Estimation Method for Gas Generation Amount of Battery

Abstract

The present application provides a method for predicting the gas production of a battery. The method for predicting the gas production of the battery includes: performing a gas production test on a first test electrolyte with a plurality of known lithium-phosphorus mass ratios of lithium and phosphorus elements to determine a first mapping relationship between the gas production and the lithium-phosphorus mass ratio; performing a gas production test on a second test electrolyte with a plurality of known lithium-sulfur mass ratios of lithium and sulfur elements to determine a second mapping relationship between the gas production and the lithium-sulfur mass ratio, wherein the solvent and lithium salt concentration of the second test electrolyte are the same as those of the first test electrolyte; determining a gas production compensation value according to the solvent and lithium salt concentration of the second test electrolyte; determining a third mapping relationship between the predicted gas production and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio according to the first mapping relationship, the second mapping relationship, and the gas production compensation value; and predicting the gas production of the battery to be predicted according to the third mapping relationship and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio of the electrolyte of the battery to be predicted.

Description

Technical Field

[0001] This application relates to the field of batteries, and particularly to a method for predicting the gas generation amount of batteries. Background Art

[0002] A lithium-ion battery is composed of a positive electrode sheet with active substances, a negative electrode sheet, an electrolyte, and a casing, etc. During the formation stage, the battery continuously generates gas, causing the battery to expand, affecting the contact between the positive and negative electrodes, increasing the battery impedance, and affecting the performance of the battery. In order to improve the performance of the battery, it is necessary to predict the gas generation amount of the battery. The composition of the electrolyte will affect the gas generation amount of the battery. Currently, the process of predicting the gas generation amount of the battery is usually as follows: injecting electrolytes with different formulations into a large number of batteries, and detecting the gas generation amount of the batteries to explore the relationship between the electrolyte formulation and the gas generation amount and predicting the gas generation amount of the battery according to this relationship. This prediction method has a long experimental period and high resource consumption. Summary of the Invention

[0003] To solve the above technical problems, this application provides a method for predicting the gas generation amount of a battery, which can predict the gas generation amount of the battery according to the mass ratio of lithium element to phosphorus element and the mass ratio of lithium element to sulfur element in the electrolyte, thereby reducing the battery verification cost, shortening the verification period, and optimizing the electrolyte formulation by predicting the gas generation amount.

[0004] This application provides a method for predicting the gas generation amount of a battery, which is applied to a battery. The battery includes an electrolyte, and the electrolyte includes a solvent and a lithium salt. The lithium salt includes at least lithium element, phosphorus element, and sulfur element. The method for predicting the gas generation amount of the battery includes the steps of: performing a gas generation amount test on a plurality of first test electrolytes with known lithium-phosphorus mass ratios of lithium element to phosphorus element to determine a first mapping relationship between the gas generation amount and the lithium-phosphorus mass ratio, wherein the first mapping relationship includes a one-to-one mapping relationship between a plurality of lithium-phosphorus mass ratios and a plurality of gas generation amounts; performing a gas generation amount test on a plurality of second test electrolytes with known lithium-sulfur mass ratios of lithium element to sulfur element to determine a second mapping relationship between the gas generation amount and the lithium-sulfur mass ratio. The solvent and lithium salt concentration of the second test electrolyte are the same as those of the first test electrolyte. The second mapping relationship includes a one-to-one mapping relationship between a plurality of lithium-sulfur mass ratios and a plurality of gas generation amounts; determining a gas generation amount compensation value according to the solvent and lithium salt concentration of the second test electrolyte; determining a third mapping relationship between the predicted gas generation amount and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio according to the first mapping relationship, the second mapping relationship, and the gas generation amount compensation value; and predicting the gas generation amount of the battery to be predicted according to the third mapping relationship and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio of the electrolyte of the battery to be predicted.

[0005] The method for predicting the gas generation amount of a battery provided in this application obtains the mapping relationship between the lithium-phosphorus mass ratio and the gas generation amount and the mapping relationship between the lithium-sulfur mass ratio and the gas generation amount by conducting gas generation tests on electrolytes with known lithium-phosphorus mass ratios and electrolytes with known lithium-sulfur mass ratios respectively. Furthermore, the mapping relationship between the predicted gas generation amount and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio is obtained, and the gas generation amount of the battery to be predicted is predicted through the mapping relationship between the predicted gas generation amount and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio, realizing the prediction of the gas generation amount of the battery according to the magnitudes of the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio in the electrolyte. Thereby, the battery verification cost can be reduced, the verification cycle can be shortened, and the electrolyte formula can be optimized by predicting the gas generation amount of the battery. Brief Description of the Drawings

[0006] To more clearly illustrate the technical solutions of this application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0007] Figure 1 It is a flowchart of the method for predicting the gas generation amount of a battery provided in an embodiment of this application.

[0008] Figure 2 It is Figure 1 a sub-flowchart of step S10 in

[0009] Figure 3 It is Figure 1 a sub-flowchart of step S20 in

[0010] Figure 4 It is Figure 1 a sub-flowchart of step S40 in

[0011] Figure 5 It is Figure 4 a sub-flowchart of step S41 in Detailed Embodiments

[0012] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the drawings in the embodiments of this application. Obviously, the described embodiments are only some of the embodiments of this application, rather than all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

[0013] In the description of this application, the terms "first", "second", "third", etc. are used to distinguish different objects, rather than to describe a specific order, and thus should not be construed as a limitation to this application.

[0014] Please refer to Figure 1 , Figure 1 which is a method for predicting the gas generation amount of a battery provided by an embodiment of the present application. The method for predicting the gas generation amount of the battery is used to predict the gas generation amount of the battery. The battery includes an electrolyte, and the electrolyte includes a solvent and a lithium salt. The lithium salt includes at least lithium element (Li), phosphorus element (P), and sulfur element (S). As Figure 1 shown, the method for predicting the gas generation amount of the battery includes the following steps:

[0015] S10: Perform gas generation tests on a plurality of first test electrolytes with known lithium-to-phosphorus mass ratios of lithium and phosphorus elements to determine a first mapping relationship between the gas generation amount and the lithium-to-phosphorus mass ratio. Among them, the first mapping relationship includes a one-to-one mapping relationship between a plurality of lithium-to-phosphorus mass ratios and a plurality of gas generation amounts.

[0016] S20: Perform gas generation tests on a plurality of second test electrolytes with known lithium-to-sulfur mass ratios of lithium and sulfur elements to determine a second mapping relationship between the gas generation amount and the lithium-to-sulfur mass ratio. The solvent and lithium salt concentration of the second test electrolyte are the same as those of the first test electrolyte. Among them, the second mapping relationship includes a one-to-one mapping relationship between a plurality of lithium-to-sulfur mass ratios and a plurality of gas generation amounts.

[0017] S30: Determine a gas generation compensation value according to the solvent and lithium salt concentration of the second test electrolyte.

[0018] S40: Determine a third mapping relationship between the predicted gas generation amount and the lithium-to-phosphorus mass ratio and the lithium-to-sulfur mass ratio according to the first mapping relationship, the second mapping relationship, and the gas generation compensation value.

[0019] S50: Predict the gas generation amount of the battery to be predicted according to the third mapping relationship and the lithium-to-phosphorus mass ratio and the lithium-to-sulfur mass ratio of the electrolyte of the battery to be predicted.

[0020] The method for predicting the gas generation amount of the battery provided by the embodiment of the present application obtains a mapping relationship between the lithium-to-phosphorus mass ratio and the gas generation amount and a mapping relationship between the lithium-to-sulfur mass ratio and the gas generation amount by performing gas generation tests on electrolytes with known lithium-to-phosphorus mass ratios and gas generation tests on electrolytes with known lithium-to-sulfur mass ratios, and then obtains a mapping relationship between the predicted gas generation amount and the lithium-to-phosphorus mass ratio and the lithium-to-sulfur mass ratio. And predict the gas generation amount of the battery to be predicted through the mapping relationship between the predicted gas generation amount and the lithium-to-phosphorus mass ratio and the lithium-to-sulfur mass ratio, realizing the prediction of the gas generation amount of the battery according to the magnitudes of the lithium-to-phosphorus mass ratio and the lithium-to-sulfur mass ratio in the electrolyte, thereby reducing the battery verification cost, shortening the verification cycle, and optimizing the electrolyte formula by predicting the gas generation amount of the battery.

[0021] Among them, the lithium salt concentration is equal to the concentration of lithium ions in the lithium salt of the electrolyte. The lithium salt may include at least a phosphorus-containing lithium salt and a sulfur-containing lithium salt.

[0022] Among them, the gas production test on the first test electrolyte with various known lithium-to-phosphorus mass ratios specifically includes: conducting a gas production test on a battery including the first test electrolyte with a known lithium-to-phosphorus mass ratio. Specifically, the first test electrolyte with a known lithium-to-phosphorus mass ratio can be injected into the battery, and the gas production test can be conducted on this battery.

[0023] Among them, the gas production test on the second test electrolyte with various known lithium-to-sulfur mass ratios specifically includes: conducting a gas production test on a battery including the second test electrolyte with a known lithium-to-sulfur mass ratio. Specifically, the second test electrolyte with a known lithium-to-sulfur mass ratio can be injected into the battery, and the gas production test can be conducted on this battery.

[0024] Among them, the positive and negative electrode plates of the battery injected with the second test electrolyte are the same as those of the battery injected with the first test electrolyte. In some embodiments, the material of the positive electrode plate may include one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium manganese oxide, and layered lithium-containing oxygen salts, and the material of the negative electrode plate may include one or more of hard carbon, soft carbon, graphite, silicon carbon, and carbon nanotubes.

[0025] Among them, the solvent and lithium salt concentration of the battery to be estimated are the same as those of the second test electrolyte, that is, estimating the gas production of the battery according to the third mapping relationship is to estimate the gas production of a battery with the same solvent and lithium salt concentration as the second test electrolyte or the first test electrolyte.

[0026] Among them, it is determined by maintaining the solvent and lithium salt concentration of the test electrolyte. The gas production tests are respectively conducted on the test electrolytes with known lithium-to-phosphorus mass ratios and known lithium-to-sulfur mass ratios to obtain the first mapping relationship between the gas production and the lithium-to-phosphorus mass ratio and the second mapping relationship between the gas production and the lithium-to-sulfur mass ratio. Then, the gas production compensation value is obtained according to the determined solvent and lithium salt concentration. Furthermore, the third mapping relationship is obtained according to the first mapping relationship, the second mapping relationship, and the gas production compensation value, so that the gas production of a battery with the same solvent and the same lithium salt concentration can be evaluated according to the third mapping relationship.

[0027] In some embodiments, the electrolyte further includes an additive, and the additive at least includes phosphorus element and / or sulfur element. The lithium-to-phosphorus mass ratio is equal to the mass of lithium element in the lithium salt divided by the sum of the mass of phosphorus element in the lithium salt and the mass of phosphorus element in the additive; the lithium-to-sulfur mass ratio is equal to the mass of lithium element in the lithium salt divided by the sum of the mass of sulfur element in the lithium salt and the mass of sulfur element in the additive. That is, in some embodiments, the phosphorus element in the lithium-to-phosphorus mass ratio comes from the lithium salt and the additive, and the sulfur element in the lithium-to-sulfur mass ratio comes from the lithium salt and the additive.

[0028] In some embodiments, the additive includes at least one or more of 1,3 - propane sultone, phosphate ester, phosphite ester, sulfate ester, and sulfite ester.

[0029] Wherein, adding the additive to the electrolyte can reduce the decomposition of the electrolyte and inhibit the gas generation of the electrolyte.

[0030] Please refer to Figure 2 , which is Figure 1 a sub - flowchart of step S10 in Figure 2 As shown in

[0031] S11: Perform gas generation tests on multiple first - test electrolytes with different lithium - to - phosphorus mass ratios and the same lithium - to - sulfur mass ratio to obtain multiple gas generation amounts.

[0032] S12: Determine the first mapping relationship between the gas generation amount and the lithium - to - phosphorus mass ratio according to the multiple gas generation amounts corresponding to the multiple lithium - to - phosphorus mass ratios. Thus, the determined first mapping relationship includes the mapping relationships between multiple lithium - to - phosphorus mass ratios and the gas generation amount.

[0033] Wherein, multiple first - test electrolytes with the same lithium - to - sulfur mass ratio and different lithium - to - phosphorus mass ratios can be prepared, and the prepared multiple first - test electrolytes are respectively injected into multiple batteries. Then, use a gas generation detection device to perform formation gas generation tests on the batteries, and obtain the gas generation amounts corresponding to the multiple first - test electrolytes by monitoring the volume change caused by the expansion of the batteries, that is, each first - test electrolyte corresponds to a gas generation amount. The battery can be a soft - package battery.

[0034] Wherein, the solvents of the multiple first - test electrolytes with the same lithium - to - sulfur mass ratio and different lithium - to - phosphorus mass ratios are the same and the lithium salt concentrations are the same. When performing the gas generation test, the materials of the positive and negative electrode plates of the multiple batteries injected with the first - test electrolytes are the same.

[0035] Among them, various first test electrolytes with the same lithium-sulfur mass ratio and different lithium-phosphorus mass ratios can be prepared by changing the type of phosphorus-containing lithium salt. In some embodiments, the first test electrolyte further includes the additive, and the additive at least includes a phosphorus-containing compound and a sulfur-containing compound. Various first test electrolytes with the same lithium-sulfur mass ratio and different lithium-phosphorus mass ratios can be prepared by adjusting the mass of the phosphorus-containing compound in the additive. For example, the types and concentrations of the phosphorus-containing lithium salt and the sulfur-containing lithium salt in the lithium salts of various first test electrolytes are the same, and various first test electrolytes with the same lithium-sulfur mass ratio and different lithium-phosphorus mass ratios are prepared by adjusting the mass of the phosphorus-containing compound in the additive.

[0036] Among them, the first mapping relationship between the gas production volume and the lithium-phosphorus mass ratio can be obtained by fitting the multiple lithium-phosphorus mass ratios and the corresponding multiple gas production volumes. In the first mapping relationship, the independent variable is the lithium-phosphorus mass ratio, and the dependent variable is the gas production volume. In some embodiments, the first mapping relationship can be a logarithmic function.

[0037] Among them, by controlling the lithium-sulfur mass ratio of the electrolyte to be unchanged while changing the lithium-phosphorus mass ratio, and testing the gas production volume corresponding to the electrolytes with different lithium-phosphorus mass ratios, the mapping relationship between the single variable lithium-phosphorus mass ratio and the gas production volume can be obtained.

[0038] Please refer to Figure 3 which is Figure 1 the sub-flowchart of step S20 in Figure 3 As shown in

[0039] S21: Testing the gas production volume of various second test electrolytes with different lithium-sulfur mass ratios and the same lithium-phosphorus mass ratio to obtain multiple gas production volumes.

[0040] S22: Determining the second mapping relationship between the gas production volume and the lithium-sulfur mass ratio according to the multiple gas production volumes corresponding to the multiple lithium-sulfur mass ratios. Thus, the determined second mapping relationship includes the mapping relationships between multiple lithium-sulfur mass ratios and the gas production volume.

[0041] Among them, various second test electrolytes with the same lithium-phosphorus mass ratio and different lithium-sulfur mass ratios can be prepared by formulation, and the various second test electrolytes prepared by formulation are respectively injected into multiple batteries, and then a gas production detection device is used to test the gas production volume during the formation of the batteries. The gas production volume corresponding to each of the various second test electrolytes is obtained by monitoring the volume change caused by the expansion of the batteries. That is, each second test electrolyte corresponds to a gas production volume. The battery can be a soft-pack battery.

[0042] Among them, the solvents of the multiple second test electrolytes with the same lithium-to-phosphorus mass ratio and different lithium-to-sulfur mass ratios are the same and the lithium salt concentrations are the same. When performing the gas production test, the materials of the positive and negative electrode plates of the multiple cells injected with the second test electrolyte are the same.

[0043] Among them, multiple second test electrolytes with the same lithium-to-phosphorus mass ratio and different lithium-to-sulfur mass ratios can be prepared by changing the types of sulfur-containing lithium salts. In some embodiments, the second test electrolyte further includes the additive, and the additive at least includes a phosphorus-containing compound and a sulfur-containing compound. Multiple second test electrolytes with the same lithium-to-phosphorus mass ratio and different lithium-to-sulfur mass ratios can be prepared by adjusting the mass of the sulfur-containing compound in the additive. For example, the types and concentrations of the phosphorus-containing lithium salt and the sulfur-containing lithium salt in the lithium salt of multiple second test electrolytes are the same, and multiple second test electrolytes with the same lithium-to-phosphorus mass ratio and different lithium-to-sulfur mass ratios are prepared by adjusting the mass of the sulfur-containing compound in the additive.

[0044] Among them, the second mapping relationship between the gas production amount and the lithium-to-sulfur mass ratio can be obtained by performing a fitting process on the multiple lithium-to-sulfur mass ratios and the corresponding multiple gas production amounts. In the second mapping relationship, the independent variable is the lithium-to-sulfur mass ratio, and the dependent variable is the gas production amount. In some embodiments, the second mapping relationship can be a quadratic function.

[0045] Among them, by controlling the lithium-to-phosphorus mass ratio of the electrolyte to be unchanged while changing the lithium-to-sulfur mass ratio, and testing the gas production amounts corresponding to the electrolytes with different lithium-to-sulfur mass ratios, the mapping relationship between the single variable lithium-to-sulfur mass ratio and the gas production amount can be obtained.

[0046] Please refer to Figure 4 which is Figure 1 the sub-flowchart of step S40 in Figure 4 As shown in

[0047] S41: Determine the first influence factor of the lithium-to-phosphorus mass ratio on the gas production amount and the second influence factor of the lithium-to-sulfur mass ratio on the gas production amount according to the first mapping relationship and the second mapping relationship.

[0048] S42: Determine the third mapping relationship between the estimated gas production amount and the lithium-to-phosphorus mass ratio and the lithium-to-sulfur mass ratio according to the first mapping relationship, the second mapping relationship, the first influence factor, the second influence factor, and the gas production amount compensation value.

[0049] Among them, by determining the first influence factor and the second influence factor according to the first mapping relationship and the second mapping relationship, and determining the third mapping relationship at least according to the first influence factor and the second influence factor, the obtained third mapping relationship takes into account the influence of both the lithium-to-phosphorus mass ratio and the lithium-to-sulfur mass ratio on the gas production amount, thereby improving the accuracy of the predicted gas production amount according to the third mapping relationship.

[0050] Please refer to Figure 5 , which is Figure 4 a sub-flowchart of step S41 in Figure 5 . In some embodiments, as Figure 5 shown, in step S41, the determining of the first influence factor of the lithium-to-phosphorus mass ratio on the gas production amount and the second influence factor of the lithium-to-sulfur mass ratio on the gas production amount according to the first mapping relationship and the second mapping relationship includes:

[0051] S411: Derive the first gas production rate of change from the first mapping relationship, and the first gas production rate of change is related to the lithium-to-phosphorus mass ratio.

[0052] S412: Derive the second gas production rate of change from the second mapping relationship, and the second gas production rate of change is related to the lithium-to-sulfur mass ratio.

[0053] S413: Add the first gas production rate of change and the second gas production rate of change to obtain the total rate of change.

[0054] S414: Divide the first gas production rate of change by the total rate of change to obtain the first influence factor, and the first influence factor is related to the lithium-to-phosphorus mass ratio and the lithium-to-sulfur mass ratio.

[0055] S415: Divide the second gas production rate of change by the total rate of change to obtain the second influence factor, and the second influence factor is related to the lithium-to-phosphorus mass ratio and the lithium-to-sulfur mass ratio.

[0056] Among them, the first gas production rate of change obtained by deriving the first mapping relationship can reflect the influence degree of the lithium-to-phosphorus mass ratio on the gas production amount when the lithium-to-sulfur mass ratio is fixed at a certain value; the second gas production rate of change obtained by deriving the second mapping relationship can reflect the influence degree of the lithium-to-sulfur mass ratio on the gas production amount when the lithium-to-phosphorus mass ratio is fixed at a certain value. And the first influence factor obtained by dividing the first gas production rate of change by the total rate of change can reflect the influence degree of the lithium-to-phosphorus mass ratio on the gas production amount when neither the lithium-to-sulfur mass ratio nor the lithium-to-phosphorus mass ratio is fixed; the second influence factor obtained by dividing the second gas production rate of change by the total rate of change can reflect the influence degree of the lithium-to-sulfur mass ratio on the gas production amount when neither the lithium-to-phosphorus mass ratio nor the lithium-to-sulfur mass ratio is fixed.

[0057] Among them, by considering the magnitude of the lithium-sulfur mass ratio in combination to determine the influence of the lithium-phosphorus mass ratio on the gas production volume, the influence factor of the lithium-phosphorus mass ratio on the gas production volume can be obtained more accurately. Similarly, by considering the magnitude of the lithium-phosphorus mass ratio in combination to determine the influence of the lithium-sulfur mass ratio on the gas production volume, the influence factor of the lithium-sulfur mass ratio on the gas production volume can be obtained more accurately, so that the third mapping relationship between the predicted gas production volume and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio can be obtained more accurately.

[0058] In some embodiments, in step S50, determining the third mapping relationship between the predicted gas production volume and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio according to the first mapping relationship, the second mapping relationship, the first influence factor, the second influence factor, and the gas production volume compensation value includes: determining the third mapping relationship as δ = αY1 - βY2 + γ, where δ is the predicted gas production volume, α is the first influence factor, Y1 is the gas production volume of the first mapping relationship, β is the second influence factor, Y2 is the gas production volume of the second mapping relationship, and γ is the gas production volume compensation value.

[0059] In some embodiments, the solvent includes carbonate compounds, and the lithium salt includes at least one or more of LiPF6, LiFSI, and LiF2O2.

[0060] In some embodiments, the lithium salt may further include one or more of LiAsF6, LiBF4, LiSbF6, LiAlCl4, LiClO4, CF3SO3Li, C4F9SO3Li, CF3COOLi, (CF3CO)2NLi, (CF3SO2)2NLi, and (C2F5SO2)NLi.

[0061] In some embodiments, the solvent may include one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, and ethylene carbonate.

[0062] Among them, when the solvent and the lithium salt concentration of the electrolyte are determined, the gas production volume compensation value is a fixed value, and different solvents (different types or different mass ratios of carbonates contained) and different lithium salt concentrations correspond to different gas production volume compensation values. Determining the gas production volume compensation value according to the solvent and the lithium salt concentration of the second test electrolyte may specifically include: determining the gas production volume compensation value corresponding to the solvent and the lithium salt concentration of the second test electrolyte according to the corresponding relationship between the solvent and the lithium salt concentration and the gas production volume compensation value.

[0063] Among them, the gas production volume compensation values corresponding to different solvents and different lithium salt concentrations may be empirical values obtained through experimental tests.

[0064] In some embodiments, the solvent of the second test electrolyte includes dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate, and the mass ratio of dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate is 1:1:1. The lithium salt concentration of the second test electrolyte is 1 mol / L. Determining the gas production compensation value according to the solvent and lithium salt concentration of the second test electrolyte includes determining that the gas production compensation value is 0.2 mL.

[0065] Among them, the gas production compensation value corresponding to the mixture of dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate (mass ratio 1:1:1) as the solvent of the electrolyte and the lithium salt concentration of 1 mol / L can be determined according to the corresponding relationship between the solvent, lithium salt concentration, and gas production compensation value. The gas production compensation value is 0.2 mL.

[0066] Among them, in some embodiments, the gas production tests on a plurality of first test electrolytes with different lithium-to-phosphorus mass ratios and the same lithium-to-sulfur mass ratio to obtain a plurality of gas production amounts may specifically include: preparing six first test electrolytes with different lithium-to-phosphorus mass ratios and the same lithium-to-sulfur mass ratio as shown in Table 1. The solvents of these six first test electrolytes are all dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate (mass ratio 1:1:1), and the lithium salt concentration is all 1 mol / L; injecting these six first test electrolytes into six soft-pack batteries respectively, placing these six soft-pack batteries in an environment of 45°C and standing for 24 h, and then using a gas production detection device to perform formation gas production tests on these six soft-pack batteries to obtain six gas production amounts as shown in Table 1. Each first test electrolyte corresponds to a gas production amount.

[0067] Table 1

[0068] Serial number Lithium to phosphorus mass ratio Gas production volume / mL 1 0.2339 2.5420 2 0.2455 2.5350 3 0.2571 2.5185 4 0.2684 2.4415 5 0.2800 2.4555 6 0.2915 2.4040

[0069] By performing a fitting process on the lithium-to-phosphorus mass ratio and the corresponding gas production amount of the above six first test electrolytes, the first mapping relationship is obtained as Y1 = -0.65ln(A) + 1.6118, where A is the lithium-to-phosphorus mass ratio and Y1 is the gas production amount.

[0070] Taking the derivative of the first mapping relationship can obtain the first gas production change rate R1, where R1 = -(0.65 / A).

[0071] Among them, the gas production amounts are tested for multiple second test electrolytes with different lithium-sulfur mass ratios and the same lithium-phosphorus mass ratio, and specifically may include: preparing six second test electrolytes with different lithium-sulfur mass ratios and the same lithium-phosphorus mass ratio as shown in Table 2. The solvents of these six second test electrolytes are all dimethyl carbonate, ethyl methyl carbonate and ethylene carbonate (mass ratio is 1:1:1), and the lithium salt concentration is all 1 mol / L; injecting these six second test electrolytes into six soft-pack batteries respectively, placing these six soft-pack batteries in an environment of 45°C and standing for 24 h, and then using gas production detection equipment to test the formation gas production amounts of these six soft-pack batteries, obtaining six gas production amounts as shown in Table 2, and each second test electrolyte corresponds to one gas production amount.

[0072] Table 2

[0073] Serial number Lithium to sulfur mass ratio Gas production volume / mL 1 1.2150 2.3920 2 1.6760 2.2480 3 1.9059 1.7355 4 2.4669 2.0050 5 3.3520 1.4070 6 4.4175 2.2670

[0074] By performing fitting processing on the lithium-sulfur mass ratios and the corresponding gas production amounts of the above six second test electrolytes, the second mapping relationship is obtained as Y2 = 0.2704B 2 - 1.6096B + 4.0252, where B is the lithium-sulfur mass ratio and Y2 is the gas production amount.

[0075] Taking the derivative of the second mapping relationship can obtain the second gas production rate of change R2, where R2 = 0.5408B - 1.6096.

[0076] Adding the first gas production rate of change and the second gas production rate of change to obtain the total rate of change R3, where R3 = (0.5408B - 1.6096 - (0.65 / A)).

[0077] Dividing the first gas production rate of change by the total rate of change to obtain the first influence factor α, where α = (-0.65 / A) / (0.5408B - 1.6096 - (0.65 / A)), dividing the second gas production rate of change by the total rate of change to obtain the second influence factor β, where β = (0.5408B - 1.6096) / (0.5408B - 1.6096 - (0.65 / A)), thereby obtaining the third mapping relationship as δ = (-0.65 / A) / (0.5408B - 1.6096 - (0.65 / A)) * (-0.65ln(A) + 1.6118) - (0.5408B - 1.6096) / (0.5408B - 1.6096 - (0.65 / A)) * (0.2704B 2 - 1.6096B + 4.0252) + 0.2.

[0078] In some embodiments, the lithium-to-phosphorus mass ratio is greater than 0.2 and less than 0.292, and the lithium-to-sulfur mass ratio is greater than 1.2 and less than 4.5.

[0079] Wherein, when the lithium-to-phosphorus mass ratio of the electrolyte is greater than 0.2 and less than 0.292, and the lithium-to-sulfur mass ratio is greater than 1.2 and less than 4.5, the conductivity of the electrolyte is 8 - 12 mS / cm, the viscosity is 1 - 4 Pa·s, the conductivity meets the requirements, and no precipitate is generated in the electrolyte, which meets the electrolyte formulation design.

[0080] The following verifies the method for predicting the gas production of the battery provided by this application through Examples 1 - 4. The following examples are only used to illustrate and explain this application and are not used to limit this application.

[0081] Example 1

[0082] Prepare an electrolyte with a lithium-to-phosphorus mass ratio of 0.2685 and a lithium-to-sulfur mass ratio of 1.9058. The solvent of the electrolyte is dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate (mass ratio 1:1:1), and the lithium salt concentration is 1 mol / L. Inject the electrolyte into a soft-pack battery, place the soft-pack battery in an environment at 45°C and let it stand for 24 h, and then use a gas production detection device to test the formation gas production of the soft-pack battery to obtain the actual gas production.

[0083] Example 2

[0084] Prepare an electrolyte with a lithium-to-phosphorus mass ratio of 0.2915 and a lithium-to-sulfur mass ratio of 1.2150. The solvent of the electrolyte is dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate (mass ratio 1:1:1), and the lithium salt concentration is 1 mol / L. Inject the electrolyte into a soft-pack battery, place the soft-pack battery in an environment at 45°C and let it stand for 24 h, and then use a gas production detection device to test the formation gas production of the soft-pack battery to obtain the actual gas production.

[0085] Example 3

[0086] Prepare an electrolyte with a lithium-to-phosphorus mass ratio of 0.2915 and a lithium-to-sulfur mass ratio of 1.9058. The solvent of the electrolyte is dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate (mass ratio 1:1:1), and the lithium salt concentration is 1 mol / L. Inject the electrolyte into a soft-pack battery, place the soft-pack battery in an environment at 45°C and let it stand for 24 h, and then use a gas production detection device to test the formation gas production of the soft-pack battery to obtain the actual gas production.

[0087] Example 4

[0088] An electrolyte solution with a lithium-to-phosphorus mass ratio of 0.2800 and a lithium-to-sulfur mass ratio of 1.6760 was prepared. The solvent of the electrolyte solution is dimethyl carbonate, ethyl methyl carbonate and ethylene carbonate (mass ratio 1:1:1), and the lithium salt concentration is 1 mol / L. Inject the electrolyte solution into a soft-pack battery, and place the soft-pack battery in an environment at 45 °C and let it stand for 24 h. Then use a gas generation detection device to test the gas generation amount during formation of the soft-pack battery to obtain the actual gas generation amount.

[0089] According to the third mapping relationship δ = (-0.65 / A) / (0.5408B - 1.6096 - (0.65 / A)) * (-0.65ln(A) + 1.6118) - (0.5408B - 1.6096) / (0.5408B - 1.6096 - (0.65 / A)) * (0.2704B 2 -1.6096B + 4.0252) + 0.2, the predicted gas generation amounts of the soft-pack batteries injected with the electrolyte solution in Examples 1-4 and the actual gas generation amounts obtained by testing Examples 1-4 are shown in Table 3.

[0090] Table 3

[0091] Lithium to phosphorus mass ratio Lithium to sulfur mass ratio Estimated gas production volume / mL Actual gas production volume / mL Example 1 0.2685 1.9058 1.8161 1.8995 Example 2 0.2915 1.2150 1.1519 1.6000 Example 3 0.2915 1.9058 1.7159 1.8098 Example 4 0.2800 1.6760 1.5869 1.7726

[0092] As can be seen from Table 3, the changing trend of the predicted gas generation amounts of Examples 1-4 according to the third mapping relationship is Example 2 < Example 4 < Example 3 < Example 1, which is consistent with the changing trend of the actual gas generation amounts obtained through experiments, and the difference between the predicted gas generation amounts and the actual gas generation amounts is small. Therefore, the gas generation amount of the battery can be predicted according to the third mapping relationship, and the formula of the electrolyte solution can be optimized according to the predicted gas generation amount.

[0093] It should be noted that for the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that this application is not limited by the described action sequence, because according to this application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0094] The above are the implementation manners of the embodiments of this application. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the embodiments of this application, several improvements and refinements can still be made, and these improvements and refinements are also regarded as the protection scope of this application.

Claims

1. A method for predicting the gas production of a battery, which is applied to the battery, and is characterized in that, The battery includes an electrolyte, the electrolyte includes a solvent and a lithium salt, the lithium salt at least includes lithium element, phosphorus element and sulfur element, and the method for predicting the gas generation amount of the battery includes: Performing a gas generation amount test on a first test electrolyte with various known lithium-phosphorus mass ratios of lithium element and phosphorus element to determine a first mapping relationship between the gas generation amount and the lithium-phosphorus mass ratio, wherein the first mapping relationship includes a one-to-one mapping relationship between multiple lithium-phosphorus mass ratios and multiple gas generation amounts; Performing a gas generation amount test on a second test electrolyte with various known lithium-sulfur mass ratios of lithium element and sulfur element to determine a second mapping relationship between the gas generation amount and the lithium-sulfur mass ratio, wherein the solvent and the lithium salt concentration of the second test electrolyte are the same as those of the first test electrolyte, and the second mapping relationship includes a one-to-one mapping relationship between multiple lithium-sulfur mass ratios and multiple gas generation amounts; Determining a gas generation amount compensation value according to the solvent and the lithium salt concentration of the second test electrolyte; Determining a third mapping relationship between the predicted gas generation amount and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio according to the first mapping relationship, the second mapping relationship and the gas generation amount compensation value; and Predicting the gas generation amount of the battery to be predicted according to the third mapping relationship and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio of the electrolyte of the battery to be predicted.

2. The method for predicting the gas production of a battery according to claim 1, wherein The determining a third mapping relationship between the predicted gas generation amount and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio according to the first mapping relationship, the second mapping relationship and the gas generation amount compensation value includes: Determining a first influence factor of the lithium-phosphorus mass ratio on the gas generation amount and a second influence factor of the lithium-sulfur mass ratio on the gas generation amount according to the first mapping relationship and the second mapping relationship; and Determining a third mapping relationship between the predicted gas generation amount and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio according to the first mapping relationship, the second mapping relationship, the first influence factor, the second influence factor and the gas generation amount compensation value.

3. The method for predicting the gas production of the battery according to claim 1, wherein The performing a gas generation amount test on a first test electrolyte with various known lithium-phosphorus mass ratios of lithium element and phosphorus element to determine a first mapping relationship between the gas generation amount and the lithium-phosphorus mass ratio includes: Performing a gas generation amount test on multiple first test electrolytes with different lithium-phosphorus mass ratios and the same lithium-sulfur mass ratio to obtain multiple gas generation amounts; Determining a first mapping relationship between the gas generation amount and the lithium-phosphorus mass ratio according to the multiple gas generation amounts corresponding to the multiple lithium-phosphorus mass ratios.

4. The method for predicting the gas production of a battery according to claim 1, characterized in that, The performing a gas generation amount test on a second test electrolyte with various known lithium-sulfur mass ratios of lithium element and sulfur element to determine a second mapping relationship between the gas generation amount and the lithium-sulfur mass ratio includes: Performing a gas generation amount test on multiple second test electrolytes with different lithium-sulfur mass ratios and the same lithium-phosphorus mass ratio to obtain multiple gas generation amounts; Determining a second mapping relationship between the gas generation amount and the lithium-sulfur mass ratio according to the multiple gas generation amounts corresponding to the multiple lithium-sulfur mass ratios.

5. The method for predicting the gas production of a battery according to claim 2, wherein The determining a first influence factor of the lithium-phosphorus mass ratio on the gas generation amount and a second influence factor of the lithium-sulfur mass ratio on the gas generation amount according to the first mapping relationship and the second mapping relationship includes: Taking the derivative of the first mapping relationship to obtain a first gas generation amount change rate, and the first gas generation amount change rate is related to the lithium-phosphorus mass ratio; Derive the second gas production change rate from the second mapping relationship, and the second gas production change rate is related to the lithium-sulfur mass ratio; Add the first gas production change rate and the second gas production change rate to obtain the total change rate; Divide the first gas production change rate by the total change rate to obtain the first influence factor, and the first influence factor is related to the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio; and Divide the second gas production change rate by the total change rate to obtain the second influence factor, and the second influence factor is related to the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio.

6. The method for predicting the gas production of a battery according to claim 2, wherein Determining the third mapping relationship between the estimated gas production and the lithium-phosphorus mass ratio and the lithium-sulfur mass ratio according to the first mapping relationship, the second mapping relationship, the first influence factor, the second influence factor, and the gas production compensation value includes: Determine that the third mapping relationship is δ = αY1 - βY2 + γ, where δ is the estimated gas production, α is the first influence factor, Y1 is the gas production of the first mapping relationship, β is the second influence factor, Y2 is the gas production of the second mapping relationship, and γ is the gas production compensation value.

7. The method for predicting the gas production of the battery according to claim 1, characterized in that, The electrolyte further includes an additive, and the additive includes at least phosphorus element and / or sulfur element. The lithium-phosphorus mass ratio is equal to the mass of the lithium element of the lithium salt divided by the sum of the mass of the phosphorus element of the lithium salt and the mass of the phosphorus element of the additive; the lithium-sulfur mass ratio is equal to the mass of the lithium element of the lithium salt divided by the sum of the mass of the sulfur element of the lithium salt and the mass of the sulfur element of the additive.

8. The method for predicting the gas production of a battery according to claim 1, wherein, The solvent includes a carbonate compound, and the lithium salt includes at least one or more of LiPF6, LiFSI, and LiF2O2.

9. The method for predicting the gas production of a battery according to claim 7, characterized in that The additive includes at least one or more of 1,3-propane sultone, phosphate ester, phosphite ester, sulfate ester, and sulfite ester.

10. The method for predicting the gas production of the battery according to claim 2, wherein The solvent of the second test electrolyte includes dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate, and the mass ratio of dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate is 1:1:

1. The lithium salt concentration of the second test electrolyte is 1 mol / L. Determining the gas production compensation value according to the solvent and lithium salt concentration of the second test electrolyte includes determining that the gas production compensation value is 0.2 mL.

11. The method for predicting the gas production of a battery according to claim 10, characterized in that, The first mapping relationship is Y1 = -0.65ln(A) + 1.6118, and the second mapping relationship is Y2 = 0.2704B 2 -1.6096B + 4.0252. The first influencing factor is (-0.65 / A) / (0.5408B - 1.6096 - (0.65 / A)), the second influencing factor is (0.5408B - 1.6096) / (0.5408B - 1.6096 - (0.65 / A)), and the third mapping relationship is δ = (-0.65 / A) / (0.5408B - 1.6096 - (0.65 / A)) * (-0.65ln(A) + 1.6118) - (0.5408B - 1.6096) / (0.5408B - 1.6096 - (0.65 / A)) * (0.2704B 2 -1.6096B + 4.0252) + 0.2, where A is the lithium-to-phosphorus mass ratio, B is the lithium-to-sulfur mass ratio, and δ is the estimated gas production volume.

12. The method for predicting the gas production of the battery according to claim 1, wherein The lithium-phosphorus mass ratio is greater than 0.2 and less than 0.292, and the lithium-sulfur mass ratio is greater than 1.2 and less than 4.5.

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