1. A battery cell detection method is characterized by comprising the following steps:

acquiring a preset voltage change rate, wherein the preset voltage change rate is the voltage change rate of the battery cell in a normal state;

acquiring to-be-detected data of a to-be-detected battery core, wherein the to-be-detected data comprises a first voltage change rate;

and comparing the first voltage change rate with the preset voltage change rate, and judging whether the battery cell to be detected is in an abnormal state according to a comparison result.

2. The cell detection method of claim 1, wherein the preset voltage change rate comprises: the voltage change rate of the battery cell in a normal state during discharging after full charging; the first voltage rate of change comprises: and a second voltage change rate when the battery cell to be detected is discharged after full charge.

3. The cell detection method according to claim 2, wherein a time required for discharging to the first detection voltage after the cell is fully charged is defined as a first detection time, and the preset voltage change rate is (full-charge voltage of the cell in the normal state — first detection voltage)/first detection time of the cell in the normal state; the first detection voltage is 1/1.25 or 1/1.5 or 1/2 or 1/3 or 1/4 of the full charge voltage of the battery cell in the normal state, or the first detection voltage is 0.

4. The cell detection method according to claim 3, wherein the second voltage change rate is (full charge voltage of the cell to be detected-first detection voltage)/first detection time of the cell to be detected.

5. The cell detection method of claim 1, wherein the preset voltage change rate comprises: the voltage change rate of the normal state of the battery cell during self-discharge termination voltage charging; the first voltage rate of change comprises: and a third voltage change rate of the cell to be detected during self-discharge termination voltage charging.

6. The cell detection method according to claim 5, wherein a time required for the cell to be charged from the discharge end voltage to a second detection voltage is defined as a second detection time, and the preset voltage change rate is (second detection voltage-discharge end voltage of the cell in the normal state)/the second detection time of the cell in the normal state; the second detection voltage is 1/1.25 or 1/1.5 or 1/2 or 1/3 or 1/4 of the full charge voltage of the battery cell in the normal state.

7. The cell detection method according to claim 6, wherein the third voltage change rate is (second detection voltage-end-of-discharge voltage of the cell to be detected)/second detection time of the cell to be detected.

8. The cell detection method of claim 1, wherein the preset voltage change rate comprises: voltage change rate when the battery cell in a normal state is fully charged and then stands; the first voltage rate of change comprises: and (4) a fourth voltage change rate when the battery cell to be detected is placed after being fully charged.

9. The cell detection method according to claim 8, wherein a voltage at a predetermined time after the cell is fully charged is defined as a third detection voltage, and the preset voltage change rate is (full-charge voltage of the cell in the normal state — third detection voltage of the cell in the normal state)/the predetermined time.

10. The cell detection method according to claim 9, wherein the fourth voltage change rate is (full charge voltage of the cell to be detected — third detection voltage of the cell to be detected)/predetermined time.

11. The cell testing method of claim 1, further comprising:

performing multiple charging/discharging cycle detection on the battery cell judged to be in the abnormal state, and acquiring a first voltage change rate of the battery cell in the abnormal state;

and if the first voltage change rate during discharging after each full charge is greater than the preset voltage change rate, judging that the electric core in the abnormal state is damaged.

12. The cell testing method of claim 1, further comprising:

performing multiple charging/discharging cycle detection on the battery cell judged to be in the abnormal state, and acquiring the capacity change of the battery cell in the abnormal state;

and if the capacity change in each charging/discharging cycle is larger than the preset capacity change, judging that the electric core in the abnormal state is damaged, wherein the preset capacity change is the capacity change in the normal state of the electric core in the charging/discharging cycle.

13. The cell testing method of claim 1, further comprising:

performing multiple charging/discharging cycle detection on the battery cell judged to be in the abnormal state, and acquiring a first voltage change rate and capacity change of the battery cell in the abnormal state;

and if the capacity change during each charging/discharging cycle is larger than the preset capacity change, and the first voltage change rate during discharging after each full charge is larger than the preset voltage change rate, judging that the electric core in the abnormal state is damaged, wherein the preset capacity change is the capacity change during the charging/discharging cycle of the electric core in the normal state.

14. The cell detection method of claim 1, wherein the data to be detected further includes a full charge voltage, and the cell detection method further comprises:

and if the difference value between the full charge voltage of the battery cell in the abnormal state and the full charge voltage of the battery cell in the normal state exceeds a first threshold value, judging that the battery cell in the abnormal state is damaged.

15. The cell testing method of claim 1, wherein the number of the cells is multiple, at least some of the cells are connected in series, and the cell testing method further comprises:

in the abnormal battery cell, the maximum deviation between the first voltage change rate and the preset voltage change rate is judged as the occurrence of damage; and/or the presence of a gas in the gas,

and in the abnormal battery cells, judging that the battery cells are damaged when the difference value between the full charge voltage and the full charge voltage of the normal battery cells is maximum.

16. A cell detection device, characterized in that the cell detection device adopts the cell detection method according to any one of claims 1 to 15.

Background

The safety of laminate polymer battery cell, especially mechanical safety is the important problem that laminate polymer battery faced at present, if fall in a lot of abominable operating modes, vibration even roll the laminate polymer battery damage that probably appears after can't discover but the in-process that end user continues to use can cause the fail safe nature hidden danger.

Therefore, it is urgently needed to find some key parameters for cell detection so as to achieve the effectiveness and rapidity of cell fault judgment.

Disclosure of Invention

In view of this, the present application provides a cell detection method and device to solve the problem that the existing battery safety judgment method is difficult to implement and has validity and rapidity for judging a cell fault.

In a first aspect, the present application provides a battery cell detection method, including: acquiring a preset voltage change rate, acquiring the voltage change rate of the battery cell with the preset voltage change rate in a normal state, acquiring the data to be detected of the battery cell to be detected, wherein the data to be detected comprises a first voltage change rate, comparing the first voltage change rate with the preset voltage change rate, and judging whether the battery cell to be detected is in an abnormal state or not according to a comparison result. The voltage change rate of the battery cell is used as a key parameter for battery cell detection, the acquired first voltage change rate is compared with a preset voltage change rate, whether the battery cell to be detected is abnormal or not is judged according to a comparison result, and the accuracy and effectiveness for identifying the abnormity of the battery cell can be improved.

In one embodiment, the preset voltage change rate comprises: the voltage change rate when discharging after the full charge of electric core of normal condition, first voltage change rate includes: and a second voltage change rate when the battery cell to be detected is discharged after full charge. Through further definitely presetting the range of the voltage change rate and the first voltage change rate, the battery cell abnormity can be identified in the discharging process after full charge, and the speed of battery cell detection is further accelerated.

In one embodiment, the time required for discharging the battery cell to the first detection voltage after the battery cell is fully charged is defined as a first detection time, and the preset voltage change rate is (full-charge voltage of the battery cell in the normal state — first detection voltage)/the first detection time of the battery cell in the normal state. The first detection voltage is 1/1.25, 1/1.5, 1/2, 1/3 or 1/4 of the full charge voltage of the battery cell in the normal state, or the first detection voltage is 0. Through further definitely presetting the voltage change rate, the battery core abnormity can be identified within the first detection time in the discharging process after full charge, and the speed of battery core detection is further accelerated.

In one embodiment, the second voltage change rate is (full charge voltage of the cell to be detected — first detection voltage)/first detection time of the cell to be detected. Through further determining the actual voltage change rate, the battery core abnormity can be identified within the first detection time in the discharging process after full charge, and the speed of battery core detection is further accelerated.

In one embodiment, the preset voltage change rate comprises: the voltage change rate when the battery cell in the normal state is charged from the discharge termination voltage includes: and a third voltage change rate of the cell to be detected during self-discharge termination voltage charging. The range of the voltage change rate and the first voltage change rate is further definitely preset, so that the abnormity of the battery cell can be identified in the self-discharge termination voltage charging process, and the detection speed of the battery cell is further accelerated.

In one embodiment, the time required for the cell to charge from the discharge end voltage to the second detection voltage is defined as a second detection time, and the preset voltage change rate is (second detection voltage — discharge end voltage of the cell in the normal state)/the second detection time of the cell in the normal state. The second detection voltage is 1/1.25 or 1/1.5 or 1/2 or 1/3 or 1/4 of the full charge voltage of the battery cell in the normal state. The battery cell abnormity can be identified within the second detection time in the self-discharge termination voltage charging process by further clearly presetting the voltage change rate, so that the detection speed of the battery cell is further accelerated.

In one embodiment, the third voltage change rate is (second detection voltage — end-of-discharge voltage of the cell to be detected)/the second detection time of the cell to be detected. By further determining the first voltage change rate, the battery core abnormality can be identified within the second detection time in the self-discharge termination voltage charging process, and the detection speed of the battery core is further accelerated.

In one embodiment, the preset voltage change rate comprises: voltage change rate when the battery cell in a normal state is fully charged and then stands; the first voltage rate of change comprises: and (4) a fourth voltage change rate when the battery cell to be detected is placed after being fully charged. Through further definitely presetting the range of the voltage change rate and the first voltage change rate, the battery cell abnormity can be identified when the battery cell to be detected is placed to the preset time after being fully charged, and further the detection speed of the battery cell is accelerated.

In one embodiment, the voltage when the battery cell is left standing for a predetermined time after being fully charged is defined as the third detection voltage, and the preset voltage change rate is (full-charge voltage of the battery cell in the normal state — third detection voltage of the battery cell in the normal state)/the predetermined time. Through further determining the preset voltage change rate, the battery cell abnormity can be identified when the battery cell to be detected is placed to the preset time after being fully charged, and the detection speed of the battery cell is further accelerated.

In one embodiment, the fourth voltage change rate is (full charge voltage of the cell to be detected — third detection voltage of the cell to be detected)/the predetermined time. Through further making clear first voltage change rate for standing after the electric core that awaits measuring is full to fill and can discern electric core unusual when predetermineeing time, and then do benefit to the detection speed that further accelerates electric core. In an embodiment, the cell detection method further includes: and performing multiple charging/discharging cycle detection on the battery cell judged to be in the abnormal state, and acquiring a first voltage change rate of the battery cell in the abnormal state.

And if the first voltage change rate during discharging after each full charge is greater than the preset voltage change rate, judging that the electric core in the abnormal state is damaged. The voltage change rate of the abnormal battery cell is used as a key parameter for battery cell detection, and the first voltage change rate of the abnormal battery cell obtained through charge/discharge cycle detection during discharge after each full charge is greater than the preset voltage change rate and is used as a judgment standard for judging whether the abnormal battery cell is damaged, so that the accuracy and efficiency for identifying the abnormal battery cell damage can be improved, and the effectiveness for judging the safety of the battery can be increased.

In an embodiment, the cell detection method further includes: and performing multiple charging/discharging cycle detection on the battery cell judged to be in the abnormal state, and acquiring the capacity change of the battery cell in the abnormal state. And if the capacity change in each charging/discharging cycle is larger than the preset capacity change, judging that the cell in the abnormal state is damaged, and changing the preset capacity into the capacity change in the normal state in the charging/discharging cycle of the cell. The capacity change of the abnormal battery cell is used as a key parameter for battery cell detection, and the capacity change of the abnormal battery cell obtained through charge/discharge cycle detection in each charge/discharge cycle is larger than the preset capacity change which is used as a judgment standard for judging whether the abnormal battery cell is damaged or not, so that the accuracy and efficiency for identifying the abnormal battery cell damage can be improved, and the effectiveness for judging the safety of the battery can be increased.

In an embodiment, the cell detection method further includes: and performing multiple charging/discharging cycle detection on the battery cell judged to be in the abnormal state, and acquiring a first voltage change rate and capacity change of the battery cell in the abnormal state.

And if the capacity change during each charge/discharge cycle is larger than the preset capacity change and the first voltage change rate during discharge after each full charge is larger than the preset voltage change rate, judging that the cell in the abnormal state is damaged and the preset capacity change is changed into the capacity change during the cell charge/discharge cycle in the normal state. The capacity change and the voltage change rate of the abnormal battery cell are simultaneously used as key parameters for battery cell detection, the capacity change of the abnormal battery cell obtained through charge/discharge cycle detection in each charge/discharge cycle is larger than the preset capacity change, and the first voltage change rate in discharge after full charge in each time is larger than the preset voltage change rate and is used as a judgment standard for judging whether the abnormal battery cell is damaged, so that the accuracy and the efficiency for identifying the abnormal battery cell damage can be improved, and the effectiveness for judging the safety of the battery can be increased.

In an embodiment, the data to be detected further includes a full charge voltage, and the cell detection method further includes: and if the difference value between the full charge voltage of the battery cell in the abnormal state and the full charge voltage of the battery cell in the normal state exceeds a first threshold value, judging that the battery cell in the abnormal state is damaged. The full charge voltage of the battery core in the abnormal state is used as a key parameter for detecting the battery core, and the difference value of the full charge voltage of the battery core in the normal state of the full charge voltage in the abnormal state, which is obtained, exceeds the first threshold value to be used as a judgment standard for judging whether the battery core in the abnormal state is damaged or not, so that the accuracy and the efficiency for identifying the damage of the battery core in the abnormal state can be improved, and the effectiveness for judging the safety of the battery can be increased.

The number of the battery cells is multiple, wherein at least part of the battery cells are connected in series. The battery cell detection method further comprises the following steps: and/or judging that the damage occurs when the difference value between the full charge voltage and the full charge voltage of the battery cell in the normal state is the largest in the battery cells in the abnormal state. The voltage change rate of the battery cell and/or the full charge voltage of the battery cell are/is used as key parameters for detecting the battery cell, and in the battery cell in the abnormal state, the first voltage change rate and the preset voltage change rate with the maximum deviation are used as the judgment standard for judging whether the battery cell in the abnormal state is damaged or not, and/or the difference value between the full charge voltage of the battery cell in the abnormal state and the full charge voltage of the battery cell in the normal state is the maximum, so that the accuracy and the efficiency for identifying the damage of the battery cell in the abnormal state can be improved, and the effectiveness for judging the safety of the battery can be increased.

In a second aspect, the present application provides a battery cell detection apparatus, which employs the battery cell detection method of any one of the first aspects of the present application. By adopting the battery core detection method, the battery core detection device can improve the accuracy and efficiency of identifying the battery core abnormity, further can timely find the abnormity of the battery, and improves the safety and reliability of the battery.

The application provides a cell detection method and a cell detection device, wherein the cell detection method compares the acquired first voltage change rate of a cell to be detected with a preset voltage change rate by taking the voltage change rate of the cell as a key parameter for cell detection, judges whether the cell to be detected is abnormal or not by comparing results, and can improve the accuracy and efficiency for identifying the cell abnormality. The Battery detection method is applied to a Battery Management System (BMS), so that the abnormal occurrence of the Battery can be found in time, and the safety and reliability of the Battery are improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic flow chart of a cell detection method according to the present application;

fig. 2 is a graph illustrating a change in a full charge voltage of a damaged cell with time according to an embodiment of the present disclosure;

FIG. 3 is an enlarged view of the curve in the dashed box shown in FIG. 2;

fig. 4 is a graph comparing the Capacity residual (Capacity Re.) of a damaged cell and the voltage change rate (Δ V/Δ T) with the Cycle number (Cycle No.) during the normal charge/discharge Cycle in the normal charge/discharge Cycle according to the embodiment of the present application with the Capacity residual (Capacity Re.) of a normal cell and the voltage change rate (Δ V/Δ T) with the Cycle number (Cycle No.);

fig. 5 is a graph comparing the variation of the Capacity residual (Capacity Re.) of a broken cell and the voltage variation rate (Δ V/Δ T) at the time of discharge after full charge with the Cycle number (Cycle No.) during the normal charge/discharge Cycle in the embodiment of the present application with the variation of the Capacity residual (Capacity Re.) of a normal state and the voltage variation rate (Δ V/Δ T) at the time of discharge after full charge with the Cycle number;

fig. 6 is a graph comparing the full charge voltage of different cells in a pouch battery of 6s1p (a battery pack formed by 6 cells connected in series) containing broken cells in an embodiment of the present application;

fig. 7 is a graph comparing first rates of change of voltage for different cells in a pouch battery of 6s1p with broken cells, in accordance with an embodiment of the present application;

fig. 8 is a block diagram of a structure of a cell detection device according to the present application.

Detailed Description

The traditional battery cell detection method has the problems of poor effectiveness or low detection speed. Based on this, the application provides a battery cell detection method and device. The technical solutions in the embodiments of the present application are clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. The following embodiments and their technical features may be combined with each other without conflict.

The application provides an embodiment of a cell detection method, as shown in fig. 1, the cell detection method includes the steps of:

s10, acquiring a preset voltage change rate, wherein the preset voltage change rate is the voltage change rate of the battery cell in a normal state;

s20, acquiring data to be detected of the battery cell to be detected, wherein the data to be detected comprises a first voltage change rate;

and S30, comparing the first voltage change rate with a preset voltage change rate, and judging whether the battery cell to be detected is in an abnormal state according to the comparison result.

Specifically, the detection principle of the battery cell detection method according to the embodiment of the application is as follows: once a battery core in the battery is damaged, the battery core can react with oxygen, water vapor and the like in the air to cause the impedance of the surface of a pole piece to be increased, particularly, under a full-charge state, the oxidability of an anode is strong, the side reaction among the air, electrolyte and an electrode is accelerated, and the loss of active lithium is caused; as shown in fig. 2 to 3, it is shown that the polarization potential of the battery is larger under charging due to the increase of polarization, and the battery reaches the upper charging limit voltage more quickly, causing a phenomenon of insufficient charging; the charge upper limit voltage is a voltage when the battery is fully charged. If the charging is not stopped even when the charging upper limit voltage is reached, it is represented as overcharging. The most direct manifestation of overcharge is: the battery is heated obviously, and if the battery is charged rapidly, the battery is heated to scald hands. Since the battery is saturated and the general charger continues to charge the battery, the battery has difficulty in increasing the voltage again and is emitted in the form of heat, which may permanently damage the battery. After the battery is fully charged, the voltage is reduced more quickly; in addition, when fully charged, the side reaction among air, electrolyte and electrodes is more obvious, the voltage drop is further accelerated, and the comprehensive expression shows that the voltage change rate (delta V/delta T) during discharging after full charge is obviously larger than that of a normal battery. For example, a side reaction in which active lithium in a lithium ion battery is converted into inactive lithium by an electrochemical reaction is more significant as the voltage applied as a side reaction increases the charging voltage of the lithium ion battery, and thus the side reaction is more significant at the time of full charge.

In the battery cell detection method provided by the embodiment of the application, the voltage change rate of the battery cell is used as a key parameter for battery cell detection; and the acquired first voltage change rate of the battery cell to be detected is compared with the preset voltage change rate, whether the battery cell to be detected is abnormal or not is judged according to the comparison result, and the accuracy and the effectiveness for identifying the battery cell abnormality can be improved. The Battery detection method is applied to the Management of a Battery Management System (BMS), so that the abnormal occurrence of the Battery can be found in time, and the safety and reliability of the Battery are improved.

In further implementations of one or more embodiments, the step S10 of presetting the voltage change rate may include: the voltage change rate when the battery cell in a normal state is discharged after being fully charged. If the time required for discharging the battery cell to the first detection voltage after the battery cell is fully charged is defined as the first detection time, the preset voltage change rate is (full charge voltage of the battery cell in the normal state — the first detection voltage)/the first detection time of the battery cell in the normal state. For example, the first detection voltage may be 1/1.25 or 1/1.5 or 1/2 or 1/3 or 1/4 of the full charge voltage of the cell in the normal state, or the first detection voltage is 0. The full charge voltage of the battery cell in the normal state, the first detection voltage and the first detection time of the battery cell in the normal state can be obtained through a discharge test after the battery cell in the normal state is fully charged.

Of course, the preset voltage change rate may also include: the voltage change rate of the normal state of the cell during self-discharge termination voltage charging. If the time required for charging the cell from the discharge end voltage to the second detection voltage is defined as the second detection time, the preset voltage change rate is (the second detection voltage — the discharge end voltage of the cell in the normal state)/the second detection time of the cell in the normal state; the discharge end voltage refers to the lowest voltage allowed when the battery is discharged; if the voltage is lower than the discharge termination voltage and then continues to discharge, the voltage at the two ends of the battery can be rapidly reduced to form deep discharge, so that the products formed on the polar plate are not easy to recover during normal charging, thereby influencing the service life of the battery. For example, the second detection voltage may be 1/1.25 or 1/1.5 or 1/2 or 1/3 or 1/4 of the full charge voltage of the cell in the normal state. The discharge end voltage of the battery cell in the normal state, the second detection voltage and the second detection time of the battery cell in the normal state can be obtained through a self-discharge end voltage charge test of the battery cell in the normal state.

Of course, the preset voltage change rate may also include: and (3) voltage change rate when the battery cell in a normal state is placed after being fully charged. If the voltage at the time when the battery cell is left standing for the predetermined time after being fully charged is defined as the third detection voltage, the preset voltage change rate is (the fully charged voltage of the battery cell in the normal state — the third detection voltage of the battery cell in the normal state)/the predetermined time. Standing after the battery is fully charged can be understood as: the battery cell itself is neither in a charging state nor in a discharging state for the load.

It should be understood that the above-mentioned normal state cell refers to a cell which remains in the original best state without change or damage. The voltage change rate of the normal-state battery cell is obtained under the same working condition as that of the battery cell to be tested. Illustratively, after full charge, discharging the normal battery cell and the battery cell to be detected at the same discharge rate, and comparing the discharge voltage change rate when the battery cell is discharged to the same voltage; and charging the normal-state battery cell and the battery cell to be detected at the same charging rate from the discharging termination voltage, charging to the same voltage, and comparing the charging voltage change rate.

In a further implementation manner of one or more embodiments, in step S20, the first voltage change rate refers to a voltage change rate actually measured when the battery cell to be detected is subjected to charge/discharge cycles or is left standing.

In further implementations of one or more embodiments, in step S20, the first voltage rate of change may include: and a second voltage change rate when the battery cell to be detected is discharged after full charge. That is, the second voltage change rate (full charge voltage of the cell to be detected — first detection voltage)/first detection time of the cell to be detected.

Of course, the first voltage rate of change may also include: and a third voltage change rate of the cell to be detected during self-discharge termination voltage charging. That is, the third voltage change rate is (second detection voltage — discharge end voltage of the cell to be detected)/second detection time of the cell to be detected.

Of course, the first voltage rate of change may also include: and (4) a fourth voltage change rate when the battery cell to be detected is placed after being fully charged. That is, the fourth voltage change rate ═ (full charge voltage of the cell to be detected — third detection voltage of the cell to be detected)/predetermined time.

In one or more embodiments, in step S30, the step of determining whether the battery cell to be detected is in an abnormal state according to the comparison result includes: if the difference value between the first voltage change rate and the preset voltage change rate is larger than the first preset difference value, judging that the electric core to be detected is in an abnormal state; and if the difference value between the first voltage change rate and the preset voltage change rate is greater than or equal to a second preset difference value and less than or equal to a first preset difference value, acquiring the data to be detected of the battery cell to be detected again, and comparing the first voltage change rate with the preset voltage change rate, wherein the first preset difference value is greater than the second preset difference value.

In one or more embodiments, after step S30, the battery cell detection method provided by the present application may further include one or more steps of further detecting and/or determining the battery cell determined as the abnormal state, which is specifically described as follows.

In further implementation manners of one or more embodiments, the cell detection method may further include:

s41, performing multiple charging/discharging cycle detection on the battery cell judged to be in the abnormal state, and acquiring a first voltage change rate of the battery cell in the abnormal state;

and S51, if the first voltage change rate during discharging after each full charge is greater than the preset voltage change rate, judging that the electric core in the abnormal state is damaged.

In further implementation manners of one or more embodiments, the cell detection method may further include:

s42, performing multiple charging/discharging cycle detection on the battery cell judged to be in the abnormal state, and acquiring the capacity change of the battery cell in the abnormal state;

and S52, if the capacity change in each charging/discharging cycle is larger than the preset capacity change, judging that the cell in the abnormal state is damaged, and changing the preset capacity into the capacity change in the normal state in the cell charging/discharging cycle.

In further implementation manners of one or more embodiments, the cell detection method further includes:

s43, performing multiple charging/discharging cycle detection on the battery cell judged to be in the abnormal state, and acquiring a first voltage change rate and capacity change of the battery cell in the abnormal state;

and S53, if the capacity change in each charging/discharging cycle is larger than the preset capacity change, and the first voltage change rate in each full-charge discharging is larger than the preset voltage change rate, judging that the cell in the abnormal state is damaged, and the preset capacity change is the capacity change in the normal state in the cell charging/discharging cycle. For example, as shown in fig. 4 and 5, it is known that a cell detection method using both the Capacity change and the voltage change rate after charge and discharge as parameters can more effectively determine whether or not a cell is damaged, when the results of comparing the change in the Capacity surplus (Capacity Re.) of a damaged cell and the voltage change rate (Δ V/Δ T) after charge and discharge with the Cycle number (Cycle No.) of a cell in a normal state with the change in the Capacity surplus (Capacity Re.) of a cell in a normal state and the change in the voltage change rate (Δ V/Δ T) after charge and discharge with the Cycle number (Cycle No.).

In further implementation manner of one or more embodiments, the data to be detected further includes a full charge voltage, and the cell detection method further includes:

and S54, if the difference value between the full charge voltage of the abnormal battery cell and the full charge voltage of the normal battery cell exceeds a first threshold value, judging that the abnormal battery cell is damaged. Alternatively, the first threshold may be 100 mV.

In a further implementation manner of one or more embodiments, the number of the battery cells is multiple, where at least some of the battery cells are connected in series, and the battery cell detection method further includes:

s55, judging that the electric core in the abnormal state is damaged when the deviation between the first voltage change rate and the preset voltage change rate is maximum; and/or the presence of a gas in the gas,

and S56, judging that the damage occurs when the difference value between the full charge voltage of the abnormal battery cell and the full charge voltage of the normal battery cell is the largest. Illustratively, a comparison of the full charge voltages of different cells in a pouch battery of 6s1p (a battery pack formed by connecting 6 cells in series) containing broken cells is shown in fig. 6, and referring to fig. 6, it can be seen that the full charge voltage of the Cell6 is significantly less than that of the cells Cell1 to Cell 5; meanwhile, as shown in fig. 7, as seen from fig. 7, the first voltage change rate of the Cell6 is significantly greater than the first voltage change rate of any one of the Cell cells 1 to 5 within the time Δ T range in comparison of the first voltage change rates of different cells in the 6s1p pouch battery containing a damaged Cell; therefore, the battery cell detection method which simultaneously adopts the full charge voltage and the voltage change rate as key parameters can more effectively judge whether the battery pack containing the series battery cells is damaged or not.

The present application further provides an embodiment of a battery cell detection apparatus, as shown in fig. 8, where the battery cell detection apparatus adopts the above battery cell detection method, including: the device comprises a preset voltage change rate providing unit 1, a to-be-detected data acquiring unit 2 and a battery core abnormity judging unit 3. The preset voltage change rate providing unit 1 is configured to obtain a preset voltage change rate, where the preset voltage change rate is a voltage change rate of a normal battery cell; the to-be-detected data acquisition unit 2 is used for acquiring to-be-detected data of the to-be-detected battery cell, wherein the to-be-detected data comprises a first voltage change rate; the battery cell abnormality judgment unit 3 is configured to compare the first voltage change rate with a preset voltage change rate, and judge whether the battery cell to be detected is in an abnormal state according to a comparison result.

In further implementation of one or more embodiments, in the preset voltage change rate providing unit 1, the preset voltage change rate may include: the voltage change rate when the battery cell in a normal state is discharged after being fully charged. If the time required for discharging the battery cell to the first detection voltage after the battery cell is fully charged is defined as the first detection time, the preset voltage change rate is (full charge voltage of the battery cell in the normal state — the first detection voltage)/the first detection time of the battery cell in the normal state. For example, the first detection voltage may be 1/1.25 or 1/1.5 or 1/2 or 1/3 or 1/4 of the full charge voltage of the cell in the normal state, or the first detection voltage is 0. The full charge voltage of the battery cell in the normal state, the first detection voltage of the battery cell in the normal state and the first detection time of the battery cell in the normal state can be obtained through a discharge test after the battery cell in the normal state is fully charged.

Of course, the preset voltage change rate may also include: the voltage change rate of the normal state of the battery cell during self-discharge termination voltage charging; if the time required for charging the cell from the discharge end voltage to the second detection voltage is defined as the second detection time, the preset voltage change rate is (the second detection voltage — the discharge end voltage of the cell in the normal state)/the second detection time of the cell in the normal state; for example, the second detection voltage may be 1/1.25 or 1/1.5 or 1/2 or 1/3 or 1/4 of the full charge voltage of the cell in the normal state. The discharge end voltage of the battery cell in the normal state, the second detection voltage and the second detection time of the battery cell in the normal state can be obtained through a self-discharge end voltage charge test of the battery cell in the normal state.

Of course, the preset voltage change rate may also include: and (3) voltage change rate when the battery cell in a normal state is placed after being fully charged. If the voltage at the time when the battery cell is left standing for the predetermined time after being fully charged is defined as the third detection voltage, the preset voltage change rate is (the fully charged voltage of the battery cell in the normal state — the third detection voltage of the battery cell in the normal state)/the predetermined time.

In further implementations of one or more embodiments, in the data acquisition unit 2 under test, the first voltage change rate may include: and a second voltage change rate when the battery cell to be detected is discharged after full charge. That is, the second voltage change rate (full charge voltage of the cell to be detected — first detection voltage)/first detection time of the cell to be detected.

Of course, the first voltage rate of change may also include: and a third voltage change rate of the cell to be detected during self-discharge termination voltage charging. That is, the third voltage change rate is (second detection voltage — discharge end voltage of the cell to be detected)/second detection time of the cell to be detected.

Of course, the first voltage rate of change may also include: and (4) a fourth voltage change rate when the battery cell to be detected is placed after being fully charged. That is, the fourth voltage change rate ═ (full charge voltage of the cell to be detected — third detection voltage of the cell to be detected)/predetermined time.

In one or more embodiments, the battery cell detection apparatus provided in the present application may further include one or more units for detecting and/or determining whether the battery cell determined as the abnormal state is damaged, specifically as follows.

In further implementation manners of one or more embodiments, the cell detection apparatus further includes: the device comprises a first voltage change rate acquisition unit and a first abnormal cell damage judgment unit, wherein the first voltage change rate acquisition unit is used for carrying out multiple charging/discharging cycle detection on the cell judged to be in the abnormal state and acquiring a first voltage change rate of the cell in the abnormal state; the first abnormal cell damage judging unit is used for judging that the cell in the abnormal state is damaged if the first voltage change rate during discharging after full charge is greater than the preset voltage change rate.

In further implementation manners of one or more embodiments, the cell detection apparatus further includes: the device comprises a capacity change acquisition unit and a second abnormal cell damage judgment unit, wherein the capacity change acquisition unit is used for carrying out multiple charging/discharging cycle detection on the cell judged to be in the abnormal state and acquiring the capacity change of the cell in the abnormal state; the second abnormal cell damage determination unit is configured to determine that the cell in the abnormal state is damaged and the preset capacity changes into a capacity change during a cell charge/discharge cycle in the normal state if the capacity change during each charge/discharge cycle is greater than the preset capacity change.

In further implementation manners of one or more embodiments, the cell detection apparatus further includes: a first voltage change rate and capacity change acquisition unit and a third abnormal cell damage judgment unit, wherein the first voltage change rate and capacity change acquisition unit is used for performing multiple charging/discharging cycle detection on the cell judged to be in the abnormal state, and acquiring a first voltage change rate and capacity change of the cell in the abnormal state; the third abnormal cell damage determination unit is configured to determine that the abnormal cell is damaged and the preset capacity is changed to the normal cell when the capacity change during the charge/discharge cycle is greater than the preset capacity change, and the second voltage change rate during the discharge after the full charge is greater than the preset voltage change rate.

In further implementation manner of one or more embodiments, the data to be detected further includes a full charge voltage, and the cell detection apparatus further includes: and the fourth abnormal cell damage judgment unit is used for judging that the abnormal cell is damaged if the difference value between the full charge voltage of the abnormal cell and the full charge voltage of the normal cell exceeds a first threshold value. Alternatively, the first threshold may be 100 mV.

In a further implementation manner of one or more embodiments, the number of the battery cells is multiple, where at least some of the battery cells are connected in series, and the battery cell detection method further includes: the fifth abnormal cell damage judgment unit is used for judging that the cell in the abnormal state has the maximum deviation between the first voltage change rate and the preset voltage change rate as the cell is damaged; and/or judging that the damage occurs when the difference value between the full charge voltage of the abnormal battery cell and the full charge voltage of the normal battery cell is maximum.

In summary, the present application provides a method and an apparatus for detecting a battery cell, in which a voltage variation rate of a battery cell is used as a key parameter for battery cell detection; and the acquired first voltage change rate of the battery cell to be detected is compared with the preset voltage change rate, whether the battery cell to be detected is abnormal or not is judged according to the comparison result, and the accuracy and the effectiveness for identifying the battery cell abnormality can be improved. The battery detection method is applied to management of the BMS, so that the abnormal occurrence of the battery can be found in time, and the safety and reliability of the battery are improved.

Although the application has been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art based upon a reading and understanding of this specification and the annexed drawings. This application is intended to embrace all such modifications and variations and is limited only by the scope of the appended claims.

That is, the above description is only an embodiment of the present application, and not intended to limit the scope of the present application, and all equivalent structures or equivalent flow transformations made by using the contents of the specification and the drawings, such as mutual combination of technical features between various embodiments, or direct or indirect application to other related technical fields, are included in the scope of the present application.

In addition, in the description of the present application, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In this application, the word "exemplary" is used to mean "serving as an example, instance, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The previous description is provided to enable any person skilled in the art to make and use the present application. In the foregoing description, various details have been set forth for the purpose of explanation. It will be apparent to one of ordinary skill in the art that the present application may be practiced without these specific details. In other instances, well-known structures and processes are not shown in detail to avoid obscuring the description of the present application with unnecessary detail. Thus, the present application is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.