Method and device for determining ratio of negative pole capacity to positive pole capacity of battery and electronic equipment

Abstract

The embodiment of the invention discloses a method and device for determining the ratio of the negative electrode capacity to the positive electrode capacity of a battery and electronic equipment, and the method comprises the steps: discharging the battery to a lower cut-off voltage, determining the total discharge capacity of the battery, and obtaining a graphite-to-lithium half-button battery for the battery, the graphite pair lithium half-button battery is obtained by assembling a graphite material of the same type as the battery, a graphite lithium intercalation curve corresponding to the graphite pair lithium half-button battery is obtained, differential processing is performed on the graphite lithium intercalation curve to obtain a first differential voltage curve, and a charging curve corresponding to the battery is obtained; performing differential processing on the charging curve to obtain a second differential voltage curve, performing phase change peak characteristic matching processing based on the first differential voltage curve and the second differential voltage curve to obtain a state of charge quantity corresponding to a phase change peak, and obtaining the total charging capacity of the battery charged to the state of charge quantity, an NP ratio for the battery is determined based on a ratio of the total charge capacity to the total discharge capacity.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method, device and electronic equipment for determining the ratio of the negative electrode capacity to the positive electrode capacity of a battery. Background Art

[0002] The ratio of the negative electrode capacity to the positive electrode capacity of a battery is also called the NP ratio. The NP ratio is a very important performance factor of a battery cell. In the field of battery technology, the NP ratio is used to evaluate whether lithium deposition will occur during battery charging and discharging. The cathode capacity data / anode capacity data is corrected according to the actual NP ratio of the battery to ensure the safety of battery lithium deposition. The NP ratio is also used to qualitatively evaluate the cathode potential of the battery to prevent the cathode potential from being too high, which may cause gas production and expansion of the battery cell. Summary of the invention

[0003] The present application provides a method, device, storage medium and electronic device for determining the ratio of the negative electrode capacity to the positive electrode capacity of a battery. The technical solution is as follows:

[0004] In a first aspect, an embodiment of the present application provides a method for determining the ratio of the negative electrode capacity to the positive electrode capacity of a battery, the method comprising:

[0005] Discharging the battery to a lower cut-off voltage of the battery, and determining a total discharge capacity of the battery;

[0006] Obtaining a graphite-to-lithium half-button cell for the battery, wherein the graphite-to-lithium half-button cell is assembled based on the same type of graphite material as the battery;

[0007] Obtaining a graphite lithium insertion curve corresponding to the graphite-lithium half-button battery, performing differentiation processing on the graphite lithium insertion curve to obtain a first differential voltage curve, and obtaining a charging curve corresponding to the battery, performing differentiation processing on the charging curve to obtain a second differential voltage curve;

[0008] Performing phase change peak feature matching processing based on the first differential voltage curve and the second differential voltage curve to obtain a state of charge quantity corresponding to the phase change peak;

[0009] The total charging capacity of the battery when charged to the state of charge is obtained, and the ratio of the negative electrode capacity to the positive electrode capacity of the battery is determined based on the ratio of the total charging capacity to the total discharging capacity.

[0010] In the embodiment of the present application, the total discharge capacity when the battery is discharged to the lower limit cut-off voltage is first determined, and a graphite-to-lithium half-button battery assembled with the same type of graphite material as the battery is obtained. The first differential voltage curve obtained by differential processing of the graphite lithium intercalation curve of the graphite-to-lithium half-button battery and the second differential voltage curve obtained by differential processing of the charging curve of the (full) battery are matched for phase change peak characteristics. To determine the state of charge corresponding to the phase change peak, the total charging capacity of the battery charged to the state of charge can be obtained, and the NP ratio for the battery is determined based on the ratio of the total charging capacity to the total discharge capacity, thereby improving or even completely solving the limitation of low accuracy in the calculation of the battery NP ratio in the related art, and the entire process of determining the ratio of the negative electrode capacity and the positive electrode capacity of the battery does not require disassembling the battery structure. The method of calculating the actual NP ratio of the battery based on the total charge and discharge capacity of the battery cell avoids the risk of disassembling the cell to damage the pole piece, and does not require the production of three electrodes, thereby optimizing the process of calculating the battery NP ratio. The method is simple to operate and has good application prospects.

[0011] In a feasible implementation manner, performing phase change peak feature matching processing based on the first differential voltage curve and the second differential voltage curve to obtain a state of charge value corresponding to the phase change peak, and obtaining a total charging capacity of the battery charged to the state of charge value includes:

[0012] Obtain the first LiC from the first differential voltage curve 12 The first state of charge quantity corresponding to the phase change peak characteristic point is obtained from the second differential voltage curve. 12 The second state of charge quantity corresponding to the phase change peak characteristic point;

[0013] It is determined that the second state of charge matches the first state of charge, and a total charging capacity of the battery when the battery is charged to the second state of charge is obtained.

[0014] In the embodiment of the present application, LiC 12 The phase change peak characteristic point is the last significant phase change of graphite, which is in the shape of a sharp peak, which can represent the contribution of graphite to the gram capacity of lithium half-button battery. 12 Phase change peak feature matching, with the help of graphite as a reference, the lithium half-button cell is accurately matched to the state of charge corresponding to the phase change peak of the battery (full battery) to be tested, so as to accurately calculate the total charging capacity based on the state of charge;

[0015] In a feasible implementation manner, the determining that the second state of charge value matches the first state of charge value includes:

[0016] If the second state of charge is the same as the first state of charge, determining that the second state of charge matches the first state of charge; or,

[0017] If the second state of charge is different from the first state of charge, and a state of charge difference between the second state of charge and the first state of charge satisfies a specified deviation range, it is determined that the second state of charge matches the first state of charge.

[0018] In the embodiment of the present application, the first differential voltage curve and the second differential voltage curve are subjected to LiC 12 During the phase change peak feature matching process, the second state of charge quantity and the first state of charge quantity corresponding to each phase change peak on the two curves are matched to see if they are the same, so that the state of charge quantity for calculating the total charging capacity can be accurately obtained when matched; or, when the second state of charge quantity and the first state of charge quantity are different, matching is performed based on whether the difference between the second state of charge quantity and the first state of charge quantity meets the specified deviation range. Within the specified deviation range, the calculation deviation is a calculation error that can be tolerated by the battery NP ratio and will not have a significant impact.

[0019] In a feasible implementation manner, the acquiring a charging curve corresponding to the battery includes:

[0020] The battery is charged at a constant current and constant voltage at at least one specified charging rate to obtain a charging curve corresponding to the specified charging rate.

[0021] In the embodiment of the present application, a charging curve corresponding to one or more specified charging rates is used to match the state of charge indicated by the appropriate graphite phase change characteristics for calculating the total charging capacity. At the same time, the constant current and constant voltage charging mode can ensure that the charging capacity of the full battery is fully utilized, and the anode capacity in the full battery is also fully utilized;

[0022] In a feasible implementation manner, the method further includes:

[0023] Determining that the second state of charge does not match the first state of charge, acquiring a next second differential voltage curve, wherein the specified charging rate corresponding to the second differential voltage curve is different from the specified charging rate corresponding to the next second differential voltage curve;

[0024] The next second differential voltage curve is used as the second differential voltage curve and the steps of obtaining the first state of charge corresponding to the first phase change peak characteristic point from the first differential voltage curve and obtaining the second state of charge corresponding to the second phase change peak characteristic point from the first differential voltage curve are performed.

[0025] In an embodiment of the present application, when the second state of charge in the current first differential voltage curve and the second differential voltage curve does not match the first state of charge, a suitable graphite phase change characteristic can be matched by obtaining the second differential voltage curve of the next different specified charging rate and then matching them, so as to facilitate the subsequent accurate calculation of the total charging capacity based on the state of charge indicated by the graphite phase change characteristic.

[0026] In a feasible implementation manner, performing phase change peak feature matching processing based on the first differential voltage curve and the second differential voltage curve to obtain a state of charge quantity corresponding to the phase change peak includes:

[0027] A specified state of charge range is determined, and phase change peak feature matching processing is performed based on the first differential voltage curve and the second differential voltage curve within the specified state of charge range to obtain a state of charge corresponding to the phase change peak.

[0028] In the embodiment of the present application, graphite lithium insertion is a multi-stage phase change reaction. A specified state of charge range is selected, and phase change peak characteristic matching is performed within the specified state of charge range. Here, the characteristic state of charge SOC selected within the specified state of charge range is LiC 12 Phase transition state of charge SOC, LiC 12 The phase change peak characteristic is the last significant phase change of graphite, and its shape is a sharp peak, which can represent the full capacity of graphite, making it convenient for the subsequent accurate calculation of the total charging capacity.

[0029] In a feasible implementation manner, discharging the battery to a lower cut-off voltage of the battery includes:

[0030] The battery is subjected to at least one round of discharge treatment based on a specified discharge rate so that the voltage of the battery reaches a lower limit cut-off voltage, and the battery is left to stand for a target time after the discharge treatment.

[0031] In the embodiment of the present application, the purpose of the static target time is to eliminate the polarization of the battery cell and restore the battery to a balanced potential. The cell potential will slightly rebound (e.g., from 3V to 3.4V). Based on this, at least one round of discharge processing is required to accurately calculate the total discharge capacity.

[0032] In a feasible implementation manner, obtaining the graphite lithium insertion curve corresponding to the graphite-to-lithium half button cell includes:

[0033] The graphite-to-lithium half-button cell is subjected to a lithium insertion test process at a specified lithium insertion rate and a lithium insertion voltage range to obtain a graphite lithium insertion curve corresponding to the graphite-to-lithium half-button cell during the lithium insertion test process.

[0034] In a feasible implementation manner, the specified discharge rate is the specified lithium insertion rate less than or equal to 0.1C, and the lithium insertion voltage range is 2V to 0.005V.

[0035] In the embodiment of the present application, the lower cut-off voltage in the lithium insertion voltage range can ensure that the lithium insertion capacity of the graphite buckle battery is fully utilized.

[0036] In a feasible implementation manner, the specified state of charge value ranges from 50% to 70%.

[0037] In the embodiment of the present application, the full battery LiC 12 The phase change characteristic is in the state of charge SOC of the specified state of charge range of "50% to 70%" in the constant current stage. The characteristics of the low state of charge SOC outside this specified state of charge range cannot represent that the anode capacity is fully utilized, and the characteristics of the high state of charge SOC outside this range do not belong to graphite and cannot represent the degree of utilization of the anode capacity.

[0038] In a feasible implementation manner, the specified deviation range is -0.5% to 0.5%.

[0039] In the embodiment of the present application, the allowable horizontal axis deviation of the characteristic state of charge SOC of the full battery and the characteristic state of charge SOC of the graphite half-button can meet the specified deviation range. The deviation within the specified deviation range corresponds to a deviation of ±0.5% in calculating the anode capacity of the full battery and a deviation of ±0.5% in calculating NP, which is the deviation that the NP ratio can accommodate.

[0040] In a second aspect, an embodiment of the present application provides a device for determining the ratio of the negative electrode capacity to the positive electrode capacity of a battery, the device comprising:

[0041] A capacity determination module, used to discharge the battery to a lower cut-off voltage of the battery and determine a total discharge capacity of the battery;

[0042] A battery acquisition module, used for acquiring a graphite-to-lithium half-button cell for the battery, wherein the graphite-to-lithium half-button cell is assembled based on the same type of graphite material as the battery;

[0043] A curve acquisition module, used to obtain a graphite lithium insertion curve corresponding to the graphite-lithium half-button battery, perform differential processing on the graphite lithium insertion curve to obtain a first differential voltage curve, and obtain a charging curve corresponding to the battery, perform differential processing on the charging curve to obtain a second differential voltage curve;

[0044] a feature matching module, configured to perform a phase change peak feature matching process based on the first differential voltage curve and the second differential voltage curve to obtain a state of charge value corresponding to the phase change peak;

[0045] The NP ratio determination module is used to obtain the total charging capacity of the battery when it is charged to the state of charge, and determine the ratio of the negative electrode capacity to the positive electrode capacity of the battery based on the ratio of the total charging capacity to the total discharging capacity.

[0046] In a third aspect, an embodiment of the present application provides a battery management system, characterized in that it is connected to a battery, the battery includes at least one battery cell, and the battery management system is used to execute the above-mentioned method steps.

[0047] In a fourth aspect, an electronic device is characterized by comprising: a body, a battery management system and a battery connected to the battery management system, wherein the battery comprises at least one battery cell;

[0048] The battery is used to supply power to the body;

[0049] The battery management system is used to execute the above method steps.

[0050] A fifth aspect is a computer storage medium, wherein the computer storage medium stores a plurality of instructions, wherein the instructions are suitable for being loaded by a processor and executing the above-mentioned method steps.

[0051] In a sixth aspect, an embodiment of the present application provides a computer program product, which stores at least one instruction, and the at least one instruction is loaded by the processor to execute the above-mentioned method steps.

[0052] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or understood by implementing the embodiments of the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 It is a flow chart of a method for determining the ratio of the negative electrode capacity and the positive electrode capacity of a battery provided in an embodiment of the present application;

[0055] Figure 2 is a schematic diagram of a discharge curve provided in an embodiment of the present application;

[0056] Figure 3It is a schematic diagram of a process for determining the total charging capacity provided in an embodiment of the present application;

[0057] Figure 4 is a schematic diagram of a differential voltage curve provided in an embodiment of the present application;

[0058] Figure 5 A device for determining the ratio of the negative electrode capacity to the positive electrode capacity of a battery provided in an embodiment of the present application;

[0059] Figure 6 It is a structural schematic diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0061] In the description of the present application, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood in specific circumstances. In addition, in the description of the present application, unless otherwise specified, "multiple" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are an "or" relationship.

[0062] In the related art, one method is to disassemble the battery cell destructively to obtain the cathode electrode sheet and the anode electrode sheet, and then measure the capacity per unit area of ​​the cathode electrode sheet and the capacity per unit area of ​​the anode electrode sheet to calculate the NP ratio. This method has the risk of introducing deviations in the calculation of the NP ratio due to the factor of disassembling and destroying the battery electrode sheet, resulting in a low accuracy of the NP ratio. Another method is to make the battery into three electrodes, monitor the rate of change of the cathode potential of the battery during the charge and discharge process to qualitatively evaluate the size of the NP ratio of the battery cell. This method cannot directly measure a clear NP ratio, and the accuracy of the NP ratio is low.

[0063] Based on the limitation of low accuracy in battery NP ratio calculation in the related art, the embodiment of the present application provides a method for determining the ratio of the negative electrode capacity and the positive electrode capacity of a battery, and a method for reflecting the actual NP ratio of the battery according to the charge and discharge curve of the battery cell, thereby avoiding the risk of disassembling the battery cell and damaging the electrode sheet, and at the same time, there is no need to make three electrodes, and the charge and discharge curve of the whole battery can be directly used for calculation, so as to improve or even completely solve the limitation of low accuracy in battery NP ratio calculation in the related art;

[0064] The present application is described in detail below with reference to specific embodiments.

[0065] In one embodiment, Figure 1 As shown, a method for determining the ratio of the negative electrode capacity to the positive electrode capacity of a battery is proposed. The method can be implemented by a computer program and can be run on a device for determining the ratio of the negative electrode capacity to the positive electrode capacity of a battery based on the von Neumann system. The computer program can be integrated into an application or run as an independent tool application. Specifically, the method for determining the ratio of the negative electrode capacity to the positive electrode capacity of a battery includes:

[0066] The NP ratio involved in this application adopts the form of "NP ratio = anode capacity / cathode capacity". The cathode capacity is determined by taking the total discharge capacity under the actual operating conditions of the battery; the anode capacity is determined by taking the total charging capacity when the anode is fully embedded and lithium deposition begins. The "full anode embedding" feature of the battery is determined based on the state of charge SOC of the graphite phase change characteristics in the battery.

[0067] S102: discharging the battery to a lower cut-off voltage of the battery, and determining a total discharge capacity of the battery;

[0068] Specifically, a battery capacity testing device is used to discharge the battery cell to a lower cut-off voltage based on a set discharge rate, and when the voltage of the battery reaches the lower cut-off voltage, the total discharge capacity of the battery recorded on the battery capacity testing device is obtained;

[0069] Exemplarily, a battery capacity testing device is used to discharge the battery cell to a lower cut-off voltage using a discharge rate such as a 0.2C rate. Typically, the cut-off voltage is the rated voltage window for the battery cell design. The lower voltage indicated by the voltage window is also the aforementioned lower cut-off voltage. For example, if the voltage window of a lithium-cobalt-graphite battery cell is 4.45-3V, the lower cut-off voltage is 3V.

[0070] Optionally, discharging the battery to the lower cut-off voltage of the battery can be performed by subjecting the battery to one or more rounds of discharge treatment at a specified discharge rate, and leaving the battery to stand after each round of discharge treatment to offset the polarization effect of the battery cell. During the standing process, the battery cell will reach an equilibrium voltage potential, at which time the voltage of the cell may be slightly higher than the lower cut-off voltage. Based on this, it is necessary to perform multiple rounds of discharge treatment based on actual conditions.

[0071] Specifically, at least one round of discharge treatment is performed on the battery based on a specified discharge rate so that the voltage of the battery reaches a lower limit cut-off voltage, and the battery is left to stand for a target time after the discharge treatment.

[0072] Exemplarily, discharging a battery to a lower cut-off voltage of the battery may refer to the following steps:

[0073] 1) Use battery capacity testing equipment to perform discharge treatment at a specified discharge rate (such as 0.2C rate) to discharge the battery cell to a lower cut-off voltage such as 3V. The cut-off voltage is the rated voltage window of the battery cell design (for example, if the voltage window of a certain lithium cobalt graphite battery cell is 4.45-3V, use the specified discharge rate to discharge to 3V);

[0074] Indicatively, the entire discharge process can be carried out by placing the battery in a constant temperature box (such as 25 degrees) using a battery capacity test device;

[0075] 2) After the battery is discharged to the cut-off voltage, it is left to stand for a target length of time, such as 5 minutes. The purpose of the standing time is to eliminate the polarization of the battery cell and restore the battery to its own equilibrium potential. The potential of the battery cell will rebound slightly (for example, it may rise from 3V to 3.4V);

[0076] 3) Carry out the next round of discharge treatment: continue to discharge at the specified discharge rate to the lower limit cut-off voltage, ensuring that the small rate discharge can fully exert the discharge capacity of the battery cell. The discharge capacity of each step in the first and third steps will be automatically recorded on the battery capacity test equipment, and the sum of the discharge capacity of the first and third steps will also be recorded. At this time, the total discharge capacity of the first and third steps is recorded as Q1; Figure 2 As shown, Figure 2 is a schematic diagram of a discharge curve. Figure 2It illustrates the process of discharging the full battery to a cut-off voltage of 3V, leaving it to rest for a target time, and then continuing to discharge it to a cut-off voltage of 3V. That is, it shows the discharge curves of the battery cell in the first and third steps of discharge. From the figure, it can be seen that the total discharge capacity of the two discharge treatments is: Q1=2500mAh.

[0077] The above steps are explained by taking the example of multiple rounds of discharge treatment as two rounds of discharge treatment. It should be noted that the specific values ​​such as multiple rounds of discharge treatment as two rounds of discharge treatment, the specified discharge rate as 0.2C, the target duration as 55 minutes in the above examples cannot be understood as limitations on the present application.

[0078] Optionally, specify a discharge rate ≤ 0.2C to ensure that the discharge capacity of the battery cell can be fully utilized at this small rate;

[0079] S104: Obtaining a graphite-to-lithium half-button cell for the battery, wherein the graphite-to-lithium half-button cell is assembled based on the same type of graphite material as the battery;

[0080] In the present application, the whole battery is avoided from being disassembled and the pole pieces are not damaged. Instead, a "graphite half-button battery" is pre-assembled using the same type of graphite material as the battery to be tested.

[0081] It can be understood that the graphite half-button battery is assembled with the same type and style of graphite material as the battery to be tested.

[0082] Indicatively, the same type of graphite powder material as the battery to be tested can be used in advance to assemble a graphite-to-lithium half-button battery (the same type of graphite powder material can be used to assemble the button battery, and the same type of graphite powder material can ensure that the gram capacity performance indicators of the button battery and the battery to be tested are consistent);

[0083] For example, taking the battery to be tested as a lithium cobalt graphite full battery as an example, how to assemble the graphite-to-lithium half-button battery for the battery to be tested is explained:

[0084] Assemble graphite-lithium half button cells using the same type of powdered graphite as the lithium-cobalt-graphite full cell;

[0085] Graphite-to-lithium half-button cell: Graphite uses the same type of powdered graphite material as the lithium-cobalt graphite full cell, acetylene black is used as the conductive agent, and polytetrafluoroethylene (PVDF) is used as the binder. The three materials of "graphite material + conductive agent + binder" are weighed in a stirring tank according to the specified total amount (such as 1000 mg) and the specified ratio (such as 8:1:1 ratio), and dry-mixed for a certain period of time (such as 30 minutes) to make the powder mixed evenly, and then N-methylpyrrolidone (NMP) is added dropwise to thicken it, and magnetic stirring is performed to form a slurry. The stirred slurry is evenly coated on the current collector with a coating machine, and the coating thickness is controlled to be a specified thickness (such as 20um). The coated film is The copper foil is placed in a vacuum oven at a specified temperature (such as 110°C) and dried for a certain period of time (such as 12h). The electrode sheet is punched into a negative electrode sheet of a specified diameter (such as 15mm) using a punching machine. The weight is A mg (such as 14mg). At the same time, the bare current collector mass is weighed as B mg (such as 5mg). The active material mass is calculated as (AB)*graphite material ratio=C mg (such as (14-5)*0.8=7.2mg). The punched graphite negative electrode sheet is transferred to a vacuum environment (such as a vacuum box) and assembled according to the negative electrode shell / lithium sheet / diaphragm / electrolyte / graphite negative electrode sheet / positive electrode shell. After the assembly is completed, a graphite-lithium half-button cell is obtained.

[0086] S106: obtaining a graphite lithium insertion curve corresponding to the graphite-lithium half-button battery, performing a differential processing on the graphite lithium insertion curve to obtain a first differential voltage curve, and obtaining a charging curve corresponding to the battery, performing a differential processing on the charging curve to obtain a second differential voltage curve;

[0087] The step of "obtaining a graphite lithium insertion curve corresponding to the graphite-to-lithium half-button cell, and performing a differential process on the graphite lithium insertion curve to obtain a first differential voltage curve" is explained as follows:

[0088] Indicatively, the graphite lithium insertion curve corresponding to the graphite-lithium half-button cell is obtained, and the graphite lithium insertion process is performed using the specified lithium insertion rate and the set lithium insertion voltage range in the "calibrating graphite button cell capacity" stage. For example, the specified lithium insertion rate can be a rate of 0.1C. Here, the "graphite-lithium half-button cell" with the specified lithium insertion rate and lithium insertion voltage range is also used to perform a graphite lithium insertion test, so as to obtain the graphite lithium insertion curve;

[0089] Furthermore, during the lithium insertion test, graphite lithium insertion is a multi-stage phase change reaction, and graphite intercalation compounds LiC will be formed in sequence at the graphite negative electrode. 24 (fourth-order GIC), LiC 18 (Third-order GIC), LiC 12 (Second-order GIC), LiC6 (First-order GIC)

[0090] For the "graphite-to-lithium half-button cell", the graphite lithium insertion test process is also the discharge and lithium insertion process of the "graphite-to-lithium half-button cell". The graphite-to-lithium half-button cell is discharged and lithium inserted at a specified lithium insertion rate, such as discharging and inserting lithium at a constant current rate of 0.1C, until the unit of the graphite-to-lithium half-button cell reaches the lower limit cutoff voltage of the lithium insertion voltage range (if the lithium insertion voltage range is 2V to 0.005V, the lower limit cutoff voltage is 0.005V). At this time, the lithium insertion capacity of the "graphite-to-lithium half-button cell" can be read from the battery capacity test equipment. Assuming that the lithium insertion capacity is 2.592mAh, the gram capacity of graphite is 2.592mAh / 7.2mg=360mAh / g;

[0091] When the "graphite half-button cell" is discharged, it can be found from the battery capacity testing equipment that its working voltage is always changing with the passage of time. The graphite lithium insertion curve can also be understood as: using the working voltage of the "graphite half-button cell" as the vertical coordinate, and the discharge time, or capacity, or state of charge (SOC), or depth of discharge (DOD) as the horizontal coordinate, the curve drawn is called the graphite lithium insertion curve.

[0092] Optional, graphite lithium insertion curve: using the working voltage of the "graphite half-button battery" as the vertical axis and the state of charge (SOC) as the horizontal axis, the graphite lithium insertion curve can be directly derived based on the battery capacity testing equipment, or the graphite lithium insertion curve can be drawn based on the relevant data of the battery capacity testing equipment.

[0093] Further, based on the (real-time) lithium insertion capacity recorded by the battery capacity test equipment during the lithium insertion test, the graphite lithium insertion curve is subjected to dV / dQ differential processing, that is, a differential voltage curve of the "graphite half-button battery" is drawn, which may also be referred to as the first differential voltage curve in this application;

[0094] As you can understand, the differential voltage curve is also called: dV / dQ curve refers to the change in voltage per unit capacity of the material;

[0095] Optionally, the specified discharge rate is the specified lithium insertion rate less than or equal to 0.1C, and the lithium insertion voltage range is 2V to 0.005V.

[0096] Indicatively, the lithium insertion voltage range of the "graphite half-button battery" is 2V-0.005V, and the lower cut-off voltage in the lithium insertion voltage range can ensure that the lithium insertion capacity of the "graphite half-button battery" is fully utilized.

[0097] Indicatively, the "graphite half-button cell" specifies a lithium insertion rate of less than or equal to 0.1C. At a higher rate, the capacity of the "graphite half-button cell" may be affected by impedance polarization, and the capacity will be greatly limited, causing itself to fail as a reference for a full battery.

[0098] The step of “obtaining a charging curve corresponding to the battery, and performing differentiation processing on the charging curve to obtain a second differential voltage curve” is interpreted as follows:

[0099] In a feasible implementation manner, the acquiring a charging curve corresponding to the battery includes:

[0100] The battery is charged at a constant current and constant voltage at at least one specified charging rate to obtain a charging curve corresponding to the specified charging rate.

[0101] The battery to be tested is charged with constant current and constant voltage at different specified charging rates using a battery capacity testing device to obtain charging curves corresponding to different specified charging rates. The constant current and constant voltage charging mode can ensure that the charging capacity of the entire battery is fully utilized, and the anode capacity of the entire battery will also be fully utilized.

[0102] Among them, constant current and constant voltage charge (CC-CV Charge) is a combination of CC charge and CV charge. During the charging process, the current is kept constant. When the voltage is charged to the upper limit voltage, the voltage is kept constant. Finally, the current gradually decreases to the set value and the charging ends.

[0103] Indicatively, the battery to be tested (full battery) can be discharged to a lower cut-off voltage (the lower cut-off voltage is the lower voltage value of the voltage window of the full battery, such as the designed voltage window is 4.45V-3V, then the lower voltage value is 3V), and then the battery is charged with constant current and constant voltage at one or more specified charging rates, so that a charging curve corresponding to each specified charging rate can be obtained.

[0104] Optionally, charging curve: using the working voltage of the battery to be tested (full battery) as the ordinate and the state of charge (SOC) as the abscissa, the charging curve can be directly derived based on the battery capacity testing equipment, or the charging curve can be drawn based on the relevant data of the battery capacity testing equipment.

[0105] Further, the charging curve is subjected to dV / dQ differential processing based on the (real-time) charging capacity recorded by the battery capacity test device during the full battery charging process, that is, a differential voltage curve of the "battery to be tested (full battery)" is drawn, which may also be referred to as the second differential voltage curve in this application;

[0106] As can be understood, the charging rate is usually specified to include the constant current step rate and the constant voltage step cut-off rate;

[0107] The battery is charged with constant current and constant voltage at a specified charging rate, that is, the battery (full battery) to be tested is charged with constant current to the upper limit voltage value of the design voltage window using the constant current step rate (such as the upper limit voltage of the design voltage window, if the design voltage window is 4.45V-3V, then the upper limit voltage value is 4.45V), and then the voltage of the battery (full battery) to be tested is maintained unchanged until the battery (full battery) to be tested reaches the constant voltage step cutoff rate, that is, the current is reduced to the set value corresponding to the constant voltage step cutoff rate, and the charging is terminated to obtain a charging curve corresponding to the specified charging rate.

[0108] Optionally, during the constant current and constant voltage charging process of the full battery, the constant current step rate in the specified charging rate is 0.1C to 1C. Within this range, the full battery LiC 12 The characteristic state of charge SOC can be compared with the LiC 12 The characteristic state of charge SOC matches; the constant voltage step cutoff rate in the specified charging rate is less than or equal to 0.05C, which can ensure that the full battery charging capacity is fully utilized.

[0109] S108: performing phase change peak feature matching processing based on the first differential voltage curve and the second differential voltage curve to obtain a state of charge value corresponding to the phase change peak;

[0110] For the differential voltage curve, the dV changes very little in the platform area and approaches 0, while in the slope area, the voltage changes abruptly, showing a "peak" feature also called a phase change peak feature. The phase change peak feature is manifested in the shape of a spike in the differential voltage curve. Therefore, the dV / dQ peak position represents the phase change process of the material.

[0111] Schematically, the first differential voltage curve processed by DVDQ differential has a phase change peak feature, and one or more second differential voltage curves processed by DVDQ differential also have a phase change peak feature;

[0112] The phase change peak feature matching process is to use the phase change peak feature in the first differential voltage curve as a reference, match it with the phase change peak feature in the second differential voltage curve corresponding to each different specified charging rate, find the target phase change peak feature in the target second differential voltage curve that matches the phase change peak feature in the first differential voltage curve, and thereby determine the state of charge corresponding to the phase change peak feature in the target second differential voltage curve, so as to facilitate the subsequent determination of the total charging capacity;

[0113] Furthermore, the obtained graphite lithium insertion curve is subjected to DVDQ differential processing to obtain the first differential voltage curve, and the state of charge SOC corresponding to the graphite phase change peak characteristic is determined in the first differential voltage curve: graphite lithium insertion is a multi-order phase change reaction, and the characteristic state of charge SOC selected here is LiC 12 State of charge SOC of phase transition;

[0114] Furthermore, the phase change peak characteristic in the first differential voltage curve is usually selected from the LiC12 phase change peak characteristic, LiC 12 The phase change peak characteristic is the last significant phase change in the process of graphite lithium insertion. The phase change peak characteristic is manifested in the shape of the first differential voltage curve as a sharp peak, which can represent the gram capacity of the "graphite rational half-button battery".

[0115] Optionally, a specified state of charge range is determined, and phase change peak feature matching processing is performed based on the first differential voltage curve and the second differential voltage curve within the specified state of charge range to obtain the state of charge corresponding to the phase change peak.

[0116] It is understandable that the range of state of charge is specified to select LiC 12 Phase transition peak characteristics, LiC 12 Phase transition peak characteristics usually occur within a specified state of charge range, usually LiC 12 The phase change peak characteristics are more informative.

[0117] Optionally, the specified state of charge value ranges from 50% to 70%.

[0118] S110: Obtaining a total charging capacity of the battery when the battery is charged to the state of charge, and determining a ratio of a negative electrode capacity to a positive electrode capacity of the battery based on a ratio of the total charging capacity to the total discharging capacity.

[0119] It can be understood that during the charging process of the battery (full battery) to be tested, the total charging capacity of the battery charged to the state of charge will be recorded by the battery capacity testing equipment, based on which the total charging capacity can be obtained.

[0120] The form of "NP ratio = anode capacity / cathode capacity" is adopted. The cathode capacity is determined by taking the total discharge capacity under the actual working conditions of the battery; the anode capacity is determined by taking the total charging capacity when the anode is fully embedded and lithium is precipitated. The "full anode embedding" feature of the battery is determined based on the state of charge SOC of the graphite phase change feature in the battery. That is, NP ratio = anode capacity / cathode capacity = total charging capacity / total discharge capacity;

[0121] Illustratively, the ratio of the total charge capacity to the total discharge capacity is calculated and used as the NP ratio for the battery.

[0122] In the embodiment of the present application, the total discharge capacity when the battery is discharged to the lower limit cut-off voltage is first determined, and a graphite-to-lithium half-button battery assembled with the same type of graphite material as the battery is obtained. The first differential voltage curve obtained by differential processing of the graphite lithium intercalation curve of the graphite-to-lithium half-button battery and the second differential voltage curve obtained by differential processing of the charging curve of the (full) battery are matched for phase change peak characteristics. To determine the state of charge corresponding to the phase change peak, the total charging capacity of the battery charged to the state of charge can be obtained, and the NP ratio for the battery is determined based on the ratio of the total charging capacity to the total discharge capacity, thereby improving or even completely solving the limitation of low accuracy in the calculation of the battery NP ratio in the related art, and the entire process of determining the ratio of the negative electrode capacity and the positive electrode capacity of the battery does not require disassembling the battery structure. The method of calculating the actual NP ratio of the battery based on the total charge and discharge capacity of the battery cell avoids the risk of disassembling the cell to damage the pole piece, and does not require the production of three electrodes, thereby optimizing the process of calculating the battery NP ratio. The method is simple to operate and has good application prospects.

[0123] See also Figure 3 , Figure 3 This is a schematic diagram of a process for determining the total charging capacity proposed in this application. Specifically:

[0124] S202: Obtaining a first LiC from the first differential voltage curve 12 The first state of charge quantity corresponding to the phase change peak characteristic point is obtained from the second differential voltage curve. 12 The second state of charge quantity corresponding to the phase change peak characteristic point;

[0125] Example 1, taking the current specified charging rate as 0.5c as an example, the interpretation is as follows:

[0126] Using a specified charging rate of 0.5C on a battery capacity test device to perform a constant current and constant voltage charging test on a full battery, and performing a differential processing on the charging curve to obtain a second differential voltage curve corresponding to the "specified charging rate of 0.5C";

[0127] Example 2, taking the current specified charging rate as 0.2c as an example, the interpretation is as follows:

[0128] Using a specified charging rate of 0.2C on a battery capacity test device to perform a constant current and constant voltage charging test on a full battery, and performing a differential processing on the charging curve to obtain a second differential voltage curve corresponding to the "specified charging rate of 0.5C";

[0129] By analogy, different specified charging rates can obtain different second differential voltage curves.

[0130] like Figure 4 , Figure 4is a schematic diagram of a differential voltage curve. Figure 4 The horizontal axis of the middle figure is SOC, and the vertical axis is dV / dQ value. Figure 4 The first differential voltage curve is shown respectively. Figure 4 The "graphite buckle curve" in the figure is the second differential voltage curve of the full battery with a specified charging rate of 0.2c, that is, Figure 4 The "full battery 0.2C curve" in the figure is the second differential voltage curve of the full battery with a specified charging rate of 0.5c, that is, Figure 4 The "Full Battery 0.5C Curve" Figure 4 The phase change peaks corresponding to the three differential voltage curves are also shown.

[0131] Exemplary, the step of "obtaining a first LiC from the first differential voltage curve 12 The first state of charge quantity corresponding to the phase transition peak characteristic point can be referred to Figure 4 "Graphite buckling curve" in:

[0132] like Figure 4 As shown, graphite half-button LiC 12 The phase change peak characteristic corresponding to the vertex indicates that the horizontal axis is LiC at 58% SOC. 12 Phase change peak, graphite half-button LiC 12 Vertex is also the first LiC 12 Phase change peak characteristic point, the first state of charge quantity is also 58% state of charge SOC;

[0133] Exemplary, the step of "obtaining a second LiC from the second differential voltage curve 12 The second state of charge corresponding to the phase transition peak characteristic point can be referred to Figure 4 The "full battery 0.2C curve" and "full battery 0.5C curve" in the "full battery 0.5C curve" are the second differential voltage curves obtained by differentiating the curve of the battery (full battery) to be tested in the 0.5C constant current charging stage. Based on the second differential voltage curve, the second LiC 12 Phase transition peak ( Figure 4 The vertex of the phase change peak of the full battery 0.5C curve is shown in the figure) The vertex corresponds to the horizontal axis, which is at 63% state of charge SOC, and the second state of charge is also 63% state of charge SOC.

[0134] Optionally, a specified state of charge value range is determined, and “obtaining a first LiC from the first differential voltage curve” is performed within the specified state of charge value range. 12 The first state of charge quantity corresponding to the phase change peak characteristic point is obtained from the second differential voltage curve. 12 The step of "determining the second state of charge quantity corresponding to the phase change peak characteristic point".

[0135] It is understandable that the range of state of charge is specified to select LiC 12 Phase transition peak characteristics, LiC 12 Phase transition peak characteristics usually occur within a specified state of charge range, usually LiC 12 The phase change peak characteristics are more informative.

[0136] Optionally, the specified state of charge value ranges from 50% to 70%.

[0137] S204: Determine whether the second state of charge matches the first state of charge, and obtain a total charging capacity of the battery when the battery is charged to the second state of charge.

[0138] Indicatively, the battery (full battery) to be tested is charged with a constant current step rate with a specified charging rate as a reference until the voltage of the battery (full battery) to be tested reaches the upper limit voltage value of the design voltage window (such as the upper limit voltage of the design voltage window, if the design voltage window is 4.45V-3V, the upper limit voltage value is 4.45V), and then the voltage of the battery (full battery) to be tested is kept unchanged until the battery (full battery) to be tested reaches the constant voltage step cutoff rate, that is, during the entire charging process when the current is reduced to the set value corresponding to the constant voltage step cutoff rate, the total charging capacity Q2 of the battery charged to the second state of charge is read. The total charging capacity Q2 can be directly read from the battery capacity test equipment.

[0139] S206: determining that the second state of charge does not match the first state of charge, obtaining a next second differential voltage curve, wherein the specified charging rate corresponding to the second differential voltage curve is different from the specified charging rate corresponding to the next second differential voltage curve;

[0140] In a feasible implementation manner, the second state of charge value matches the first state of charge value, which may be that the second state of charge value is the same as the first state of charge value;

[0141] Optionally, if the second state of charge is the same as the first state of charge, it is determined that the second state of charge matches the first state of charge; if the second state of charge is different from the first state of charge, it is determined that the second state of charge does not match the first state of charge;

[0142] In a feasible implementation manner, the second state of charge value matches the first state of charge value by a difference between the second state of charge value and the first state of charge value satisfying a specified deviation range;

[0143] If the second state of charge is different from the first state of charge, and a difference between the second state of charge and the first state of charge satisfies a specified deviation range, determining that the second state of charge matches the first state of charge;

[0144] If the second state of charge is different from the first state of charge, and the state of charge difference between the second state of charge and the first state of charge does not satisfy a specified deviation range, it is determined that the second state of charge does not match the first state of charge.

[0145] Optionally, the specified deviation range is -0.5% to 0.5%. The specified deviation range corresponds to a deviation of ±0.5% for calculating the anode capacity of the full battery and a deviation of ±0.5% for calculating NP, which is an acceptable deviation of the NP ratio.

[0146] Indicatively, you can refer to the following steps:

[0147] Detecting whether a second state of charge quantity matches the first state of charge quantity;

[0148] If the second state of charge value matches the first state of charge value, obtaining a total charging capacity of the battery to be tested (full battery) charged to the second state of charge value;

[0149] If the second state of charge does not match the first state of charge, it is necessary to obtain a next second differential voltage curve corresponding to a next specified charging rate, and execute step S202;

[0150] The current second differential voltage curve is Figure 4 The "full battery 0.5C curve" corresponding to the specified charging rate of 0.5C is explained.

[0151] The first state of charge is 58% state of charge SOC;

[0152] The second state of charge corresponding to the “full battery 0.5C curve” is 63% state of charge SOC;

[0153] It can be seen that the first state of charge (58% state of charge SOC) does not match the second state of charge (63% state of charge SOC), so it is necessary to obtain the second differential voltage curve corresponding to the next specified charging rate, use the next second differential voltage curve as the second differential voltage curve, and perform the steps of obtaining the first state of charge corresponding to the first phase change peak characteristic point from the first differential voltage curve, and obtaining the second state of charge corresponding to the second phase change peak characteristic point from the first differential voltage curve.

[0154] S208: Using the next second differential voltage curve as the second differential voltage curve and executing the steps of obtaining the first state of charge corresponding to the first phase change peak characteristic point from the first differential voltage curve and obtaining the second state of charge corresponding to the second phase change peak characteristic point from the first differential voltage curve.

[0155] Optionally, before performing phase change peak feature matching, the battery may be charged at a constant current and constant voltage at one or more specified charging rates to obtain a charging curve corresponding to one or more specified charging rates, and the charging curve may be differentiated to obtain one or more second differential voltage curves; when executing S206: determining that the second state of charge quantity does not match the first state of charge quantity, the next second differential voltage curve may be directly obtained, and then executing S208;

[0156] Optionally, before performing phase change peak feature matching, the battery may be first charged with constant current and constant voltage at the current specified charging rate to obtain a charging curve corresponding to the current specified charging rate, and the charging curve is differentiated to obtain the current second differential voltage curve; when executing S206: if it is determined that the second state of charge does not match the first state of charge, it is necessary to determine the next specified charging rate of the specified charging rate, the next specified charging rate is obtained based on the charging rate adjustment, and then the battery is charged with constant current and constant voltage at the next specified charging rate to obtain a charging curve corresponding to the next specified charging rate, the charging curve is differentiated to obtain the next second differential voltage curve, and then S208 is executed;

[0157] In the embodiment of the present application, LiC 12 The phase change peak characteristic point is the last significant phase change of graphite, which is in the shape of a sharp peak, which can represent the contribution of graphite to the gram capacity of lithium half-button battery. 12 Phase change peak feature matching, so as to accurately match the lithium half-button battery with the state of charge corresponding to the phase change peak of the battery (full battery) to be tested by means of graphite as a reference, so as to accurately calculate the total charging capacity based on the state of charge; and, the first differential voltage curve and the second differential voltage curve are LiC 12 During the phase change peak feature matching process, the second state of charge quantity and the first state of charge quantity corresponding to each phase change peak on the two curves are matched to see if they are the same, so that the state of charge quantity for calculating the total charging capacity can be accurately obtained when matched; or, when the second state of charge quantity and the first state of charge quantity are different, matching is performed based on whether the difference between the second state of charge quantity and the first state of charge quantity meets the specified deviation range. Within the specified deviation range, the calculation deviation is a calculation error that can be tolerated by the battery NP ratio and will not have a significant impact.

[0158] The validity of the method for determining the ratio of the negative electrode capacity to the positive electrode capacity of the battery in this application is verified as follows:

[0159] The NP ratio of the battery cell can be disassembled and measured to verify the accuracy of the NP ratio obtained by the method for determining the ratio of the negative electrode capacity and the positive electrode capacity of the battery of this application:

[0160] The battery cell to be tested (full battery) was disassembled and the anode mass was weighed = 12.85g, and the bare current collector mass was weighed before the battery cell was prepared and was 5.803g;

[0161] Further, the mass of the anode active material = 12.85 g - 5.803 g = 7.047 g;

[0162] Further, anode capacity = 7.046g*360mAh / g = 2536.56mAh

[0163] Disassembly calculation NP ratio = anode capacity / Q1 = 2536.56 / 2500 = 1.015

[0164] For the battery to be tested (full battery), the method for determining the ratio of the negative electrode capacity and the positive electrode capacity of the battery of this application is adopted, and the total discharge capacity is: Q1 = 2500mAh, such as Figure 4 As shown, at a constant current rate of 0.2C, LiC 12 The peak corresponds to the horizontal axis of 58% SOC, which is similar to the LiC 12 The peak points correspond to the same state of charge SOC, and the match is successful. The capacity of 0.2C constant current charging to 4.45V constant voltage to 0.05C is read from the battery capacitance test equipment, that is, the total charging capacity of the battery charged to 58% state of charge SOC is Q2 = 2537mAh, and the cell NP ratio = Q2 / Q1 = 1.015, which is the same as the design value.

[0165] It can be seen that the NP ratio obtained by the method for determining the ratio of the negative electrode capacity and the positive electrode capacity of the battery of the present application is consistent with the designed NP ratio of the battery cell and the NP actually measured after disassembly, and the method for determining the ratio of the negative electrode capacity and the positive electrode capacity of the battery of the present application is accurate.

[0166] The following will be combined Figure 5 , the device for determining the ratio of the negative electrode capacity to the positive electrode capacity of a battery provided in this specification is introduced in detail. It should be noted that, Figure 5 The battery negative electrode capacity and positive electrode capacity ratio determination device shown is used to implement this manual Figure 1 to Figure 4 For the convenience of explanation, only the parts related to this specification are shown. For the specific technical details not disclosed, please refer to this specification. Figure 1 to Figure 4 The embodiment shown.

[0167] See also Figure 5 , which shows a schematic diagram of the structure of the device for determining the ratio of the negative electrode capacity and the positive electrode capacity of the battery of the present specification. The device for determining the ratio of the negative electrode capacity and the positive electrode capacity of the battery 1 can be implemented as all or part of the device through software, hardware or a combination of both. According to some embodiments, the device for determining the ratio of the negative electrode capacity and the positive electrode capacity of the battery 1 includes a capacity determination module 11, a battery acquisition module 12, a curve acquisition module 13, a feature matching module 14 and an NP ratio determination module 15, which are specifically used to:

[0168] A capacity determination module 11, configured to discharge the battery to a lower cut-off voltage of the battery and determine a total discharge capacity of the battery;

[0169] A battery acquisition module 12, used for acquiring a graphite-to-lithium half-button cell for the battery, wherein the graphite-to-lithium half-button cell is assembled based on the same type of graphite material as the battery;

[0170] A curve acquisition module 13 is used to obtain a graphite lithium insertion curve corresponding to the graphite-lithium half-button battery, perform differential processing on the graphite lithium insertion curve to obtain a first differential voltage curve, and obtain a charging curve corresponding to the battery, perform differential processing on the charging curve to obtain a second differential voltage curve;

[0171] A feature matching module 14 is used to perform phase change peak feature matching processing based on the first differential voltage curve and the second differential voltage curve to obtain a state of charge value corresponding to the phase change peak;

[0172] The NP ratio determination module 15 is used to obtain the total charging capacity of the battery when the battery is charged to the state of charge, and determine the NP ratio of the battery based on the ratio of the total charging capacity to the total discharging capacity.

[0173] Optionally, the feature matching module 14 is used to:

[0174] Obtain the first LiC from the first differential voltage curve 12 The first state of charge quantity corresponding to the phase change peak characteristic point is obtained from the second differential voltage curve. 12 The second state of charge quantity corresponding to the phase change peak characteristic point;

[0175] It is determined that the second state of charge matches the first state of charge, and the total charging capacity of the battery charged to the second state of charge is obtained through the NP ratio determination module 15.

[0176] Optionally, the feature matching module 14 is used to:

[0177] If the second state of charge is the same as the first state of charge, determining that the second state of charge matches the first state of charge; or,

[0178] If the second state of charge is different from the first state of charge, and a state of charge difference between the second state of charge and the first state of charge satisfies a specified deviation range, it is determined that the second state of charge matches the first state of charge.

[0179] Optionally, the curve acquisition module 13 is used to:

[0180] The battery is charged at a constant current and constant voltage at at least one specified charging rate to obtain a charging curve corresponding to the specified charging rate.

[0181] Optionally, the feature matching module 14 is used to:

[0182] Determining that the second state of charge does not match the first state of charge, acquiring a next second differential voltage curve, wherein the specified charging rate corresponding to the second differential voltage curve is different from the specified charging rate corresponding to the next second differential voltage curve;

[0183] The next second differential voltage curve is used as the second differential voltage curve and the steps of obtaining the first state of charge corresponding to the first phase change peak characteristic point from the first differential voltage curve and obtaining the second state of charge corresponding to the second phase change peak characteristic point from the first differential voltage curve are performed.

[0184] Optionally, the feature matching module 14 is used to:

[0185] A specified state of charge range is determined, and phase change peak feature matching processing is performed based on the first differential voltage curve and the second differential voltage curve within the specified state of charge range to obtain a state of charge corresponding to the phase change peak.

[0186] Optionally, the capacity determination module 11 is used to:

[0187] The battery is subjected to at least one round of discharge treatment based on a specified discharge rate so that the voltage of the battery reaches a lower limit cut-off voltage, and the battery is left to stand for a target time after the discharge treatment.

[0188] Optionally, the curve acquisition module 13 is used to:

[0189] The graphite-to-lithium half-button cell is subjected to a lithium insertion test process at a specified lithium insertion rate and a lithium insertion voltage range to obtain a graphite lithium insertion curve corresponding to the graphite-to-lithium half-button cell during the lithium insertion test process.

[0190] Optionally, the specified discharge rate is the specified lithium insertion rate less than or equal to 0.1C, and the lithium insertion voltage range is 2V to 0.005V.

[0191] Optionally, the specified state of charge value ranges from 50% to 70%.

[0192] Optionally, the specified deviation range is -0.5% to 0.5%.

[0193] Optionally, the constant current step rate in the specified charging rate is 0.1C to 1C, and the constant voltage step cutoff rate in the specified charging rate is less than or equal to 0.05C.

[0194] It should be noted that the device for determining the ratio of the negative electrode capacity and positive electrode capacity of a battery provided in the above embodiment only uses the division of the above functional modules as an example when executing the method for determining the ratio of the negative electrode capacity and positive electrode capacity of a battery. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the device for determining the ratio of the negative electrode capacity and positive electrode capacity of a battery provided in the above embodiment belongs to the same concept as the method for determining the ratio of the negative electrode capacity and positive electrode capacity of a battery. The implementation process thereof is detailed in the method embodiment, which will not be repeated here.

[0195] The above serial numbers in this specification are for description only and do not represent the advantages or disadvantages of the embodiments.

[0196] The present specification also provides a computer storage medium, which can store multiple instructions, which are suitable for being loaded and executed by a processor as described above. Figure 1 to Figure 4 The method for determining the ratio of the negative electrode capacity to the positive electrode capacity of the battery in the embodiment shown in the figure can be found in the specific implementation process. Figure 1 to Figure 4 The specific description of the illustrated embodiment will not be repeated here.

[0197] The present specification also provides a computer program product, which stores at least one instruction, and the at least one instruction is loaded and executed by the processor as described above. Figure 1 to Figure 4 The method for determining the ratio of the negative electrode capacity to the positive electrode capacity of the battery in the embodiment shown in the figure can be found in the specific implementation process. Figure 1 to Figure 4 The specific description of the illustrated embodiment will not be repeated here.

[0198] Please refer to Figure 6, is a structural block diagram of an electronic device provided in an embodiment of this specification. The electronic device in this specification may include one or more of the following components: a processor 110, a memory 120, an input device 130, an output device 140, and a bus 150. The processor 110, the memory 120, the input device 130, and the output device 140 may be connected via a bus 150.

[0199] The processor 110 may include one or more processing cores. The processor 110 uses various interfaces and lines to connect various parts of the entire terminal, and executes various functions and processes data of the terminal 100 by running or executing instructions, programs, code sets or instruction sets stored in the memory 120, and calling data stored in the memory 120. Optionally, the processor 110 can be implemented in at least one hardware form of digital signal processing (DSP), field-programmable gate array (FPGA), and programmable logic array (PLA). The processor 110 can integrate one or a combination of a central processing unit (CPU), a graphics processing unit (GPU), and a modem. Among them, the CPU mainly processes the operating system, user interface, and application programs; the GPU is responsible for rendering and drawing display content; and the modem is used to process wireless communications. It can be understood that the above-mentioned modem may not be integrated into the processor 110, but may be implemented separately through a communication chip.

[0200] The memory 120 may include a random access memory (RAM) or a read-only memory (ROM). Optionally, the memory 120 includes a non-transitory computer-readable storage medium. The memory 120 may be used to store instructions, programs, codes, code sets, or instruction sets.

[0201] The input device 130 is used to receive input commands or data, and the input device 130 includes but is not limited to a keyboard, a mouse, a camera, a microphone, or a touch device. The output device 140 is used to output commands or data, and the output device 140 includes but is not limited to a display device and a speaker. In the embodiment of this specification, the input device 130 may be a temperature sensor for obtaining the operating temperature of the terminal. The output device 140 may be a speaker for outputting audio signals.

[0202] In addition, those skilled in the art will appreciate that the structure of the terminal shown in the above drawings does not constitute a limitation on the terminal, and the terminal may include more or fewer components than shown, or combine certain components, or arrange the components differently. For example, the terminal also includes a radio frequency circuit, an input unit, a sensor, an audio circuit, a wireless fidelity (WIFI) module, a power supply, a Bluetooth module, and other components, which will not be described in detail here.

[0203] In the embodiments of this specification, the execution subject of each step may be the electronic device described above. Optionally, the execution subject of each step is the operating system of the terminal. The operating system may be an Android system, an IOS system, or other operating systems, which is not limited in the embodiments of this specification.

[0204] exist Figure 6 In the electronic device, the processor 110 can be used to call the program stored in the memory 120 and execute it to implement the method for determining the ratio of the negative electrode capacity and the positive electrode capacity of the battery as described in the various method embodiments of this specification.

[0205] The battery negative electrode capacity and positive electrode capacity ratio provided in the embodiment of the present application are determined, and its implementation principle and the technical effects produced are the same as those in the aforementioned method embodiment. For the sake of brief description, for matters not mentioned in the device embodiment, reference can be made to the corresponding contents in the aforementioned method embodiment.

[0206] It should be noted that the device for determining the ratio of the negative electrode capacity and positive electrode capacity of a battery provided in the above embodiment only uses the division of the above functional modules as an example when executing the method for determining the ratio of the negative electrode capacity and positive electrode capacity of a battery. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the device for determining the ratio of the negative electrode capacity and positive electrode capacity of a battery provided in the above embodiment belongs to the same concept as the method for determining the ratio of the negative electrode capacity and positive electrode capacity of a battery. The implementation process thereof is detailed in the method embodiment, which will not be repeated here.

[0207] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0208] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0209] The above disclosure is only the preferred embodiment of the present application, which certainly cannot be used to limit the scope of rights of the present application. Therefore, equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A method for determining the ratio of the negative electrode capacity to the positive electrode capacity of a battery, characterized in that: The method comprises: Discharging the battery to a lower cut-off voltage of the battery, and determining a total discharge capacity of the battery; Obtaining a graphite-to-lithium half-button cell for the battery, wherein the graphite-to-lithium half-button cell is assembled based on the same type of graphite material as the battery; Obtaining a graphite lithium insertion curve corresponding to the graphite-lithium half-button battery, performing differentiation processing on the graphite lithium insertion curve to obtain a first differential voltage curve, and obtaining a charging curve corresponding to the battery, performing differentiation processing on the charging curve to obtain a second differential voltage curve; Performing phase change peak feature matching processing based on the first differential voltage curve and the second differential voltage curve to obtain a state of charge quantity corresponding to the phase change peak; The total charging capacity of the battery when charged to the state of charge is obtained, and the ratio of the negative electrode capacity to the positive electrode capacity of the battery is determined based on the ratio of the total charging capacity to the total discharging capacity.

2. The method according to claim 1, characterized in that The performing phase change peak feature matching processing based on the first differential voltage curve and the second differential voltage curve to obtain a state of charge value corresponding to the phase change peak, and obtaining a total charging capacity of the battery charged to the state of charge value, comprises: Obtain the first LiC from the first differential voltage curve 12 The first state of charge quantity corresponding to the phase change peak characteristic point is obtained from the second differential voltage curve. 12 The second state of charge quantity corresponding to the phase change peak characteristic point; It is determined that the second state of charge matches the first state of charge, and a total charging capacity of the battery when the battery is charged to the second state of charge is obtained.

3. The method according to claim 2, characterized in that The determining that the second state of charge quantity matches the first state of charge quantity includes: If the second state of charge is the same as the first state of charge, determining that the second state of charge matches the first state of charge; or, If the second state of charge is different from the first state of charge, and the difference between the second state of charge and the first state of charge satisfies a specified deviation range, it is determined that the second state of charge matches the first state of charge, and the specified deviation range is -0.5% to 0.5%.

4. The method according to claim 2, characterized in that: The obtaining of a charging curve corresponding to the battery includes: The battery is charged with constant current and constant voltage at at least one specified charging rate to obtain a charging curve corresponding to the specified charging rate, wherein the constant current step rate in the specified charging rate is 0.1C to 1C, and the constant voltage step cutoff rate in the specified charging rate is less than or equal to 0.05C.

5. The method according to claim 4, characterized in that The method further comprises: Determining that the second state of charge does not match the first state of charge, acquiring a next second differential voltage curve, wherein the specified charging rate corresponding to the second differential voltage curve is different from the specified charging rate corresponding to the next second differential voltage curve; The next second differential voltage curve is used as the second differential voltage curve and the steps of obtaining the first state of charge corresponding to the first phase change peak characteristic point from the first differential voltage curve and obtaining the second state of charge corresponding to the second phase change peak characteristic point from the first differential voltage curve are performed.

6. The method according to claim 1, characterized in that The performing phase change peak feature matching processing based on the first differential voltage curve and the second differential voltage curve to obtain a state of charge quantity corresponding to the phase change peak includes: A specified state of charge range is determined, and phase change peak feature matching processing is performed based on the first differential voltage curve and the second differential voltage curve within the specified state of charge range to obtain a state of charge corresponding to the phase change peak, wherein the specified state of charge range is 50% to 70%.

7. The method according to claim 1, characterized in that The step of discharging the battery to a lower cut-off voltage of the battery comprises: The battery is subjected to at least one round of discharge treatment based on a specified discharge rate so that the voltage of the battery reaches a lower limit cut-off voltage, and the battery is left to stand for a target time after the discharge treatment.

8. The method according to claim 1, characterized in that: The step of obtaining a graphite lithium insertion curve corresponding to the graphite-to-lithium half button cell comprises: The graphite-to-lithium half-button cell is subjected to a lithium insertion test at a specified lithium insertion rate and a lithium insertion voltage range to obtain a graphite lithium insertion curve corresponding to the graphite-to-lithium half-button cell during the lithium insertion test, wherein the specified discharge rate is less than or equal to 0.1C, and the lithium insertion voltage range is 2V to 0.005V.

9. A computer storage medium, characterized in that The computer storage medium stores a plurality of instructions, and the instructions are suitable for being loaded by a processor and executing the method steps according to any one of claims 1 to 8.

10. An electronic device, characterized in that: include: A processor and a memory; wherein the memory stores a computer program, and the computer program is suitable for being loaded by the processor and executing the method steps as claimed in any one of claims 1 to 8.

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