Capacity grading method of high-capacity battery

Abstract

The invention provides a capacity grading method for a high-capacity battery, and the method comprises the steps: carrying out the constant-current discharge of a fully charged battery to a first discharge cut-off voltage according to a first preset current rate at a preset environment temperature, standing for a first preset time length, and enabling the first preset current rate to be smaller than or equal to the maximum continuous charging current of the battery; and performing constant-current discharge on the battery according to a second preset current rate to a second discharge cut-off voltage, standing for a second preset duration, the second preset current rate being less than or equal to the maximum continuous charging current of the battery, and the second discharge cut-off voltage being less than the first discharge cut-off voltage, so that the battery is discharged more fully, the polarization influence is reduced, and the battery quality is improved. The battery capacity obtained through capacity grading is more accurate, the battery state can be better distinguished, more microcosmic lithium is removed from the negative electrode of the battery, a part of lithium difficult to remove under high voltage can be removed, the lithium precipitation problem of the battery can be improved, the cycle life of the battery is prolonged, and the safety of the battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a capacity division method for large-capacity batteries. Background Art

[0002] Lithium-ion battery is a secondary battery with the advantages of high safety, high specific energy, good high and low temperature performance, low self-discharge, and long cycle. It can be widely used in various scenarios such as automotive power, energy storage, and ship power. During the battery manufacturing process, a complete charge and discharge is required to obtain the capacity, and the battery cell gear is divided accordingly to ensure that the capacity of the same gear is highly consistent and meet the requirements for group use.

[0003] In order to increase product competitiveness, R&D personnel usually design higher capacity battery cells. For higher capacity battery cells, the existing capacity division method is adopted, that is, the capacity division process of static-constant current charging-constant voltage charging-static constant current discharge. The electrolyte is difficult to fully infiltrate, and the lithium ion mass transfer process is affected, which can easily cause lithium precipitation in the battery cell, affect the battery capacity division effect, and cause abnormal cycle capacity attenuation or even safety failure after the battery cell is offline, reducing battery performance. Summary of the invention

[0004] The embodiment of the present invention provides a method for capacity division of a large-capacity battery, which can improve the technical problem that battery lithium deposition affects the capacity division effect and reduces battery performance.

[0005] In a first aspect, an embodiment of the present invention provides a method for sizing a large-capacity battery, wherein the method for activating battery capacity and the method for sizing a large-capacity battery include:

[0006] At a preset ambient temperature, the fully charged battery is discharged at a constant current according to a first preset current rate to a first discharge cut-off voltage, and left to stand for a first preset time, wherein the first preset current rate is less than or equal to the maximum continuous charging current of the battery;

[0007] The battery is discharged at a constant current according to a second preset current rate to a second discharge cut-off voltage, and is left to stand for a second preset time, wherein the second preset current rate is less than or equal to the maximum continuous charging current of the battery, and the second discharge cut-off voltage is less than the first discharge cut-off voltage.

[0008] In a second aspect, an embodiment of the present invention further provides a capacity division device for a large-capacity battery, the capacity division device for a large-capacity battery comprising:

[0009] A first discharge module, used to discharge the fully charged battery at a first preset current rate at a preset ambient temperature to a first discharge cut-off voltage, and leave it for a first preset time, wherein the first preset current rate is less than or equal to the maximum continuous charging current of the battery;

[0010] The second discharge module is used to perform constant current discharge on the battery according to a second preset current rate to a second discharge cut-off voltage, and stand for a second preset time, wherein the second preset current rate is less than or equal to the maximum continuous charging current of the battery, and the second discharge cut-off voltage is less than the first discharge cut-off voltage.

[0011] In a third aspect, an embodiment of the present invention provides an electronic device, the electronic device comprising:

[0012] one or more processors;

[0013] Memory; and

[0014] One or more applications, wherein the one or more applications are stored in the memory and are configured to be executed by the processor to implement the large-capacity battery capacity division method described in any one of the first aspects.

[0015] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program is loaded by a processor to execute the large-capacity battery capacity division method described in any one of the first aspects.

[0016] In a fifth aspect, the present application also provides a computer program product, including a computer program / instruction, which, when executed by a processor, is used to execute the steps in the large-capacity battery capacity division method described in any one of the first aspects above.

[0017] Beneficial effects of the embodiments of the present invention:

[0018] In an embodiment of the present invention, by subjecting a fully charged battery to two constant current discharges, and the second discharge cut-off voltage is less than the first discharge cut-off voltage, the battery can be discharged more fully, the polarization effect is reduced, the battery capacity obtained by capacity division is more accurate, the battery state can be better distinguished, and the negative electrode of the battery can be microscopically de-lithiated more, and a portion of lithium that is difficult to be de-lithiated under high voltage can be de-lithiated, so that more gas in the microscopic cavity of the negative electrode can be removed, and subsequent electrolyte can enter more easily, thereby improving the wettability of the electrolyte to the electrode sheet, and improving the problem of lithium deposition in the battery. At the same time, standing for a preset time helps to ensure the stability of the internal reaction of the battery, the discharge of residual gas and the infiltration of the electrolyte, further improving the problem of lithium deposition in the battery, improving the capacity division effect of the battery, and improving the cycle life and safety of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 It is a schematic flow chart of an embodiment of a method for dividing a large-capacity battery provided by an embodiment of the present invention;

[0021] Figure 2 is a schematic flow chart of another embodiment of a method for dividing a large-capacity battery provided by an embodiment of the present invention;

[0022] Figure 3 It is a schematic diagram of electrolyte infiltration of batteries in a control group and an implementation group provided by an embodiment of the present invention;

[0023] Figure 4 It is a schematic diagram of the lithium deposition and non-lithium deposition conditions of the batteries in the control group and the implementation group provided in the embodiments of the present application;

[0024] Figure 5 1 is a schematic diagram of the structure of an embodiment of a large-capacity battery capacity division device provided in an embodiment of the present application;

[0025] Figure 6 It is a schematic diagram of the structure of an embodiment of an electronic device provided in the embodiments of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. In the present invention, unless otherwise specified, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the drawings; while "inside" and "outside" refer to the outline of the device.

[0027] The large-capacity battery in this application is a lithium battery with a nominal capacity greater than 280Ah.

[0028] The inventors have found that in order to increase product competitiveness, researchers often increase the surface density of active materials, supplemented by fine-tuning other design parameters, to achieve the design of higher capacity batteries without changing the volume of the battery cells. However, this method will make the negative electrode coating material denser, reduce the porosity, make it more difficult for the electrolyte to infiltrate, and affect the lithium ion mass transfer process, resulting in the existing battery capacity division step, which will cause lithium deposition in the battery cells. For this reason, the present application proposes a capacity division method for large-capacity batteries to improve the lithium deposition problem of batteries, thereby enhancing the capacity division effect of large-capacity batteries and improving battery performance.

[0029] like Figure 1 As shown, it is a schematic flow chart of an embodiment of a method for dividing a large-capacity battery in an embodiment of the present application. The method for dividing a large-capacity battery includes the following steps S10 to S20:

[0030] S10. Under a preset ambient temperature, discharge the fully charged battery at a constant current according to a first preset current rate to a first discharge cut-off voltage, and leave it alone for a first preset time, wherein the first preset current rate is less than or equal to the maximum continuous charging current of the battery.

[0031] The fully charged battery is a fully charged lithium-ion battery, such as a lithium iron phosphate battery of a calibrated capacity. The fully charged battery can be obtained by performing constant current charging on the battery to be divided into different capacities.

[0032] The preset ambient temperature is the preset ambient temperature of the environment in which the fully charged battery is divided, such as a normal temperature of 25°C, or a common temperature of the battery manufacturing process, thereby eliminating the need to repurchase equipment to divide the capacity of the fully charged battery, thereby reducing costs.

[0033] The first preset time length is a preset battery rest time, such as 5 minutes, 10 minutes, etc. The first preset rest time length means that the battery is neither charged nor discharged during the first preset time length.

[0034] The first discharge cut-off voltage is the cut-off voltage reached after the first constant current discharge of the fully charged battery, such as 2.5 V. It can be confirmed that when the fully charged battery is used normally, the corresponding first discharge cut-off voltage and the maximum continuous charging current are determined, and the first preset current ratio is less than or equal to the maximum continuous charging current of the battery to be activated, for example, the first preset current ratio is 0.3 times the maximum continuous charging current of the battery.

[0035] Specifically, at a preset ambient temperature, the fully charged battery is discharged at a constant current rate according to a first preset current rate, and discharged to a first discharge cut-off voltage of the fully charged battery, that is, at a preset ambient temperature, the fully charged battery is discharged at a constant current rate less than or equal to the maximum continuous charging current of the battery to be activated, so that the voltage of the battery after constant current discharge reaches the first discharge cut-off voltage, that is, the battery is not fully discharged, which saves time for battery capacity division, and at the same time, the battery is discharged at a constant current rate less than or equal to the maximum continuous charging current of the battery to be activated. Since there is no abuse of the battery, the battery will not be damaged, thereby achieving protection of the battery, and standing for the first preset time helps to ensure the stability of the internal reaction of the battery, the discharge of residual gas and the infiltration of the electrolyte, which is beneficial to improve the problem of lithium plating at the negative electrode of the battery.

[0036] S20, performing constant current discharge on the battery at a second preset current rate to a second discharge cut-off voltage, and leaving the battery to stand for a second preset time, wherein the second preset current rate is less than or equal to the maximum continuous charging current of the battery, and the second discharge cut-off voltage is less than the first discharge cut-off voltage.

[0037] The second preset current ratio is less than or equal to the maximum continuous charging current of the battery. Exemplarily, the second preset current ratio is 0.03 times the maximum continuous charging current of the battery.

[0038] The second discharge cut-off voltage is the cut-off voltage reached after the fully charged battery is discharged at a constant current for the second time. The second discharge cut-off voltage is less than the first discharge cut-off voltage, such as 2.0V.

[0039] Specifically, after the fully charged battery is discharged at a constant current rate to a first discharge cut-off voltage according to a first preset current rate and left to stand for a first preset time, it is continuously discharged at a constant current rate to a second discharge cut-off voltage and then left to stand for a second preset time. Since the second discharge cut-off voltage is less than the first discharge cut-off voltage, that is, the second discharge cut-off voltage is lower, the battery is discharged more fully, the polarization effect is reduced, the battery capacity obtained by capacity division is more accurate, and the battery state can be better distinguished. Moreover, the cut-off voltage of the second constant current discharge is lower than the cut-off voltage of the first constant current discharge, so that the negative electrode of the battery is more microscopically de-lithiated, and a part of the lithium that is difficult to be de-lithiated under high voltage is de-lithiated. In this way, more gas in the microscopic cavity of the negative electrode can be excluded, and the subsequent electrolyte is easier to enter, thereby improving the wettability of the electrolyte to the electrode sheet, and improving the problem of lithium deposition in the battery. Moreover, standing for a second preset time helps to ensure the stability of the internal reaction of the battery, the discharge of residual gas and the infiltration of the electrolyte, further improving the problem of lithium deposition in the battery, and improving the cycle life and safety of the battery.

[0040] It can be understood that in this embodiment, the fully charged battery is discharged twice at a constant current, and the second discharge cut-off voltage is less than the first discharge cut-off voltage, so that the battery is discharged more fully, the polarization effect is reduced, the battery capacity obtained by capacity division is more accurate, the battery state can be better distinguished, and the negative electrode of the battery can de-lithium more microscopically, and a part of the lithium that is difficult to de-lithiate under high voltage will be de-lithiated, so that more gas in the microscopic cavity of the negative electrode can be removed, and the subsequent electrolyte can enter more easily, thereby improving the wettability of the electrolyte to the electrode sheet, which can improve the problem of lithium plating in the battery, and standing for a second preset time helps to ensure the stability of the internal reaction of the battery, the discharge of residual gas and the infiltration of the electrolyte, further improving the problem of lithium plating in the battery and improving the cycle life and safety of the battery.

[0041] In the capacity division step of the above-mentioned large-capacity battery capacity division method, at a preset ambient temperature, the fully charged battery is discharged at a constant current rate to a first discharge cut-off voltage, and is left standing for a first preset time, wherein the first preset current rate is less than or equal to the maximum continuous charging current of the battery 1C. By discharging the fully charged battery at a constant current rate less than or equal to the maximum continuous charging current of the battery to be activated at the preset ambient temperature, the voltage of the battery after constant current discharge reaches the first discharge cut-off voltage, that is, the battery is not fully discharged, saving the time for battery capacity division. At the same time, the battery is discharged at a constant current rate less than or equal to the maximum continuous charging current of the battery to be activated. Since the battery is not over-discharged, it will not be damaged, thereby achieving protection of the battery. Moreover, standing for the first preset time helps to ensure the stability of the internal reaction of the battery, the discharge of residual gas and the infiltration of the electrolyte, thereby helping to improve the problem of lithium plating at the negative electrode of the battery. The battery is discharged at a constant current according to a second preset current rate to a second discharge cut-off voltage, and is left standing for a second preset time, wherein the second preset current rate is less than or equal to the maximum continuous charging current of the battery, the second discharge cut-off voltage is less than the first discharge cut-off voltage, and the second discharge cut-off voltage is less than the first discharge cut-off voltage, so that the battery discharges more fully, reduces the polarization effect, makes the battery capacity obtained by capacity division more accurate, can better distinguish the battery state, makes the negative electrode of the battery microscopically de-lithium more, and will de-lithium a part that is difficult to de-lithiate under high voltage, so that more gas in the microscopic cavity of the negative electrode can be excluded, and the subsequent electrolyte is easier to enter, thereby improving the wettability of the electrolyte to the electrode sheet, and can improve the problem of lithium deposition in the battery, and standing for the second preset time helps to ensure the stability of the internal reaction of the battery, the discharge of residual gas and the infiltration of the electrolyte, further improves the problem of lithium deposition in the battery, and improves the cycle life and safety of the battery.

[0042] Furthermore, if Figure 2As shown, before the fully charged battery is discharged at a constant current according to a first preset current rate to a first discharge cut-off voltage at a preset ambient temperature, the method further includes:

[0043] S30, at the preset ambient temperature, charging the battery to be capacity divided at a third preset current rate with a constant current to a charging cut-off voltage of the battery to be capacity divided, and leaving it to stand for a third preset time.

[0044] The battery to be capacity divided is a lithium-ion battery, such as a lithium iron phosphate battery with a rated capacity greater than 280Ah.

[0045] When the battery to be activated is confirmed to be in normal use, the corresponding charging cut-off voltage and maximum continuous charging current are determined, and the third preset current ratio is less than or equal to the maximum continuous charging current of the battery to be activated. For example, the charging cut-off voltage is 3.65V, and the third preset current ratio is 0.3C.

[0046] Specifically, at a preset ambient temperature, the battery to be divided into different capacities is charged with a constant current at a first preset current rate, and is charged to a charging cut-off voltage of the battery to be divided into different capacities, that is, at a preset ambient temperature, the battery to be divided into different capacities is fully charged with a constant current at a rate that is less than or equal to the maximum continuous charging current of the battery to be activated. Since the battery to be divided into different capacities is not overcharged, and the first preset current rate is less than or equal to the maximum continuous charging current of the battery to be activated, the battery to be divided into different capacities will not be damaged, thereby achieving protection of the battery to be divided into different capacities.

[0047] S40, performing constant current charging on the capacity-divided battery at a fourth preset current rate to the charging cut-off voltage, and leaving it to stand for a fourth preset time to form the fully charged battery, wherein the fourth preset current rate is less than the third preset current rate.

[0048] Specifically, after the battery to be divided is charged with constant current to the charging cut-off voltage of the battery to be divided, the battery to be divided is continuously charged with constant current according to the fourth preset current rate until the voltage of the battery to be divided reaches the preset cut-off voltage, and the fourth preset current rate is less than the third preset current rate, so as to ensure that the battery is fully charged. At the same time, in this embodiment, the battery to be divided is charged with constant current twice, and the voltage of the battery to be divided is charged to the charging cut-off voltage, so that the battery to be divided is fully activated, the battery capacity is improved, and the lithium ions in the battery to be divided are fully embedded in the negative electrode graphite, providing a larger microscopic deformation, so as to discharge the fully charged battery later, so that the lithium ions are fully embedded in / out of the graphite negative electrode for multiple times, the distance between the graphite layers becomes larger / smaller, and the graphite particles expand / shrink and deform, which exerts a force on the residual gas in the particle gap, breaks the gas-liquid interface, and the electrolyte enters the negative electrode gap and fully infiltrates, which greatly improves the problem of lithium precipitation in the battery, and greatly improves the battery division effect and battery performance.

[0049] Further, after the battery to be divided into different capacities is subjected to constant-current charging according to a fourth preset current rate to the charging cut-off voltage, and is left to stand for a fourth preset time to form the fully charged battery, the method further includes: executing the steps of: at the preset ambient temperature, the battery to be divided into different capacities is subjected to constant-current charging according to a third preset current rate to the charging cut-off voltage of the battery to be divided into different capacities, and is left to stand for a third preset time; and the battery to be divided into different capacities is subjected to constant-current charging according to the third preset current rate to the charging cut-off voltage, and is left to stand for a fourth preset time, until the first execution number of statistical executions reaches a preset number of times.

[0050] The preset number of times may be 2, 3 or 4 times.

[0051] Specifically, steps S30-S40 are repeatedly performed to realize multiple constant-current charging of the battery to be divided, and the voltage of the battery to be divided is charged to the charging cut-off voltage, so that the battery to be divided is further fully activated, the battery capacity is further improved, and the lithium ions in the battery to be divided are further fully embedded in the negative electrode graphite, providing a larger micro deformation. On this basis, steps S10-S20 are performed to realize multiple constant-current discharges of the fully charged battery, so that the lithium ions are fully embedded in / out of the graphite negative electrode multiple times, the distance between the graphite layers becomes larger / smaller, and the graphite particles expand / shrink and deform, which exerts a force on the residual gas in the gap between the particles, breaks the gas-liquid interface, and the electrolyte enters the negative electrode gap and fully infiltrates, which greatly improves the problem of lithium precipitation in the battery and greatly improves the battery division effect and battery performance.

[0052] Furthermore, before the battery to be divided is subjected to constant current charging at a third preset current rate to a charging cut-off voltage of the battery to be divided at the preset ambient temperature, the method further comprises: allowing the battery to be divided to stand for a fifth preset time at the preset ambient temperature so that the surface temperature of the battery to be divided is within the preset ambient temperature range.

[0053] Specifically, the battery to be divided is left to stand at a preset ambient temperature for a fifth preset time period so that the surface temperature of the battery to be divided is within the preset ambient temperature range, thereby reducing the temperature difference between the battery to be divided and the preset ambient temperature and improving the subsequent battery division efficiency.

[0054] Furthermore, the preset number of times is 2 to 4 times.

[0055] Specifically, the preset number of times can be 2 times, that is, continuing to cycle step S30-step S40 twice, or it can be 2 times or 3 times. By cycling the aforementioned steps S30-step S40 twice or three times, the effect of lithium ions in the battery being removed from the positive electrode and embedded in the negative electrode is further improved, thereby increasing the battery capacity.

[0056] It is worth noting that the preset number of times can be flexibly set according to actual circumstances and adjusted accordingly.

[0057] Furthermore, the first discharge cut-off voltage is greater than 2.3V and less than 2.8V, and the second discharge cut-off voltage is greater than 2.0V and less than 2.2V.

[0058] Specifically, the first discharge cut-off voltage is greater than 2.3 V and less than 2.8 V, and preferably, the first discharge cut-off voltage is 2.5 V. The second discharge cut-off voltage is greater than 2.0 V and less than 2.2 V, and preferably, the second discharge cut-off voltage is 2.0 V. In this embodiment, by determining the first discharge cut-off voltage and the second discharge cut-off voltage, constant current discharge is subsequently performed based on the first discharge cut-off voltage and the second discharge cut-off voltage, thereby avoiding over-discharge of the battery to be divided into different capacities.

[0059] Furthermore, after the battery is subjected to constant current discharge at a second preset current rate to a second discharge cut-off voltage and left to stand for a second preset time, the method further includes: cyclically executing the steps of, at a preset ambient temperature, subjecting the fully charged battery to constant current discharge at a first preset current rate to a first discharge cut-off voltage and leaving it to stand for a first preset time; and subjecting the battery to constant current discharge at a second preset current rate to a second discharge cut-off voltage and leaving it to stand for a second preset time, until the second number of executions is statistically executed is reached.

[0060] The setting number can be 1 or 2 times.

[0061] Specifically, step S10-step S10 is repeatedly performed to realize multiple constant current discharges of the battery to be divided, and the voltage of the battery to be divided is charged to the charging cut-off voltage, so that the battery discharges more fully, further reduces the polarization effect, makes the battery capacity obtained by capacity division more accurate, can better distinguish the battery state, and makes the negative electrode of the battery microscopically de-lithium more, and a part of the lithium that is difficult to be de-lithiated under high voltage will be de-lithiated, so that more gas in the microscopic cavity of the negative electrode can be excluded, and the subsequent electrolyte is easier to enter, thereby improving the wettability of the electrolyte to the electrode sheet, and further improving the problem of battery lithium deposition.

[0062] Furthermore, the preset ambient temperature is 20°C to 40°C.

[0063] Specifically, the preset ambient temperature is 20°C to 40°C, preferably, the preset ambient temperature is 25°C to 35°C. The preset ambient temperature is a common temperature of the battery manufacturing process, which avoids re-purchasing equipment and saves the cost of the battery capacity division process.

[0064] Furthermore, the first preset current ratio is 0.1 to 0.5 times the maximum continuous charging current of the battery, and the second preset current ratio is 0.02 to 0.05 times the maximum continuous charging current of the battery.

[0065] Specifically, the first preset current ratio is 0.1 to 0.5 times the maximum continuous charging current of the battery, the second preset current ratio is 0.02 to 0.05 times the maximum continuous charging current of the battery, and the first preset current ratio and the second preset current ratio are both less than or equal to the maximum continuous charging current of the battery to be divided, do not involve abuse of the battery to be divided, and do not damage the battery to be divided.

[0066] It is worth noting that the first preset current magnification and the second preset current magnification can be flexibly set according to actual conditions and adjusted accordingly.

[0067] Furthermore, the battery to be divided is a lithium iron phosphate battery, and the surface density of the negative electrode active coating in the lithium iron phosphate battery is greater than 175g / m 2 Less than 185g / m 2 .

[0068] Specifically, the surface density of the negative electrode active coating in the lithium iron phosphate battery is greater than 175g / m 2 Less than 185g / m 2 The surface density of the negative electrode active coating is increased, thereby increasing the capacity of the lithium iron phosphate battery.

[0069] Furthermore, the battery to be divided is a lithium iron phosphate battery, and the proportion of charging and discharging materials in the lithium iron phosphate battery is greater than 90%.

[0070] Specifically, the proportion of charge and discharge materials in the lithium iron phosphate battery is greater than 90%, for example, the proportion of charge and discharge materials in the lithium iron phosphate battery is 92%, thereby increasing the capacity of the lithium iron phosphate battery.

[0071] Furthermore, the charging cut-off voltage is 3.65V.

[0072] Specifically, the charging cut-off voltage is 3.65V. In this embodiment, the charging cut-off voltage is determined so that charging and discharging are subsequently performed based on the charging cut-off voltage to avoid overcharging and over-discharging of the battery to be divided into different capacities.

[0073] Furthermore, the first preset time length, the second preset time length, the third preset time length, the fourth preset time length and the fifth preset time length are 1 minute to 10 minutes.

[0074] Specifically, the first preset time length, the second preset time length, the third preset time length, the fourth preset time length and the fifth preset time length may be the same or different, and the first preset time length, the second preset time length, the third preset time length, the fourth preset time length and the fifth preset time length are 1min-10min, ensuring that the temperature difference between the battery to be divided and the preset ambient temperature is reduced, and also helping to achieve stable internal battery reaction, residual gas discharge and electrolyte infiltration, thereby improving battery lithium precipitation, and improving subsequent battery division effect and battery safety.

[0075] It is worth noting that the first preset time length, the second preset time length, the third preset time length, the fourth preset time length and the fifth preset time length can all be flexibly set according to actual circumstances and adjusted accordingly.

[0076] Furthermore, after performing constant current discharge on the battery according to a second preset current rate to a second discharge cut-off voltage and standing for a second preset time, the method further includes: adjusting the battery's state of charge to a shipping state of charge.

[0077] Specifically, after step S20, step S50 may be added: adjusting the battery's state of charge to a shipping state of charge, i.e., continuing to charge the battery, such as charging the battery until the battery's state of charge (SOC) is 20%-40%, so that the battery's shipping state SOC meets the shipping conditions.

[0078] It should be noted that the capacity division step in this embodiment is also applicable to other non-capacity division processes, such as an aging process, a formation process, etc., which can improve the performance and cycle life of the battery.

[0079] In one example, the manufacturing process of a large-capacity lithium iron phosphate battery (with a nominal capacity of a fixed value) is selected for single variable verification, and the implementation group (a capacity separation step is set in this embodiment) and the control group (a common capacity separation step) are respectively used. After the battery is offline, the capacity test defined in GB / T36276-2018 is performed, and the capacity test data is counted. Among them, the capacity separation step of the control group is as follows:

[0080] T10, let stand for 1 to 10 minutes;

[0081] T20, 0.1~0.5C constant current charging to 3650mV;

[0082] T30, 3650mV constant voltage charging, cut-off current 0.02~0.05C;

[0083] T40, let stand for 1 to 10 minutes;

[0084] T50, 0.1~0.5C constant current discharge to 2500mV;

[0085] T60, let stand for 1 to 10 minutes;

[0086] T70, end.

[0087] After the battery is offline, a capacity test defined in GB / T36276-2018 is performed, and the capacity test data is counted, as shown in Table 1, which is a comparative data table of the calibrated capacities of offline batteries with the capacity separation step set in this embodiment (implementation group) and the capacity separation step set in the control group.

[0088] Table 1, the comparison data of the calibrated capacity of the off-line batteries of a certain model of large-capacity lithium iron phosphate battery with different capacity division processes:

[0089]

[0090] It can be seen from Table 1 that there is no significant difference in the calibrated capacity between the control group and the implementation group, indicating that the battery capacity division method in this embodiment can increase the battery capacity.

[0091] After completing the capacity division step, the standardized charging (full charge) defined in GB / T36276-2018 is carried out, and then the batteries are disassembled to compare the lithium plating conditions at the negative electrode interfaces of different groups. As shown in Table 2, this is a comparison data table of lithium plating conditions at the negative electrode interfaces of off-line batteries of a certain model of large-capacity lithium iron phosphate batteries with different capacity division processes.

[0092] Table 2, a comparison of lithium plating at the negative electrode interface of a certain type of large-capacity lithium iron phosphate battery with different capacity separation processes:

[0093]

[0094]

[0095] As can be seen from Table 2, the batteries in the control group all deposited lithium, while the batteries in the implementation group did not deposit lithium, indicating that the battery capacity division method in this embodiment can eliminate the problem of lithium deposition.

[0096] like Figure 3 As shown, it is a schematic diagram of the electrolyte infiltration of the batteries in the control group and the implementation group. The left figure is a schematic diagram of the electrolyte infiltration of the battery in the control group. It can be seen from the figure that the residual gas in the micropores of the graphite negative electrode generates air pressure (the blank and red arrow parts in the figure), and the gas-liquid interface makes it difficult for the electrolyte (blue) to be pressed in and infiltrated. The right figure is a schematic diagram of the electrolyte infiltration of the battery in the implementation group. It can be seen from the figure that the graphite negative electrode rebounds and shrinks, and the force generated breaks the gas-liquid interface, the micropore gas falls out, and the electrolyte is pressed in and infiltrated well, thereby improving the lithium precipitation problem.

[0097] like Figure 4As shown, it is a schematic diagram of the lithium deposition and non-lithium deposition of the batteries in the control group and the implementation group. The left figure is a schematic diagram of the lithium deposition of the batteries in the control group. The gray-white area circled in red in the left figure is lithium deposition, and the right figure is a schematic diagram of the non-lithium deposition of the batteries in the implementation group. Therefore, it can be seen from the comparison of the lithium deposition and non-lithium deposition of the batteries in the above control group and the implementation group that the capacity division method of the large-capacity battery in the embodiment of the present application can improve the lithium deposition problem and improve the capacity division effect and performance of the battery.

[0098] In order to better implement the large-capacity battery capacity division method in the embodiment of the present application, on the basis of the large-capacity battery capacity division method, the embodiment of the present application also provides a large-capacity battery capacity division device, such as Figure 5 As shown, the large-capacity battery capacity division device 200 includes:

[0099] The first discharge module 201 is used to discharge the fully charged battery at a first preset current rate at a preset ambient temperature to a first discharge cut-off voltage, and leave it for a first preset time, wherein the first preset current rate is less than or equal to the maximum continuous charging current of the battery;

[0100] The second discharging module 202 is used to perform constant current discharge on the battery according to a second preset current rate to a second discharge cut-off voltage, and leave it standing for a second preset time, wherein the second preset current rate is less than or equal to the maximum continuous charging current of the battery, and the second discharge cut-off voltage is less than the first discharge cut-off voltage.

[0101] In one embodiment, the large-capacity battery capacity division device 200 further includes:

[0102] A first charging module is used to perform constant current charging of the battery to be divided according to a third preset current rate at the preset ambient temperature to a charging cut-off voltage of the battery to be divided, and to stand for a third preset time;

[0103] The second charging module is used to perform constant current charging on the divided capacity battery according to a fourth preset current rate to the charging cut-off voltage, and to stand for a fourth preset time to form the fully charged battery, wherein the fourth preset current rate is less than the third preset current rate.

[0104] In one embodiment, the large-capacity battery capacity division device 200 further includes:

[0105] The cyclic charging module is used to execute the steps of: performing constant current charging of the battery to be divided according to a third preset current rate to the charging cut-off voltage of the battery to be divided according to the preset ambient temperature, and standing for a third preset time; performing constant current charging of the battery to be divided according to a fourth preset current rate to the charging cut-off voltage, and standing for a fourth preset time, until the first execution number of statistical executions reaches a preset number of times.

[0106] In one embodiment, the large-capacity battery capacity division device 200 further includes:

[0107] A cyclic discharge module, used to perform the steps of discharging the fully charged battery at a first preset current rate to a first discharge cut-off voltage under a preset ambient temperature and leaving the battery standing for a first preset time;

[0108] The battery is discharged at a constant current according to a second preset current rate to a second discharge cut-off voltage, and left to stand for a second preset time until the second execution number of executions reaches a set number of times.

[0109] The embodiment of the present application further provides an electronic device, which integrates any of the large-capacity battery capacity division devices provided in the embodiment of the present application, and the electronic device includes:

[0110] one or more processors;

[0111] Memory; and

[0112] One or more applications, wherein the one or more applications are stored in the memory and are configured to be executed by the processor to execute the large-capacity battery capacity division method described in any of the above-mentioned large-capacity battery capacity division method embodiments.

[0113] The present application also provides an electronic device that integrates any of the large-capacity battery capacity division devices provided in the present application. Figure 6 As shown, it shows a schematic diagram of the structure of the electronic device involved in the embodiment of the present application, specifically:

[0114] The electronic device may include components such as a processor 301 with one or more processing cores, a memory 302 with one or more computer-readable storage media, a power supply 303, and an input unit 304. Those skilled in the art will appreciate that Figure 6 The electronic device structure shown in the figure does not constitute a limitation on the electronic device, and may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0115] The processor 301 is the control center of the electronic device. It uses various interfaces and lines to connect various parts of the entire electronic device. By running or executing software programs and / or modules stored in the memory 302, and calling data stored in the memory 302, it executes various functions of the electronic device and processes data, thereby monitoring the electronic device as a whole. Optionally, the processor 301 may include one or more processing cores; preferably, the processor 301 may integrate an application processor and a modem processor, wherein the application processor mainly processes the operating system, user interface, and application programs, and the modem processor mainly processes wireless communications. It is understandable that the above-mentioned modem processor may not be integrated into the processor 301.

[0116] The memory 302 can be used to store software programs and modules. The processor 301 executes various functional applications and data processing by running the software programs and modules stored in the memory 302. The memory 302 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data created according to the use of the electronic device, etc. In addition, the memory 302 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other volatile solid-state storage devices. Accordingly, the memory 302 may also include a memory controller to provide the processor 301 with access to the memory 302.

[0117] The electronic device also includes a power supply 303 for supplying power to each component. Preferably, the power supply 303 can be logically connected to the processor 301 through a power management system, so that the power management system can manage charging, discharging, power consumption and other functions. The power supply 303 can also include one or more DC or AC power supplies, recharging systems, power failure detection circuits, power converters or inverters, power status indicators and other arbitrary components.

[0118] The electronic device may further include an input unit 304, which may be used to receive input digital or character information and generate keyboard, mouse, joystick, optical or trackball signal input related to user settings and function control.

[0119] Although not shown, the electronic device may further include a display unit, etc., which will not be described in detail herein. Specifically in this embodiment, the processor 301 in the electronic device will load the executable files corresponding to the processes of one or more application programs into the memory 302 according to the following instructions, and the processor 301 will run the application programs stored in the memory 302, thereby realizing various functions, as follows:

[0120] At a preset ambient temperature, the fully charged battery is discharged at a constant current according to a first preset current rate to a first discharge cut-off voltage, and left to stand for a first preset time, wherein the first preset current rate is less than or equal to the maximum continuous charging current of the battery;

[0121] The battery is discharged at a constant current according to a second preset current rate to a second discharge cut-off voltage, and is left to stand for a second preset time, wherein the second preset current rate is less than or equal to the maximum continuous charging current of the battery, and the second discharge cut-off voltage is less than the first discharge cut-off voltage.

[0122] A person of ordinary skill in the art will appreciate that all or part of the steps in the various methods of the above embodiments may be completed by instructions, or by controlling related hardware through instructions. The instructions may be stored in a computer-readable storage medium and loaded and executed by a processor.

[0123] To this end, an embodiment of the present application provides a computer-readable storage medium, which may include: a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk, etc. A computer program is stored thereon, and the computer program is loaded by a processor to execute the steps in any of the large-capacity battery capacity division methods provided in the embodiments of the present application. For example, the computer program can be loaded by a processor to execute the following steps:

[0124] At a preset ambient temperature, the fully charged battery is discharged at a constant current according to a first preset current rate to a first discharge cut-off voltage, and left to stand for a first preset time, wherein the first preset current rate is less than or equal to the maximum continuous charging current of the battery;

[0125] The battery is discharged at a constant current according to a second preset current rate to a second discharge cut-off voltage, and is left to stand for a second preset time, wherein the second preset current rate is less than or equal to the maximum continuous charging current of the battery, and the second discharge cut-off voltage is less than the first discharge cut-off voltage.

[0126] The embodiment of the present application also provides a computer program product, including a computer program / instruction, which, when executed by a processor, is used to execute the steps in any of the large-capacity battery capacity division methods provided in the embodiment of the application.

[0127] The embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for dividing the capacity of a large-capacity battery, characterized in that: The steps include: At a preset ambient temperature, the fully charged battery is discharged at a constant current according to a first preset current rate to a first discharge cut-off voltage, and left to stand for a first preset time, wherein the first preset current rate is less than or equal to the maximum continuous charging current of the battery; The battery is discharged at a constant current according to a second preset current rate to a second discharge cut-off voltage, and is left to stand for a second preset time, wherein the second preset current rate is less than or equal to the maximum continuous charging current of the battery, and the second discharge cut-off voltage is less than the first discharge cut-off voltage.

2. The method for dividing the capacity of a large-capacity battery according to claim 1, characterized in that: Before the fully charged battery is discharged at a constant current according to a first preset current rate to a first discharge cut-off voltage at the preset ambient temperature, the method further includes: At the preset ambient temperature, the battery to be divided is charged with a constant current according to a third preset current rate to a charging cut-off voltage of the battery to be divided, and is left standing for a third preset time; The divided-capacity battery is charged with constant current according to a fourth preset current rate to the charging cut-off voltage, and left to stand for a fourth preset time to form the fully charged battery, wherein the fourth preset current rate is less than the third preset current rate.

3. The method for dividing the capacity of a large-capacity battery according to claim 2, characterized in that: After the battery to be divided into different capacities is charged with constant current according to the fourth preset current rate to the charging cut-off voltage and left to stand for a fourth preset time to form the fully charged battery, the method further includes: The steps of performing constant current charging of the battery to be divided according to a third preset current rate to a charging cut-off voltage of the battery to be divided and standing for a third preset time at the preset ambient temperature; performing constant current charging of the battery to be divided according to a fourth preset current rate to the charging cut-off voltage and standing for a fourth preset time are performed until the first execution number of statistical executions reaches a preset number of times.

4. The method for dividing the capacity of a large-capacity battery according to any one of claims 1 to 3, characterized in that: After the battery is discharged at a constant current according to a second preset current rate to a second discharge cut-off voltage and left to stand for a second preset time, the method further includes: Executing the method of discharging the fully charged battery at a first preset current rate at a preset ambient temperature to a first discharge cut-off voltage, and leaving the battery to stand for a first preset time; The battery is discharged at a constant current according to a second preset current rate to a second discharge cut-off voltage, and left to stand for a second preset time until the second execution number of executions reaches a set number of times.

5. The method for dividing the capacity of a large-capacity battery according to claim 2, characterized in that: Before the battery to be divided into different capacities is charged at a third preset current rate at the preset ambient temperature to a charging cut-off voltage of the battery to be divided into different capacities, the method further comprises: The battery to be capacity divided is left to stand at the preset ambient temperature for a fifth preset time period, so that the surface temperature of the battery to be capacity divided is within the preset ambient temperature range.

6. The method for dividing the capacity of a large-capacity battery according to claim 1, characterized in that: The first discharge cut-off voltage is greater than 2.3V and less than 2.8V, and the second discharge cut-off voltage is greater than 2.0V and less than 2.2V.

7. The method for dividing the capacity of a large-capacity battery according to claim 2, characterized in that: The first preset current ratio is 0.1 to 0.5 times the maximum continuous charging current of the battery, and the second preset current ratio is 0.02 to 0.05 times the maximum continuous charging current of the battery.

8. The method for dividing the capacity of a large-capacity battery according to any one of claims 2, 3, 5 or 7, characterized in that: The battery to be divided is a lithium iron phosphate battery, and the surface density of the negative electrode active coating in the lithium iron phosphate battery is greater than 175g / m 2 Less than 185g / m 2 .

9. The method for dividing the capacity of a large-capacity battery according to any one of claims 2, 3, 5 or 7, characterized in that: The battery to be divided is a lithium iron phosphate battery, and the proportion of charging and discharging materials in the lithium iron phosphate battery is greater than 90%.

10. The method for dividing the capacity of a large-capacity battery according to any one of claims 1, 2, 3, 5, 6 or 7, characterized in that: After the battery is discharged at a constant current according to a second preset current rate to a second discharge cut-off voltage and left to stand for a second preset time, the method further includes: The state of charge of the battery is adjusted to a shipping state of charge.

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