Battery low temperature discharge method
By charging, silencing, discharging and resuscitation of the battery in a low temperature environment, the discharge cutoff voltage is corrected, and the problem of difficulty in discharging the battery in a low temperature environment is solved, the battery's performance at high temperature is maintained, and the cost is reduced.
Patent Information
- Application Number
- CN202411899623.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-04-04
AI Technical Summary
The prior art is difficult to achieve normal discharge of the battery in a low-temperature environment, and the large amount of low-temperature additives will affect the high-temperature cycle and rate performance of the battery, increasing costs.
By charging at an ambient temperature of 20°C to 45°C, and then standing, discharge and re-stand under a low temperature environment, voltage changes are recorded, discharge cutoff voltage is corrected to eliminate partial polarization and activate battery activity.
The normal discharge of the battery in a low-temperature environment is achieved, the disadvantage of adding a large amount of low-temperature additives is avoided, the performance of the battery at high temperatures is maintained, and the cost is reduced.
Smart Images
Figure CN119764630A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of battery discharge, and in particular to a battery low-temperature discharge method. Background Art
[0002] The application of low-temperature batteries has always been a difficult problem in the battery field. In low-temperature environments, the dynamics of the battery is greatly affected, the activity of the material and the electrolyte is greatly reduced, and ion transmission is difficult. At present, the development of low-temperature batteries mainly focuses on adding suitable low-temperature additives to the electrolyte to reduce the viscosity and melting point of the electrolyte.
[0003] Current low-temperature additives, such as linear carboxylates, have lower melting points than commonly used linear carbonates. At the same time, carboxylate solvents with different chain lengths (such as methyl acetate (MA), ethyl acetate (EA), ethyl propionate (EP) and ethyl butyrate (EB)) have different effects on the degree of reduction in the melting point of the electrolyte, among which low-chain carboxylate solvents can more effectively reduce the melting point of the electrolyte. In addition, increasing the content of linear carboxylates can further reduce the melting point and viscosity of the electrolyte. For example, when the content of EB in the electrolyte is higher than 75%, the graphite|lithium manganese oxide soft-pack battery can operate at -60°C.
[0004] However, too high a content of linear carboxylic acid ester solvent will affect the high temperature cycle and rate performance of the battery. The higher the content of low temperature additive, the more easily other performances of the battery will be affected, and the higher the cost of the battery.
[0005] Therefore, it is necessary to provide a method for discharging a battery in a low temperature environment without adding a large amount of low temperature additives. Summary of the invention
[0006] In view of the defects in the prior art, an object of the present invention is to provide a low-temperature discharge method for a battery.
[0007] A low-temperature battery discharge method according to the present invention comprises the following steps:
[0008] Step S1, charging the battery to 5%-100% SOC with a first current at an ambient temperature of 20° C. to 45° C.;
[0009] Step S2, the battery is placed in a low temperature environment for a first period of time, and the voltage V1 after the placement is completed is recorded;
[0010] Step S3, in a low temperature environment, the battery is discharged with a second current to a discharge cut-off voltage, and the discharge initial voltage V2, the discharge end time T1, and the discharge end voltage V3 are recorded;
[0011] Step S4, the battery is placed in a low temperature environment, and the voltage V4 at the start of the placement is recorded;
[0012] Step S5: Determine the discharge status of the battery according to steps S1 to S4.
[0013] Preferably, in step S1, charging to 100% SOC with a first current;
[0014] Step S5 includes: if T1≤60S, it is determined that the battery cannot be discharged at low temperature, and the discharge cut-off voltage in step S3 needs to be corrected.
[0015] Preferably, in step S1, the battery is charged with the first current until the SOC of the battery is greater than 50% SOC and less than 100% SOC;
[0016] Step S5 includes:
[0017] If the battery discharge capacity is less than 3% SOC in step S3, it is determined that the battery cannot be discharged at low temperature, and the discharge cut-off voltage in step S3 needs to be corrected.
[0018] Preferably, in step S1, the battery is charged with a first current until the SOC of the battery is ≤50%;
[0019] Step S5 includes:
[0020] If the battery discharge capacity is less than 5% SOC in step S3, it is determined that the battery cannot be discharged under this condition, and the cut-off voltage of the second current discharge in step S3 needs to be corrected.
[0021] Preferably, the first current is 0.01C0-2C0.
[0022] Preferably, the first time period is 20-24 hours.
[0023] Preferably, in step S3, 0.01C0<second current<4C0.
[0024] Preferably, in step S1, the battery is charged to 100% SOC with the first current; and if T1≤60S;
[0025] The discharge cut-off voltage in step S3 is corrected, wherein the corrected discharge cut-off voltage V 修 =V1-V2-V4;
[0026] According to the corrected battery cut-off voltage V 修 , repeat steps S1-S4 until T1>60S; the discharge cut-off voltage of S3 is V 修 , and the discharge cut-off voltage in each repetition of steps S1-S4 is the same as the discharge cut-off voltage in the first repetition of steps S1-S4.
[0027] Preferably, when in step S1, the SOC of the battery charged with the first current is greater than 50% SOC and less than 100% SOC; and in step S3, the discharge capacity of the battery is less than 3% SOC;
[0028] The discharge cut-off voltage in step S3 is corrected, wherein the corrected discharge cut-off voltage V 修 =V3-(V2-V4); according to the corrected battery cut-off voltage V 修 , repeat steps S1-S4 until the battery discharge capacity is greater than or equal to 3% SOC in step S3; the discharge cut-off voltage of S3 is V 修 , and the discharge cut-off voltage in each repetition of steps S1-S4 is the same as the discharge cut-off voltage in the first repetition of steps S1-S4.
[0029] Preferably, when in step S1, the battery is charged with the first current until the SOC of the battery is ≤50%; and in step S3, the battery discharge capacity is less than 5% SOC;
[0030] The discharge cut-off voltage in step S3 is corrected, wherein the corrected discharge cut-off voltage V 修 =V3-(V1+V4-2V2);
[0031] According to the corrected battery cut-off voltage V 修 , repeat steps S1-S4 until the battery discharge capacity in step S3 is greater than or equal to 5% SOC; wherein the discharge cut-off voltage of S3 is V 修 , and the discharge cut-off voltage in each repetition of steps S1-S4 is the same as the discharge cut-off voltage in the first repetition of steps S1-S4.
[0032] Compared with the prior art, the present invention has the following beneficial effects:
[0033] The present invention obtains a corrected discharge cut-off voltage of a battery according to the voltage changes during the processes of standing, discharging, and standing after discharge at low temperature, thereby eliminating part of the polarization of the battery; and divides different correction methods of the discharge cut-off voltage according to different charging SOCs, thereby activating the activity of the battery and realizing the normal operation of the battery at low temperature. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:
[0035] Figure 1 This is a flow chart of a method for determining low-temperature discharge of a battery in Embodiment 1 of the present invention;
[0036] Figure 2This is a voltage curve diagram after correction in the second embodiment of the present invention;
[0037] Figure 3 This is a voltage curve diagram after correction in the third embodiment of the present invention. DETAILED DESCRIPTION
[0038] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.
[0040] like Figure 1 As shown, a method for determining low-temperature discharge of a battery according to the present invention comprises the following steps:
[0041] Step S1, charging the battery to 5%-100% SOC with a first current at an ambient temperature of 20° C. to 45° C.;
[0042] Step S2, the battery is placed in a low temperature environment for a first period of time, and the voltage V1 after the placement is completed is recorded;
[0043] Step S3, in a low temperature environment, the battery is discharged with a second current to a discharge cut-off voltage, and the discharge initial voltage V2, the discharge end time T1, and the discharge end voltage V3 are recorded;
[0044] Step S4, the battery is placed in a low temperature environment, and the voltage V4 at the start of the placement is recorded;
[0045] Step S5: Determine the discharge status of the battery according to steps S1 to S4.
[0046] It should be noted that the initial capacity of the battery of the present application is recorded as C0. The positive electrode material of the battery is one or more of lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium cobalt oxide, and lithium manganese oxide. The negative electrode material of the battery is graphite, or a silicon-based negative electrode material. The discharge cut-off voltage in step S3 can be actually selected according to the actual battery system, for example, the battery discharge cut-off voltage is V0, and V0 is 2.0V-2.5V.
[0047] It should be noted that in step S2, the battery low temperature environment can be actually determined according to the actual use condition of the target battery. For example, if the target battery needs to be used at -30°C, the battery low temperature environment is -30°C. Generally, the battery low temperature environment is -60°C to 0°C.
[0048] In some embodiments, the first current is 0.01C0-2C0. It should be noted that C0 in the present application refers to the initial capacity of the battery, for example, if the initial capacity of the battery is 300AH, the first current ranges from 3A to 600A.
[0049] In some embodiments, the first period of time is 20-24 hours.
[0050] In some embodiments, the standing time period in step S4 is 10-30 minutes.
[0051] In some implementations, in step S3, 0.01C0<second current<4C0.
[0052] Specifically, in one embodiment:
[0053] When the battery is charged to 100% SOC with the first current in step S1, step S5 includes: if T1≤60S, it is determined that the battery cannot be discharged at low temperature, and the discharge cut-off voltage in step S3 needs to be corrected; on the contrary, if T1 is greater than 60S, it is considered that the battery can be discharged in the low temperature environment, and the discharge cut-off voltage does not need to be corrected.
[0054] Further, the discharge cut-off voltage in step S3 is corrected, wherein the corrected discharge cut-off voltage V 修 =V1-V2-V4;
[0055] According to the corrected battery cut-off voltage V 修 , repeat steps S1-S4 until T1>60S; the discharge cut-off voltage of S3 is V 修 , and the discharge cut-off voltage in each repetition of steps S1-S4 is the same as the discharge cut-off voltage in the first repetition of steps S1-S4.
[0056] Specifically, in another embodiment:
[0057] When in step S1, the battery is charged with the first current until the SOC is greater than 50% SOC and less than 100% SOC;
[0058] Step S5 includes:
[0059] If the battery discharge capacity is less than 3% SOC in step S3, it is determined that the battery cannot be discharged at low temperature, and the discharge cut-off voltage in step S3 needs to be corrected; conversely, if the battery discharge capacity is greater than or equal to 3% SOC in step S3, it is considered that the battery can be discharged in the low temperature environment, and there is no need to correct the discharge cut-off voltage.
[0060] Further, the discharge cut-off voltage in step S3 is corrected, wherein the corrected discharge cut-off voltage V修 =V3-(V2-V4);
[0061] According to the corrected battery cut-off voltage V 修 , repeat steps S1-S4 until the battery discharge capacity is greater than or equal to 3% SOC in step S3; the discharge cut-off voltage of S3 is V 修 , and the discharge cut-off voltage in each repetition of steps S1-S4 is the same as the discharge cut-off voltage in the first repetition of steps S1-S4.
[0062] Specifically, in yet another embodiment:
[0063] When in step S1, the battery is charged with the first current until the SOC of the battery is ≤50%;
[0064] Step S5 includes:
[0065] If the battery discharge capacity is less than 5% SOC in step S3, it is determined that the battery cannot be discharged under this condition, and the cut-off voltage of the second current discharge in step S3 needs to be corrected; conversely, if the battery discharge capacity is greater than or equal to 5% SOC in step S3, it is considered that the battery can be discharged under this low temperature environment, and there is no need to correct the discharge cut-off voltage.
[0066] Further, the discharge cut-off voltage in step S3 is corrected, wherein the corrected discharge cut-off voltage V 修 =V3-(V1+V4-2V2);
[0067] According to the corrected battery cut-off voltage V 修 , repeat steps S1-S4 until the battery discharge capacity in step S3 is greater than or equal to 5% SOC; wherein the discharge cut-off voltage of S3 is V 修 , and the discharge cut-off voltage in each repetition of steps S1-S4 is the same as the discharge cut-off voltage in the first repetition of steps S1-S4.
[0068] The present invention obtains a corrected discharge cut-off voltage of a battery according to the voltage changes during the processes of standing, discharging, and standing after discharge at low temperature, thereby eliminating part of the polarization of the battery; and divides different correction methods of the discharge cut-off voltage according to different charging SOCs, thereby activating the activity of the battery and realizing the normal operation of the battery at low temperature.
[0069] Embodiment 2
[0070] Based on the first embodiment, a low-temperature discharge method of a battery is provided according to the present invention.
[0071] The battery tested in this embodiment has a battery discharge time T1≤60s, and is determined to be unable to discharge at low temperatures, as follows;
[0072] Step S1, charging the battery to 100% SOC at 25°C using 0.5C0 constant current and constant voltage;
[0073] Step S2, placing the battery at -30°C for 20 hours, and recording the voltage after the placement, which is recorded as V1 of 3.5009V;
[0074] Step S3, discharge the battery with a current of 0.5C0, and the discharge cut-off voltage is 2.0V; record the discharge initial voltage, recorded as V2 (1.8297V), record the discharge end time T1 (0.002S), and record the discharge end voltage V3 (1.8297V);
[0075] Step S4, let the battery stand for 30 minutes, and read the starting voltage of the standing state, which is recorded as V4 (0.6395V);
[0076] The data of the above steps are shown in Table 1. If T1 < 60s, the battery cannot be discharged at this temperature.
[0077] Table 1
[0078]
[0079] The data in Table 1 show that due to the huge polarization, the battery directly reaches the protection voltage of 1.8V at the beginning of discharge, making the battery unable to discharge at -30℃. If the battery is to be discharged, the discharge cut-off voltage V in step S3 needs to be corrected. 修 , V 修 =V1-V2-V4,V 修 =1.03V.
[0080] According to the corrected battery cut-off voltage, steps S1-S4 are repeated until T1>60S; wherein the discharge cut-off voltage of S3 is 1.03V, and the discharge cut-off voltage in each repetition of steps S1-S4 is the same as the discharge cut-off voltage in the first repetition of steps S1-S4 (i.e., each subsequent repetition of steps S1-S4, the discharge cut-off voltage in step S3 is 1.03V).
[0081] As shown in Table 2 below, the specific steps of repeatedly performing steps S1-S4 in this embodiment are as follows:
[0082] Table 2:
[0083]
[0084] After 4 cold starts (ie, the number of repetitions of steps S1-S4 is 4), the battery can discharge normally and the activity of the materials in the battery is activated. It should be noted that in the 4 repetitions of steps S1-S4, the discharge cut-off voltage of step S3 in each repetition is 1.03V.
[0085] like Figure 2 The voltage curve diagram after correction of Example 2 is shown. It can be seen from the diagram that after the discharge cut-off voltage is corrected, the battery can be discharged from the open circuit voltage to the corrected discharge cut-off voltage, and the battery can be discharged at a small current.
[0086] Embodiment 3
[0087] Based on Example 1, according to another low-temperature battery discharge method provided by the present invention, the battery capacity tested in this embodiment is 100Ah;
[0088] S1, charge the battery to 95% SOC at 25°C using 0.5C0 constant current and constant voltage;
[0089] S2, place the battery at -25℃ for 20 hours, and record the voltage after the end of the storage period, which is recorded as V1;
[0090] S3, discharge the battery with a current of 1C0, and the discharge cut-off voltage is 2.5V; record the discharge initial voltage, recorded as V2, and the discharge end voltage V3;
[0091] S4, let the battery stand for 30 minutes, read the starting voltage of standing, and record it as V4;
[0092] The test results are shown in Table 3, which show that the discharge capacity of the battery is less than 3% SOC;
[0093] Table 3
[0094]
[0095] As shown above, since the discharge capacity is less than 3% SOC, it is determined that the battery cannot be discharged at this high current. At this time, the discharge cut-off voltage at high current needs to be corrected, V 修 =V3-(V2-V4); V 修 =1.58V.
[0096] According to the corrected battery cut-off voltage V 修 , repeat steps S1-S4 until the battery discharge capacity in step S3 is greater than or equal to 3% SOC; the discharge cut-off voltage of S3 is V 修 , and the discharge cut-off voltage in each repetition of steps S1-S4 is the same as the discharge cut-off voltage in the first repetition of steps S1-S4.
[0097] The specific process of repeatedly executing steps S1-S4 will not be described in detail here.
[0098] like Figure 3 The corrected voltage can alleviate the larger polarization state of the battery, slowly activate the activity of the active materials of the battery, and enable the battery to discharge normally.
[0099] Those skilled in the art know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.
[0100] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.
[0101] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.
Claims
1. A method for low-temperature discharge of a battery, characterized in that: The steps include: Step S1, charging the battery to 5%-100% SOC with a first current at an ambient temperature of 20° C. to 45° C.; Step S2, the battery is placed in a low temperature environment for a first period of time, and the voltage V1 after the placement is completed is recorded; Step S3, in a low temperature environment, the battery is discharged with a second current to a discharge cut-off voltage, and the discharge initial voltage V2, the discharge end time T1, and the discharge end voltage V3 are recorded; Step S4, the battery is placed in a low temperature environment, and the voltage V4 at the start of the placement is recorded; Step S5: Determine the discharge status of the battery according to steps S1 to S4.
2. The low temperature discharge method of a battery as claimed in claim 1, characterized in that: In step S1, charging to 100% SOC with a first current; Step S5 includes: if T1≤60S, it is determined that the battery cannot be discharged at low temperature, and the discharge cut-off voltage in step S3 needs to be corrected.
3. The low temperature discharge method of a battery as claimed in claim 1, characterized in that: When in step S1, the battery is charged with the first current until the SOC of the battery is greater than 50% SOC and less than 100% SOC; Step S5 includes: If the battery discharge capacity is less than 3% SOC in step S3; It is determined that the battery cannot be discharged at low temperature, and the discharge cut-off voltage in step S3 needs to be corrected.
4. The low temperature discharge method of a battery as claimed in claim 1, characterized in that: In step S1, the battery is charged with a first current until the SOC of the battery is ≤50%; Step S5 includes: If the battery discharge capacity is less than 5% SOC in step S3, it is determined that the battery cannot be discharged under this condition, and the cut-off voltage of the second current discharge in step S3 needs to be corrected.
5. The low temperature discharge method of a battery as claimed in claim 1, characterized in that: The first current is 0.01C0-2C0.
6. The low temperature discharge method of a battery as claimed in claim 1, characterized in that: The first time period is 20-24 hours.
7. The low temperature discharge method of a battery as claimed in claim 1, characterized in that: In step S3, 0.01C0<second current<4C0.
8. The low temperature discharge method of a battery as claimed in claim 2, characterized in that: The discharge cut-off voltage in step S3 is corrected, wherein the corrected discharge cut-off voltage V 修 =V1-V2-V4; According to the corrected battery cut-off voltage V 修 , repeat steps S1-S4 until T1>60S; the discharge cut-off voltage of S3 is V 修 , and the discharge cut-off voltage in each repetition of steps S1-S4 is the same as the discharge cut-off voltage in the first repetition of steps S1-S4.
9. The low temperature discharge method of a battery as claimed in claim 3, characterized in that: The discharge cut-off voltage in step S3 is corrected, wherein the corrected discharge cut-off voltage V 修 =V3-(V2-V4); According to the corrected battery cut-off voltage V 修 , repeat steps S1-S4 until the battery discharge capacity is greater than or equal to 3% SOC in step S3; the discharge cut-off voltage of S3 is V 修 , and the discharge cut-off voltage in each repetition of steps S1-S4 is the same as the discharge cut-off voltage in the first repetition of steps S1-S4.
10. The low temperature discharge method of a battery as claimed in claim 4, characterized in that: The discharge cut-off voltage in step S3 is corrected, wherein the corrected discharge cut-off voltage V 修 =V3-(V1+V4-2V2); According to the corrected battery cut-off voltage V 修 , repeat steps S1-S4 until the battery discharge capacity in step S3 is greater than or equal to 5% SOC; wherein the discharge cut-off voltage of S3 is V 修 , and the discharge cut-off voltage in each repetition of steps S1-S4 is the same as the discharge cut-off voltage in the first repetition of steps S1-S4.