cause changes in the peak area and peak position of the IC curve, and the loss of intercalation / deintercalation ions will also cause changes in the peak position of the IC curve, to ensure the singularity of quantitative conditions, the peak position can be selected as a characteristic for quantifying the loss of intercalation / deintercalation ions, and the peak area can be selected as a characteristic for quantifying the loss of the positive / negative electrode active materials with a plateau. Therefore, in the above S2 step, one of the loss of positive and negative active materials in the calibration battery can be correlated with the peak area of ​​the IC curve in the IC curve set of the calibration battery, and the other of the loss of positive and negative active materials in the calibration battery can be correlated with the peak height of the IC curve in the IC curve set of the calibration battery; the loss of intercalation / deintercalation ions in the calibration battery can be correlated with the peak position of the IC curve in the IC curve set of the calibration battery.

[0087] As one implementation method, in order to ensure that the loss of positive and negative electrode active materials or the loss of intercalation / deintercalation ions can be quantified independently using specific IC curve characteristic values, the battery system applicable to the calibration battery has the following characteristics: one of the positive and negative electrodes of the calibration battery is a plateau material, and the other is a material without a plateau or with an indistinct plateau. The positive electrode of the calibration battery is a positive electrode material with a plateau. In this case, the loss of positive electrode active material in the calibration battery corresponds to the peak area of ​​the IC curve in the IC curve set of the calibration battery (i.e., in step S2 above, a quantitative relationship is established between the loss of positive electrode active material and the peak area of ​​the calibration battery). The negative electrode of the calibration battery is a negative electrode material without a plateau or with an indistinct plateau. The loss of negative electrode active material in the calibration battery corresponds to the peak height of the IC curve in the IC curve set of the calibration battery (i.e., in step S2 above, a quantitative relationship is established between the loss of negative electrode active material and the peak height of the calibration battery). The loss of intercalation / deintercalation ions in the calibration battery corresponds to the peak position of the IC curve in the IC curve set of the calibration battery (i.e., in step S2 above, a quantitative relationship is established between the loss of intercalation / deintercalation ions in the calibration battery and the peak position of the calibration battery). Alternatively, the positive electrode of the calibration battery is a positive electrode material with no plateau or an indistinct plateau, and the loss of positive electrode active material in the calibration battery corresponds to the peak height of the IC curve in the IC curve set of the calibration battery (i.e., in step S2 above, a quantitative relationship is established between the loss of positive electrode active material and the peak height of the calibration battery); the negative electrode of the calibration battery is a negative electrode material with a plateau, and the loss of negative electrode active material in the calibration battery corresponds to the peak area of ​​the IC curve in the IC curve set of the calibration battery (i.e., in step S2 above, a quantitative relationship is established between the loss of negative electrode active material and the peak area of ​​the calibration battery); the loss of intercalation / deintercalation ions in the calibration battery corresponds to the peak position of the IC curve in the IC curve set of the calibration battery (i.e., in step S2 above, a quantitative relationship is established between the loss of intercalation / deintercalation ions in the calibration battery and the peak position of the calibration battery). In summary, the correspondence between the characteristic values ​​of the IC curves in the IC curve set and the various losses is as follows: a change in the area of ​​a peak in the IC curve set corresponds to the loss of material with a plateau; a change in the height of a peak in the IC curve set corresponds to the loss of material without a plateau or with an indistinct plateau; and a change in the position of a peak in the IC curve set corresponds to the loss of intercalation / deintercalation ions. Of course, in other embodiments, the positive and negative electrodes of the calibration battery can also be materials with plateaus, but the plateaus in the positive and negative electrode usage areas covered by the peaks must not overlap.

[0088] As one implementation method, to more clearly correlate the changes in the characteristic values ​​of the IC curves in the IC curve set with the loss of positive electrode active material, the loss of negative electrode active material, and the loss of intercalation / deintercalation ions, in step S2 above, the peak position, peak area, and peak height of the IC curves in the IC curve set of the calibration battery are respectively the first characteristic values ​​of different peaks in the IC curves of the IC curve set of the calibration battery (for example, extracting the peak position of peak A, the peak area of ​​peak B, and the peak height of peak C in the IC curve set, where peaks A, B, and C are different peaks in the IC curve set); and when extracting the characteristic values ​​of the IC curves in the IC curve set of the calibration battery, the first characteristic values ​​of the peaks with the largest changes in peak position, peak area, and peak height are selected respectively (i.e., peaks with more obvious characteristic value changes are selected). As one implementation method, in step S2 above, when extracting the first characteristic values ​​of the IC curves in the IC curve set of the calibration battery, the peak position of the first peak, the peak area of ​​the largest area among the middle peaks, and the peak height of the last peak can be selected respectively.

[0089] Specifically, such as Figures 1 to 5c As shown, the calibration battery is illustrated using graphite (a material with a plateau) as the negative electrode and ternary NCM (a material with no or indistinct plateau) as the positive electrode. This calibration battery is a lithium-ion battery. The IC curve of this calibration battery using the graphite-ternary NCM system includes four peaks, which are, from low potential to high potential, Peak1 (peak 1 in the figure), Peak2 (peak 2 in the figure), Peak3 (peak 3 in the figure), and Peak4 (peak 4 in the figure).

[0090] like Figure 2a and Figure 2b As shown, Figure 2a The diagram illustrates the positive electrode OCP curve, negative electrode OCP curve, and full cell OCV curve of the calibration battery when the loss of positive electrode active material is 0% (i.e., no loss), 15%, and 30%, respectively. When the loss of positive electrode active material is 0%, the loss of negative electrode active material and the loss of intercalation / deintercalation ions are both 0%. Figure 2b The IC curves of the calibration battery are shown when the loss of positive electrode active material is 0%, 15%, and 30%, respectively. Figure 2a As shown, when the NCM of the cathode material is lost, the cathode OCP curve shrinks, and the slope of the cathode OCP curve changes, becoming different from... Figure 2b The correspondence of Peak4 on the IC curve is most obvious; the shape of the negative electrode OCP curve does not change, only the negative electrode usage area becomes shorter, so the height of the last peak (Peak4) can be used to represent the loss of positive electrode active material.

[0091] By performing curve fitting between the peak height of Peak4 and the loss of the positive electrode active material, a linear relationship was established, thus obtaining the first relationship between the peak height of Peak4 and the loss of the positive electrode active material, as follows: Figure 5a As shown, the quantitative relationship between the peak height of Peak4 and the loss of positive electrode active material is: y1 = -0.3971x1 + 14.745 (note that x1 is a percentage value; for example, if the loss of positive electrode active material is 15%, then x1 = 15 should be substituted into the formula), where x1 represents the loss of positive electrode active material and y1 represents the peak height of Peak4. In step S5 above, after calculating the peak height of Peak4 on the IC curve of the battery under test at the first rate, substituting it into the above formula yields the loss of positive electrode active material LACM of the battery under test.

[0092] like Figure 3a and Figure 3b As shown, Figure 3a The diagram illustrates the positive electrode OCP curve, negative electrode OCP curve, and full cell OCV curve of the calibrated battery when the loss of negative electrode active material is 0% (i.e., no loss), 15%, and 30%, respectively. When the loss of negative electrode active material is 0%, the loss of positive electrode active material and the loss of intercalation / deintercalation ions are both 0%. Figure 3b The IC curves of the calibrated battery are shown when the loss of negative electrode active material is 0%, 15%, and 30%, respectively. Figure 3a As shown, when graphite loss occurs in the negative electrode, the shape of the positive electrode OCP curve remains unchanged, while the negative electrode OCP curve contracts, and the width of each plateau on the negative electrode OCP curve changes, corresponding to the following effects. Figure 3b The changes in peak area and peak position of the IC curve; since the loss of intercalation / deintercalation ions (usable lithium loss) also causes changes in the peak position of the IC curve, the peak area of ​​the IC curve is selected as a characteristic for quantitatively measuring the loss of negative electrode active material. Theoretically, each peak area can represent the loss of negative electrode active material, but since the change of the second plateau is the most obvious, the area of ​​the second peak (Peak2) is selected to represent the loss of negative electrode active material.

[0093] By curve fitting between the peak area of ​​Peak2 and the loss of the negative electrode active material, a linear relationship was established, thus obtaining a quantitative relationship between the peak area of ​​Peak2 and the loss of the negative electrode active material, as follows: Figure 5bAs shown, the quantitative relationship between the peak area of ​​Peak2 and the loss of negative electrode active material is: y2 = -0.0966x2 + 10.382 (Note that x2 is a percentage value; for example, if the loss of negative electrode active material is 15%, then x2 = 15 should be substituted into the formula), where x2 represents the loss of negative electrode active material and y2 represents the peak area of ​​Peak2. In step S5 above, after calculating the peak area of ​​Peak2 on the IC curve of the battery under test at the first rate, substituting it into the above formula yields the loss of negative electrode active material LAAM of the battery under test.

[0094] like Figure 4a and Figure 4b As shown, Figure 4a The diagram illustrates the positive electrode OCP curve, negative electrode OCP curve, and full cell OCV curve of the calibrated battery when the amount of deintercalation / intercalation ion loss (usable lithium loss) is 0% (i.e. no loss), 15%, and 30%, respectively. When the amount of deintercalation / intercalation ion loss is 0%, the loss of positive electrode active material and the loss of negative electrode active material are both 0%. Figure 4b The IC curves of the calibrated battery are shown at ion deintercalation / intercalation loss rates (usable lithium loss rates) of 0%, 15%, and 30%. Figure 4a As shown, under the loss of intercalation / deintercalation ions (usable lithium loss), the shapes of both the positive and negative electrode OCP curves remain unchanged, while the negative electrode OCP curve shifts, manifested as a change in the position of each peak. Observation Figure 4b The position of Peak1 was found to be the most significant, so the position of Peak1 was selected to represent the loss of intercalation / deintercalation ions (which can be used for lithium loss).

[0095] By curve fitting and establishing a linear relationship between the peak position of Peak1 and the loss of intercalation / deintercalation ions (usable lithium loss), a quantitative relationship between the peak position of Peak1 and the loss of intercalation / deintercalation ions (usable lithium loss) is obtained, as follows: Figure 5c As shown, the quantitative relationship between the peak position of Peak1 and the amount of deintercalation / intercalation ion loss (usable lithium loss) is: y3 = 0.003x3 + 3.4663 (Note that x3 is a percentage value; for example, if the deintercalation / intercalation ion loss is 15%, then x3 = 15 should be substituted into the formula), where x3 represents the amount of deintercalation / intercalation ion loss (usable lithium loss), and y3 represents the peak position of Peak1. In step S5 above, after calculating the peak position of Peak1 on the IC curve of the battery under test at the first rate, substituting it into the above formula yields the amount of deintercalation / intercalation ion loss (usable lithium loss) LII of the battery under test.

[0096] The principles of this invention will be further explained below:

[0097] The IC curve is obtained by differentiating the total cell capacity with respect to the voltage, i.e., IC = dQ / dOCV; while the total cell voltage OCV is obtained by subtracting the negative cell's OCP from the positive cell's OCP, i.e., OCV = OCP. pos -OCP neg Therefore, the IC curve includes the voltage characteristics of the positive and negative electrode operating regions.

[0098] The peak position of the IC curve is related to the plateau of the OCP curves of the positive and negative electrodes. Taking a lithium-ion battery with a graphite negative electrode and a ternary (NCM) positive electrode system as an example, such as... Figure 1 As shown, graphite typically exhibits three distinct plateaus within its operating range, denoted as Plateau 1, Plateau 2, and Plateau 3. The positive electrode also exhibits a plateau at high voltage, denoted as Plateau 4. Correspondingly, the IC curve shows four peaks: peak 1, peak 2, peak 3, and peak 4, from low to high potential (positioned from bottom to top in the figure), correspond to negative electrode plateau 1, plateau 2, plateau 3, and positive electrode plateau 4, respectively. Therefore, the features extracted from the IC curve correspond to the characteristics of the positive and negative electrode OCP curves.

[0099] Battery aging modes can be categorized into intercalation / deintercalation ion loss (LII loss), positive electrode active material loss (LACM loss), and negative electrode active material loss (LAAM loss). When only intercalation / deintercalation ion loss occurs, the change in the positive / negative electrode operating region manifests as a shift of the positive / negative electrode OCP curves relative to the BOL state (i.e., initial state) towards higher potentials, with the plateau shifting upwards and the corresponding IC peak position changing. When only positive (or negative) electrode loss occurs, the OCP operating region of the positive (or negative) electrode shrinks. For materials with a pronounced plateau, such as graphite, lithium titanate, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium manganese oxide, Na3V2(PO4)3, Na2Fe2(CN)6, and NaNi, the loss will be more pronounced. 0.6 Fe 0.25 Mn 0.15 O2, etc., are reflected in the change of IC peak area. For materials with no plateau or an indistinct plateau, such as lithium cobalt oxide, ternary materials and soft carbon, the region where the OCP curve is close to linear is reflected in the change of IC peak height.

[0100] Voltage and IC curves with LACM loss, LAAM loss, and LII loss of 0%, 15%, and 30% respectively are selected as examples.

[0101] like Figure 2a As shown, in LACM mode, losses occur at the positive electrode, the positive electrode OCP curve shrinks, and the slope of the positive electrode OCP curve increases at high potentials, corresponding to... Figure 2b The height of peak 4 decreased; no loss occurred at the negative electrode, corresponding to... Figure 2b The area of ​​the middle peak 2 remains unchanged.

[0102] like Figure 3a As shown, in LAAM mode, losses occur at the negative electrode, the negative electrode OCP curve shrinks, and the length of the negative electrode OCP curve plateau becomes shorter, corresponding to... Figure 3b The area of ​​peak 2 decreased; no loss occurred at the positive electrode, corresponding to... Figure 3b The height of the middle peak 4 remains unchanged.

[0103] like Figure 4a As shown, in LII mode, there is a loss of intercalation / deintercalation ions, but no loss occurs at either the positive or negative electrode. The length of the OCP curve plateau at the negative electrode remains unchanged, corresponding to the area of ​​peak 2 in 4b remaining unchanged. The slope of the OCP curve at the positive electrode remains unchanged, corresponding to... Figure 4b The height of peak 4 remains unchanged, only the negative electrode OCP curve shifts, and the position of the negative electrode OCP plateau moves, corresponding to... Figure 4b Changes in the position of the middle peak 1.

[0104] Figures 5a to 5c A schematic diagram illustrating the relationship between battery loss and peak characteristic values ​​under different aging modes, such as... Figures 5a to 5c As shown, the LACM loss is linearly related to the height of peak 4, the LAAM loss is linearly related to the area of ​​peak 2, and the LII loss is linearly related to the position of peak 1. Therefore, the loss of positive and negative electrodes or intercalation / deintercalation ions under different aging modes can be calculated by observing the changes in the peak characteristics of the IC curve. Figures 7a to 7c These are schematic diagrams illustrating the relationship between the peak position, peak height, and peak area of ​​the battery under test and the rate capability, as shown below. Figures 7a to 7c As shown, the position of peak 1 has a linear relationship with the rate, the height of peak 4 has a linear relationship with the rate, and the area of ​​peak 2 has a linear relationship with the rate. Therefore, based on the relationship between the peak characteristics of the IC curve of the battery under test and the rate, the position of peak 1, the height of peak 4, and the area of ​​peak 2 at the first rate can be calculated. Then, based on the relationship between LII loss and peak 1 position, LACM loss and peak 4 height, and LAAM loss and peak 2 area, the loss of positive electrode active material LACM, the loss of negative electrode active material LAAM, and the loss of intercalation / deintercalation ions LII at the first rate can be calculated. Since the capacity loss of the battery is usually determined by the dominant loss among the above three types, the SOH of the battery under test can be calculated using the SOH calculation formula: SOH = 100% - max(LII, LAAM, LACM).

[0105] The following example illustrates the steps of the method for assessing the health status of the battery under test:

[0106] 1. For example Figures 1 to 4bAs shown, the calibration battery in its initial state is charged or discharged at a rate of 0.05C (i.e., the first rate is 0.05C) to obtain the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in its initial state.

[0107] The design calibration battery has positive electrode active material loss, negative electrode active material loss, and deintercalation / intercalation ion loss of 15% and 30%, respectively. Based on the designed positive electrode active material loss, negative electrode active material loss, and deintercalation / intercalation ion loss, the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state are proportionally shrunk and translated to obtain the positive electrode OCP curve and negative electrode OCP curve of the calibration battery when the positive electrode active material loss, negative electrode active material loss, and deintercalation / intercalation ion loss are 15% and 30%, respectively.

[0108] Based on the positive electrode OCP curves and negative electrode OCP curves of the calibrated battery when the loss of positive electrode active material, the loss of negative electrode active material, and the loss of intercalation / deintercalation ions are 0%, 15%, and 30%, respectively, the OCV curves of the calibrated battery when the loss of positive electrode active material, the loss of negative electrode active material, and the loss of intercalation / deintercalation ions are 0%, 15%, and 30%, respectively.

[0109] Based on the various OCV curves of the calibration battery, the IC curves of the calibration battery at the loss of positive electrode active material, loss of negative electrode active material, and loss of intercalation / deintercalation ions are obtained respectively, forming an IC curve set.

[0110] 2. For example Figures 5a to 5c As shown, the peak height of Peak4, the peak area of ​​Peak2, and the peak position of Peak1 of the IC curves in each IC curve group of the calibration battery are extracted respectively. The first relationship between the loss of positive electrode active material and the peak height of Peak4, the loss of negative electrode active material and the peak area of ​​Peak2, and the loss of intercalation / deintercalation ions and the peak position of Peak1 are established respectively.

[0111] 3. For example Figure 6a and Figure 6b As shown, the battery under test was charged or discharged at rates of 0.05C, 0.33C, 0.5C and 1C, respectively. The voltage and capacity of the battery under test were recorded during the charging or discharging process, and the voltage-capacity curves and IC curves of the battery under test at rates of 0.05C, 0.33C, 0.5C and 1C were obtained.

[0112] 4. For example Figures 7a to 7cAs shown, the peak height of Peak4, the peak area of ​​Peak2, and the peak position of Peak1 of the IC curves of the battery under test at 0.05C, 0.33C, 0.5C, and 1C rates are extracted respectively. Secondary relationships are established between the peak height of Peak4 and the rate, the peak area of ​​Peak2 and the rate, and the peak position of Peak1 and the rate, respectively. (The last sentence appears to be incomplete and possibly refers to a different topic.) Figure 7b As shown, since the peak height of Peak4 remains essentially constant at different magnifications, the second relationship between the peak height of Peak4 and the magnification can be considered a constant. Figure 7c As shown, the second relationship between the peak area of ​​Peak2 and the magnification is y4 = -1.8811x4 + 9.9566, where x4 represents the magnification and y4 represents the peak area of ​​Peak2. Figure 7a As shown, the second relationship between the peak position of Peak1 and the magnification is y5 = 0.1004x5 + 3.4996, where x5 represents the magnification and y5 represents the peak position of Peak1.

[0113] 5. Substitute the first rate (0.05C) into the above-mentioned second relationships to obtain the peak height of Peak4, the peak area of ​​Peak2, and the peak position of Peak1 of the battery under test at the first rate; then substitute the peak height of Peak4, the peak area of ​​Peak2, and the peak position of Peak1 of the battery under test at the first rate into the corresponding first relationships to obtain the loss of positive electrode active material LACM, the loss of negative electrode active material LAAM, and the loss of intercalation / deintercalation ions LII of the battery under test at the first rate;

[0114] Substitute the loss of positive electrode active material LACM, the loss of negative electrode active material LAAM, and the loss of intercalation / deintercalation ions LII into the SOH calculation formula. According to the SOH calculation formula: SOH=100%-max(LII,LAAM,LACM), the SOH of the battery under test can be obtained.

[0115] Example 1

[0116] The main instruments and equipment used in this embodiment include a computer, a Shenzhen Xinwei battery tester (CT-4004-5V300A-NTFA), and a high and low temperature chamber. The battery tester is used to charge and discharge the battery, and the high and low temperature chamber is used to control the test temperature of the battery.

[0117] In this embodiment, the measurement object is lithium-ion battery A. The positive electrode of lithium-ion battery A is made of ternary material, the negative electrode is made of graphite material, the lithium salt in the electrolyte is lithium hexafluorophosphate, and the capacity is 21Ah. Lithium-ion battery A is an end-of-life battery.

[0118] The specific steps are as follows:

[0119] 1. Charge or discharge the calibration battery in its initial state (BOL state) at a rate of 0.05C (i.e., the first rate is 0.05C) to obtain the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state. That is, obtain the positive electrode OCP curve and negative electrode OCP curve when the loss of positive electrode active material, the loss of negative electrode active material, and the loss of intercalation / deintercalation ions are all 0%. The calibration battery is the same type as lithium-ion battery A, and the positive and negative electrode materials and electrolytes of the calibration battery and lithium-ion battery A are the same.

[0120] In the IC architecture module of the computer, the loss of positive active material, negative active material, and intercalation / deintercalation ion loss of the calibration battery are designed to be 15% and 30%, respectively. Based on the designed loss of positive active material, negative active material, and intercalation / deintercalation ion loss, the positive and negative OCP curves of the calibration battery in the initial state are proportionally shrunk and shifted to obtain the positive and negative OCP curves of the calibration battery when the loss of positive active material, negative active material, and intercalation / deintercalation ion loss are 15% and 30%, respectively.

[0121] Based on the positive and negative electrode OCP curves of the calibrated battery at 0%, 15%, and 30% losses of positive active material, negative active material, and intercalation / deintercalation ions, respectively, the OCV curves of the calibrated battery at 0%, 15%, and 30% losses of positive active material, negative active material, and intercalation / deintercalation ions, respectively, are obtained (e.g. Figure 2a , 3a (as shown in 4a);

[0122] Based on the various OCV curves of the calibration battery, the IC curves of the calibration battery at 0%, 15%, and 30% for positive electrode active material loss, negative electrode active material loss, and intercalation / deintercalation ion loss, respectively, were obtained, forming an IC curve set (e.g., Figure 2b , 3b (as shown in 4b).

[0123] 2. Extract the peak height of Peak4, the peak area of ​​Peak2, and the peak position of Peak1 from each IC curve group of the calibration battery, and establish the first relationship between the loss of positive electrode active material and the peak height of Peak4, the loss of negative electrode active material and the peak area of ​​Peak2, and the loss of intercalation / deintercalation ions and the peak position of Peak1, respectively.

[0124] Specifically, the first relationship between the loss of positive electrode active material and the peak height of Peak4 is: y1 = -0.3971x1 + 14.745, where x1 represents the loss of positive electrode active material and y1 represents the peak height of Peak4 (e.g., ...). Figure 5a (as shown);

[0125] The first relationship between the loss of negative electrode active material and the peak area of ​​Peak2 is: y2 = -0.0966x2 + 10.382, where x2 represents the loss of negative electrode active material and y2 represents the peak area of ​​Peak2 (e.g., ...). Figure 5b (as shown);

[0126] The first relationship between the loss of intercalation / deintercalation ions and the peak position of Peak1 is: y3 = 0.003x3 + 3.4663, where x3 represents the loss of intercalation / deintercalation ions, and y3 represents the peak position of Peak1 (e.g., ...). Figure 5c (As shown).

[0127] 3. Place lithium-ion battery A in a high-low temperature chamber, set the temperature of the high-low temperature chamber to 25℃, and allow the high-low temperature chamber to reach thermal equilibrium (let the high-low temperature chamber stand for 2 hours to be considered to have reached thermal equilibrium), and connect lithium-ion battery A to the battery tester.

[0128] 4. Using a battery tester, discharge lithium-ion battery A at a constant current rate of 0.33C until its cutoff voltage V. min (2.7V), rest for 1 hour, then charge lithium-ion battery A at a constant current rate of 0.05C until its cutoff voltage V. max (4.25V), the charging voltage and capacity of lithium-ion battery A are recorded using a computer.

[0129] 5. Repeat steps 3 and 4 above, replacing the charging rate in step 4 with 0.33C, 0.5C and 1C respectively, until all tests are completed.

[0130] 6. For example Figure 8 As shown, based on the charging voltage and capacity of lithium-ion battery A at charging rates of 0.05C, 0.33C, 0.5C and 1C, the IC curves of lithium-ion battery A at charging rates of 0.05C, 0.33C, 0.5C and 1C are obtained.

[0131] 7. Extract the peak height of Peak4, peak area of ​​Peak2, and peak position of Peak1 from the IC curves of lithium-ion battery A at charging rates of 0.05C, 0.33C, 0.5C, and 1C. Establish second relationships between the peak height of Peak4 and the charging rate, the peak area of ​​Peak2 and the charging rate, and the peak position of Peak1 and the charging rate for lithium-ion battery A. (See the schematic diagram of the relationship between peak position and charging rate for lithium-ion battery A.) Figure 7a As shown in the diagram, the relationship between the peak height and rate capability of lithium-ion battery A is illustrated in the reference diagram. Figure 7b As shown in the diagram, the relationship between the peak area and rate capability of lithium-ion battery A is illustrated in the reference diagram. Figure 7c As shown.

[0132] Specifically, the second relationship between the peak area of ​​Peak2 and the charging rate is: y4 = -1.8811x4 + 9.9566, where x4 represents the charging rate and y4 represents the peak area of ​​Peak2 (e.g., ...). Figure 7c (as shown);

[0133] The second relationship between the peak position of Peak1 and the charging rate is: y5 = 0.1004x5 + 3.4996, where x5 represents the charging rate and y5 represents the peak position of Peak1 (e.g., ...). Figure 7a (as shown);

[0134] Since the peak height of Peak4 remains essentially constant across different magnifications, the second relationship between the peak height of Peak4 and the magnification can be considered a constant: y6 = 13.550, where y6 represents the peak height of Peak4 (e.g., ...). Figure 7b (As shown).

[0135] 8. The real-time rate of lithium-ion battery A is 1C. Substituting the first rate of 0.05C into the above-mentioned second relationships, we obtain the peak area of ​​Peak2, the peak position of Peak1, and the peak height of Peak4 of lithium-ion battery A at the first rate of 0.05C. Then, we substitute the peak area of ​​Peak2, the peak position of Peak1, and the peak height of Peak4 of lithium-ion battery A at the first rate of 0.05C into the corresponding first relationships in step 2 above, respectively, to obtain the positive electrode active material loss LACM, the negative electrode active material loss LAAM, and the intercalation / deintercalation ion loss LII of lithium-ion battery A at the first rate of 0.05C.

[0136] The specific results are shown in Table 1. Table 1 lists the calculated peak 1 position, peak 2 area, and peak 4 height of lithium-ion battery A at 0.05C, as well as the LII loss, LACM loss, and LAAM loss of lithium-ion battery A.

[0137] Table 1

[0138] feature Calculated value (0.05C) Loss (%) Peak 1 position 3.505 LII:13.21 Peak 2 area 9.863 LAAM: 5.38 Peak 4 height 13.550 LACM: 3.01

[0139] Substituting the loss of positive electrode active material LACM, negative electrode active material LAAM, and intercalation / deintercalation ion loss LII of lithium-ion battery A into the SOH calculation formula, according to the SOH calculation formula: SOH = 100% - max(LII, LAAM, LACM), the SOH of lithium-ion battery A at a real-time rate of 1C is found to be 86.79%. Through actual testing using the direct discharge method, the SOH of lithium-ion battery A at 1C is found to be 88.32%, with an error (the difference between the actual SOH and the estimated SOH) of 1.53%. Judging from the error value, the SOH estimation method provided by this invention has high accuracy.

[0140] Example 2

[0141] The main instruments and equipment used in this embodiment include a computer, a Shenzhen Xinwei battery tester (CT-4004-5V300A-NTFA), and a high and low temperature chamber. The battery tester is used to charge and discharge the battery, and the high and low temperature chamber is used to control the test temperature of the battery.

[0142] In this embodiment, the measurement object is lithium-ion battery B. The positive electrode of lithium-ion battery B is made of ternary material, the negative electrode is made of graphite material, the lithium salt in the electrolyte is lithium hexafluorophosphate, and the capacity is 21Ah. Lithium-ion battery B is an end-of-life battery.

[0143] The specific steps are as follows:

[0144] 1. Charge or discharge the calibration battery in its initial state (BOL state) at a rate of 0.05C (i.e., the first rate is 0.05C) to obtain the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state. That is, obtain the positive electrode OCP curve and negative electrode OCP curve when the loss of positive electrode active material, the loss of negative electrode active material, and the loss of intercalation / deintercalation ions are all 0%. The calibration battery is the same type as lithium-ion battery B, and the positive and negative electrode materials and electrolytes of the calibration battery and lithium-ion battery B are the same.

[0145] In the IC architecture module of the computer, the loss of positive active material, negative active material, and intercalation / deintercalation ion loss of the calibration battery are designed to be 15% and 30%, respectively. Based on the designed loss of positive active material, negative active material, and intercalation / deintercalation ion loss, the positive and negative OCP curves of the calibration battery in the initial state are proportionally shrunk and translated to obtain the positive and negative OCP curves of the calibration battery when the loss of positive active material, negative active material, and intercalation / deintercalation ion loss are 15% and 30%, respectively.

[0146] Based on the positive and negative electrode OCP curves of the calibrated battery at 0%, 15%, and 30% losses of positive active material, negative active material, and intercalation / deintercalation ions, respectively, the OCV curves of the calibrated battery at 0%, 15%, and 30% losses of positive active material, negative active material, and intercalation / deintercalation ions, respectively, are obtained (e.g. Figure 2a , 3a (as shown in 4a);

[0147] Based on the various OCV curves of the calibration battery, the IC curves of the calibration battery at 0%, 15%, and 30% for positive electrode active material loss, negative electrode active material loss, and intercalation / deintercalation ion loss, respectively, were obtained, forming an IC curve set (e.g., Figure 2b , 3b (as shown in 4b).

[0148] 2. Extract the peak height of Peak4, the peak area of ​​Peak2, and the peak position of Peak1 from each IC curve group of the calibration battery, and establish the first relationship between the loss of positive electrode active material and the peak height of Peak4, the loss of negative electrode active material and the peak area of ​​Peak2, and the loss of intercalation / deintercalation ions and the peak position of Peak1, respectively.

[0149] Specifically, the first relationship between the loss of positive electrode active material and the peak height of Peak4 is: y1 = -0.3971x1 + 14.745, where x1 represents the loss of positive electrode active material and y1 represents the peak height of Peak4 (e.g., ...). Figure 5a (as shown);

[0150] The first relationship between the loss of negative electrode active material and the peak area of ​​Peak2 is: y2 = -0.0966x2 + 10.382, where x2 represents the loss of negative electrode active material and y2 represents the peak area of ​​Peak2 (e.g., ...). Figure 5b (as shown);

[0151] The first relationship between the loss of intercalation / deintercalation ions and the peak position of Peak1 is: y3 = 0.003x3 + 3.4663, where x3 represents the loss of intercalation / deintercalation ions, and y3 represents the peak position of Peak1 (e.g., ...). Figure 5c (As shown).

[0152] 3. Place lithium-ion battery B in a high-low temperature chamber, set the temperature of the high-low temperature chamber to 25℃, and allow the high-low temperature chamber to reach thermal equilibrium (let the high-low temperature chamber stand for 2 hours to be considered to have reached thermal equilibrium), and connect lithium-ion battery B to the battery tester.

[0153] 4. Using a battery tester, discharge the lithium-ion battery B at a constant current rate of 0.33C until its cutoff voltage V. min (2.7V), rest for 1 hour, then charge lithium-ion battery B at a constant current rate of 0.05C until its cutoff voltage V. max (4.25V), the charging voltage and capacity of lithium-ion battery B were recorded using a computer.

[0154] 5. Repeat steps 3 and 4 above, replacing the charging rate in step 4 with 0.33C, 0.5C and 1C respectively, until all tests are completed.

[0155] 6. For example Figure 9 As shown, based on the charging voltage and capacity of lithium-ion battery B at charging rates of 0.05C, 0.33C, 0.5C and 1C, the IC curves of lithium-ion battery B at charging rates of 0.05C, 0.33C, 0.5C and 1C are obtained.

[0156] 7. Extract the peak height of Peak4, the peak area of ​​Peak2, and the peak position of Peak1 from the IC curves of lithium-ion battery B at charging rates of 0.05C, 0.33C, 0.5C, and 1C, respectively. Establish the second relationship between the peak height of Peak4 and the charging rate, the second relationship between the peak area of ​​Peak2 and the charging rate, and the second relationship between the peak position of Peak1 and the charging rate for lithium-ion battery B, respectively.

[0157] Specifically, the second relationship between the peak area of ​​Peak2 and the charging rate is: y4 = -2.6199x4 + 10.454, where x4 represents the charging rate and y4 represents the peak area of ​​Peak2 (e.g., ...). Figure 10c (as shown);

[0158] The second relationship between the peak position of Peak1 and the charging rate is: y5 = 0.1248x5 + 3.5052, where x5 represents the charging rate and y5 represents the peak position of Peak1 (e.g., ...). Figure 10a (as shown);

[0159] Since the peak height of Peak4 remains essentially constant across different magnifications, the second relationship between the peak height of Peak4 and the magnification can be considered a constant: y6 = 14.152, where y6 represents the peak height of Peak4 (e.g., ...). Figure 10b (As shown).

[0160] 8. The real-time rate of lithium-ion battery B is 1C. Substituting the first rate of 0.05C into the above-mentioned second relationships, we obtain the peak area of ​​Peak2, the peak position of Peak1, and the peak height of Peak4 of lithium-ion battery B at the first rate of 0.05C. Then, we substitute the peak area of ​​Peak2, the peak position of Peak1, and the peak height of Peak4 of lithium-ion battery B at the first rate of 0.05C into the corresponding first relationships in step 2 above, respectively, to obtain the positive electrode active material loss LACM, the negative electrode active material loss LAAM, and the intercalation / deintercalation ion loss LII of lithium-ion battery B at the first rate of 0.05C.

[0161] The specific results are shown in Table 2. Table 2 lists the calculated peak 1 position, peak 2 area, and peak 4 height of lithium-ion battery B at 0.05C, as well as the LII loss, LACM loss, and LAAM loss of lithium-ion battery B.

[0162] Table 2

[0163] feature Calculated value (0.05C) Loss (%) Peak 1 position 3.511 LII: 15.57 Peak 2 area 10.323 LAAM: 0.61 Peak 4 height 14.152 LACM: 1.49

[0164] Substituting the loss of positive electrode active material LACM, negative electrode active material LAAM, and intercalation / deintercalation ion loss LII of lithium-ion battery B into the SOH calculation formula, according to the SOH calculation formula: SOH = 100% - max(LII, LAAM, LACM), the SOH of lithium-ion battery B at a real-time rate of 1C is found to be 84.43%. Actual testing using the direct discharge method yielded an SOH of 84.21% for lithium-ion battery B at 1C, with an error (the difference between the actual SOH and the estimated SOH) of 0.22%. Based on the error value, the SOH estimation method provided by this invention has high accuracy.

[0165] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for assessing the health status of a battery, characterized in that, Includes the following steps: S1. Provide a calibration battery and obtain IC curves of charging or discharging at a first rate when the calibration battery has multiple different positive electrode active material loss amounts, multiple different negative electrode active material loss amounts, and multiple different intercalation / deintercalation ion loss amounts. S2. Extract the first feature value of each IC curve group of the calibration battery, and establish a first relationship between the loss of positive electrode active material, the loss of negative electrode active material and the loss of intercalation / deintercalation ions of the calibration battery and the corresponding first feature value; wherein, the first feature value includes the peak position, peak area and peak height of the IC curve in the IC curve group of the calibration battery. S3. Charge or discharge the battery under test at multiple different second rates to obtain the IC curves of the battery under test at multiple different second rates. S4. Extract the second feature values ​​of each IC curve of the battery under test at multiple different second rates, and establish a second relationship between the second feature values ​​and the rate; wherein, the second feature values ​​include the peak position, peak area and peak height of the peak on the IC curve of the battery under test; S5. Substitute the first rate into the second relationship in step S4 to obtain the second characteristic value of the battery under test at the first rate; then substitute the second characteristic value of the battery under test at the first rate into the first relationship in step S2 to obtain the positive electrode active material loss LACM, negative electrode active material loss LAAM, and deintercalation / intercalation ion loss LII of the battery under test at the first rate. The SOH of the battery under test is obtained according to the SOH calculation formula: SOH = 100% - max(LII, LAAM, LACM).

2. The method for assessing battery health status as described in claim 1, characterized in that, The first multiplier is less than or equal to 0.1C.

3. The method for assessing battery health status as described in claim 1, characterized in that, Of the multiple different second multipliers, at least some of the second multipliers are greater than or equal to the first multiplier.

4. The method for assessing battery health status as described in claim 1, characterized in that, The difference between adjacent second multipliers is greater than or equal to 0.1C.

5. The method for assessing battery health status as described in claim 1, characterized in that, The number of the second multiplier is at least three.

6. The method for assessing battery health status as described in claim 1, characterized in that, The values ​​of the loss of positive electrode active material, loss of negative electrode active material, and loss of intercalation / deintercalation ions in the calibration battery are all greater than or equal to 0.

7. The method for assessing battery health status as described in claim 6, characterized in that, The above S1 step specifically includes: A calibration battery is provided, and the calibration battery is charged or discharged at a first rate to obtain the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state. Based on the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state, the OCV curve of the calibration battery in the initial state is obtained. The initial state is the state in which the loss of positive electrode active material, the loss of negative electrode active material, and the loss of intercalation / deintercalation ions of the calibration battery are all 0. Multiple positive electrode active material loss values ​​greater than 0, multiple negative electrode active material loss values ​​greater than 0, and multiple deintercalation / intercalation ion loss values ​​greater than 0 are designed respectively. Based on the designed positive electrode active material loss values, negative electrode active material loss values, and deintercalation / intercalation ion loss values, the positive electrode OCP curve and negative electrode OCP curve of the calibration battery in the initial state are proportionally shrunk and translated, thereby obtaining the positive electrode OCP curve and negative electrode OCP curve of the calibration battery under multiple positive electrode active material loss values ​​greater than 0, multiple negative electrode active material loss values ​​greater than 0, and multiple deintercalation / intercalation ion loss values ​​greater than 0, respectively. Then, the OCV curve of the calibration battery under multiple positive electrode active material loss values ​​greater than 0, multiple negative electrode active material loss values ​​greater than 0, and multiple deintercalation / intercalation ion loss values ​​greater than 0 are obtained respectively. Based on the various OCV curves of the calibration battery, IC curve sets of the calibration battery under multiple different positive electrode active material loss amounts, multiple different negative electrode active material loss amounts, and multiple different intercalation / deintercalation ion loss amounts are obtained respectively.

8. The method for assessing battery health status as described in claim 1, characterized in that, In step S2 above, any one of the loss of positive electrode active material, loss of negative electrode active material, and loss of intercalation / deintercalation ions in the calibration battery corresponds to any one of the peak position, peak area, and peak height of the IC curve in the IC curve set of the calibration battery, and the loss of positive electrode active material, loss of negative electrode active material, and loss of intercalation / deintercalation ions in the calibration battery respectively correspond to different first characteristic values.

9. The method for assessing battery health status as described in claim 8, characterized in that, In step S2 above, one of the loss of positive electrode active material and the loss of negative electrode active material in the calibration battery corresponds to the peak area of ​​the IC curve in the IC curve set of the calibration battery, and the other of the loss of positive electrode active material and the loss of negative electrode active material in the calibration battery corresponds to the peak height of the IC curve in the IC curve set of the calibration battery; the loss of intercalation / deintercalation ions in the calibration battery corresponds to the peak position of the IC curve in the IC curve set of the calibration battery.

10. The method for assessing battery health status as described in claim 8, characterized in that, In step S2 above, the first feature value is the peak position, peak area, or peak height of different peaks in the IC curves of the IC curve group of the calibrated battery.

11. The method for assessing battery health status as described in claim 10, characterized in that, In step S2 above, when extracting the first feature value of the IC curve in the IC curve group of the calibration battery, the peak position of the first peak, the peak area of ​​the largest peak among the intermediate peaks, and the peak height of the last peak in the IC curve group of the calibration battery are selected respectively.

12. The method for assessing battery health status as described in any one of claims 1-11, characterized in that, Both the first relation and the second relation are linear relations.

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