Method, device and system for determining discharge cut-off voltage of battery

Abstract

The invention relates to a battery discharge cut-off voltage determination method, device and system, and the method comprises the steps: obtaining a negative electrode voltage change curve corresponding to the discharge of a three-electrode battery at different cycle times; wherein the three-electrode battery comprises a positive electrode, a negative electrode and a reference electrode arranged between the positive electrode and the negative electrode, and the voltage of the negative electrode is the voltage of the negative electrode relative to the reference electrode; according to the negative electrode voltage change curve, a first discharge cycle index is determined, and the first discharge cycle index is the cycle index corresponding to the condition that the battery capacity attenuation reaches a preset threshold value; calculating to obtain a target discharge cut-off voltage as a discharge cut-off voltage of the battery from the second discharge cycle number; wherein the second discharge cycle index is a cycle index before the first discharge cycle index.

Description

Technical Field

[0001] The present disclosure relates to battery technology, and more specifically, to a method, device and system for determining a battery discharge cut-off voltage. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density, long cycle life, low self-discharge, fast charge and discharge, and good safety. They are widely used in various digital products, electronic devices, electric vehicles, energy storage and other fields. Lithium-ion batteries will experience irreversible aging and degradation during their use, which is mainly affected by battery materials (active materials, electrolytes, etc.), battery design (battery structure, electrode engineering, etc.) and usage conditions (charge and discharge rate, discharge depth, etc.). At present, researchers have studied a large number of lithium-ion battery materials to improve the cycle stability of active materials, thereby extending battery life. However, due to cost, quality control, safety and other considerations, the method of improving materials to increase battery life is not conducive to commercial application.

[0003] In the existing battery life management, studies have shown that the evolution of the negative electrode voltage during the cycle is the main reason for accelerated battery degradation. Avoiding extreme voltage at the negative electrode can delay battery degradation.

[0004] Therefore, a new technical solution is provided by utilizing the change of the electrode voltage of the negative electrode to delay battery degradation and extend the battery life. Summary of the invention

[0005] One object of the present invention is to provide a new technical solution for a method for determining a battery discharge cut-off voltage.

[0006] According to a first aspect of the present invention, a method for determining a battery discharge cut-off voltage is provided, comprising:

[0007] Obtaining a negative electrode voltage change curve corresponding to discharge of a three-electrode battery at different cycle times; wherein the three-electrode battery comprises a positive electrode, a negative electrode and a reference electrode arranged between the positive electrode and the negative electrode, and the negative electrode voltage is the voltage of the negative electrode relative to the reference electrode;

[0008] Determine a first discharge cycle number according to the negative electrode voltage change curve, wherein the first discharge cycle number is the cycle number corresponding to when the battery capacity attenuation reaches a preset threshold;

[0009] A target discharge cut-off voltage is calculated to serve as a discharge cut-off voltage of the battery starting from a second discharge cycle number, wherein the second discharge cycle number is a cycle number before the first discharge cycle number.

[0010] Optionally, the negative electrode voltage change curve is a curve of the corresponding relationship between the negative electrode voltage and the battery capacity during the discharge process; wherein,

[0011] The determining of the first discharge cycle number according to the negative electrode voltage variation curve comprises:

[0012] Determining a negative electrode voltage differential curve according to the negative electrode voltage variation curve;

[0013] The first discharge cycle number is determined according to the negative electrode voltage differential curve.

[0014] Optionally, determining a negative electrode voltage differential curve according to the negative electrode voltage change curve includes:

[0015] Differentiate the negative electrode voltage data and the battery capacity data in the negative electrode voltage variation curve to obtain dV / dQ;

[0016] The battery capacity data in the negative electrode voltage variation curve is used as the horizontal axis data, and the dV / dQ is used as the vertical axis data to obtain the negative electrode voltage differential curve.

[0017] Optionally, determining the first discharge cycle number according to the negative electrode voltage differential curve includes:

[0018] Obtaining at least one first peak from the negative electrode voltage differential curve corresponding to the first discharge, and obtaining at least one second peak from the negative electrode voltage differential curve corresponding to each other discharge;

[0019] Establishing the corresponding relationship between the first wave peak and the second wave peak;

[0020] Determine the dV / dQ difference corresponding to the first wave peak and the second wave peak having a one-to-one correspondence relationship by using the correspondence between the first wave peak and the second wave peak;

[0021] When the difference exceeds a preset difference, a first discharge cycle number is determined.

[0022] Optionally, the calculating and obtaining the target discharge cut-off voltage includes:

[0023] Calculating the change rate of the discharge cut-off voltage of the battery under the first discharge cycle number;

[0024] Acquire an initial discharge cut-off voltage; wherein the initial discharge cut-off voltage is a discharge cut-off voltage of the battery before the second discharge cycle number;

[0025] The target discharge cut-off voltage is calculated according to the initial discharge cut-off voltage and the change rate.

[0026] Optionally, the calculating the change rate of the discharge cut-off voltage of the battery under the first discharge cycle number includes:

[0027] Acquire the negative electrode voltage when the first discharge is completed and the negative electrode voltage when the discharge is completed under the first discharge cycle number;

[0028] The change rate of the discharge cut-off voltage of the battery at the first discharge cycle number is calculated according to the negative electrode voltage at the completion of the first discharge and the negative electrode voltage at the completion of the discharge at the first discharge cycle number.

[0029] Optionally, the discharge at different cycle numbers is a small rate discharge.

[0030] According to a second aspect of the present invention, there is provided a device for determining a battery discharge cut-off voltage, comprising:

[0031] An acquisition module, used for acquiring a negative electrode voltage change curve corresponding to discharge of a three-electrode battery at different cycle times; wherein the three-electrode battery comprises a positive electrode, a negative electrode and a reference electrode arranged between the positive electrode and the negative electrode, and the negative electrode voltage is the voltage of the negative electrode relative to the reference electrode;

[0032] A discharge cycle number determination module, used for a first discharge cycle number, wherein the first discharge cycle number is the cycle number corresponding to when the battery capacity attenuation reaches a preset threshold;

[0033] The discharge cut-off voltage calculation module is used to calculate a target discharge cut-off voltage to serve as a discharge cut-off voltage of the battery starting from a second discharge cycle number, wherein the second discharge cycle number is a cycle number before the first discharge cycle number.

[0034] According to a third aspect of the present invention, a device for determining a battery discharge cut-off voltage is provided, comprising a memory and a processor, wherein the memory stores a computer program, and the computer program is used to control the processor to operate to execute the method for determining a battery discharge cut-off voltage according to any one of the first aspect of the present invention.

[0035] According to a fourth aspect of the present invention, a system for determining a battery discharge cut-off voltage is provided, comprising a three-electrode battery and a device for determining a battery discharge cut-off voltage as described in the second aspect or the third aspect.

[0036] The method for determining the discharge cut-off voltage of a battery provided by the present invention obtains a negative electrode voltage change curve corresponding to discharge under different cycle numbers of a three-electrode battery, determines the first discharge cycle number corresponding to when the battery capacity attenuation reaches a preset threshold value according to the negative electrode voltage change curve, calculates and obtains a target discharge cut-off voltage, and uses it as the discharge cut-off voltage of the battery after the second discharge cycle number. An accurate adjustment node of the discharge cut-off voltage and an accurate adjusted discharge cut-off voltage can be obtained, and then the discharge cut-off voltage of the battery can be accurately adjusted, thereby delaying the attenuation of the battery capacity and extending the service life of the battery. At the same time, during the use of the battery, the utilization efficiency of the battery can be maximized.

[0037] Features and advantages of the embodiments of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the embodiments of the specification.

[0039] Figure 1 is a processing flow chart of a method for determining a battery discharge cut-off voltage according to an embodiment of the present invention.

[0040] Figure 2 Schematic diagram of the principle structure of a three-electrode battery according to an embodiment of the present invention.

[0041] Figure 3 is a schematic diagram of a voltage variation curve according to an embodiment of the present invention.

[0042] Figure 4 is based on Figure 3 The schematic diagram of the negative electrode voltage differential curve obtained by showing the negative electrode voltage change curve.

[0043] Figure 5 Schematic diagram of negative electrode voltage at the completion of discharge at different discharge cycle numbers according to one embodiment of the present invention.

[0044] Figure 6 Schematic diagram of battery capacity at different discharge cycle times according to an embodiment of the present invention.

[0045] Figure 7 The figure is a principle block diagram of a device for determining a battery discharge cut-off voltage according to an embodiment of the present invention.

[0046] Figure 8 1 is a schematic diagram of the hardware structure of a device for determining a battery discharge cut-off voltage according to an embodiment of the present invention.

[0047] Fig. 9 The figure is a principle block diagram of a system for determining a battery discharge cut-off voltage according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] Various exemplary embodiments of the present specification will now be described in detail with reference to the accompanying drawings.

[0049] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the embodiments of the present specification and its application or uses.

[0050] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0051] The method for determining the battery discharge cut-off voltage provided by the present invention is applicable to all lithium-ion batteries.

[0052] Before executing the method for determining the battery discharge cut-off voltage provided by the present invention, a three-electrode battery is provided.

[0053] The preparation method of the three-electrode battery can refer to the following method. Obtain a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte as raw materials for the three-electrode battery. These raw materials come from a lithium-ion battery of the model to be tested. Take part of the positive electrode sheet and connect it to the negative electrode sheet, charge it at a preset rate (for example, a 0.02C rate), use a tester to monitor the potential of the positive electrode sheet to a preset potential (for example, 3.414V) when the charging is stopped, and the positive electrode sheet with the preset potential is used as a reference electrode. The positive electrode sheet, the reference electrode, the negative electrode sheet, the separator and the electrolyte are assembled together into a three-electrode battery, and the reference electrode is arranged between the positive electrode sheet and the negative electrode sheet. It should be noted that during the charging and discharging process of the three-electrode battery, the potential of the reference electrode can be maintained at a difference from the preset potential that is less than the preset difference.

[0054] In one embodiment of the present invention, a method for determining a battery discharge cut-off voltage is provided. Figure 1 As shown, the method for determining the battery discharge cut-off voltage in this embodiment may include the following steps S110 to S130.

[0055] Step S110, obtaining a negative electrode voltage variation curve corresponding to discharge of a three-electrode battery under different cycle times; wherein the three-electrode battery includes a positive electrode, a negative electrode and a reference electrode arranged between the positive electrode and the negative electrode, and the negative electrode voltage is the voltage of the negative electrode relative to the reference electrode.

[0056] Figure 2 Schematic diagram of the principle structure of a three-electrode battery according to an embodiment of the present invention. Figure 2 , negative voltage V负极 is the voltage of the negative electrode relative to the reference electrode. Figure 2 The positive electrode voltage and the full cell voltage are also shown. 正极 is the voltage of the positive electrode relative to the reference electrode. Full cell voltage V 全电池 is the voltage of the positive electrode relative to the negative electrode.

[0057] In one embodiment, a capacity decay experiment is performed on a three-electrode battery, and a charge and discharge operation of the capacity decay experiment includes the following steps S201 to S204.

[0058] Step S201, leaving the three-electrode battery to stand for 10 minutes.

[0059] Step S202, charging the three-electrode battery at a small rate until the full battery voltage reaches the charging cut-off voltage. The small rate may be 0.09C. The charging cut-off voltage is set according to the battery model, for example, 3.8V.

[0060] Step S203, leaving the three-electrode battery to stand for 10 minutes.

[0061] Step S204, discharge the three-electrode battery at a small rate until the full battery voltage reaches the discharge cut-off voltage. The small rate may be 0.09C. The discharge cut-off voltage is set according to the battery model, for example, 2.0V.

[0062] The charging and discharging operations are cyclically performed according to the above steps S201 to S204 to obtain a negative electrode voltage variation curve corresponding to each discharge.

[0063] Step S120, determining a first discharge cycle number according to the negative electrode voltage change curve, wherein the first discharge cycle number is the cycle number corresponding to when the battery capacity attenuation reaches a preset threshold.

[0064] Figure 3 is a schematic diagram of a voltage variation curve according to an embodiment of the present invention. Figure 3 The positive electrode voltage change curve corresponding to the 1st discharge, the positive electrode voltage change curve corresponding to the 300th discharge, the negative electrode voltage change curve corresponding to the 1st discharge, the negative electrode voltage change curve corresponding to the 300th discharge, the full battery voltage change curve corresponding to the 1st discharge, and the full battery voltage change curve corresponding to the 300th discharge are shown.

[0065] The positive electrode voltage change curve is the corresponding relationship curve between the positive electrode voltage and the battery capacity during the discharge process. The negative electrode voltage change curve is the corresponding relationship curve between the negative electrode voltage and the battery capacity during the discharge process. The full battery voltage change curve is the corresponding relationship curve between the full battery voltage and the battery capacity during the discharge process.

[0066] Specifically, the positive electrode tab lead-out part and the negative electrode tab lead-out part are connected to the positive and negative electrodes of the tester respectively, and the full battery voltage change curve is collected in real time. The positive electrode tab lead-out part and the reference electrode tab lead-out part are connected to the multi-path voltage collector respectively, and the positive electrode voltage change curve is collected in real time. The negative electrode tab lead-out part and the reference electrode tab lead-out part are connected to the multi-path voltage collector respectively, and the negative electrode voltage change curve is collected in real time.

[0067] from Figure 3 It can be seen that the positive electrode voltage change curve corresponding to the first discharge and the positive electrode voltage change curve corresponding to the 300th discharge are basically overlapped, and the negative electrode voltage change curve corresponding to the first discharge and the negative electrode voltage change curve corresponding to the 300th discharge are quite different. It can be seen here that the negative electrode voltage change is the main reason for the battery capacity decay. Therefore, the negative electrode voltage change curve can be used to determine the number of discharge cycles corresponding to when the battery capacity decay reaches the preset threshold.

[0068] Step S130, calculating and obtaining a target discharge cut-off voltage to serve as a discharge cut-off voltage of the battery starting from a second discharge cycle number, wherein the second discharge cycle number is a cycle number before the first discharge cycle number.

[0069] The discharge cut-off voltage of the battery before the second discharge cycle is the initial discharge cut-off voltage. The discharge cut-off voltage of the battery after the second discharge cycle is the target discharge cut-off voltage. The target discharge cut-off voltage is greater than the initial discharge cut-off voltage.

[0070] Taking the 300th discharge cycle number corresponding to when the battery capacity attenuation reaches the preset threshold as an example, the second discharge cycle number may be a set cycle number before the 300th, for example, the 285th.

[0071] The method for determining the discharge cut-off voltage of a battery provided in an embodiment of the present invention obtains a negative electrode voltage change curve corresponding to discharge of a three-electrode battery under different cycle times, determines the discharge cycle number corresponding to when the battery capacity attenuation reaches a preset threshold value according to the negative electrode voltage change curve, calculates and obtains a target discharge cut-off voltage as the discharge cut-off voltage of the battery after the second discharge cycle number, and can obtain an accurate adjustment node of the discharge cut-off voltage and an accurate adjusted discharge cut-off voltage, thereby accurately adjusting the discharge cut-off voltage of the battery, delaying the attenuation of the battery capacity, and extending the service life of the battery. At the same time, during the use of the battery, the utilization efficiency of the battery can be maximized.

[0072] In one embodiment, step S120 specifically includes: determining a negative electrode voltage differential curve according to the negative electrode voltage variation curve; and determining the first discharge cycle number according to the negative electrode voltage differential curve.

[0073] The negative electrode voltage differential curve is a corresponding relationship curve between differential data and battery capacity, and the differential data is data obtained by performing differential processing on the battery capacity and the negative electrode voltage.

[0074] In one embodiment, the negative electrode voltage differential curve is determined by: differentiating the negative electrode voltage data and the battery capacity data in the negative electrode voltage change curve respectively to obtain dV / dQ; using the battery capacity data in the negative electrode voltage change curve as the horizontal axis data and dV / dQ as the vertical axis data to obtain the negative electrode voltage differential curve.

[0075] In one embodiment, determining the first discharge cycle number according to the negative electrode voltage differential curve specifically includes: obtaining at least one first peak from the negative electrode voltage differential curve corresponding to the first discharge, and obtaining at least one second peak from the negative electrode voltage differential curve corresponding to each other discharge; establishing a correspondence between the first peak and the second peak; using the correspondence between the first peak and the second peak, determining the difference in dV / dQ corresponding to the first peak and the second peak having a one-to-one correspondence; and determining the first discharge cycle number when the difference exceeds a preset difference.

[0076] Figure 4 is based on Figure 3 The schematic diagram of the negative electrode voltage differential curve obtained by showing the negative electrode voltage change curve. Figure 4 The negative electrode voltage differential curve corresponding to the first discharge and the negative electrode voltage differential curve corresponding to the 300th discharge are shown.

[0077] See also Figure 4 , obtain four first peaks from the negative electrode voltage differential curve corresponding to the first discharge, namely peak a, peak b, peak c, and peak d. Obtain four second peaks from the negative electrode voltage differential curve corresponding to the 300th discharge, namely peak A, peak B, peak C, and peak D. The peaks corresponding to peak a, peak b, peak c, and peak d are peak A, peak B, peak C, and peak D, respectively. Then, determine the difference in dV / dQ corresponding to peak a and peak A, the difference in dV / dQ corresponding to peak b and peak B, the difference in dV / dQ corresponding to peak c and peak C, and the difference in dV / dQ corresponding to peak d and peak D. When at least one of the four differences exceeds the preset difference, determine that the 300th is the number of discharge cycles corresponding to when the battery capacity attenuation reaches the preset threshold. When the four differences do not exceed the preset differences, it is determined that the 300th time is not the discharge cycle number corresponding to when the battery capacity attenuation reaches the preset threshold.

[0078] In one embodiment, step S130 specifically includes: calculating the change rate of the discharge cut-off voltage of the battery under the first discharge cycle number; obtaining the initial discharge cut-off voltage; wherein the initial discharge cut-off voltage is the discharge cut-off voltage of the battery before the second discharge cycle number; and calculating the target discharge cut-off voltage according to the initial discharge cut-off voltage and the change rate.

[0079] In one embodiment, the rate of change of the discharge cut-off voltage of the battery under the corresponding discharge cycle number when the battery capacity attenuation reaches a preset threshold is calculated, including: obtaining the negative electrode voltage when the first discharge is completed and the negative electrode voltage when the discharge is completed under the first discharge cycle number; according to the negative electrode voltage when the first discharge is completed and the negative electrode voltage when the discharge is completed under the first discharge cycle number, calculating the rate of change of the discharge cut-off voltage of the battery under the first discharge cycle number.

[0080] Specifically, the change rate of the discharge cut-off voltage of the battery under the first discharge cycle number is calculated based on the following calculation formula (1):

[0081]

[0082] Where Δ is the change rate of the battery’s discharge cut-off voltage under the first discharge cycle number, V 负1 is the negative electrode voltage when the first discharge is completed, V 负i is the negative electrode voltage when the discharge is completed under the first discharge cycle number.

[0083] The target discharge cut-off voltage is calculated based on the following formula (2):

[0084] V 截止 =V1×Δ—Calculation formula (2),

[0085] Among them, V 截止 is the target discharge cut-off voltage, V1 is the initial discharge cut-off voltage, and Δ is the rate of change of the discharge cut-off voltage of the battery under the first discharge cycle number.

[0086] Figure 5 is a schematic diagram of the negative electrode voltage when the discharge is completed under different discharge cycle numbers according to an embodiment of the present invention. Taking the discharge cycle number corresponding to the 300th discharge when the battery capacity attenuation reaches the preset threshold as an example, see Figure 5 , the negative electrode voltage at the completion of the first discharge is 0.82V, and the negative electrode voltage at the completion of the 300th discharge is 1.16V. Based on the above calculation formula (1), the change rate of the battery's discharge cut-off voltage is calculated to be 1.415. The initial discharge cut-off voltage is 2V. Based on the above calculation formula (2), the target discharge cut-off voltage is calculated to be 2.83V.

[0087] from Figure 5It can also be seen that when the discharge is completed, the negative electrode voltage increases with the increase in the number of discharge cycles. If the battery is kept in this state, the negative electrode of the battery may be at risk of SEI film decomposition, electrolyte decomposition, or even current collector corrosion, which is irreversible damage to the battery and will accelerate the battery's decay. Therefore, it is necessary to increase the battery's discharge cut-off voltage to slow down the battery's decay.

[0088] Figure 6 is a schematic diagram of battery capacity at different discharge cycles according to an embodiment of the present invention. Figure 6 , the figure shows two curves, curve a is a schematic diagram of the battery capacity change corresponding to the battery's discharge cut-off voltage not being adjusted during the discharge cycle, and curve b is a schematic diagram of the battery capacity change corresponding to the battery's discharge cut-off voltage being adjusted during the discharge cycle.

[0089] In the discharge cycle corresponding to curve a, the discharge cut-off voltage of the battery is 2.0V in each discharge cycle. In the discharge cycle corresponding to curve b, before the 285th discharge cycle, the discharge cut-off voltage of the battery is 2.0V. After the 285th discharge cycle, the discharge cut-off voltage of the battery is 2.83V. Comparing curve a and curve b, it can be seen that after the discharge cut-off voltage of the battery is adjusted during the discharge cycle, the battery attenuation is delayed.

[0090] An embodiment of the present invention provides a device for determining a battery discharge cut-off voltage, such as Figure 7 The battery discharge cut-off voltage determination device 700 comprises an acquisition module 710 , a discharge cycle number determination module 720 and a discharge cut-off voltage calculation module 730 .

[0091] The acquisition module 710 is used to obtain the negative electrode voltage change curve corresponding to the discharge of the three-electrode battery under different cycle times; wherein the three-electrode battery includes a positive electrode, a negative electrode and a reference electrode arranged between the positive electrode and the negative electrode, and the negative electrode voltage is the voltage of the negative electrode relative to the reference electrode.

[0092] The discharge cycle number determination module 720 is used to determine a first discharge cycle number, wherein the first discharge cycle number is the cycle number corresponding to when the battery capacity attenuation reaches a preset threshold.

[0093] The discharge cut-off voltage calculation module 730 is used to calculate and obtain a target discharge cut-off voltage as a discharge cut-off voltage of the battery starting from a second discharge cycle number, wherein the second discharge cycle number is a cycle number located before the first discharge cycle number.

[0094] In one embodiment, the negative electrode voltage change curve is a curve of the corresponding relationship between the negative electrode voltage and the battery capacity during the discharge process. The discharge cycle number determination module 720 is also used to determine the negative electrode voltage differential curve according to the negative electrode voltage change curve; and determine the first discharge cycle number according to the negative electrode voltage differential curve.

[0095] In one embodiment, the discharge cycle number determination module 720 is also used to differentiate the negative electrode voltage data and the battery capacity data in the negative electrode voltage change curve respectively to obtain dV / dQ; the battery capacity data in the negative electrode voltage change curve is used as the horizontal axis data, and dV / dQ is used as the vertical axis data to obtain the negative electrode voltage differential curve.

[0096] In one embodiment, the discharge cycle number determination module 720 is also used to obtain at least one first peak from the negative electrode voltage differential curve corresponding to the first discharge, and to obtain at least one second peak from the negative electrode voltage differential curve corresponding to each other discharge; establish a correspondence between the first peak and the second peak; use the correspondence between the first peak and the second peak to determine the difference in dV / dQ corresponding to the first peak and the second peak with a one-to-one correspondence; and determine the first discharge cycle number when the difference exceeds a preset difference.

[0097] In one embodiment, the discharge cut-off voltage calculation module 730 is used to calculate the change rate of the discharge cut-off voltage of the battery under the first discharge cycle number; obtain the initial discharge cut-off voltage; wherein the initial discharge cut-off voltage is the discharge cut-off voltage of the battery before the second discharge cycle number; and calculate the target discharge cut-off voltage based on the initial discharge cut-off voltage and the change rate.

[0098] In one embodiment, the discharge cut-off voltage calculation module 730 is used to obtain the negative electrode voltage when the first discharge is completed and the negative electrode voltage when the discharge is completed under the first discharge cycle number; according to the negative electrode voltage when the first discharge is completed and the negative electrode voltage when the discharge is completed under the first discharge cycle number, the change rate of the discharge cut-off voltage of the battery under the first discharge cycle number is calculated.

[0099] In one embodiment, the discharge at different cycle times is a small rate discharge.

[0100] An embodiment of the present invention provides a device for determining a battery discharge cut-off voltage, such as Figure 8 The device 800 for determining the battery discharge cut-off voltage includes a memory 820 and a processor 810. The memory 820 stores a computer program, and the computer program is used to control the processor 810 to operate so as to execute the method for determining the battery discharge cut-off voltage in any of the above embodiments.

[0101] An embodiment of the present invention provides a system for determining a battery discharge cut-off voltage. Fig. 9 The system for determining the battery discharge cut-off voltage comprises a three-electrode battery and a device for determining the battery discharge cut-off voltage as provided in any of the above embodiments.

[0102] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. For the device embodiment, its related parts can be referred to the partial description of the method embodiment.

[0103] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0104] The embodiments of the present specification may be systems, methods and / or computer program products. The computer program product may include a computer-readable storage medium carrying computer instructions for causing a processor to implement various aspects of the embodiments of the present specification.

[0105] A computer-readable storage medium may be a tangible device that can hold and store computer instructions used by a computer instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which computer instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0106] The computer instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device through a network layer, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network layer may include copper transmission cables, optical fiber transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. The network layer adapter card or network layer interface in each computing / processing device receives the computer instructions from the network layer and forwards the computer instructions for storage in a computer-readable storage medium in each computing / processing device.

[0107] The flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems, methods and computer program products according to the multiple embodiments of this specification. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a computer instruction, and a part of a module, a program segment or a computer instruction contains one or more executable computer instructions for realizing the specified logical function. In some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or the flowchart, and the combination of the boxes in the block diagram and / or the flowchart can be implemented by a dedicated hardware-based system that performs the specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions. It is well known to those skilled in the art that it is equivalent to implement it by hardware, implement it by software, and implement it by combining software and hardware.

[0108] The embodiments of the present specification have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for determining a battery discharge cut-off voltage, characterized in that: include: Obtaining a negative electrode voltage change curve corresponding to discharge of a three-electrode battery at different cycle times; wherein the three-electrode battery comprises a positive electrode, a negative electrode and a reference electrode arranged between the positive electrode and the negative electrode, and the negative electrode voltage is the voltage of the negative electrode relative to the reference electrode; Determine a first discharge cycle number according to the negative electrode voltage change curve, wherein the first discharge cycle number is the cycle number corresponding to when the battery capacity attenuation reaches a preset threshold; A target discharge cut-off voltage is calculated to serve as a discharge cut-off voltage of the battery starting from a second discharge cycle number; wherein the second discharge cycle number is a cycle number before the first discharge cycle number.

2. The method according to claim 1, characterized in that The negative electrode voltage change curve is a curve of the corresponding relationship between the negative electrode voltage and the battery capacity during the discharge process; wherein, The determining of the first discharge cycle number according to the negative electrode voltage variation curve comprises: Determining a negative electrode voltage differential curve according to the negative electrode voltage variation curve; The first discharge cycle number is determined according to the negative electrode voltage differential curve.

3. The method according to claim 2, characterized in that Determining the negative electrode voltage differential curve according to the negative electrode voltage change curve includes: Differentiate the negative electrode voltage data and the battery capacity data in the negative electrode voltage variation curve to obtain dV / dQ; The battery capacity data in the negative electrode voltage variation curve is used as the horizontal axis data, and the dV / dQ is used as the vertical axis data to obtain the negative electrode voltage differential curve.

4. The method according to claim 3, characterized in that Determining the first discharge cycle number according to the negative electrode voltage differential curve includes: Obtaining at least one first peak from the negative electrode voltage differential curve corresponding to the first discharge, and obtaining at least one second peak from the negative electrode voltage differential curve corresponding to each other discharge; Establishing the corresponding relationship between the first wave peak and the second wave peak; Determine the dV / dQ difference corresponding to the first wave peak and the second wave peak having a one-to-one correspondence relationship by using the correspondence between the first wave peak and the second wave peak; When the difference exceeds a preset difference, a first discharge cycle number is determined.

5. The method according to claim 1, characterized in that The calculation to obtain the target discharge cut-off voltage includes: Calculating the change rate of the discharge cut-off voltage of the battery under the first discharge cycle number; Acquire an initial discharge cut-off voltage; wherein the initial discharge cut-off voltage is a discharge cut-off voltage of the battery before the second discharge cycle number; The target discharge cut-off voltage is calculated according to the initial discharge cut-off voltage and the change rate.

6. The method according to claim 5, characterized in that The calculating and obtaining the change rate of the discharge cut-off voltage of the battery under the first discharge cycle number includes: Acquire the negative electrode voltage when the first discharge is completed and the negative electrode voltage when the discharge is completed under the first discharge cycle number; The change rate of the discharge cut-off voltage of the battery at the first discharge cycle number is calculated according to the negative electrode voltage at the completion of the first discharge and the negative electrode voltage at the completion of the discharge at the first discharge cycle number.

7. The method according to any one of claims 1 to 6, characterized in that: The discharge under the different cycle times is a small rate discharge.

8. A device for determining a battery discharge cut-off voltage, characterized in that: include: An acquisition module, used for acquiring a negative electrode voltage change curve corresponding to discharge of a three-electrode battery at different cycle times; wherein the three-electrode battery comprises a positive electrode, a negative electrode and a reference electrode arranged between the positive electrode and the negative electrode, and the negative electrode voltage is the voltage of the negative electrode relative to the reference electrode; A discharge cycle number determination module, used to determine a first discharge cycle number, wherein the first discharge cycle number is the cycle number corresponding to when the battery capacity attenuation reaches a preset threshold; The discharge cut-off voltage calculation module is used to calculate a target discharge cut-off voltage to serve as a discharge cut-off voltage of the battery starting from a second discharge cycle number, wherein the second discharge cycle number is a cycle number before the first discharge cycle number.

9. A device for determining a battery discharge cut-off voltage, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program, and the computer program is used to control the processor to operate so as to execute the method for determining a battery discharge cut-off voltage according to any one of claims 1 to 7.

10. A system for determining a battery discharge cut-off voltage, characterized in that: The invention comprises a three-electrode battery and a device for determining the battery discharge cut-off voltage as claimed in claim 8 or 9.

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