Method for determining aging time of battery and application thereof

Abstract

The invention provides a method for determining the aging time of a battery and application of the method, and relates to the technical field of biology. The method for determining the aging time of the battery, provided by the invention, comprises the following steps: shelving and aging the battery subjected to liquid injection sealing, detecting the capacitance of positive and negative pole pieces of the battery in the shelving and aging process, and taking the time required for reaching the maximum capacitance of the battery as the optimal aging time of the battery. According to the research of the inventor, the capacitance of the battery is positively correlated with the contact area of an electrolyte and a pole piece in the shelving and aging process, so that the invention provides a method for determining the optimal shelving and aging time of the battery by detecting the capacitance of the battery. The method is simple and convenient, is accurate in detection, and is beneficial to improving the production efficiency of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a method for determining the aging time of a battery and its application. Background Art

[0002] Generally, after lithium batteries and sodium-ion batteries are injected with electrolyte and before formation, they need to be aged for a period of time to ensure that the electrolyte fully infiltrates the pores of the positive and negative electrodes. An overly long aging time will affect production efficiency, while an overly short time will affect the performance of the battery. Moreover, the selection of the aging time varies with the change of the aging temperature. Therefore, it is relatively difficult to accurately determine the aging time.

[0003] In view of this, the present invention is specifically proposed. Summary of the Invention

[0004] The first object of the present invention is to provide a method for determining the aging time of a battery to solve the above technical problems.

[0005] The second object of the present invention is to provide the application of the above method for determining the aging time of a battery in battery preparation.

[0006] In order to achieve the above objects, the following technical solutions are specifically adopted:

[0007] In a first aspect, the present invention provides a method for determining the aging time of a battery, including the following steps:

[0008] The battery after injection and sealing is aged, and the capacitance of the positive and negative electrode plates of the battery is detected during the aging process. The time required for the battery to reach the maximum capacitance is the optimal aging time of the battery.

[0009] As a further technical solution, the method for detecting the capacitance is as follows:

[0010] The battery is subjected to a CV test to obtain two current values I1 and I2 corresponding to the open-circuit voltage of the battery at different CV sweep rates, and △I = 0.5*|I1 - I2| is recorded; with △I as the dependent variable and the CV sweep rate as the independent variable, △I and the CV are linearly fitted, and the slope of the fitted curve is the capacitance.

[0011] As a further technical solution, an electrochemical workstation is used for the CV test.

[0012] As a further technical solution, the CV sweep rate is in the range of 1 - 4 mV / s.

[0013] As a further technical solution, the battery is subjected to a CV test at CV sweep rates of 1 mV / s, 2 mV / s, 3 mV / s, and 4 mV / s respectively.

[0014] As a further technical solution, the scanning range of the CV test is within ±25 mV of the open-circuit voltage of the battery.

[0015] As a further technical solution, the battery includes a lithium-ion battery and a sodium-ion battery.

[0016] As a further technical solution, the types of the battery include a cylindrical battery and a laminated battery.

[0017] In a second aspect, the present invention provides an application of the above method for determining the aging time of a battery in battery preparation.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] Through research by the inventor, it is found that the capacitance of the positive and negative electrode plates of the battery during the shelf aging process is positively correlated with the contact area between the electrolyte and the electrode plates. Accordingly, the present invention proposes a method for determining the optimal shelf aging time of the battery by detecting the capacitance of the battery. This method is simple and convenient, and the detection is accurate, which helps to improve the production efficiency of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 It is a schematic diagram of the process of electrolyte infiltrating the electrode plate;

[0022] Figure 2 It is the CV curve of lithium manganate battery 3 with a scanning rate of 1 mV / s;

[0023] Figure 3 It is the linear fitting curve of △I-CV scanning rate of lithium manganate battery 3;

[0024] Figure 4 It is the variation relationship of the capacitance of different batteries with the aging time. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The implementation of the present invention will be described in detail below in combination with the embodiments and examples. However, those skilled in the art will understand that the following embodiments and examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention. Those not specified in specific conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments not specified in the manufacturer are all conventional products that can be obtained through commercial purchase.

[0026] As Figure 1 shown, after the battery is injected with the electrolyte, in the initial stage, the electrolyte infiltrates the surface layer of the electrode sheet. After a period of time, the electrolyte penetrates into the inner pores, and the contact area with the active material of the electrode sheet gradually increases, and finally the electrode sheet is completely infiltrated. Based on this, the present solution is proposed. This solution characterizes the change of the contact area between the electrolyte and the electrode sheet over time to determine the optimal shelf time.

[0027] In a first aspect, the present invention provides a method for determining the aging time of a battery, including the following steps:

[0028] The battery after injection and sealing is placed for aging, and the capacitance of the positive and negative electrode sheets of the battery is detected during the aging process. The time required for the battery to reach the maximum capacitance is the optimal aging time of the battery.

[0029] Through research by the inventor, it is found that the capacitance of the battery during the aging process is positively correlated with the contact area between the electrolyte and the electrode sheet. Based on this, the present invention proposes a method for determining the optimal shelf aging time of the battery by detecting the capacitance of the battery. This method is simple and convenient, and the detection is accurate, which helps to improve the production efficiency of the battery.

[0030] In some optional embodiments, the method for detecting the capacitance is as follows:

[0031] Perform a CV test on the battery to obtain two current values I1 and I2 corresponding to the open circuit voltage of the battery at different CV sweep rates, and record △I = 0.5*|I1 - I2|; taking △I as the dependent variable and the CV sweep rate as the independent variable, linearly fit △I and CV, and the slope of the fitting curve is the capacitance.

[0032] In some optional embodiments, a potentiostat is used to perform the CV test.

[0033] The present invention does not specifically limit the range of the CV sweep rate, which can be selected according to the capacity of the battery and the range of the potentiostat. In some optional embodiments, the CV sweep rate is in the range of 1-4 mV / s.

[0034] The present invention does not impose specific restrictions on the specifically selected CV sweep rate, as long as the capacitance value can be accurately obtained after linear fitting. In some alternative embodiments, the battery is subjected to CV tests at CV sweep rates of 1 mV / s, 2 mV / s, 3 mV / s, and 4 mV / s respectively.

[0035] In the present invention, the scanning range of the CV test needs to include the open-circuit voltage of the battery. In some alternative embodiments, the scanning range of the CV test is within ±25 mV of the open-circuit voltage of the battery.

[0036] In some alternative embodiments, the battery includes a lithium-ion battery and a sodium-ion battery.

[0037] The method for determining the aging time of a battery provided by the present invention is applicable to various batteries, such as lithium-ion batteries and sodium-ion batteries.

[0038] In some alternative embodiments, the types of the battery include a cylindrical battery and a laminated battery.

[0039] The method provided by the present invention is applicable to the determination of the aging time of cylindrical batteries and laminated batteries.

[0040] In a second aspect, the present invention provides an application of the above method for determining the aging time of a battery in battery preparation.

[0041] The method provided by the present invention can accurately determine the shelf aging time of a battery, greatly improving the production efficiency of the battery.

[0042] The present invention will be further described below through specific examples. However, it should be understood that these examples are only for more detailed description and should not be construed as limiting the present invention in any way.

[0043] Example 1

[0044] Lithium manganese oxide battery 1:

[0045] Positive electrode sheet: Lithium manganese oxide, conductive agent, and binder are mixed into a slurry in a ratio of 97:1:2, and after coating, drying, and rolling, a positive electrode sheet is obtained with a surface density of 44 mg / cm 2 , and the compaction density is 2.9 g / cm 3 ;

[0046] Negative electrode sheet: Graphite, conductive agent, binder, and thickener are mixed into a slurry in a ratio of 95:1.5:2:1.5, and after coating, drying, and rolling, a negative electrode sheet is obtained with a surface density corresponding to that of the positive electrode (ensuring that the negative electrode capacity / positive electrode capacity = 1.15), and the compaction is 1.5 g / cm 3 .

[0047] Lithium manganese oxide battery 2:

[0048] Positive electrode sheet: Lithium manganate, conductive agent, and binder are mixed into a slurry in a ratio of 97:1:2, and after coating, drying, and rolling, a positive electrode sheet is obtained with a surface density of 48 mg / cm 2 , and the tap density is 2.9 g / cm 3 ;

[0049] Negative electrode sheet: Graphite, conductive agent, binder, and thickening agent are mixed into a slurry in a ratio of 95:1.5:2:1.5, and after coating, drying, and rolling, a negative electrode sheet is obtained with a surface density corresponding to that of the positive electrode (ensuring that the negative electrode capacity / positive electrode capacity = 1.15), and the tap density is 1.5 g / cm 3 .

[0050] Lithium manganate battery 3:

[0051] Positive electrode sheet: Lithium manganate, conductive agent, and binder are mixed into a slurry in a ratio of 97:1:2, and after coating, drying, and rolling, a positive electrode sheet is obtained with a surface density of 52 mg / cm 2 , and the tap density is 2.9 g / cm 3 ;

[0052] Negative electrode sheet: Graphite, conductive agent, binder, and thickening agent are mixed into a slurry in a ratio of 95:1.5:2:1.5, and after coating, drying, and rolling, a negative electrode sheet is obtained with a surface density corresponding to that of the positive electrode (ensuring that the negative electrode capacity / positive electrode capacity = 1.15), and the tap density is 1.5 g / cm 3 .

[0053] The above positive and negative electrode sheets and separator are assembled into a laminated battery, filled with electrolyte (the electrolyte solvent is ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate (the mass ratio of ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate is 1:1:1), the solute is lithium hexafluorophosphate, and the concentration is 1 mol / L), and sealed. During the standing and aging process, the CV curve is tested every 4 h, the CV sweep rates are 1, 2, 3, and 4 mV / s respectively, and the scanning range is the open circuit voltage of the battery ±25 mV, Figure 2 shows the CV curve of lithium manganate battery 3 at a sweep rate of 1 mV / s. At each scanning speed, the two current values corresponding to the open circuit voltage are I1 and I2 respectively, and △I = 0.5 * |I1 - I2|; plotting △I against the scanning speed, the slope of the linearly fitted straight line is the capacitance Cdl, Figure 3 shows the △I - CV sweep rate linearly fitted curve of lithium manganate battery 3.

[0054] The variation relationship of the capacitance of the three batteries with the aging time is as Figure 4As shown. In the flat region of capacitance change (where the capacitance reaches the maximum value), it is the optimal aging time of the battery. It is determined that the aging time for a surface density of 32 is about 28 h, for a surface density of 48 is about 36 h, and for a surface density of 52 is about 40 h. The battery capacities at different aging times are shown in the table. The capacity is significantly too low at an aging time of 10 h and tends to be stable at around 40 h.

[0055] To verify the accuracy of the method of the present invention, taking lithium manganese oxide battery 3 (with a surface density of 52) of the same batch as an example, after assembling the battery and injecting the electrolyte, the batteries were aged for 10, 20, 30, 40, and 50 h respectively under the same environment, with 3 replicates in each group. Then the capacities of the batteries were detected, and the results are shown in Table 1.

[0056] Table 1

[0057]

[0058] As can be seen from Table 1, when the aging time is 40 h and 50 h, the battery capacities are basically the same and reach stability, indicating that the method of the present invention has good accuracy.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining battery aging time, characterized in that: The following steps are involved: The battery after liquid injection and sealing is placed aside for aging. During the aging process, the capacitance of the positive and negative electrodes of the battery is tested. The time required for the battery to reach the maximum capacitance is the optimal aging time of the battery.

2. The method for determining battery aging time according to claim 1, characterized in that: The detection method of the capacitance is as follows: The battery is subjected to a CV test to obtain two current values ​​I1 and I2 corresponding to the open circuit voltage of the battery at different CV scan rates, where △I=0.5*|I1-I2|. With △I as the dependent variable and CV scan rate as the independent variable, △I and CV are linearly fitted, and the slope of the fitting curve is the capacitance.

3. The method for determining battery aging time according to claim 2, characterized in that: The CV test was carried out using an electrochemical workstation.

4. The method for determining battery aging time according to claim 2, characterized in that: The CV scan rate was in the range of 1-4 mV / s.

5. The method for determining battery aging time according to claim 4, characterized in that: The battery was subjected to CV tests at CV scan rates of 1 mV / s, 2 mV / s, 3 mV / s and 4 mV / s, respectively.

6. The method for determining battery aging time according to claim 2, characterized in that: The scanning interval of the CV test is within the range of ±25mV of the open circuit voltage of the battery.

7. The method for determining battery aging time according to claim 1, characterized in that: The batteries include lithium-ion batteries and sodium-ion batteries.

8. The method for determining battery aging time according to claim 1, characterized in that: The types of batteries include cylindrical batteries and laminated batteries.

9. Use of the method for determining battery aging time according to any one of claims 1 to 8 in battery preparation.

Images