Method for calculating standing time after liquid injection of lithium ion battery

Abstract

The application discloses a kind of lithium ion battery injection post standing time calculation method, comprising the following steps: multiple first battery grouping, according to preset condition injection post standing, obtain multiple liquid loss amount and multiple standing time;Multiple liquid loss amount and multiple standing time are fitted to obtain the liquid loss equation of the first battery;According to the liquid loss equation of the first battery and the first battery parameter, obtain electrolyte parameter and injection coefficient;According to the electrolyte parameter and the injection coefficient and second battery parameter, obtain the liquid loss equation of second battery;According to the liquid loss equation of the second battery, formulate the standing time of the second battery;Wherein, the electrolyte and injection mode used by the first battery and the second battery are all same.This method can effectively solve the problem of experience, blindness of existing standing time formulation method, and then ensure the efficiency and quality of standing process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power battery production, in particular to a calculation method of standing time after electrolyte injection of a lithium ion battery. BACKGROUND

[0002] The development of manufacturing process is an important aspect to promote the development of lithium ion battery technology, and the infiltration of electrolyte (including electrolyte injection process and standing process) is one of the key links in the manufacturing process.

[0003] For lithium ion batteries, the longer the standing time, the more sufficient the electrolyte infiltration, the smaller the liquid loss, and the better the battery performance and life. However, for the manufacture of lithium ion batteries, the standing time is related to the infiltration efficiency and production cost, therefore, how to develop a reasonable standing time for different types of batteries is the key to improve efficiency and reduce production cost.

[0004] And the existing method of developing standing time is to first select an empirical time, and then adjust the high-temperature standing time according to the performance of the produced battery cell. This method is not only time-consuming and laborious, but also lacks sufficient accuracy.

[0005] Therefore, to provide a calculation method of standing time after electrolyte injection of a lithium ion battery which can solve the problem of empiricism and blindness of the existing standing time development method, and further ensure the efficiency and quality of the standing process is an urgent problem for those skilled in the art. SUMMARY

[0006] The purpose of the present application is to provide a calculation method of standing time after electrolyte injection of a lithium ion battery, which has clear logic and can effectively solve the problem of empiricism and blindness of the existing standing time development method, and further ensure the efficiency and quality of the standing process.

[0007] In order to achieve the above purpose, the technical scheme provided by the present application is as follows:

[0008] A calculation method of standing time after electrolyte injection of a lithium ion battery, comprising the following steps:

[0009] Grouping a plurality of first battery cells, standing after electrolyte injection according to a preset condition, obtaining a plurality of liquid loss amounts and a plurality of standing times;

[0010] Fitting a plurality of the liquid loss amounts and a plurality of the standing times to obtain a liquid loss equation of the first battery cell;

[0011] Obtaining electrolyte parameters and an electrolyte injection coefficient according to the liquid loss equation of the first battery cell and the first battery cell parameters;

[0012] Obtaining a liquid loss equation of a second battery cell according to the electrolyte parameters and the electrolyte injection coefficient and second battery cell parameters;

[0013] determining the standing time of the second battery cell according to the liquid loss equation of the second battery cell;

[0014] wherein the electrolyte and the electrolyte injection method used by the first battery cell and the second battery cell are the same.

[0015] Preferably, before grouping the plurality of first battery cells, obtaining the plurality of liquid losses and the plurality of standing times according to the preset condition, further comprising:

[0016] constructing a Washburn equation;

[0017] correcting the Washburn equation according to the porosity of the lithium electronic battery to obtain a first equation;

[0018] correcting the deformed first equation according to the injection coefficient to obtain a second equation;

[0019] correcting the second equation according to the lithium electronic battery parameters to obtain a third equation.

[0020] Preferably, the Washburn equation is specifically:

[0021] wherein c is the shape coefficient of the capillary tube, r is the average capillary radius, γ is the surface tension of the liquid, η is the viscosity of the liquid, h is the rising height of the electrolyte, and t is the standing time.

[0022] Preferably, the first equation is specifically:

[0023] wherein Δm is the liquid retention, ρ sol is the density of the electrolyte, A is the cross-sectional area of the electrode, P is the porosity of the electrode, r is the effective pore size of the electrode, γ is the surface tension of the electrolyte, η is the viscosity of the electrolyte, and θ is the contact angle between the electrolyte and the porous electrode.

[0024] Preferably, the second equation is specifically:

[0025] wherein, M is the injection amount, and b is the injection coefficient.

[0026] Preferably,

[0027] The lithium electronic battery parameters include the cross-sectional area of the positive electrode A1, the cross-sectional area of the negative electrode A2, and the cross-sectional area of the separator A3.

[0028] The porosity of the lithium electronic battery includes the porosity of the positive electrode P1, the porosity of the negative electrode P2, and the porosity of the separator P3.

[0029] The third equation is specifically:

[0030] Preferably, the liquid loss equation of the first battery cell is specifically:

[0031] Wherein, the positive electrode cross-sectional area of the first battery cell is A1', the positive electrode porosity is P1', the negative electrode cross-sectional area is A2', the negative electrode porosity is P2', the separator cross-sectional area is A3', the separator porosity is P3', the liquid injection amount is M1, the electrolyte parameter of the first battery cell is alpha = K / (A1' P1' + A2' P2' + A3' P3'), and the liquid injection coefficient b = B / M1.

[0032] Preferably, the liquid loss equation of the second battery cell is specifically:

[0033] Wherein, the positive electrode cross-sectional area of the first battery cell is A1", the positive electrode porosity is P1", the negative electrode cross-sectional area is A2", the negative electrode porosity is P2", the separator cross-sectional area is A3", the separator porosity is P3", and the liquid injection amount is M2.

[0034] The calculation method of the standing time of the lithium ion battery provided by the application is to group a plurality of first battery cells, and to stand after liquid injection according to a preset condition, wherein the preset condition refers to the difference in standing time after liquid injection of different groups of first battery cells, a plurality of standing times and a plurality of liquid loss amounts are obtained according to the difference in standing time after liquid injection, a liquid loss equation of the first battery cell is fitted according to the plurality of standing times and the plurality of liquid loss amounts, an electrolyte parameter and a liquid injection coefficient are obtained according to the liquid loss equation of the first battery cell and the first battery cell parameters, a liquid loss equation of the second battery cell is calculated and obtained according to the calculated electrolyte parameter and the liquid injection coefficient and the second battery cell parameters, and the standing time of the second battery cell is determined according to the liquid loss equation of the second battery cell. In the designed calculation method, the electrolyte and the liquid injection method used by the first battery cell and the second battery cell are the same. The electrolyte parameter and the liquid injection coefficient are creatively introduced, the liquid loss equation of the battery cell is constructed, the experience and blindness problems of the existing standing time determination method can be effectively solved, the standing time of the second battery cell can be determined according to the liquid loss equation of the second battery cell, and then the efficiency and quality of the standing process can be ensured. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0036] Figure 1 A flow chart of a calculation method of a standing time after liquid injection of a lithium ion battery is provided for the present application;

[0037] Figure 2 A relationship diagram between liquid loss amount and standing time in step S2 is provided for the embodiment of the present application;

[0038] Figure 3 A flow chart of a method of obtaining a third equation before step S1 is provided for the embodiment of the present application. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0040] The embodiments of the present application are written in a progressive manner.

[0041] The present application provides a calculation method of a standing time after liquid injection of a lithium ion battery. The technical problem that the prior art selects an empirical time first, then adjusts the high-temperature standing time according to the performance of the produced battery cell, which is time-consuming and laborious, and lacks sufficient accuracy is solved.

[0042] A calculation method of a standing time after liquid injection of a lithium ion battery, comprising the following steps:

[0043] S1. Grouping a plurality of first battery cells, standing after liquid injection according to a preset condition, obtaining a plurality of liquid loss amounts and a plurality of standing times;

[0044] S2. Fitting the plurality of liquid loss amounts and the plurality of standing times to obtain a liquid loss amount equation of the first battery cell;

[0045] S3. Obtaining an electrolyte parameter and a liquid injection coefficient according to the liquid loss amount equation of the first battery cell and a first battery cell parameter;

[0046] S4. Obtaining a liquid loss amount equation of a second battery cell according to the electrolyte parameter and the liquid injection coefficient and a second battery cell parameter;

[0047] S5. Formulating a standing time of the second battery cell according to the liquid loss amount equation of the second battery cell;

[0048] The electrolyte and the liquid injection method used by the first battery cell and the second battery cell are the same.

[0049] In step S1, the same batch of battery cells 1 are grouped for experiments, with no less than 20 battery cells in each group, and each group is left to stand for different lengths of time after liquid injection to obtain multiple data points of liquid loss m (average) - standing time t.

[0050] In this embodiment, step S1 is specifically: the same batch of 278494 model battery cells (electrolyte E16) are divided into four groups (20pcs in each group), and experiments are conducted with standing times of 6h, 13h, 18h and 38h, and the results are as follows:

[0051] Group Standing time (h) Liquid loss (g) Group 1 6 0..4311 Group 2 13 0..3750 Group 3 18 0..3428 Group 4 38 0..2482

[0052] In step S2, the multiple liquid losses and the multiple corresponding standing times are fitted to obtain a liquid loss equation of the first battery cell.

[0053] In this embodiment, the formula is used to linearly fit the experimental data. As shown in Figure 2 , for the 278494 battery cell, the liquid loss and standing time in the above table are fitted, and the liquid loss equation of the 278494 battery cell is:

[0054] In step S3, the electrolyte parameters and the liquid injection coefficient are calculated according to the fitted liquid loss equation of the first battery cell and the parameters of the first battery cell.

[0055] In this embodiment, the parameters of the first battery cell are known by inquiry, i.e., the positive electrode cross-sectional area of 278494 is 106.12mm 2 , the porosity is 0.2078, the negative electrode cross-sectional area is 137.98mm 2 , the porosity is 0.2389, the diaphragm cross-sectional area is 55.30mm 2 , the porosity is 0.45, and the liquid injection amount M1 is 5.1g. Calculation can obtain the electrolyte parameters a of E16 = 0.0493 / (106.12x0.2078+137.98x0.2389+55.30x0.45) = 0.062g / (cm 2 xh 0.5 ), and the liquid injection coefficient b = 0.5522 / 5.1 = 0.1083.

[0056] In step S4, the liquid loss equation of the second battery cell is calculated according to the calculated electrolyte parameters, the liquid injection coefficient and the parameters of the second battery cell.

[0057] In this embodiment, the positive electrode cross-sectional area of the 695672 battery cell of E16 is 226.58mm 2 , the porosity is 0.2039, the negative electrode cross-sectional area is 227.39mm 2, the diaphragm cross-sectional area is 72.80 mm 2 , the porosity is 0.45, and the liquid injection amount is 7.6 g. The liquid loss amount equation of 695672 can be calculated according to the electrolyte parameters a and the liquid injection coefficient b, and is as follows:

[0058]

[0059] In step S5, the standing time of the second battery cell is determined according to the liquid loss amount equation of the second battery cell.

[0060] In this embodiment, when the actual liquid loss amount of the 695672 battery cell is 0.3 g, the standing time should be set to 46 h; when the actual liquid loss amount of the 695672 battery cell is 0.2 g, the standing time should be set to 65 h. In this way, the standing time of the battery cell can be scientifically and effectively determined, thereby improving the production efficiency and reducing the production cost.

[0061] Preferably, before the plurality of first battery cells are grouped, the plurality of liquid loss amounts and the plurality of standing times are obtained according to the preset condition, the method further comprises the following steps:

[0062] A1. constructing a Washburn equation;

[0063] A2. correcting the Washburn equation according to the porosity of the lithium-ion battery to obtain a first equation;

[0064] A3. correcting the deformed first equation according to the liquid injection coefficient to obtain a second equation;

[0065] A4. correcting the second equation according to the parameters of the lithium-ion battery to obtain a third equation.

[0066] In step A1, the lithium-ion battery is a typical gap-pore structure, and on the other hand, the main driving force for electrolyte infiltration is capillary force, so the liquid loss amount and the standing time can be described based on the Washburn equation.

[0067] In step A2, the lithium-ion battery is a pore structure, and there is a certain porosity P. Therefore, the Washburn equation can be corrected to obtain a corrected Washburn equation.

[0068] In step A3, the first equation is deformed to obtain the relationship between the liquid loss amount m and the liquid retention amount Δm, i.e. m=M-Δm. The infiltration process of the electrolyte is divided into the liquid injection process and the standing process (including normal temperature standing and high temperature standing), so the liquid injection coefficient b is introduced to correct the liquid injection amount M.

[0069] In step A4, considering the influence of the positive and negative electrode sheets and the diaphragm on infiltration, the positive electrode sheet cross-sectional area, the negative electrode sheet cross-sectional area, the diaphragm cross-sectional area, and the positive electrode sheet porosity, the negative electrode sheet porosity, and the diaphragm porosity are introduced to modify the second equation to obtain the third equation.

[0070] Preferably, the Washburn equation is specifically:

[0071] Wherein, c is the capillary shape coefficient, r is the average capillary radius, γ is the surface tension of the liquid, η is the viscosity of the liquid, h is the electrolyte rising height, and t is the standing time.

[0072] Preferably, the first equation is specifically:

[0073] Wherein, Δm is the liquid retention amount, ρ sol is the electrolyte density, A is the electrode cross-sectional area, P is the electrode porosity, r is the effective pore size of the electrode, γ is the surface tension of the electrolyte, η is the viscosity of the electrolyte, and θ is the contact angle between the electrolyte and the porous electrode.

[0074] Preferably, the second equation is specifically:

[0075] Wherein, M is the liquid injection amount, and b is the liquid injection coefficient.

[0076] Preferably,

[0077] The lithium electronic battery parameters include the positive electrode sheet cross-sectional area A1, the negative electrode sheet cross-sectional area A2, and the diaphragm cross-sectional area A3.

[0078] The lithium electronic battery porosity includes the positive electrode sheet porosity P1, the negative electrode sheet porosity P2, and the diaphragm porosity P3.

[0079] The third equation is specifically:

[0080] Preferably, the liquid loss amount equation of the first cell is specifically:

[0081] Wherein, the positive electrode cross-sectional area of the first cell is A1', the positive electrode porosity is P1', the negative electrode cross-sectional area is A2', the negative electrode porosity is P2', the diaphragm cross-sectional area is A3', the diaphragm porosity is P3', the liquid injection amount is M1, the electrolyte parameter used by the first cell is α = K / (A1'·P1'+A2'·P2'+A3'·P3'), and the liquid injection coefficient b = B / M1.

[0082] Preferably, the liquid loss amount equation of the second cell is specifically:

[0083] Among them, the positive electrode cross-sectional area of ​​the first cell is A1", the positive electrode porosity is P1", the negative electrode cross-sectional area is A2", the negative electrode porosity is P2", the diaphragm cross-sectional area is A3", the diaphragm porosity is P3", and the liquid injection volume is M2.

[0084] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0085] The above provides a detailed description of a method for calculating the settling time of a lithium-ion battery after electrolyte filling, as provided by this invention. The above description of the disclosed embodiments enables those skilled in the art to implement or use this invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, this invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for calculating the standing time of a lithium ion battery after liquid injection, characterized in that, The method comprises the following steps: constructing a Washburn equation; correcting the Washburn equation according to the porosity of the lithium ion battery to obtain a first equation; correcting the deformed first equation according to the injection coefficient to obtain a second equation; correcting the second equation according to the parameters of the lithium ion battery to obtain a third equation; grouping a plurality of first battery cells, standing after injection according to a preset condition, obtaining a plurality of liquid loss amounts and a plurality of standing times; fitting the plurality of liquid loss amounts and the plurality of standing times based on the third equation to obtain a liquid loss equation of the first battery cell; obtaining electrolyte parameters and an injection coefficient according to the liquid loss equation of the first battery cell and the parameters of the first battery cell; obtaining a liquid loss equation of a second battery cell according to the electrolyte parameters and the injection coefficient and the parameters of the second battery cell; formulating a standing time of the second battery cell according to the liquid loss equation of the second battery cell; wherein the electrolyte and the injection method used by the first battery cell and the second battery cell are the same; The first battery cell parameter, the second battery cell parameter include a positive electrode sheet Cross-sectional area, negative electrode tab cross-sectional area, separator cross-sectional area, positive electrode tab porosity, negative electrode tab porosity, separator porosity, and liquid injection amount.

2. The method of claim 1, wherein the method is characterized by: The Washburn equation is specifically: ; where c is a capillary shape coefficient, r is an average capillary radius, γ is a surface tension of the liquid, η is a viscosity of the liquid, h is an electrolyte rising height, and t is a standing time, is a contact angle of the electrolyte with the porous electrode.

3. The method of claim 2, wherein the method is characterized by: The first equation is specifically: ; where Δm is the liquid retention amount, where ρ is the electrolyte density, A is the cross-sectional area of the electrode, P is the porosity of the electrode, r is the effective pore size of the electrode, γ is the surface tension of the electrolyte, η is the viscosity of the electrolyte, and θ is the contact angle of the electrolyte with the porous electrode.

4. The method of claim 3, wherein the method is characterized by: The second equation is specifically: wherein, M is the amount of liquid injected, b is the injection coefficient, and m is the amount of liquid lost.

5. The method for calculating the standing time of the lithium ion battery after injection according to claim 4, wherein, the parameters of the lithium ion battery include a positive electrode sheet cross-sectional area A1, a negative electrode sheet cross-sectional area A2, and a diaphragm cross-sectional area A3; the porosity of the lithium ion battery includes a positive electrode sheet porosity P1, a negative electrode sheet porosity P2, and a diaphragm porosity P3; The third equation is specifically: .

6. The method of claim 5, wherein the method is characterized by: The liquid loss equation of the first battery cell is specifically: Wherein, the liquid loss amount equation of the first battery cell is a linear equation obtained by linear fitting a plurality of liquid loss amounts and a plurality of standing times based on the third equation, B is the intercept of the linear equation, and K is the slope of the linear equation; the positive electrode cross-sectional area of the first battery cell is A1', the positive electrode porosity is P1', the negative electrode cross-sectional area is A2', the negative electrode porosity is P2', the separator cross-sectional area is A3', the separator porosity is P3', the liquid injection amount is M1, and the electrolyte parameters used by the first battery cell are , the liquid injection coefficient .

7. The method of claim 6, wherein the method is characterized by: The liquid loss equation of the second battery cell is specifically: wherein the positive electrode cross-sectional area of the first battery cell is A1", the positive electrode porosity is P1", the negative electrode cross-sectional area is A2", the negative electrode porosity is P2", the diaphragm cross-sectional area is A3", the diaphragm porosity is P3", and the injection amount is M2.

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