CN114035096B

CN114035096B - SOH evaluation method for electrochemical device, electronic equipment and battery system

Info

Publication number: CN114035096B
Application number: CN202111432267.4A
Authority: CN
Inventors: 贺国达; 陈英杰
Original assignee: Dongguan Poweramp Technology Ltd
Current assignee: Dongguan Poweramp Technology Ltd
Priority date: 2021-11-29
Filing date: 2021-11-29
Publication date: 2023-12-26
Anticipated expiration: 2041-11-29
Also published as: CN114035096A

Abstract

The embodiment of the application provides an electrochemical device health degree SOH evaluation method, electronic equipment and a battery system. The method comprises the following steps: performing an intermittent charging operation on the electrochemical device, acquiring a reference internal resistance of the electrochemical device and a lithium SOC in the intermittent charging operation, the reference internal resistance being used to indicate the internal resistance when the electrochemical device is charged to the first SOC; the SOH of the electrochemical device is determined based on the lithium-ion SOC, the reference internal resistance, and a pre-established mapping relationship of the lithium-ion SOC-reference internal resistance-SOH. Based on the above-described scheme, the accuracy of SOH estimation of the electrochemical device is improved in consideration of the internal resistance and the lithium-precipitation state of the electrochemical device, and simultaneously estimating SOH from two dimensions of the internal resistance and the lithium-precipitation state of the electrochemical device.

Description

SOH evaluation method for electrochemical device, electronic equipment and battery system

Technical Field

The present disclosure relates to the field of electrochemical technologies, and in particular, to a method for evaluating health SOH of an electrochemical device, an electronic device, and a battery system.

Background

The lithium ion battery has the advantages of large specific energy density, long cycle life, high nominal voltage, low self-discharge rate, small volume, light weight and the like, and has wide application in the field of new energy.

With the high-speed development of tablet computers, mobile phones, electric vehicles and energy storage devices in recent years, and due to the continuous development of new energy industries, the market demand for lithium ion batteries is also increasing. The reliability and safety of lithium ion batteries are one of the most concerned problems in battery application, and by accurately evaluating and predicting the State of Health (SOH) of lithium ion batteries, the reliability and safety of lithium ion batteries can help to judge the hidden trouble and life condition of an electrochemical device, and can provide references for maintenance and replacement of the electrochemical device. Therefore, how to accurately evaluate and predict the health of lithium ion batteries is a urgent problem to be solved.

Disclosure of Invention

An object of the embodiments of the present application is to provide an SOH evaluation method of an electrochemical device, an electronic apparatus, and a battery system, so as to improve accuracy in evaluating SOH of the electrochemical device.

According to a first aspect of embodiments of the present application, there is provided an SOH evaluation method of an electrochemical device, including: performing an intermittent charging operation on the electrochemical device, in which a reference internal resistance and a lithium SOC of the electrochemical device are acquired, the reference internal resistance being used to indicate the internal resistance when the electrochemical device is charged to a first SOC; determining the SOH of the electrochemical device based on the lithium-precipitation SOC, the reference internal resistance, and a pre-established mapping relationship of lithium-precipitation SOC-reference internal resistance-SOH. Since the SOH is evaluated from both the internal resistance and the lithium-precipitating state of the electrochemical device in consideration, and at the same time, the accuracy of the SOH evaluation of the electrochemical device is improved.

In one embodiment of the present application, after determining the SOH of the electrochemical device based on the lithium-out SOC, the reference internal resistance, and a pre-established mapping of the lithium-out SOC-reference internal resistance-SOH, the method further comprises: and correcting the SOH. By correcting the SOH, a large deviation of the SOH can be avoided, and thus the calculation accuracy of the SOH can be further improved.

In one embodiment of the present application, the method further comprises, prior to the intermittent charging operation of the electrochemical device: acquiring the current charge-discharge cycle number of the electrochemical device; the modifying the SOH includes: and correcting the SOH according to the current charge-discharge cycle number. Based on the current charge-discharge cycle number, the SOH is corrected, so that the SOH can be estimated from three dimensions of the current charge-discharge cycle number, lithium precipitation and internal resistance, and the calculation accuracy of the SOH is improved.

In one embodiment of the present application, said modifying said SOH according to said current number of charge-discharge cycles comprises: determining SOH corresponding to the current charge-discharge cycle number according to the current charge-discharge cycle number and a pre-established mapping relation of the charge-discharge cycle number and the SOH; determining an SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number; and correcting the SOH by using the SOH allowable range.

In one embodiment of the present application, the determining the SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number includes: determining a lower limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number minus a first positive error; and determining the upper limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number plus a first positive error. Thereby, the SOH allowable range is determined in a relatively simple manner.

In one embodiment of the present application, the first positive error ranges from 0% to 5%.

In one embodiment of the present application, said modifying said SOH using said SOH allowable range comprises: if the SOH is greater than the upper limit value of the SOH allowable range, correcting the SOH to the upper limit value; and if the SOH is smaller than the lower limit value of the SOH allowable range, correcting the SOH to the lower limit value. Therefore, SOH determined based on the lithium-ion separation SOC and the reference internal resistance is limited in an SOH allowable range, larger deviation in the calculation process of the SOH is avoided, and the calculation accuracy of the SOH is improved.

In one embodiment of the present application, the method is performed on a periodic basis, and the modifying the SOH comprises: and correcting the SOH based on the SOH determined in the previous period. By correcting the SOH determined at the present period by the SOH determined at the previous period, it is possible to eliminate in a relatively simple manner a significant error that may occur when determining the SOH at the present period, improving the accuracy of SOH evaluation.

In one embodiment of the present application, the SOH determined based on the previous cycle is corrected, including at least one of: if the SOH is larger than the SOH determined in the previous period, correcting the SOH into the SOH determined in the previous period; or if the SOH is less than the SOH determined in the previous period minus the second positive error, correcting the SOH to be the SOH determined in the previous period minus the second positive error.

In one embodiment of the present application, the second positive error ranges from 0.01% to 0.1%.

In one embodiment of the present application, the intermittent charging includes a plurality of charging periods and a plurality of intermittent periods, the performing an intermittent charging operation on the electrochemical device, in which a reference internal resistance and a lithium SOC of the electrochemical device are obtained, includes: acquiring an internal resistance and an SOC of the electrochemical device during the interruption; obtaining a first curve based on the SOC and the internal resistance during each break, the first curve representing a variation of the internal resistance with the SOC; the lithium-ion SOC is determined based on the first curve, and the reference internal resistance is determined based on the first curve.

In one embodiment of the present application, the determining the lithium-eluting SOC based on the first curve includes at least one of mode A1 and mode A2. The mode A1 includes: differentiating the first curve to obtain a first differential curve; determining whether the first differential curve has a maximum value and a minimum value; and if the maximum value and the minimum value exist, determining the SOC corresponding to the maximum value as the lithium-precipitation SOC. The mode A2 includes: differentiating the first curve to obtain a first differential curve; differentiating the first differential curve to obtain a second differential curve; and determining the SOC corresponding to the point where the ordinate of the second differential curve appears smaller than zero for the first time as the lithium precipitation SOC.

In one embodiment of the present application, the mapping relationship of the lithium-precipitation SOC-reference internal resistance-SOH is pre-established by: acquiring a sample electrochemical device set; performing intermittent charging operation on a sample electrochemical device in the sample electrochemical device set, wherein reference internal resistance and lithium SOC of the sample electrochemical device are obtained in the intermittent charging operation; calibrating SOH of the sample electrochemical device; and establishing a mapping relation between the lithium-precipitation SOC and the reference internal resistance and the SOH based on the reference internal resistance and the lithium SOC of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

In one embodiment of the present application, the pre-established charge-discharge cycle number-SOH mapping relationship is pre-established by: acquiring the charge-discharge cycle number of a sample electrochemical device in the sample electrochemical device set before performing intermittent charging operation on the sample electrochemical device; and establishing a mapping relation between the charge and discharge cycle number and SOH based on the charge and discharge cycle number of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

According to a second aspect of embodiments of the present application, there is provided a battery system comprising a processor, a machine-readable storage medium storing machine-executable instructions executable by the processor for implementing the method of any one of the preceding aspects, and a sensor for detecting at least one of a pressure or a temperature of an electrochemical device.

According to a third aspect of embodiments of the present application, there is provided an electronic device including: comprising the battery system according to the second aspect.

According to a fourth aspect of embodiments of the present application, there is provided an electronic device, including: lithium-separating SOC analysis device and SOH determination device. The lithium-separated SOC analysis device is configured to perform an intermittent charging operation on the electrochemical device, in which a reference internal resistance of the electrochemical device, which is used to indicate the internal resistance when the electrochemical device is charged to a first SOC, and a lithium SOC are acquired. The SOH determining means is configured to determine SOH of the electrochemical device based on the lithium-ion SOC, the reference internal resistance, and a pre-established mapping relationship of the lithium-ion SOC-reference internal resistance-SOH. Since the SOH is evaluated from both the internal resistance and the lithium-precipitating state of the electrochemical device in consideration, and at the same time, the accuracy of the SOH evaluation of the electrochemical device is improved.

In one embodiment of the present application, the electronic device further includes SOH correction means for correcting the SOH of the electrochemical device after determining the SOH based on the lithium-analysis SOC, the reference internal resistance, and a pre-established mapping relationship of the lithium-analysis SOC-reference internal resistance-SOH. By correcting the SOH, a large deviation of the SOH can be avoided, and thus the calculation accuracy of the SOH can be further improved.

In one embodiment of the present application, the electronic apparatus further comprises obtaining means for obtaining a current charge-discharge cycle number of the electrochemical device before the intermittent charging operation is performed on the electrochemical device. The SOH correction device is specifically configured to correct the SOH according to the current charge-discharge cycle number. Based on the current charge-discharge cycle number, the SOH is corrected, so that the SOH can be estimated from three dimensions of the current charge-discharge cycle number, lithium precipitation and internal resistance, and the calculation accuracy of the SOH is improved.

In one embodiment of the present application, the SOH correction device is specifically configured to: determining SOH corresponding to the current charge-discharge cycle number according to the current charge-discharge cycle number and a pre-established mapping relation of the charge-discharge cycle number and the SOH; determining an SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number; and correcting the SOH by using the SOH allowable range.

In one embodiment of the present application, the SOH correction device is specifically configured to: determining a lower limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number minus a first positive error; and determining the upper limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number plus a first positive error. Thereby, the SOH allowable range is determined in a relatively simple manner.

In one embodiment of the present application, the SOH correction device is specifically configured to: if the SOH is greater than the upper limit value of the SOH allowable range, correcting the SOH to the upper limit value; and if the SOH is smaller than the lower limit value of the SOH allowable range, correcting the SOH to the lower limit value. Therefore, SOH determined based on the lithium-ion separation SOC and the reference internal resistance is limited in an SOH allowable range, larger deviation in the calculation process of the SOH is avoided, and the calculation accuracy of the SOH is improved.

In one embodiment of the present application, the SOH determining device is specifically configured to determine the SOH on a periodic basis; the SOH correction device is specifically configured to correct the SOH based on the SOH determined in the previous cycle. By correcting the SOH determined at the present period by the SOH determined at the previous period, it is possible to eliminate in a relatively simple manner a significant error that may occur when determining the SOH at the present period, improving the accuracy of SOH evaluation.

In one embodiment of the present application, the SOH correction device is specifically configured to perform at least one of the following: if the SOH is larger than the SOH determined in the previous period, correcting the SOH into the SOH determined in the previous period; or if the SOH is less than the SOH determined in the previous period minus the second positive error, correcting the SOH to be the SOH determined in the previous period minus the second positive error.

In one embodiment of the present application, the lithium analysis SOC analysis apparatus is specifically configured to: acquiring an internal resistance and an SOC of the electrochemical device during the interruption; obtaining a first curve based on the SOC and the internal resistance during each break, the first curve representing a variation of the internal resistance with the SOC; the lithium-ion SOC is determined based on the first curve, and the reference internal resistance is determined based on the first curve.

In one embodiment of the present application, the lithium analysis SOC analysis apparatus is specifically configured to: at least one of the modes A1 and A2 is performed. The mode A1 includes: differentiating the first curve to obtain a first differential curve; determining whether the first differential curve has a maximum value and a minimum value; and if the maximum value and the minimum value exist, determining the SOC corresponding to the maximum value as the lithium-precipitation SOC. The mode A2 includes: differentiating the first curve to obtain a first differential curve; differentiating the first differential curve to obtain a second differential curve; and determining the SOC corresponding to the point where the ordinate of the second differential curve appears smaller than zero for the first time as the lithium precipitation SOC.

According to the embodiment of the application, the SOH evaluation method, the electronic equipment and the battery system of the electrochemical device are provided, and the intermittent charging operation is performed on the electrochemical device, so that the reference internal resistance and the lithium-precipitation SOC of the electrochemical device are obtained in the intermittent charging operation, and the SOH of the electrochemical device is determined based on the lithium-precipitation SOC, the reference internal resistance and the pre-established mapping relation of the lithium-precipitation SOC-the reference internal resistance and the SOH, so that the internal resistance and the lithium-precipitation state of the electrochemical device are considered, and the SOH is evaluated from two dimensions of the internal resistance and the lithium-precipitation state of the electrochemical device at the same time, and the accuracy of SOH evaluation of the electrochemical device is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments of the present application will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the embodiments of the present application, and other drawings may be obtained according to these drawings for a person having ordinary skill in the art.

FIG. 1 is a flow chart of steps of a method for evaluating the health SOH of an electrochemical device according to an embodiment of the present application;

FIG. 2 is an exemplary flow chart of step 110 according to an embodiment of the present application;

FIG. 3 is a flow chart of steps of another method for SOH assessment of an electrochemical device according to an embodiment of the present application;

FIG. 4 is an exemplary flow chart of step 114 according to an embodiment of the present application;

FIG. 5 is a schematic diagram of SOH versus SOH allowed range determined based on lithium-ion SOC and reference internal resistance according to an embodiment of the application;

FIG. 6 is a flow chart illustrating steps of another SOH evaluation method for an electrochemical device according to an embodiment of the present application;

fig. 7 is an exemplary flowchart of step 116 of an embodiment of the present application.

Fig. 8 is a step flowchart of a process for establishing a mapping relationship between lithium-ion battery system on a chip (SOC) -reference internal resistance-SOH and a mapping relationship between the number of charge and discharge cycles-SOH according to an embodiment of the present application;

Fig. 9 is a step flowchart of an establishment procedure of a mapping relationship of an exemplary lithium-ion precipitation SOC-reference internal resistance-SOH, and a mapping relationship of the number of charge-discharge cycles-SOH according to an embodiment of the present application;

FIG. 10 is a block diagram of an electronic device according to an embodiment of the present application;

fig. 11 is a block diagram of a charging device according to an embodiment of the present application; and

fig. 12 is a block diagram of a battery system according to an embodiment of the present application.

Detailed Description

For the purposes of making the objects, technical solutions, and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other technical solutions obtained by a person skilled in the art based on the examples in the present application fall within the scope of protection of the present application.

Specific implementations of embodiments of the present application are described below with reference to the accompanying drawings.

In the context of the embodiments of the present application, the present application is exemplified by a lithium ion battery as an example of an electrochemical device, but the electrochemical device of the present disclosure is not limited to only a lithium ion battery.

Embodiments of the present application provide an electrochemical device health SOH assessment method, the subject of which may be a battery management system (Battery Management System, BMS). As shown in fig. 1, the method comprises the steps of:

Step 110: the electrochemical device is subjected to an intermittent charging operation in which a reference internal resistance and a lithium State of Charge (SOC) of the electrochemical device are obtained.

In the embodiment of the application, the reference internal resistance is used for indicating a corresponding internal resistance value when the electrochemical device is charged to the first SOC in the intermittent charging process. The first SOC may be 50%. It should be appreciated that 40%, 60%, or any other suitable SOC may be selected as the first SOC, which is not limited in this embodiment. The lithium-eluting SOC may refer to an SOC related to a lithium-eluting state of the electrochemical device. The smaller the lithium-eluting SOC, the more serious the lithium-eluting state.

In the embodiments of the present application, the intermittent charging operation may refer to a process of performing the intermittent charging operation on the electrochemical device. Specifically, in one implementation, the intermittent charging operation includes a plurality of charging periods and a plurality of intermittent periods. Illustratively, charging the electrochemical device during a first charging period, then stopping the charging, and after a first intermittent period, continuing to charge the electrochemical device during a second charging period, and repeating this until the SOC of the electrochemical device reaches a first threshold. It can be appreciated that as intermittent charging proceeds, the SOC of the electrochemical device increases accordingly, and the embodiment of the present application may stop intermittent charging when the SOC of the electrochemical device reaches the first critical value, and complete the intermittent charging operation. The first critical value in the embodiment of the present application is not particularly limited as long as the object of the present application can be achieved, and for example, the first critical value may be 60%, 70%, 80%, 90% or 100%. The charging mode in the intermittent charging operation is not particularly limited in the embodiment of the application, and the purpose of the embodiment of the application can be achieved, and the intermittent charging mode can be constant-voltage charging, constant-current and constant-voltage charging or segmented constant-current charging.

Referring to fig. 2, in one implementation, step 110 includes:

step 1101, obtaining an internal resistance and an SOC of the electrochemical device during the interruption.

In the embodiment of the present application, in the intermittent charging operation, the internal resistance of the electrochemical device may be determined based on the terminal voltage and the charging current of the electrochemical device detected during each of the discontinuities.

The internal resistance of the electrochemical device is determined during the current interruption period is described as an example. Specifically, a first terminal voltage of an electrochemical device at a start time point during the interruption period and a second terminal voltage of the electrochemical device at an End time point during the interruption period are acquired (for example, acquired through an Analog Front End (AFE) of the BMS), a voltage difference between the first terminal voltage and the second terminal voltage is determined, and an internal resistance of the electrochemical device is determined based on the voltage difference and a charging current of the electrochemical device detected during the charging period.

In the embodiment of the present application, for the intermittent charging operation, the SOC of the electrochemical device may be determined based on a pre-stored voltage-SOC relationship table. For example, a voltage-SOC relation table in which SOCs of electrochemical devices corresponding to different terminal voltages, for example, 85% SOCs for 4.2V and 90% SOCs for 4.3V, may be stored in advance in the BMS. Thus, in the intermittent charging operation, after the terminal voltage of the electrochemical device at the end time point of the current intermittent period is obtained, the SOC of the electrochemical device can be determined based on the terminal voltage and the voltage-SOC relationship table. It is to be understood that the SOC of the electrochemical device may also be determined based on the terminal voltage at the starting time point of the current intermittent period of the electrochemical device and the voltage-SOC relationship table, which is not limited in this embodiment.

Step 1102, obtaining a first curve based on the SOC and the internal resistance during each break.

In this embodiment of the present application, after acquiring the SOC and the internal resistance of the electrochemical device during each intermittent period, a plurality of data pairs composed of the SOC and the internal resistance may be obtained, and the SOC of the electrochemical device may be taken as an abscissa, and the internal resistance of the electrochemical device may be taken as an ordinate, and points represented by these data pairs may be filled in a coordinate system, and after fitting, a first curve may be obtained, where the first curve represents a change of the internal resistance of the electrochemical device along with the SOC.

It can be understood that the more densely the SOC and internal resistance data of the electrochemical device are collected, the more data pairs are obtained, and a finer first curve can be obtained. The process of curve fitting using data is well known to those skilled in the art, and the embodiments of the present application are not particularly limited.

Step 1103, determining a lithium-ion SOC based on the first curve, and determining a reference internal resistance based on the first curve.

In this embodiment of the present application, since the first curve represents the change of the internal resistance with the SOC, determining the reference internal resistance based on the first curve may include: the target point when the SOC is the first SOC is determined on the first curve, and the internal resistance of the target point is taken as the reference internal resistance, so that the reference internal resistance of the electrochemical device can be accurately determined by a simpler method. It should be understood that the reference internal resistance may also be determined by calculating a ratio of the voltage to the current according to the terminal voltage and the charging current when the electrochemical device is charged to the first SOC, which is not limited in this embodiment.

In embodiments of the present application, determining the lithium-ion SOC based on the first curve may be implemented in a variety of ways. The following is exemplified by two specific implementations.

In one specific implementation, the process of determining the lithium-ion SOC based on the first curve may be manner A1. Mode A1 includes:

and step A11, differentiating the first curve to obtain a first differential curve.

Since the first curve represents the change of the internal resistance R of the electrochemical device with the SOC of the electrochemical device, the first differential curve obtained by differentiating the first curve, that is, the first differential curve is a first-order differential curve of the first curve, which actually represents the rate of change of the internal resistance of the electrochemical device with the SOC.

Step A12, determining whether the first differential curve has a maximum value and a minimum value.

Mathematically, when the first differential curve has both maxima and minima, it is stated that the original flat region on the first differential curve exhibits a more pronounced undulating change, i.e., an abnormal decrease. In the embodiment of the present application, the first differential curve represents the rate of change of the internal resistance of the electrochemical device with the SOC. When no abnormal decrease in the rate of change occurs in the flat region of the curve, it indicates that the electrochemical device has no active lithium precipitated. When the change rate is abnormally reduced in the flat area of the curve, active lithium is precipitated on the surface of the negative electrode and contacts with the negative electrode, and the negative electrode graphite part is connected with a lithium metal device in parallel, so that the impedance of the whole negative electrode part is reduced, the internal resistance of the electrochemical device is abnormally reduced when active lithium is precipitated, and correspondingly, the flat area of the first differential curve is abnormally reduced.

And step A13, if the maximum value and the minimum value exist, determining the SOC corresponding to the maximum value as the lithium precipitation SOC.

When the maximum value and the minimum value exist, the lithium precipitation tendency of the electrochemical device at the maximum value or the lithium precipitation already occurs, and the SOC corresponding to the maximum value is determined as the lithium precipitation SOC, so that the lithium precipitation SOC of the electrochemical device is reasonably determined, the subsequent evaluation or prediction of the SOH of the electrochemical device according to the lithium precipitation SOC is facilitated, and the use safety of the electrochemical device is improved.

In this other specific implementation, the process of determining the lithium-ion SOC based on the first curve may be the mode A2. Mode A2 includes:

and step A21, differentiating the first curve to obtain a first differential curve.

The step a21 is the same as the step a11, and can be understood with reference to the step a11, and will not be described herein.

And step A22, differentiating the first differential curve to obtain a second differential curve.

Wherein the second differential curve can be understood as the second differential curve of the first curve

And A23, determining that the SOC corresponding to the point where the ordinate of the second differential curve is smaller than zero for the first time is the lithium precipitation SOC.

If the ordinate of the second differential curve is smaller than zero, determining the SOC corresponding to the point of the second differential curve, where the ordinate is smaller than zero for the first time, as the lithium precipitation SOC.

It should be understood that the above two specific implementations of determining the lithium-ion SOC are merely alternative implementations, and are not limiting of the examples of the present application.

In an embodiment of the present application, step 110 may be performed by a lithium-ion analysis device. The lithium-ion separation SOC analysis device 1010 is not particularly limited in the embodiment of the present application, as long as intermittent charging operation can be achieved. For example, the lithium-eluting SOC analysis arrangement 1010 may be a controller unit (Microcontroller Unit, MCU) in a battery management system (Battery Management System, BMS) board. The operation of the process shown above is for illustrative purposes only.

Step 102: the SOH of the electrochemical device is determined based on the lithium-ion SOC, the reference internal resistance, and a pre-established mapping relationship of the lithium-ion SOC-reference internal resistance-SOH.

In particular, SOH of an electrochemical device characterizes the current electrochemical device's ability to store electrical energy relative to a new electrochemical device, representing the state of the electrochemical device in percent from the beginning of life to the end of life, for quantitatively describing the current performance state of the electrochemical device.

The mapping relation of the lithium-precipitation SOC and the reference internal resistance-SOH is used for indicating the variation relation of the SOH along with the lithium-precipitation SOC and the internal resistance. The smaller the lithium-separating SOC, the more serious the lithium-separating degree, and the smaller the SOH of the electrochemical device. Meanwhile, the greater the internal resistance of the electrochemical device, the smaller the SOH of the electrochemical device. That is, as the lithium-eluting SOC is smaller, the internal resistance is larger and the SOH of the electrochemical device is smaller. The mapping relationship of lithium-precipitation SOC-reference internal resistance-SOH is pre-established, and the specific establishment procedure is described in detail in the examples below. The mapping relation of lithium-precipitation SOC-reference internal resistance-SOH may be stored in an internal memory device of the BMS in advance, or may be stored in other memory devices accessible to the BMS, from which the BMS obtains at the time of use.

In a specific implementation, the mapping of lithium-eluting SOC-reference internal resistance-SOH includes at least one lithium-eluting SOC, at least one reference internal resistance, and at least one SOH corresponding to the at least one lithium-eluting SOC and the at least one reference internal resistance. Referring to table 1, table 1 is a mapping relationship of an exemplary lithium-analysis SOC-reference internal resistance-SOH provided in the embodiment of the present application, in which a plurality of lithium-analysis SOCs, a plurality of reference internal resistances, and SOHs corresponding to the respective lithium-analysis SOCs and the reference internal resistances are recorded.

TABLE 1

As can be seen from table 1, when the reference internal resistance is fixed, the lithium-eluting SOC gradually decreases from left to right, and each SOH gradually decreases. When the lithium-separating SOC is fixed, the reference internal resistance gradually increases from top to bottom, and each SOH gradually decreases. That is, the smaller the lithium-eluting SOC, the smaller the corresponding SOH; the greater the reference internal resistance, the smaller the corresponding SOH. It should be understood that table 1 is only one example for explaining the mapping relationship of the lithium-analysis SOC to the reference internal resistance to SOH, and the interval values of the lithium-analysis SOC and the reference internal resistance in table 1 may be set according to actual needs, and the embodiment of the present application is not particularly limited.

In one embodiment of the present application, in determining the SOH, the lithium-extracted SOC and the reference internal resistance closest to the current lithium-extracted SOC and the current reference internal resistance in the map may be determined as the target lithium-extracted SOC and the target reference internal resistance, and then the SOH may be determined based on the target lithium-extracted SOC and the target reference internal resistance table, thereby determining the SOH of the electrochemical device at a faster rate. The current lithium precipitation SOC and the current reference internal resistance are respectively obtained by carrying out intermittent charging operation on the electrochemical device at the current moment and obtaining the reference internal resistance and the lithium SOC of the electrochemical device in the intermittent charging operation. In another embodiment of the present application, in determining the SOH, the SOH may be determined based on a linear difference between the two lithium-extracted SOCs close to the current lithium-extracted SOCs and the current reference internal resistance and the reference internal resistance, and thus the SOH of the electrochemical device may be more accurately determined.

In the embodiment of the application, the reference internal resistance and the lithium-precipitation SOC of the electrochemical device are obtained through intermittent charging operation on the electrochemical device, and the SOH of the electrochemical device is determined based on the lithium-precipitation SOC, the reference internal resistance and the pre-established mapping relation of the lithium-precipitation SOC-reference internal resistance-SOH, so that the internal resistance and the lithium-precipitation state of the electrochemical device are considered, and the SOH is evaluated from two dimensions of the internal resistance and the lithium-precipitation state of the electrochemical device at the same time, and the accuracy of SOH evaluation on the electrochemical device is improved.

In one embodiment of the present application, the method further comprises: and correcting SOH.

In the process of determining the SOH through steps 110 and 112, there is a large deviation between the obtained lithium-precipitation SOC and the reference internal resistance, which may be caused by interference or calculation error, so that the determined SOH is caused to have a large deviation, and by correcting the SOH, the SOH is reduced to have a large deviation, thereby further improving the calculation accuracy of the SOH.

Specifically, as shown in fig. 3, in one implementation of the present application, before performing the intermittent charging operation on the electrochemical device, the method further includes: step 111, the current charge/discharge cycle number of the electrochemical device is obtained. Accordingly, correcting SOH includes: step 114, according to the current charge-discharge cycle number, the SOH is corrected.

The charge-discharge cycle may be referred to as a cycle in which the electrochemical device is fully charged and fully discharged once. In the use process of the electrochemical device, when the electrochemical device reaches a complete charging cycle, that is, the electrochemical device accumulates full charge and full discharge once, the number of charging and discharging cycles of the electrochemical device is increased by 1. The charge and discharge cycle number may be stored in an internal storage device of the electrochemical device so that the charge and discharge cycle number is read from the internal storage device by the BMS of the electrochemical device when necessary.

In general, an electrochemical device has a certain charge and discharge life, i.e., the number of charge and discharge cycles that the electrochemical device can perform with a certain capacity. As the number of charge and discharge cycles increases, SOH of the electrochemical device gradually decreases. Therefore, the current charge-discharge cycle number may reflect SOH of the electrochemical device to some extent. Based on the current charge-discharge cycle number, the SOH is corrected, so that the SOH can be estimated from three dimensions of the current charge-discharge cycle number, lithium precipitation and internal resistance, and the calculation accuracy of the SOH is improved.

As shown in fig. 4, in one specific implementation, step 114 includes:

step 114A1, determining the SOH corresponding to the current charge/discharge cycle number according to the current charge/discharge cycle number and the pre-established mapping relationship between the charge/discharge cycle number and the SOH.

Step 114A2, determining an SOH allowable range based on the SOH corresponding to the current charge/discharge cycle number.

Step 114A3, the SOH is corrected by using the SOH allowable range.

The following describes steps 114A1 to 114A3 in detail.

In step 114A1, the SOH corresponding to the current charge/discharge cycle number is determined from the current charge/discharge cycle number and the pre-established charge/discharge cycle number-SOH mapping relationship.

The mapping relation between the charge and discharge cycle number and the SOH is used for indicating the variation relation of the SOH along with the charge and discharge cycle number. The higher the number of charge-discharge cycles, the smaller the SOH. The mapping relation of the charge-discharge cycle number-SOH is pre-established, and a specific establishment procedure is described in detail in the following examples. The mapping relation of the charge-discharge cycle number to SOH may be stored in an internal storage device of the BMS in advance, or may be stored in other storage devices accessible to the BMS, and acquired from the storage devices by the BMS at the time of use.

In a specific implementation, the mapping relationship of the charge-discharge cycle number to the SOH includes at least one charge-discharge cycle number and at least one SOH mapping relationship corresponding to the at least one charge-discharge cycle number. Referring to table 2, table 2 is a mapping relationship between the exemplary charge-discharge cycle number and SOH provided in the embodiment of the present application, and a plurality of charge-discharge cycle numbers and SOH corresponding to each charge-discharge cycle number are recorded in the table.

TABLE 2

As can be seen from table 2, the number of charge and discharge cycles gradually increases from left to right, and SOH corresponding to each charge and discharge cycle gradually decreases. In addition, at the initial stage of use of the electrochemical device (i.e., the number of charge-discharge cycles is relatively small), the corresponding SOH changes more slowly, while at the final stage of use of the electrochemical device, the corresponding SOH changes more rapidly. It should be understood that table 2 is only one example for illustrating the mapping relationship of the charge-discharge cycle number to SOH, and the interval value of the charge-discharge cycle number in table 2 may be set according to actual needs, and the embodiment of the present application is not particularly limited.

In one embodiment of the present application, when determining the SOH corresponding to the current charge-discharge cycle number, the charge-discharge cycle number closest to the current charge-discharge cycle number in the mapping relationship may be determined as the target charge-discharge cycle number, and then the SOH corresponding to the current charge-discharge cycle number is determined based on the target charge-discharge cycle number lookup table, so as to more quickly determine the SOH corresponding to the current charge-discharge cycle number. In another embodiment of the present application, when determining the SOH corresponding to the current charge-discharge cycle number, linear interpolation may be performed based on two charge-discharge cycle numbers close to the current charge-discharge cycle number, so as to determine the SOH corresponding to the current charge-discharge cycle number more accurately.

In step 114A2, an SOH allowable range is determined based on the SOH corresponding to the current charge-discharge cycle number.

In use, the SOH of the electrochemical device is affected by various factors such as the temperature of the application environment, the charge-discharge rate, the charge-discharge depth, etc., and varies with the same number of charge-discharge cycles, for example, fluctuates within a certain allowable range. In order to take into consideration the influence of various factors that are possible, an SOH allowable range is determined based on the SOH corresponding to the current charge-discharge cycle number, so that the SOH is subsequently corrected using the SOH allowable range, thereby enabling the SOH evaluation method provided by the present embodiment to be applicable to various operating conditions.

Specifically, in one implementation of the present application, determining an SOH allowable range based on an SOH corresponding to a current charge-discharge cycle number includes: determining a lower limit value of an SOH allowable range as SOH corresponding to the current charge-discharge cycle number minus a first positive error; the upper limit value of the SOH allowable range is determined as SOH corresponding to the current charge-discharge cycle number plus the first positive error, whereby the SOH allowable range is determined in a relatively simple manner as shown in fig. 5.

Wherein, the range of the first positive error can be 0% -5%. In one embodiment, the first positive error may be 3% to determine a reasonable SOH tolerance for a variety of operating conditions.

It should be understood that the SOH allowable range may be determined in other manners based on SOH corresponding to the current charge-discharge cycle number, which is not limited in the embodiment of the present application.

In step 114A3, SOH is corrected using the SOH allowable range.

Specifically, in one implementation, if SOH is greater than the upper limit of the SOH allowable range, SOH is corrected to the upper limit of the SOH allowable range; if SOH is smaller than the lower limit value of the SOH allowable range, the SOH is corrected to the upper limit value of the SOH allowable range. As shown in fig. 5, the thin solid line represents SOH (determined by SOH based on the lithium-ion precipitation SOC and the reference internal resistance _R-LP Indicated by a thick solid line), SOH (indicated by SOH) corresponding to the number of charge and discharge cycles _cycle Indicated), the dashed line indicates the SOH allowable range. As shown in fig. 5, the SOH determined based on the lithium-ion-extracted SOC and the reference internal resistance is limited within the SOH allowable range, so that a large deviation occurring in the calculation process of the SOH is avoided, and the calculation accuracy of the SOH is improved.

It should be understood that SOH may be modified in other possible manners using the SOH allowable range, which is not limited by the embodiments of the present application.

In the embodiment of the application, since the charge-discharge cycle number can reflect the SOH of the electrochemical device to a certain extent, the SOH is corrected based on the current charge-discharge cycle number, so that the SOH is evaluated from three dimensions of the current charge-discharge cycle number, lithium precipitation and internal resistance at the same time, and the calculation accuracy of the SOH is provided.

In one embodiment of the present application, the method of evaluating SOH of an electrochemical device shown in fig. 1 and/or fig. 4 is performed periodically. For example, the SOH evaluation method of an electrochemical device is performed once every charge-discharge cycle of the electrochemical device. Accordingly, in the embodiment shown in fig. 6, correcting SOH further includes: step 116, based on the SOH determined in the previous cycle, correcting the SOH. Since the SOH of the electrochemical device gradually decreases as the number of charge and discharge cycles increases during the use of the electrochemical device, the SOH determined in the current cycle is corrected by using the SOH determined in the previous cycle, and thus, obvious errors that may occur when determining the SOH in the current cycle can be eliminated in a relatively simple manner, and the accuracy of SOH estimation can be improved.

Specifically, as shown in fig. 7, in one specific implementation, step 116 may include:

step 116A, if the SOH is greater than the SOH determined in the previous cycle, correcting the SOH to the SOH determined in the previous cycle.

That is, the SOH determined in the previous cycle is used to replace the SOH determined in the current cycle, and the rising SOH determined in the current cycle is directly removed, so that obvious errors possibly occurring when the SOH is determined in the current cycle are eliminated in a simple manner, and the accuracy of SOH evaluation is improved.

With continued reference to fig. 7, in one particular implementation, step 116 may further include:

step 116B, if the SOH is less than the SOH determined in the previous cycle minus the second positive error, correcting the SOH to be the SOH determined in the previous cycle minus the second positive error.

In general, SOH of an electrochemical device gradually decreases as the electrochemical device is used. The SOH of the electrochemical device is slowly reduced in the early stage of use of the electrochemical device, and is rapidly reduced in the end stage of use of the electrochemical device. However, even at the end of use of the electrochemical device, the SOH of the electrochemical device is not reduced more than a specific value. That is, the difference in SOH determined for two adjacent cycles should be less than the second positive error. For example, the SOH difference may be 0.1%. It should be appreciated that the SOH difference may be other values between 0.01% and 0.1%, for example 0.05, which is not limited in this embodiment.

If the SOH determined by two adjacent periods is larger than the second positive error, the SOH determined by the current period has larger deviation. By correcting the SOH determined in the current period to the SOH determined in the previous period and subtracting the second positive error, the SOH determined in the current period and possibly having larger deviation can be directly removed, so that the SOH of the electrochemical device is prevented from being changed greatly in two adjacent periods due to interference and calculation errors, and the quality of the electrochemical device is questioned by a user.

In the embodiment of the present application, step 116 includes both step 116A and step 116B to improve the accuracy of calculating SOH of the electrochemical device. It should be appreciated that in other embodiments, step 116 may include only step 116A, or only step 116B, which is not limited in this embodiment. In addition, to avoid redundancy, fig. 6 shows steps 114 to 116 being included in the step of correcting SOH, and it should be understood that in other embodiments, the step 116 may be included only in correcting SOH, which is not limited in this embodiment.

Fig. 8 is a step flowchart of a process for establishing a mapping relationship between lithium-ion battery SOC-reference internal resistance-SOH according to an embodiment of the present application. As shown in fig. 8, the method includes:

step 810, obtaining a sample set of electrochemical devices.

In an embodiment of the present application, the sample electrochemical device set includes N sample electrochemical devices, where N is an integer greater than or equal to 1. Each of the N-sample electrochemical devices is the same as the electrochemical device type, performance, and the like in the embodiments of the present application.

Step 812, performing intermittent charging operation on the sample electrochemical devices in the sample electrochemical device set, and acquiring reference internal resistance and lithium SOC of the sample electrochemical devices in the intermittent charging operation.

In the embodiment of the application, before intermittent charging operation is performed on N sample electrochemical devices in the sample electrochemical device set, the N sample electrochemical devices are subjected to charging and discharging cycle operation for a preset number of times under M operation conditions. After the completion of the charge-discharge cycle operation for the preset number of times, intermittent charge operation is performed on each sample electrochemical device, and the reference internal resistance and the lithium SOC of each sample electrochemical device are obtained in the intermittent charge operation.

The M operation conditions can comprise combinations of different charge and discharge multiplying powers, different charge and discharge depths and different environment temperatures. One sample electrochemical device corresponds to one operating condition, M being a positive integer greater than or equal to 1 and less than or equal to N.

The preset number of times may be set as needed, and the performance of the sample electrochemical device gradually decreases as the number of cycles increases. Since each sample electrochemical device is subjected to a intermittent charging operation after completion of a preset number of charge-discharge cycle operations, the reference internal resistance and the lithium-precipitating SOC of each sample electrochemical device are obtained in the intermittent charging operation. Therefore, under the condition that the total circulation number is fixed, the smaller the preset times, the more the obtained reference internal resistance and lithium SOC of the sample electrochemical device are, and the more accurate the mapping relation between the lithium precipitation SOC and the reference internal resistance and the SOH is determined in the follow-up process. In the embodiment of the present application, the preset number of times may be between 50 and 200 times. In one embodiment, the preset number of times may be 100 times.

The above two processes (i.e., performing the charge-discharge cycle operation for the sample electrochemical device for a preset number of times, performing the intermittent charge operation for the sample electrochemical device after the completion of the charge-discharge cycle operation for the preset number of times) are repeatedly performed until the total number of cycles of the charge-discharge cycle operation reaches a preset number or the performance state of the sample electrochemical device is lower than a preset threshold (e.g., the ratio of the current maximum capacity of the sample electrochemical device to the rated capacity of the sample electrochemical device is lower than a preset ratio).

Wherein the total cycle number of the charge-discharge cycle operation is an integer multiple of the preset times. For example, assuming that the above two processes are performed P times and the preset number of times is Q times for each sample electrochemical device, the total number of cycles of the charge-discharge cycle operation corresponding to each sample electrochemical device is p×q times. Further, also assuming that the above two processes are performed P times for each sample electrochemical device, the reference internal resistance and the lithium SOC corresponding to the P groups may be acquired for each sample electrochemical device.

It should be understood that the process of acquiring the reference internal resistance and the lithium-ion SOC of the sample electrochemical device in the intermittent charging operation is similar to the process of acquiring the reference internal resistance and the lithium-ion SOC of the sample electrochemical device in the intermittent charging operation in the embodiment of fig. 1 and 3, and the process of acquiring the reference internal resistance and the lithium-ion SOC of the sample electrochemical device in the intermittent charging operation may be referred to the corresponding descriptions in the embodiment of fig. 1 and 4, and will not be repeated herein.

Step 814, calibrating the SOH of the sample electrochemical device.

In the embodiment of the present application, step 814 may be performed after each of the charge-discharge cycle operations performed for the sample electrochemical device for a preset number of times. Specifically, the SOH of the sample electrochemical device may be calibrated from the perspective of the sample electrochemical device capacity. SOH of the sample electrochemical device may also be calibrated from the perspective of the battery discharge capacity. Of course, the SOH of the sample electrochemical device may be calibrated from other angles as well. How the SOH of a sample electrochemical device is calibrated is illustrated below by two alternative implementations.

In an alternative implementation, calibrating the SOH of the sample electrochemical device may include: the current maximum capacity of the sample electrochemical device and the rated capacity of the sample electrochemical device are obtained, and the ratio of the current maximum capacity of the sample electrochemical device to the rated capacity of the sample electrochemical device is taken as SOH of the sample electrochemical device. Thereby enabling the SOH of the sample electrochemical device to be calibrated from the electrochemical device capacity perspective. The current maximum capacity of the sample electrochemical device refers to the maximum capacity that the sample electrochemical device can reach after each preset number of charge-discharge cycles of the sample electrochemical device.

In another alternative implementation, calibrating the SOH of the sample electrochemical device may include: and acquiring the current maximum discharge capacity of the sample electrochemical device and the maximum discharge capacity of the sample electrochemical device when the sample electrochemical device is not in use, and taking the ratio of the current maximum discharge capacity of the sample electrochemical device to the maximum discharge capacity of the sample electrochemical device when the sample electrochemical device is not in use as SOH of the sample electrochemical device. Thereby enabling the SOH of the sample electrochemical device to be calibrated from the standpoint of the amount of power placed on the electrochemical device. The current maximum discharge capacity of the sample electrochemical device is the maximum discharge capacity which can be achieved by the sample electrochemical device after the sample electrochemical device is subjected to the preset times of charge-discharge cyclic operation each time.

Step 816, establishing a mapping relationship between the lithium-precipitation SOC and the reference internal resistance-SOH based on the reference internal resistance and the lithium SOC of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

Specifically, for each sample electrochemical device in a sample electrochemical device set, a mapping relationship of lithium precipitation SOC-reference internal resistance-SOH under corresponding operation conditions of the sample electrochemical device is established based on the reference internal resistance and lithium precipitation SOC in multiple groups of data of the sample electrochemical device acquired in the repeated operation process and the corresponding calibrated SOH. For example, a plurality of reference internal resistances, a plurality of lithium-ion SOCs and calibrated SOHs under the operation conditions are correspondingly stored in a two-dimensional table form, and the mapping relation shown in table 1 is obtained.

After that, optionally, weighting processing can be performed based on the mapping relation of the lithium-precipitation SOC-reference internal resistance-SOH under each operation condition, so as to obtain the final mapping relation of the lithium-precipitation SOC-reference internal resistance-SOH. For example, different weights can be given to mapping relations between lithium-precipitation SOC and reference internal resistance-SOH under different operation conditions, and a weighted average of mapping relations between lithium-precipitation SOC and reference internal resistance-SOH under different operation conditions is obtained as a final mapping relation between lithium-precipitation SOC and reference internal resistance-SOH.

It should be understood that after the final lithium-ion SOC-reference internal resistance-SOH mapping is obtained, the final lithium-ion SOC-reference internal resistance-SOH mapping may be stored for use in evaluating SOH at the actual stage of use.

It should be understood that, in the embodiment of the present application, the steps 810 to 816 are merely for explaining steps that may be included in the SOH assessment method of an electrochemical device provided in the embodiment of the present application, and the order of execution between the steps is not limited. For example, steps 812 and 814 may be performed after each sample electrochemical device is obtained. For another example, step 814 may be performed after each sample electrochemical device is obtained, and then step 812 may be performed.

In the embodiment of the application, the mapping relation of the lithium-precipitation SOC-reference internal resistance-SOH is established by carrying out the cyclic test on the specific electrochemical device under different operation conditions, so that the mapping relation of the lithium-precipitation SOC-reference internal resistance-SOH is applicable to various operation conditions, and therefore, in the subsequent use stage, the SOH with higher precision can be determined by looking up a table according to the lithium-precipitation SOC-reference internal resistance.

With continued reference to fig. 8, in one embodiment of the present application, the method further comprises:

step 818, obtaining the number of charge-discharge cycles of the sample electrochemical device before performing intermittent charge operation on the sample electrochemical devices in the sample electrochemical device set.

Specifically, in one implementation, the number of cycles of one charge-discharge operation is recorded before each sample electrochemical device is subjected to intermittent charge operation and after each sample electrochemical device is subjected to a preset number of charge-discharge cycles. The number of cycles of charge-discharge cycle operation recorded each time is an integer multiple of the preset number of times. For example, it is assumed that the charge-discharge cycle operation is repeated P times for each sample electrochemical device for a preset number of times. P corresponding charge-discharge cycle numbers can be acquired.

Step 820, establishing a mapping relationship between the charge-discharge cycle number and the SOH based on the charge-discharge cycle number of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

Specifically, for each sample electrochemical device in the sample electrochemical device set, a mapping relationship of the charge-discharge cycle number-SOH under the corresponding operation condition of the sample electrochemical device is established based on the obtained multiple charge-discharge cycle numbers of the sample electrochemical device and the corresponding calibrated SOH. For example, the number of charge and discharge cycles and the calibrated SOH under the operating condition may be correspondingly stored in the form of a two-dimensional table, so as to obtain a mapping relationship as shown in table 2.

Thereafter, optionally, weighting processing may be performed based on the mapping relationship between the charge-discharge cycle number and the SOH under each operating condition, so as to obtain the final charge-discharge cycle number-SOH. For example, different weights can be given to mapping relations between lithium-precipitation SOC and reference internal resistance-SOH under different operation conditions, and a weighted average of mapping relations between lithium-precipitation SOC and reference internal resistance-SOH under different operation conditions is obtained as a final mapping relation between lithium-precipitation SOC and reference internal resistance-SOH.

In the embodiment of the application, the mapping relation of the lithium-precipitation SOC-reference internal resistance-SOH and the mapping relation of the charge-discharge cycle number-SOH are established by carrying out the cyclic test on the specific electrochemical device under different operation conditions, so that the mapping relation of the lithium-precipitation SOC-reference internal resistance-SOH and the mapping relation of the charge-discharge cycle number-SOH are applicable to various operation conditions, and meanwhile, the SOH can be estimated from three dimensions of the lithium-precipitation SOC, the reference internal resistance and the charge-discharge cycle number in the actual use stage, and the estimation precision of the SOH is improved.

In order to better understand the process of establishing the mapping relationship between the lithium-precipitation SOC-reference internal resistance-SOH and the mapping relationship between the charge-discharge cycle number-SOH in the embodiment of the present application, a process of obtaining the mapping relationship between the lithium-precipitation SOC-reference internal resistance-SOH and the mapping relationship between the charge-discharge cycle number-SOH under one operation condition will be described in detail by way of a specific example with reference to fig. 9. In this example, the preset number of times is 100, and the first SOH is 70%, wherein the first SOH is used to indicate a ratio of a current maximum capacity of the sample electrochemical device to a rated capacity of the sample electrochemical device when the sample electrochemical device performance drops to be unsuitable for reuse. Further, in this example, the SOH of the sample electrochemical device is calibrated from the perspective of the electrochemical device capacity. That is, the ratio of the current maximum capacity of the sample electrochemical device to the rated capacity of the sample electrochemical device is taken as the SOH of the sample electrochemical device. As shown in fig. 9, the method includes:

step 910, performing 100 charge and discharge operations on the sample electrochemical device.

Step 912, performing intermittent charging operation on the sample electrochemical device, and acquiring a reference internal resistance and a lithium SOC of the sample electrochemical device in the intermittent charging operation;

Step 914, calibrating SOH of the sample electrochemical device, and correspondingly storing the reference internal resistance, the lithium SOC, the current charge-discharge cycle number and the calibrated SOH of the electrochemical device;

step 916, determining that the SOH of the calibration sample electrochemical device is less than 70%, if not, returning to steps 910 to 914, and if yes, executing step 918.

Step 918, based on the stored lithium-precipitation SOC and reference internal resistance of each sample electrochemical device and the calibrated SOH, establishing a mapping relationship between the lithium-precipitation SOC and the reference internal resistance-SOH under the operation condition, and based on the stored charge-discharge cycle number and the calibrated SOH of each sample electrochemical device, establishing a mapping relationship between the charge-discharge cycle number and the SOH under the operation condition.

It should be understood that the specific implementation process of step 910 to step 918 may refer to the corresponding steps in the embodiments shown in fig. 1 and 3, and will not be described in detail herein for avoiding redundancy.

The embodiment of the application also provides an electronic device 1000, as shown in fig. 10, which includes a lithium analysis SOC analysis apparatus 1010 and an SOH determination apparatus 1012.

The lithium-ion SOC analysis device 1010 is configured to perform an intermittent charging operation of the electrochemical device, in which a reference internal resistance of the electrochemical device and a lithium-ion SOC are obtained. The reference internal resistance is used to indicate the internal resistance when the electrochemical device is charged to the first SOC.

The SOH determination means 1012 is for determining the SOH of the electrochemical device based on the lithium-ion SOC, the reference internal resistance, and a pre-established mapping relationship of the lithium-ion SOC-reference internal resistance-SOH.

An electrochemical device may be included in the electronic apparatus of the embodiments of the present application. The electronic device may be, for example, a new energy vehicle, a mobile phone, a tablet computer, etc. with built-in lithium ion battery, a device with data processing capabilities. The configuration of the lithium analysis SOC analysis apparatus 1010 and the SOH determination apparatus 1012 in the embodiment of the present application is not particularly limited as long as the respective functions can be realized.

In one implementation of the present application, the electronic device further includes SOH correction means for correcting the SOH after determining the SOH of the electrochemical device based on the lithium-precipitation SOC, the reference internal resistance, and a pre-established mapping relationship of the lithium-precipitation SOC-reference internal resistance-SOH.

In one implementation of the present application, the electronic device further includes an obtaining device for obtaining a current charge-discharge cycle number of the electrochemical device before the intermittent charging operation is performed on the electrochemical device. The SOH correction device is specifically used for correcting SOH according to the current charge and discharge cycle number.

In one implementation of the present application, the SOH correction device is specifically configured to: determining SOH corresponding to the current charge-discharge cycle number according to the current charge-discharge cycle number and a pre-established mapping relation of the charge-discharge cycle number to the SOH; determining an SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number; and correcting the SOH by using the SOH allowable range.

In one implementation of the present application, the SOH correction device is specifically configured to: determining a lower limit value of an SOH allowable range as SOH corresponding to the current charge-discharge cycle number minus a first positive error; the upper limit value of the SOH allowable range is determined as SOH corresponding to the current charge-discharge cycle number plus a first positive error.

In one implementation of the present application, the first positive error ranges from 0% to 5%.

In one implementation manner of the present application, the SOH correction device is specifically configured to: if SOH is larger than the upper limit value of the SOH allowable range, correcting SOH to be the upper limit value; and if the SOH is smaller than the lower limit value of the SOH allowable range, correcting the SOH to the lower limit value.

In one implementation of the present application, SOH determination means 1012 determines SOH on a periodic basis. The SOH correction device is specifically configured to correct SOH based on SOH determined in the previous cycle.

In one implementation of the present application, the SOH correction device is specifically configured to perform at least one of the following: if the SOH is greater than the SOH determined in the previous period, correcting the SOH to be the SOH determined in the previous period; or if the SOH is less than the SOH determined in the previous cycle minus the second positive error, correcting the SOH to the SOH determined in the previous cycle minus the second positive error.

In one implementation of the present application, the second positive error ranges from 0.01% to 0.1%.

In one implementation of the present application, the lithium-ion separation SOC analysis apparatus 1010 is specifically configured to: acquiring an internal resistance and an SOC of the electrochemical device during the interruption; based on the SOC and the internal resistance in each intermittent period, a first curve is obtained, wherein the first curve represents the change of the internal resistance along with the SOC; based on the first curve, a lithium-ion SOC is determined, and based on the first curve, a reference internal resistance is determined.

In one implementation of the present application, the lithium-ion separation SOC analysis apparatus 1010 is specifically configured to: at least one of the modes A1 and A2 is performed. Mode A1 includes: differentiating the first curve to obtain a first differential curve; determining whether the first differential curve has a maximum value and a minimum value; and if the maximum value and the minimum value exist, determining the SOC corresponding to the maximum value as the lithium precipitation SOC. Mode A2 includes: differentiating the first curve to obtain a first differential curve; differentiating the first differential curve to obtain a second differential curve; and determining the SOC corresponding to the point where the ordinate of the second differential curve appears smaller than zero for the first time as the lithium precipitation SOC.

In one implementation of the present application, the mapping relationship of lithium-analysis SOC-reference internal resistance-SOH is pre-established by: acquiring a sample electrochemical device set; performing intermittent charging operation on a sample electrochemical device in the sample electrochemical device set, and acquiring reference internal resistance and lithium-precipitating SOC of the sample electrochemical device in the intermittent charging operation; calibrating SOH of the sample electrochemical device; and establishing a mapping relation between the lithium precipitation SOC and the reference internal resistance and the SOH based on the reference internal resistance and the lithium SOC of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

In one implementation of the present application, the pre-established mapping relationship of the charge-discharge cycle number to SOH is pre-established by: acquiring the charge-discharge cycle number of a sample electrochemical device before intermittent charging operation is performed on the sample electrochemical devices in the sample electrochemical device set; and establishing a mapping relation between the charge and discharge cycle number and the SOH based on the charge and discharge cycle number of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

The electronic device in the embodiment of the present application may be used to implement the corresponding lithium analysis detection method in the foregoing multiple method embodiments, and has the beneficial effects of the corresponding method embodiments, which are not described herein again. In addition, the functional implementation of each device in the electronic apparatus of this embodiment may refer to the description of the corresponding parts in the foregoing method embodiments, which is not repeated herein.

The embodiment of the application further provides a charging device, as shown in fig. 11, the charging device 1100 includes a processor 1101 and a processor 1102, and the charging device 1110 may further include a charging circuit module 1103, an interface 1104, a power interface 1105, and a rectifying circuit 116. The charging circuit module 1103 is configured to perform intermittent charging operation on the lithium ion battery (i.e. the electrochemical device); the charging circuit module 1103 may also be configured to collect parameters such as terminal voltage and charging current of the lithium ion battery, and send the parameters to the processor; interface 1104 is used for electrically connecting with electrochemical device 2000; the power interface 1105 is used for connecting with an external power supply; the rectifying circuit 1106 is used for rectifying an input current; the processor 1102 stores machine executable instructions that are executable by the processor, and the processor 1101 implements the method steps described in any of the method embodiments described above when executing the machine executable instructions.

The embodiment of the application also provides a computer readable storage medium, and a computer program is stored in the computer readable storage medium, and when the computer program is executed by a processor, the method steps of any one of the method embodiments are realized.

The present embodiment also provides a battery system, as shown in fig. 12, where the battery system 1200 includes a second processor 1201 and a second machine readable storage medium 1202, and the battery system 1200 may further include a charging circuit module 1203, a lithium ion battery 1204, and a second interface 1205. The charging circuit module 1203 is configured to perform intermittent charging operation on the lithium ion battery; the charging circuit module 1203 may also be configured to collect parameters such as terminal voltage and charging current of the lithium ion battery, and send these parameters to the second processor. The second interface 1205 is for interfacing with the external charger 1300; the external charger 1300 is used for providing power; the second machine-readable storage medium 1202 stores machine-executable instructions executable by the processor, which when executed by the second processor 1201 implement the method steps described in any of the method embodiments above. The external charger 1300 may include a first processor 1301, a first machine-readable storage medium 1302, a first interface 1303 and corresponding rectifying circuits, and may be a commercially available charger, and the structure of the external charger is not specifically limited in the embodiments of the present application.

The embodiment of the application also provides electronic equipment, which comprises the battery system.

The machine-readable storage medium may include random access memory (Random Access Memory, RAM) or nonvolatile memory (non-volatile memory), such as at least one magnetic disk memory. Optionally, the memory may also be at least one memory device located remotely from the aforementioned processor.

The processor may be a general-purpose processor, including a central processing unit (Central Processing Unit, CPU for short), a network processor (Network Processor, NP for short), etc.; but also digital signal processors (Digital Signal Processing, DSP for short), application specific integrated circuits (Application Specific Integrated Circuit, ASIC for short), field-programmable gate arrays (Field-Programmable Gate Array, FPGA for short) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

For the electronic device/charging apparatus/storage medium/battery system embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference is made to the description of the method embodiments for relevant points.

Claims

1. A method for assessing the health SOH of an electrochemical device, comprising:

performing an intermittent charging operation on the electrochemical device, in which a reference internal resistance and a lithium SOC of the electrochemical device are acquired, the reference internal resistance being used to indicate the internal resistance when the electrochemical device is charged to a first SOC;

determining the SOH of the electrochemical device based on the lithium-precipitation SOC, the reference internal resistance, and a pre-established mapping relationship of lithium-precipitation SOC-reference internal resistance-SOH.

2. The method according to claim 1, wherein after determining the SOH of the electrochemical device based on the lithium-out SOC, the reference internal resistance, and a pre-established mapping of lithium-out SOC-reference internal resistance-SOH, the method further comprises: and correcting the SOH.

3. The method of claim 2, wherein prior to performing the intermittent charging operation on the electrochemical device, the method further comprises: acquiring the current charge-discharge cycle number of the electrochemical device;

the modifying the SOH includes: and correcting the SOH according to the current charge-discharge cycle number.

4. A method according to claim 3, wherein said modifying said SOH according to said current charge-discharge cycle number comprises:

Determining SOH corresponding to the current charge-discharge cycle number according to the current charge-discharge cycle number and a pre-established mapping relation of the charge-discharge cycle number and the SOH;

determining an SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number;

and correcting the SOH by using the SOH allowable range.

5. The method of claim 4, wherein the determining an SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number comprises:

determining a lower limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number minus a first positive error;

and determining the upper limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number plus a first positive error.

6. The method of claim 5, wherein the first positive error is in the range of 0% to 5%.

7. The method of claim 4, wherein said modifying said SOH using said SOH allowable range comprises:

if the SOH is greater than the upper limit value of the SOH allowable range, correcting the SOH to the upper limit value;

and if the SOH is smaller than the lower limit value of the SOH allowable range, correcting the SOH to the lower limit value.

8. The method of claim 2, wherein the method is performed on a periodic basis, the modifying the SOH comprising:

and correcting the SOH based on the SOH determined in the previous period.

9. The method of claim 8, wherein the modifying the SOH based on the SOH determined at the previous cycle comprises at least one of:

if the SOH is larger than the SOH determined in the previous period, correcting the SOH into the SOH determined in the previous period; or alternatively

And if the SOH is smaller than the SOH determined in the previous period minus the second positive error, correcting the SOH to be the SOH determined in the previous period minus the second positive error.

10. The method of claim 9, wherein the second positive error ranges from 0.01% to 0.1%.

11. The method of claim 1, wherein the intermittent charging comprises a plurality of charging periods and a plurality of intermittent periods, the performing an intermittent charging operation on the electrochemical device in which a reference internal resistance and a lithium SOC of the electrochemical device are obtained, comprising:

acquiring an internal resistance and an SOC of the electrochemical device during the interruption;

obtaining a first curve based on the SOC and the internal resistance during each break, the first curve representing a variation of the internal resistance with the SOC;

The lithium-ion SOC is determined based on the first curve, and the reference internal resistance is determined based on the first curve.

12. The method of claim 11, wherein the determining the lithium-eluting SOC based on the first curve includes at least one of mode A1 and mode A2, wherein,

the mode A1 includes:

differentiating the first curve to obtain a first differential curve;

determining whether the first differential curve has a maximum value and a minimum value;

if the maximum value and the minimum value exist, determining the SOC corresponding to the maximum value as the lithium-precipitation SOC;

the mode A2 includes:

differentiating the first curve to obtain a first differential curve;

differentiating the first differential curve to obtain a second differential curve;

and determining the SOC corresponding to the point where the ordinate of the second differential curve appears smaller than zero for the first time as the lithium precipitation SOC.

13. The method of claim 4, wherein the mapping of lithium-eluting SOC-reference internal resistance-SOH is pre-established by:

acquiring a sample electrochemical device set;

performing intermittent charging operation on a sample electrochemical device in the sample electrochemical device set, wherein reference internal resistance and lithium SOC of the sample electrochemical device are obtained in the intermittent charging operation;

Calibrating SOH of the sample electrochemical device;

and establishing a mapping relation between the lithium-precipitation SOC and the reference internal resistance and the SOH based on the reference internal resistance and the lithium SOC of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

14. The method of claim 13, wherein the pre-established charge-discharge cycle number-SOH mapping is pre-established by:

acquiring the charge-discharge cycle number of a sample electrochemical device in the sample electrochemical device set before performing intermittent charging operation on the sample electrochemical device;

and establishing a mapping relation between the charge and discharge cycle number and SOH based on the charge and discharge cycle number of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

15. A battery system comprising a processor, a machine-readable storage medium storing machine-executable instructions executable by the processor for performing the method of any one of claims 1-14, and a sensor for detecting at least one of a pressure or a temperature of an electrochemical device.

16. An electronic device, wherein the electronic device comprises the battery system of claim 15.

17. An electronic device, comprising: a lithium-separating SOC analysis device and an SOH determination device;

the lithium-separating SOC analysis device is configured to perform an intermittent charging operation on an electrochemical device, in which a reference internal resistance and a lithium SOC of the electrochemical device are obtained, the reference internal resistance being used to indicate an internal resistance when the electrochemical device is charged to a first SOC;

the SOH determining means is configured to determine SOH of the electrochemical device based on the lithium-ion SOC, the reference internal resistance, and a pre-established mapping relationship of the lithium-ion SOC-reference internal resistance-SOH.

18. The electronic device according to claim 17, wherein the electronic device further comprises SOH correction means for correcting the SOH of the electrochemical means after determining the SOH based on the lithium-out SOC, the reference internal resistance, and a pre-established mapping relationship of lithium-out SOC-reference internal resistance-SOH.

19. The electronic apparatus according to claim 18, wherein the electronic apparatus further comprises obtaining means for obtaining a current charge-discharge cycle number of the electrochemical device before the intermittent charging operation is performed on the electrochemical device;

The SOH correction device is specifically configured to correct the SOH according to the current charge-discharge cycle number.

20. The electronic device of claim 19, wherein the SOH correction means is specifically configured to:

and correcting the SOH by using the SOH allowable range.

21. The electronic device of claim 20, wherein the SOH correction means is specifically configured to:

22. The electronic device of claim 21, wherein the first positive error ranges from 0% to 5%.

23. The electronic device of claim 20, wherein the SOH correction means is specifically configured to:

24. The electronic device of claim 18, wherein the SOH determining means is specifically configured to determine the SOH on a periodic basis;

the SOH correction device is specifically configured to correct the SOH based on the SOH determined in the previous cycle.

25. The electronic device of claim 24, wherein the SOH correction means is specifically configured to perform at least one of:

26. The electronic device of claim 25, wherein the second positive error is in a range of 0.01% to 0.1%.

27. The electronic device of claim 17, wherein the intermittent charging includes a plurality of charging periods and a plurality of intermittent periods, the lithium-ion SOC analysis apparatus being specifically configured to:

28. The electronic device of claim 27, wherein the lithium analysis SOC analysis apparatus is specifically configured to: at least one of the modes A1 and A2 is performed, wherein,

the mode A1 includes:

differentiating the first curve to obtain a first differential curve;

the mode A2 includes:

differentiating the first curve to obtain a first differential curve;

29. The electronic device of claim 20, wherein the mapping of lithium-eluting SOC-reference internal resistance-SOH is pre-established by:

Acquiring a sample electrochemical device set;

calibrating SOH of the sample electrochemical device;

30. The electronic device of claim 29, wherein the pre-established charge-discharge cycle number-SOH mapping is pre-established by: