Lithium battery health state detection method and device

Abstract

The embodiment of the invention discloses a lithium battery health state detection method and a lithium battery health state detection device. The detection method comprises the following steps: acquiring a first open-circuit voltage of the lithium battery in a first temperature interval; acquiring a second open-circuit voltage and a third open-circuit voltage of the lithium battery in the second temperature interval; wherein the second temperature interval is lower than the first temperature interval, the second open-circuit voltage is the maximum value of the lithium battery in the second temperature interval, and the third open-circuit voltage is the stable value of the lithium battery in the second temperature interval; and determining the health state of the lithium battery according to the first open-circuit voltage, the second open-circuit voltage and the third open-circuit voltage. According to the technical scheme provided by the embodiment of the invention, the nondestructive detection method for the internal micro-short circuit state of the lithium battery is realized, qualitative detection and quantitative calculation of the internal micro-short circuit state of the lithium battery are realized, the health state of the lithium battery is accurately judged, and normal use of the lithium battery is not influenced.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery detection, and in particular to a method and device for detecting the health status of a lithium battery. Background Art

[0002] Nowadays, lithium batteries are widely used in various smart meters such as electricity meters, water meters, and gas meters. They are also constantly being used and developed in the fields of transportation, security, the Internet of Things, etc., which also puts higher requirements on the performance of lithium batteries.

[0003] The low self-discharge rate of lithium batteries in the open circuit state is one of the key characteristics that affects their performance. However, there is no effective method to qualitatively and quantitatively determine whether the battery is well insulated or whether there is an internal micro-short circuit in the open circuit state. This is generally determined by the open circuit voltage. However, because the open circuit voltage of a lithium battery is not a completely stable value and varies with factors such as the storage time, ambient temperature, passivation state, and internal trace impurities, it can often only be determined when the internal short circuit is obvious and the open circuit voltage changes significantly. Therefore, it is impossible to accurately determine the specific extent of the lithium battery micro-short circuit, and the judgment results are subject to large errors. Summary of the Invention

[0004] The present invention provides a method and device for detecting the health status of a lithium battery to solve the problem that the existing lithium battery health status detection method has large errors and cannot make qualitative and quantitative judgments, thereby realizing qualitative detection and quantitative calculation of lithium batteries and accurately judging the health status of lithium batteries.

[0005] According to one aspect of the present invention, a method for detecting the health status of a lithium battery is provided, comprising:

[0006] Obtaining a first open circuit voltage of the lithium battery in a first temperature range;

[0007] Obtaining a second open circuit voltage and a third open circuit voltage of the lithium battery in a second temperature range; wherein the second temperature range is lower than the first temperature range, the second open circuit voltage is a maximum value of the lithium battery in the second temperature range, and the third open circuit voltage is a stable value of the lithium battery in the second temperature range;

[0008] The health state of the lithium battery is determined according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage.

[0009] Optionally, obtaining a first open circuit voltage of the lithium battery in a first temperature range includes:

[0010] Controlling the lithium battery to pre-discharge according to a preset discharge rate;

[0011] The pre-discharged lithium battery is placed in the first temperature range for a first preset time, and a first open circuit voltage of the lithium battery is obtained.

[0012] Optionally, obtaining a second open circuit voltage and a third open circuit voltage of the lithium battery in a second temperature range includes:

[0013] The lithium battery is placed in the second temperature range for a second preset time; and a second open circuit voltage and a third open circuit voltage of the lithium battery are obtained.

[0014] Optionally, determining the health state of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage includes:

[0015] If the first open circuit voltage is greater than or equal to a first preset value, the second open circuit voltage is greater than or equal to a second preset value, and the third open circuit voltage is greater than or equal to a third preset value, it is determined that the lithium battery is in a normal state.

[0016] Optionally, determining the health state of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage further includes:

[0017] If the first open circuit voltage is greater than or equal to a fourth preset value, the second open circuit voltage is less than a second preset value, and / or the third open circuit voltage is less than a third preset value, it is determined that the lithium battery is in a slight short circuit state;

[0018] If the first open circuit voltage is less than a fourth preset value, it is determined that the lithium battery is in a short circuit state.

[0019] Optionally, determining that the lithium battery is in a micro-short circuit state includes:

[0020] If the second open circuit voltage is greater than the first open circuit voltage, and the third open circuit voltage is greater than the first open circuit voltage, it is determined that the lithium battery is in a slight short circuit state;

[0021] If the second open circuit voltage is greater than the first open circuit voltage, and the third open circuit voltage is less than or equal to the first open circuit voltage, it is determined that the lithium battery is in a moderate slight short circuit state;

[0022] If the second open circuit voltage is less than or equal to the first open circuit voltage, and the third open circuit voltage is less than or equal to the first open circuit voltage, it is determined that the lithium battery is in a severe micro-short circuit state.

[0023] Optionally, after determining the health status of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage, the method further includes:

[0024] The storage-year self-discharge ratio of the lithium battery is determined according to the health status of the lithium battery.

[0025] Optionally, determining the storage-year self-discharge ratio of the lithium battery according to the health status of the lithium battery includes:

[0026] If the lithium battery is in a normal state, the storage-year self-discharge ratio of the lithium battery is 0.01;

[0027] If the lithium battery is in a severe micro-short circuit state, the storage-year self-discharge ratio of the lithium battery is greater than 0.5;

[0028] If the lithium battery is in a mild micro-short circuit state or a moderate micro-short circuit state, the storage-year self-discharge ratio of the lithium battery is determined according to the first open-circuit voltage, the second open-circuit voltage, and the third open-circuit voltage.

[0029] Optionally, when the lithium battery is in a mild short-circuit state, the calculation formula for the storage-year self-discharge ratio of the lithium battery is:

[0030]

[0031] When the lithium battery is in a moderate micro-short circuit state, the calculation formula for the storage-year self-discharge ratio of the lithium battery is:

[0032]

[0033] Wherein, W is the storage-year self-discharge ratio of the lithium battery, V1 is the first open-circuit voltage of the lithium battery, V2 is the second open-circuit voltage of the lithium battery, and V3 is the third open-circuit voltage of the lithium battery.

[0034] According to another aspect of the present invention, a device for detecting the health status of a lithium battery is provided, comprising:

[0035] A first data acquisition module, configured to acquire a first open circuit voltage of the lithium battery in a first temperature range;

[0036] a second data acquisition module, configured to acquire a second open circuit voltage and a third open circuit voltage of the lithium battery in a second temperature range; wherein the second temperature range is lower than the first temperature range, the second open circuit voltage is the maximum value of the lithium battery in the second temperature range, and the third open circuit voltage is the stable value of the lithium battery in the second temperature range;

[0037] A health status determination module is used to determine the health status of the lithium battery according to the first open circuit voltage, the second open circuit voltage and the third open circuit voltage.

[0038] The technical solution of the embodiment of the present invention first obtains a first open circuit voltage of the lithium battery in a first temperature range, and then obtains a second open circuit voltage and a third open circuit voltage of the lithium battery in a second temperature range, wherein the second open circuit voltage is the maximum value of the open circuit voltage of the lithium battery in a low temperature environment, and the third open circuit voltage is the stable value of the open circuit voltage of the lithium battery in a low temperature environment, and finally determines the health status of the lithium battery based on the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage. The detection method of the embodiment of the present invention realizes non-destructive detection of the micro-short circuit state inside the lithium battery, and the detection method is simple. It only needs to obtain the open circuit voltage of the lithium battery in different temperature environments, which will not cause damage to the lithium battery. After the detection is completed, it will not affect the normal use of the lithium battery. The health status of the lithium battery is judged according to the open circuit voltage at different temperatures, which realizes qualitative detection of the micro-short circuit situation inside the lithium battery, improves the accuracy of the detection results, accurately judges the health status of the lithium battery, and promptly discovers potential micro-short circuit problems, avoiding safety accidents caused by lithium battery failures.

[0039] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A flow chart of a method for detecting the health status of a lithium battery provided by an embodiment of the present invention;

[0042] Figure 2 A flowchart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention;

[0043] Figure 3 A flowchart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention;

[0044] Figure 4 A flowchart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention;

[0045] Figure 5 A flowchart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention;

[0046] Figure 6The following is a curve diagram showing the change of open circuit voltage of lithium battery in different states;

[0047] Figure 7 A flowchart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention;

[0048] Figure 8 A flowchart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention;

[0049] Figure 9 A flowchart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention;

[0050] Figure 10 A schematic structural diagram of a lithium battery health status detection device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0052] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0053] Figure 1 This is a flowchart of a method for detecting the health status of a lithium battery, provided in an embodiment of the present invention. This embodiment of the present invention is applicable to detecting micro-short circuits within lithium batteries. This method can be performed by a lithium battery health status detection device, which can be implemented in hardware and / or software.

[0054] like Figure 1 As shown, the detection method provided by the embodiment of the present invention includes:

[0055] S110: Obtain a first open circuit voltage of the lithium battery in a first temperature range.

[0056] Specifically, before detecting the micro-short circuit inside the lithium battery, the lithium battery can be placed in a first temperature range for a preset time, and then the first open circuit voltage of the lithium battery is obtained. The first temperature range is a temperature range under normal temperature. For example, the range of the first temperature range can be 20°C-26°C, and the preset time can be between 12-36 hours. The first temperature range and the preset time can be set according to actual conditions. Generally, the internal temperature of the lithium battery is required to reach the first temperature range. The lithium battery is placed in the first temperature range for a period of time. After the internal temperature of the lithium battery is also within the temperature range, the positive and negative poles of the lithium battery are connected to a voltage measuring device, and the first open circuit voltage of the lithium battery at this time is obtained through the voltage measuring device.

[0057] S120: Obtain a second open circuit voltage and a third open circuit voltage of the lithium battery in a second temperature range.

[0058] Specifically, after obtaining the first open circuit voltage of the lithium battery in the first temperature range, the lithium battery is placed in an environment of the second temperature range, and the second open circuit voltage and the third open circuit voltage of the lithium battery are obtained in the second temperature range. The temperature in the second temperature range is lower than the temperature in the first temperature range, and the second temperature range is a temperature range in a low temperature environment. Exemplarily, the range of the second temperature range can be -43°C to -37°C. In the second temperature range, the open circuit voltage of the lithium battery will first rise to a maximum value and then slightly drop to a stable value. The second open circuit voltage and the third open circuit voltage of the lithium battery are obtained in the second temperature range by a voltage acquisition device, wherein the second open circuit voltage is the maximum value of the open circuit voltage of the lithium battery in the second temperature range, and the third open circuit voltage is the stable value of the open circuit voltage of the lithium battery in the second temperature range.

[0059] S130: Determine a health state of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage.

[0060] Specifically, after obtaining the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage of the lithium battery, the micro-short circuit situation inside the lithium battery can be determined based on the magnitude relationship among the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage, and a qualitative judgment can be made on the specific situation of the micro-short circuit inside the lithium battery to determine the health status of the lithium battery. The open circuit voltage of lithium batteries in different health states is different, and the change in the open circuit voltage of lithium batteries may not be obvious under normal temperature. However, under low temperature conditions, due to the slow reaction rate inside the lithium battery, the impact of different health states on the open circuit voltage is more significant, resulting in a more obvious change in the open circuit voltage. The health status of the lithium battery can be determined based on the change in the open circuit voltage under normal temperature and low temperature conditions, thereby improving the convenience and accuracy of detection.

[0061] The method for detecting the health status of a lithium battery provided in an embodiment of the present invention first obtains a first open circuit voltage of the lithium battery under normal temperature, then obtains a second open circuit voltage and a third open circuit voltage of the lithium battery under low temperature, wherein the second open circuit voltage is the maximum value of the open circuit voltage of the lithium battery under low temperature, and the third open circuit voltage is the stable value of the open circuit voltage of the lithium battery under low temperature, and finally determines the health status of the lithium battery based on the first open circuit voltage, the second open circuit voltage and the third open circuit voltage. The detection method of the embodiment of the present invention realizes non-destructive detection of the micro-short circuit state inside the lithium battery, and the detection method is simple. It only needs to obtain the open circuit voltage of the lithium battery under different temperature environments, which will not cause damage to the lithium battery. After the detection is completed, it will not affect the normal use of the lithium battery, and realizes qualitative detection of the micro-short circuit situation inside the lithium battery, improves the accuracy of the detection results, accurately judges the health status of the lithium battery, promptly discovers potential micro-short circuit problems, and avoids safety accidents caused by lithium battery failures.

[0062] Optional, Figure 2 This is a flow chart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention. Figure 2 , the detection method provided by the embodiment of the present invention includes:

[0063] S210: Control the lithium battery to pre-discharge according to a preset discharge rate.

[0064] Specifically, when testing for micro-short circuits within lithium batteries, to ensure the accuracy and reliability of subsequent test data and to prevent the impact of storage passivation or the presence of small amounts of impurities on subsequent lithium battery testing, the lithium battery must be pre-discharged before testing. The pre-discharge rate can be 0.005C-0.01C, and the depth of discharge can be 0.1%-0.5%.

[0065] S220: placing the pre-discharged lithium battery in a first temperature range for a first preset time, and obtaining a first open circuit voltage of the lithium battery.

[0066] Specifically, after pre-discharging the lithium battery, the pre-discharged lithium battery is stored in a first temperature range for a first preset time, so that the external temperature of the lithium battery is within the first temperature range. The lithium battery is also placed in the first temperature range for a period of time to ensure that the internal temperature of the lithium battery is also within the first temperature range, thereby preventing the internal and external temperature of the lithium battery from affecting the test results. After the internal temperature is within the first temperature range, the stable value of the open-circuit voltage of the lithium battery is obtained using a voltage measuring device, and the stable value of the open-circuit voltage of the lithium battery is recorded as the first open-circuit voltage.

[0067] S230: Obtain a second open circuit voltage and a third open circuit voltage of the lithium battery in a second temperature range.

[0068] S240: Determine a health state of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage.

[0069] The method for detecting the health status of a lithium battery provided by the present invention performs a small amount of pre-discharge before detecting the lithium battery, thereby avoiding the influence of storage passivation of the lithium battery or the presence of a small amount of impurities on subsequent lithium battery detection, and further improving the accuracy of the detection results.

[0070] Optional, Figure 3 This is a flow chart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention. Figure 3 , the detection method provided by the embodiment of the present invention includes:

[0071] S310: Obtain a first open circuit voltage of the lithium battery in a first temperature range.

[0072] S320: Place the lithium battery in a second temperature range for a second preset time; and obtain a second open circuit voltage and a third open circuit voltage of the lithium battery.

[0073] Specifically, after obtaining the first open-circuit voltage of the lithium battery at room temperature, it is also necessary to obtain the second and third open-circuit voltages of the lithium battery at a second temperature range, where the second temperature range is the temperature range under a low-temperature environment. Before obtaining the second and third open-circuit voltages, connect the lithium battery to a voltage measuring device, place the lithium battery in the second temperature range, and place the voltage measuring device in an external room temperature environment. Record the changes in the open-circuit voltage of the lithium battery under low-temperature conditions. In a low-temperature environment, the open-circuit voltage of the lithium battery will first rise and then fall to a stable value. The highest value of the open-circuit voltage rise of the lithium battery is recorded as the second open-circuit voltage, and then the stable value of the open-circuit voltage of the lithium battery is recorded as the third open-circuit voltage.

[0074] S330 : Determine a health state of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage.

[0075] The method for detecting the health status of a lithium battery provided by the present invention obtains the open circuit voltage of a lithium battery under normal temperature conditions, and obtains the maximum value and stable value of the open circuit voltage of a lithium battery under low temperature conditions. By judging the health status of a lithium battery based on the open circuit voltage of the lithium battery under different environments, not only can abnormal lithium batteries be accurately judged, but also the accuracy and reliability of micro-short circuit detection inside the lithium battery can be improved, thereby improving the accuracy of judging the health status of the lithium battery.

[0076] Optional, Figure 4This is a flow chart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention. Figure 4 , the detection method provided by the embodiment of the present invention includes:

[0077] S410: Obtain a first open circuit voltage of the lithium battery in a first temperature range.

[0078] S420: placing the pre-discharged lithium battery in a first temperature range for a first preset time, and obtaining a first open circuit voltage of the lithium battery.

[0079] S430: If the first open circuit voltage is greater than or equal to the first preset value, the second open circuit voltage is greater than or equal to the second preset value, and the third open circuit voltage is greater than or equal to the third preset value, it is determined that the lithium battery is in a normal state.

[0080] Specifically, after obtaining the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage of the lithium battery, the health status of the lithium battery can be determined based on the magnitude relationship between the first open circuit voltage and the first preset value, the magnitude relationship between the second open circuit voltage and the second preset value, and the magnitude relationship between the third open circuit voltage and the third preset value. If the first open circuit voltage is greater than or equal to the first preset value, the second open circuit voltage is greater than or equal to the second preset value, and the third open circuit voltage is greater than or equal to the third preset value, it is determined that the lithium battery is in a normal state at this time, indicating that no micro-short circuit occurs inside the lithium battery and the battery insulation state is good. Among them, the first preset value, the second preset value, and the third preset value are not specifically limited in the embodiment of the present invention and can be set according to actual needs. For example, the first preset value can be 3.65V, the second preset value can be 3.70V, and the third preset value can be 3.67V.

[0081] S440: If the first open circuit voltage is greater than or equal to the fourth preset value, the second open circuit voltage is less than the second preset value, and / or the third open circuit voltage is less than the third preset value, it is determined that the lithium battery is in a micro-short circuit state.

[0082] Specifically, if the first open-circuit voltage is greater than or equal to the fourth preset value, and the second open-circuit voltage is less than the second preset value and / or the third open-circuit voltage is less than the third preset value, it indicates that a micro-short circuit occurs inside the lithium battery. That is, if the first open-circuit voltage is greater than or equal to the fourth preset value and the second open-circuit voltage is less than the second preset value, a micro-short circuit occurs inside the lithium battery; if the first open-circuit voltage is greater than or equal to the fourth preset value and the third open-circuit voltage is less than the third preset value, a micro-short circuit also occurs inside the lithium battery; if the first open-circuit voltage is greater than or equal to the fourth preset value, the second open-circuit voltage is less than the second preset value and the third open-circuit voltage is less than the third preset value, a micro-short circuit also occurs inside the lithium battery. Among them, the fourth preset value is not limited in the embodiment of the present invention and can be set according to actual needs. For example, the fourth preset value can be 3.64V.

[0083] S450: If the first open circuit voltage is less than a fourth preset value, determine that the lithium battery is in a short circuit state.

[0084] Specifically, if the first open-circuit voltage of the lithium battery at room temperature is less than the fourth preset value, it indicates that the lithium battery is in a short-circuit state. If the open-circuit voltage of the lithium battery at room temperature is less than the fourth preset value, it indicates that the lithium battery is completely short-circuited and the remaining capacity of the lithium battery will be consumed in a short period of time.

[0085] Optional, Figure 5 This is a flow chart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention. Figure 5 , the detection method provided by the embodiment of the present invention includes:

[0086] S510: Obtain a first open circuit voltage of the lithium battery in a first temperature range.

[0087] S520: Place the pre-discharged lithium battery in a first temperature range for a first preset time, and obtain a first open circuit voltage of the lithium battery.

[0088] S530: If the first open circuit voltage is greater than or equal to the first preset value, the second open circuit voltage is greater than or equal to the second preset value, and the third open circuit voltage is greater than or equal to the third preset value, it is determined that the lithium battery is in a normal state.

[0089] S540. If the first open circuit voltage is greater than or equal to the fourth preset value, the second open circuit voltage is less than the second preset value and / or the third open circuit voltage is less than the third preset value, and the second open circuit voltage is greater than the first open circuit voltage, and the third open circuit voltage is greater than the first open circuit voltage, then it is determined that the lithium battery is in a mild micro-short circuit state.

[0090] Specifically, after determining that the lithium battery is in a micro-short circuit state based on the first, second, and third open-circuit voltages, it is necessary to further determine the specific extent of the micro-short circuit within the lithium battery based on the first, second, and third open-circuit voltages. If the second open-circuit voltage is greater than the first open-circuit voltage, and the third open-circuit voltage is also greater than the first open-circuit voltage, that is, the stable open-circuit voltage value of the lithium battery in a low-temperature environment is greater than the open-circuit voltage in a normal-temperature environment, it indicates that the lithium battery is in a mild micro-short circuit state.

[0091] S550. If the first open circuit voltage is greater than or equal to the fourth preset value, the second open circuit voltage is less than the second preset value and / or the third open circuit voltage is less than the third preset value, and the second open circuit voltage is greater than the first open circuit voltage, and the third open circuit voltage is less than or equal to the first open circuit voltage, then it is determined that the lithium battery is in a moderate micro-short circuit state.

[0092] Specifically, if the second open-circuit voltage is greater than the first open-circuit voltage, and the third open-circuit voltage is less than or equal to the first open-circuit voltage, that is, the maximum value of the open-circuit voltage of the lithium battery in a low-temperature environment is greater than the open-circuit voltage in a normal temperature environment, but the stable value of the open-circuit voltage in a low-temperature environment is less than the open-circuit voltage in a normal temperature environment, it means that there is a moderate micro-short circuit condition inside the lithium battery at this time.

[0093] S560. If the first open circuit voltage is greater than or equal to the fourth preset value, the second open circuit voltage is less than the second preset value and / or the third open circuit voltage is less than the third preset value, and the second open circuit voltage is less than or equal to the first open circuit voltage, and the third open circuit voltage is less than or equal to the first open circuit voltage, then it is determined that the lithium battery is in a severe micro-short circuit state.

[0094] Specifically, if the second open circuit voltage is less than or equal to the first open circuit voltage, the third open circuit voltage is less than or equal to the first open circuit voltage, and the highest and lowest values of the lithium battery in a low temperature environment are lower than the open circuit voltage in a normal temperature environment, it means that the micro-short circuit inside the lithium battery is more serious, and the lithium battery is in a severe micro-short circuit state.

[0095] S570: If the first open circuit voltage is less than a fourth preset value, determine that the lithium battery is in a short circuit state.

[0096] For example, Figure 6 The following is a curve diagram showing the change of open circuit voltage of lithium battery under different states. Figure 6 As shown, Class A is a lithium battery in a normal state with no internal micro-short circuit phenomenon, Class B is a lithium battery in a state of mild internal micro-short circuit, Class C is a lithium battery in a state of moderate internal micro-short circuit, and Class D is a lithium battery in a state of severe internal micro-short circuit.

[0097] The method for detecting the health status of a lithium battery provided by the present invention judges the micro-short circuit condition inside the lithium battery based on the first open-circuit voltage under normal temperature, and the second and third open-circuit voltages under low temperature. The detection process will not cause damage to the lithium battery and will not affect the normal use of the lithium battery. Through multi-dimensional detection, a qualitative judgment of the micro-short circuit condition inside the lithium battery is achieved, the accuracy of the detection is improved, early warning and risk assessment are achieved, and the life of the lithium battery is extended.

[0098] Optional, Figure 7 This is a flow chart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention. Figure 7 , the detection method provided by the embodiment of the present invention includes:

[0099] S610: Obtain a first open circuit voltage of the lithium battery in a first temperature range.

[0100] S620: Place the pre-discharged lithium battery in a first temperature range for a first preset time, and obtain a first open circuit voltage of the lithium battery.

[0101] S630: Determine a health state of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage.

[0102] S640: Determine the storage-year self-discharge ratio of the lithium battery according to the health status of the lithium battery.

[0103] Specifically, after determining the health status of the lithium battery based on the first, second, and third open-circuit voltages, it is also necessary to determine the storage-year self-discharge ratio of the lithium battery based on the health status of the lithium battery to achieve quantitative judgment of the lithium battery. Lithium batteries of different health levels have different storage-year self-discharge ratios. A lithium battery in a normal state has the lowest storage-year self-discharge ratio, while a lithium battery in a completely short-circuited state has the highest storage-year self-discharge ratio.

[0104] Optional, Figure 8 This is a flow chart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention. Figure 8 , the detection method provided by the embodiment of the present invention includes:

[0105] S710: Obtain a first open circuit voltage of the lithium battery in a first temperature range.

[0106] S720: Place the pre-discharged lithium battery in a first temperature range for a first preset time, and obtain a first open circuit voltage of the lithium battery.

[0107] S730: Determine a health status of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage.

[0108] S740: If the lithium battery is in normal condition, the storage-year self-discharge ratio of the lithium battery is 0.01.

[0109] Specifically, if the lithium battery is in normal condition and there is no micro-short circuit inside the lithium battery, it can be determined that the annual self-discharge ratio of the lithium battery is 0.01, the micro-short circuit current inside the lithium battery can be ignored, and the storage life of the lithium battery is about 100 years.

[0110] S750: If the lithium battery is in a severe micro-short circuit state, the storage-year self-discharge ratio of the lithium battery is greater than 0.5.

[0111] Specifically, if the lithium battery is in a severe micro-short circuit state, the storage-year self-discharge ratio of the lithium battery is greater than 0.5, and the micro-short circuit current of the lithium battery is greater than 68.5uA, the lithium battery will be completely self-discharged within 2 years, and the storage life is less than 2 years.

[0112] S760: If the lithium battery is in a mild micro-short circuit state or a moderate micro-short circuit state, determine the storage-year self-discharge ratio of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage.

[0113] Specifically, if the lithium battery is in a mild micro-short circuit state or a moderate micro-short circuit state, it is necessary to determine the storage-year self-discharge ratio of the lithium battery based on the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage. The lithium battery in a mild micro-short circuit state or a moderate micro-short circuit state can be stored in a high-temperature environment for a period of time, and then discharged with a current of 0.001C, and the discharge capacity of the lithium battery in the high-temperature environment is recorded. The self-discharge current in the high-temperature environment is determined based on the discharge capacity in the high-temperature environment and the average discharge capacity of the lithium battery. The micro-short circuit current in a high-temperature environment is four times that in a normal temperature environment. Then, based on the acceleration principle of chemical reactions, the self-discharge current of the battery in a normal temperature environment is calculated. Among them, the high-temperature environment can be 43±3°C, and the storage time in a high-temperature environment can be set according to actual conditions. The average discharge capacity of the lithium battery can be obtained from the manufacturer. The calculation formula for the storage-year self-discharge ratio of a lithium battery is:

[0114]

[0115] Among them, W is the storage year self-discharge ratio of the lithium battery, C1 is the average discharge capacity of the lithium battery, C2 is the discharge capacity of the lithium battery in a high temperature environment, and H is the storage time of the lithium battery in a high temperature environment.

[0116] By obtaining the annual self-discharge ratio of lithium batteries in each state multiple times and fitting the test results of lithium batteries in different states, it can be determined that if the lithium battery is in a mild micro-short circuit state, the annual self-discharge ratio of the lithium battery in storage can be determined based on the first open-circuit voltage, the second open-circuit voltage, and the third open-circuit voltage. When the lithium battery is in a moderate micro-short circuit state, the calculation formula for the annual self-discharge ratio of the lithium battery in storage is:

[0117]

[0118] If the lithium battery is in a moderate micro-short circuit state, the storage-year self-discharge ratio of the lithium battery can be determined based on the second open circuit voltage and the third open circuit voltage. When the lithium battery is in a moderate micro-short circuit state, the calculation formula for the storage-year self-discharge ratio of the lithium battery is:

[0119]

[0120] Wherein, W is the storage-year self-discharge ratio of the lithium battery, V1 is the first open-circuit voltage of the lithium battery, V2 is the second open-circuit voltage of the lithium battery, and V3 is the third open-circuit voltage of the lithium battery.

[0121] When a lithium battery is in a short-circuit state, it will consume itself in a short period of time and is not recommended for use. For example, the following table shows the annual storage self-discharge rate, storage life, and micro-short-circuit current for lithium batteries in various states.

[0122]

[0123] Among them, the 1# lithium battery is in normal condition and is classified as A. The annual storage self-discharge ratio of this type is about 0.01, the storage life is about 100 years, and the internal micro-short-circuit current is negligible. The 2# lithium battery is in a mild micro-short-circuit state and is classified as B. According to the first open circuit voltage, second open circuit voltage, and third open circuit voltage of the lithium battery, the annual storage self-discharge ratio is 0.197, the storage life is 5.08 years, and the internal micro-short-circuit current is 27uA. The 3# lithium battery is in a moderate micro-short-circuit state and is classified as C. According to the second open circuit voltage and third open circuit voltage of the lithium battery, the annual storage self-discharge ratio is 0.285, the storage life is 3.51 years, and the internal micro-short-circuit current is 39uA. The 4# lithium battery is in a severe micro-short-circuit state. Through a large number of tests, it is known that the annual storage self-discharge ratio of the lithium battery in this state is greater than 0.5, the internal micro-short-circuit current is greater than 68.5uA, and it will be consumed within 2 years. The 5# lithium battery is in a short-circuit state. The lithium battery will be completely consumed within a certain period of time. It is dangerous and is not recommended for use.

[0124] The lithium battery health status detection method provided by the present invention, after qualitatively determining the lithium battery, determines the annual storage self-discharge ratio, micro-short-circuit current, and storage life of the lithium battery based on the first, second, and third open-circuit voltages, thereby achieving quantitative calculation of the lithium battery. This improves the accuracy of lithium battery judgment. By providing specific numerical indicators to reflect the battery's performance status, the method provides a full understanding of the lithium battery's own status and allows for timely detection of the lithium battery's status, enabling the implementation of appropriate solutions and avoiding safety accidents caused by lithium battery failures.

[0125] Optional, Figure 9 This is a flow chart of another method for detecting the health status of a lithium battery provided by an embodiment of the present invention. Figure 9 In a method for detecting the health status of a lithium battery provided by an embodiment of the present invention, the lithium battery is first pre-discharged to eliminate the influence of passivation or impurities on the lithium battery. The pre-discharged lithium battery is then stored in a room temperature environment (23±3°C) for a period of time to allow the internal and external temperatures of the lithium battery to reach the above-mentioned ambient temperature. The open circuit voltage returns to a normal value and stabilizes. The normal value V1 of the battery is recorded as the first open circuit voltage. When the lithium battery is placed in a low temperature environment (-40±3°C), the change in the open circuit voltage of the lithium battery is recorded. The lithium battery voltage first increases, then decreases, and then tends to stabilize. The maximum value V2 and the stable value V3 of the open circuit voltage of the lithium battery are recorded. The maximum value V2 is used as the second open circuit voltage, and the stable value V3 is used as the third open circuit voltage. Then compare the relative sizes of the first open-circuit voltage V1, the second open-circuit voltage V2 and the third open-circuit voltage V3 to qualitatively judge the degree of micro-short circuit of the lithium battery, and substitute the first open-circuit voltage V1, the second open-circuit voltage V2 and the third open-circuit voltage V3 into the corresponding formula to calculate the micro-short-circuit current of the lithium battery and the usable life of the battery, thereby realizing quantitative calculation of the lithium battery.

[0126] The lithium battery health status detection method provided by the embodiment of the present invention first obtains a first open-circuit voltage of the lithium battery at room temperature, then obtains a second open-circuit voltage and a third open-circuit voltage of the lithium battery at low temperature, and finally determines the health status of the lithium battery based on the first, second, and third open-circuit voltages. This method achieves qualitative detection and quantitative calculation of micro-short circuits within the lithium battery, accurately determining the health status of the lithium battery, promptly identifying potential micro-short circuit problems, and avoiding safety accidents caused by lithium battery failures.

[0127] An embodiment of the present invention also provides a device for detecting the health status of a lithium battery. Figure 10 This is a schematic diagram of a device for detecting the health status of a lithium battery provided by an embodiment of the present invention. Figure 10 As shown, the lithium battery health status detection device 100 includes:

[0128] The first data acquisition module 10 is configured to acquire a first open circuit voltage of the lithium battery in a first temperature range.

[0129] The second data acquisition module 20 is used to obtain a second open circuit voltage and a third open circuit voltage of the lithium battery in a second temperature range; wherein the second temperature range is lower than the first temperature range, the second open circuit voltage is the maximum value of the lithium battery in the second temperature range, and the third open circuit voltage is the stable value of the lithium battery in the second temperature range.

[0130] The health state determination module 30 is configured to determine the health state of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage.

[0131] In this embodiment of the present invention, a first data acquisition module acquires a first open-circuit voltage of a lithium battery at room temperature, a second data acquisition module acquires second and third open-circuit voltages at low temperature, and finally a health status determination module determines the health status of the lithium battery. This method only requires measuring the open-circuit voltage of the lithium battery at different temperatures, which simplifies the requirements for testing equipment and personnel. It eliminates interference from factors such as internal impurities, battery hysteresis, and battery storage time, improving detection accuracy and enabling timely detection of potential micro-short circuits, thereby avoiding safety incidents caused by lithium battery failures.

[0132] The lithium battery health status detection device provided in the embodiment of the present invention can execute the lithium battery health status detection method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0133] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for detecting the health status of a lithium battery, characterized in that: include: Obtaining a first open circuit voltage of the lithium battery in a first temperature range; Obtaining a second open circuit voltage and a third open circuit voltage of the lithium battery in a second temperature range; wherein the second temperature range is lower than the first temperature range, the second open circuit voltage is a maximum value of the lithium battery in the second temperature range, and the third open circuit voltage is a stable value of the lithium battery in the second temperature range; The health state of the lithium battery is determined according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage.

2. The detection method according to claim 1, wherein Obtaining a first open circuit voltage of the lithium battery in a first temperature range includes: Controlling the lithium battery to pre-discharge according to a preset discharge rate; The pre-discharged lithium battery is placed in the first temperature range for a first preset time, and a first open circuit voltage of the lithium battery is obtained.

3. The detection method according to claim 1, wherein Obtaining a second open circuit voltage and a third open circuit voltage of the lithium battery in a second temperature range includes: The lithium battery is placed in the second temperature range for a second preset time; and a second open circuit voltage and a third open circuit voltage of the lithium battery are obtained.

4. The detection method according to claim 1, wherein Determining the health state of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage includes: If the first open circuit voltage is greater than or equal to a first preset value, the second open circuit voltage is greater than or equal to a second preset value, and the third open circuit voltage is greater than or equal to a third preset value, it is determined that the lithium battery is in a normal state.

5. The detection method according to claim 4, characterized in that Determining the health state of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage further includes: If the first open circuit voltage is greater than or equal to a fourth preset value, the second open circuit voltage is less than a second preset value, and / or the third open circuit voltage is less than a third preset value, it is determined that the lithium battery is in a slight short circuit state; If the first open circuit voltage is less than a fourth preset value, it is determined that the lithium battery is in a short circuit state.

6. The detection method according to claim 5, characterized in that Determining that the lithium battery is in a slight short circuit state includes: If the second open circuit voltage is greater than the first open circuit voltage, and the third open circuit voltage is greater than the first open circuit voltage, it is determined that the lithium battery is in a slight short circuit state; If the second open circuit voltage is greater than the first open circuit voltage, and the third open circuit voltage is less than or equal to the first open circuit voltage, it is determined that the lithium battery is in a moderate slight short circuit state; If the second open circuit voltage is less than or equal to the first open circuit voltage, and the third open circuit voltage is less than or equal to the first open circuit voltage, it is determined that the lithium battery is in a severe micro-short circuit state.

7. The detection method according to claim 6, characterized in that After determining the health status of the lithium battery according to the first open circuit voltage, the second open circuit voltage, and the third open circuit voltage, the method includes: The storage-year self-discharge ratio of the lithium battery is determined according to the health status of the lithium battery.

8. The detection method according to claim 7, characterized in that Determining the storage-year self-discharge ratio of the lithium battery according to the health status of the lithium battery includes: If the lithium battery is in a normal state, the storage-year self-discharge ratio of the lithium battery is 0.01; If the lithium battery is in a severe micro-short circuit state, the storage-year self-discharge ratio of the lithium battery is greater than 0.5; If the lithium battery is in a mild micro-short circuit state or a moderate micro-short circuit state, the storage-year self-discharge ratio of the lithium battery is determined according to the first open-circuit voltage, the second open-circuit voltage, and the third open-circuit voltage.

9. The detection method according to claim 8, characterized in that When the lithium battery is in a slightly short-circuited state, the calculation formula for the storage-year self-discharge ratio of the lithium battery is: When the lithium battery is in a moderate micro-short circuit state, the calculation formula for the storage-year self-discharge ratio of the lithium battery is: Wherein, W is the storage-year self-discharge ratio of the lithium battery, V1 is the first open-circuit voltage of the lithium battery, V2 is the second open-circuit voltage of the lithium battery, and V3 is the third open-circuit voltage of the lithium battery.

10. A device for detecting the health status of a lithium battery, characterized in that: include: A first data acquisition module, configured to acquire a first open circuit voltage of the lithium battery in a first temperature range; a second data acquisition module, configured to acquire a second open circuit voltage and a third open circuit voltage of the lithium battery in a second temperature range; wherein the second temperature range is lower than the first temperature range, the second open circuit voltage is the maximum value of the lithium battery in the second temperature range, and the third open circuit voltage is the stable value of the lithium battery in the second temperature range; A health status determination module is used to determine the health status of the lithium battery according to the first open circuit voltage, the second open circuit voltage and the third open circuit voltage.

Images