Isotope-based battery thermal runaway gas production traceability method

Abstract

The invention provides an isotope-based battery thermal runaway gas production tracing method, which comprises the following steps of: performing isotope labeling on one of battery materials, and preparing the isotope-labeled battery material into one of isotope-labeled battery components; preparing the battery material which is not subjected to isotope labeling into one of unlabeled battery components; respectively carrying out an adiabatic thermal runaway experiment on one of the isotope labeled battery compositions and one of the unlabeled battery compositions to obtain a gas production composition of the one of the isotope labeled battery compositions and a gas production composition of the one of the unlabeled battery compositions; and obtaining a gas production source of the target gas based on the gas production composition of the two. According to the method, the battery electrolyte or the battery positive electrode is prepared by using an isotope calibration method, then the adiabatic thermal runaway test and the gas production composition test are performed, and the traceability of the gas production components of the lithium ion battery is realized by comparing and analyzing the ratio of labeled elements to unlabeled elements, so that guidance is provided for optimizing the material ratio of the battery; the purposes of reducing the thermal runaway risk of the battery and improving the safety of the battery are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and particularly relates to a method for tracing the origin of gas generated during thermal runaway of batteries based on isotopes. Background Art

[0002] Lithium-ion batteries have the advantages of long service life and high energy density. At present, they are considered to be the most promising energy systems for electric vehicles, and their advantages in other fields such as electricity and energy storage are becoming increasingly obvious. However, when lithium-ion batteries are abused or encounter abnormal situations, thermal runaway will occur, usually accompanied by heat release, gas emission, fire and explosion. In recent years, new energy vehicles including hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), battery electric vehicles (BEV) and fuel cell vehicles (FCV) have become the key development directions of the automotive industries of various countries. At the same time, since the problem of thermal runaway of lithium-ion batteries still cannot be fundamentally solved, the thermal runaway problem of batteries remains an important obstacle to the wider popularization and application of electric vehicles. When a lithium-ion battery undergoes thermal runaway, a large amount of toxic and harmful combustible gases will be generated, which is one of the main reasons for secondary explosions and will seriously endanger people's lives and property safety. Therefore, it is very important to accurately test the chain reaction that occurs during the thermal runaway of lithium-ion batteries with different material systems, explain the mechanism therein, and clarify the source of the gas related to the thermal runaway risk.

[0003] At the present stage, gas detection technologies such as Figure 1 as shown, mostly use an adiabatic accelerating calorimeter (ARC) to conduct a thermal runaway experiment on a certain material of the battery, and then analyze the collected gas by gas chromatography-mass spectrometry (GC-MS). Although the results can reveal some mechanisms of thermal runaway, they only generally speculate on the chemical reactions that occur during the thermal runaway of lithium-ion batteries based on the material compositions of the positive electrode, negative electrode and electrolyte and according to the gas detection results, and the results are not accurate. This is because the gas generated during the thermal runaway of lithium-ion batteries mainly comes from the decomposition and mutual reaction of the positive electrode material and the electrolyte. There are a large number of chain reactions inside, and the electrolyte is composed of multiple lithium salts, organic solvents and additives. Therefore, it is impossible to accurately judge the main chemical substance sources of toxic and harmful gases by simply testing the combustion situation of a certain material.

[0004] In view of this, developing a method for tracing the origin of gas generated during thermal runaway of batteries based on isotopes, which can reveal the gas generation sources of lithium-ion batteries, quantify the gas generation proportion of each substance, and then guide the material ratio scheme during the preparation of lithium-ion batteries, has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The object of the present invention is to solve the problems existing in the above-mentioned prior art, and provides a method for tracing the origin of gas generated during battery thermal runaway based on isotopes. First, the isotope labeling method (such as using 13 C, 16 O, etc.) is used to label different battery materials, and then a control group and an experimental group are established to achieve the purpose of tracing the origin of the gas generated during battery thermal runaway. Finally, the detailed process of the internal chain reaction during the thermal runaway of lithium-ion batteries is sorted out, and the source of the release of toxic and harmful gases is found, so as to realize the guidance of the material ratio scheme during the preparation of lithium-ion batteries.

[0006] A method for tracing the origin of gas generated during battery thermal runaway based on isotopes, comprising:

[0007] S1: Isotopically label one of the battery materials, and prepare the isotopically labeled battery material into one of the isotopically labeled battery components; prepare the unlabeled battery material into one of the unlabeled battery components; wherein, the battery material is the material for preparing the battery positive electrode or the material for preparing the battery electrolyte; one of the battery components is the battery electrolyte or the battery positive electrode;

[0008] S2: Respectively conduct adiabatic thermal runaway experiments on one of the isotopically labeled battery components and one of the unlabeled battery components to obtain the gas production composition of one of the isotopically labeled battery components and the gas production composition of one of the unlabeled battery components;

[0009] S3: Compare the gas production composition of one of the isotopically labeled battery components with the gas production composition of one of the unlabeled battery components to obtain the gas production source of the target gas.

[0010] In a preferred embodiment of the present invention,

[0011] S1: Isotopically label the material for preparing the battery electrolyte, and prepare the isotopically labeled material for preparing the battery electrolyte into an isotopically labeled battery electrolyte; prepare the unlabeled material for preparing the battery electrolyte into an unlabeled battery electrolyte;

[0012] S2: Respectively conduct adiabatic thermal runaway experiments on the isotopically labeled battery electrolyte and the unlabeled battery electrolyte to obtain the gas production composition of the isotopically labeled electrolyte and the gas production composition of the unlabeled battery electrolyte;

[0013] S3: Compare the gas production composition of the isotopically labeled battery electrolyte with the gas production composition of the unlabeled battery electrolyte to obtain the gas production source of the target gas.

[0014] In a preferred embodiment of the present invention,

[0015] S1: Isotopically label the materials for preparing the battery positive electrode, and prepare the isotopically labeled materials for preparing the battery positive electrode into isotopically labeled battery positive electrodes; prepare the materials for preparing the battery positive electrode without isotopic labeling into unlabeled battery positive electrodes;

[0016] S2: Conduct adiabatic thermal runaway experiments on the isotopically labeled battery positive electrode and the unlabeled battery positive electrode respectively to obtain the gas production composition of the isotopically labeled positive electrode and the gas production composition of the unlabeled battery positive electrode;

[0017] S3: Compare the gas production composition of the isotopically labeled battery positive electrode with the gas production composition of the unlabeled battery positive electrode to obtain the gas production source of the target gas.

[0018] In a preferred embodiment of the present invention, in step S1,

[0019] Select 13 C, D, 18 Any one of O to isotopically label the battery materials.

[0020] In a preferred embodiment of the present invention, in step S1,

[0021] The materials for preparing the battery electrolyte are organic solvents; and / or,

[0022] The materials for preparing the battery positive electrode are binders;

[0023] Preferably,

[0024] The organic solvent is any one of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate; and / or,

[0025] The binder is polyvinylidene fluoride or sodium carboxymethyl cellulose.

[0026] In a preferred embodiment of the present invention, in step S2, conduct the adiabatic thermal runaway experiment in an adiabatic accelerating calorimeter.

[0027] In a preferred embodiment of the present invention, in step S2,

[0028] The initial temperature in the test container of the adiabatic accelerating calorimeter is 40 - 50 °C; and / or,

[0029] The step temperature in the test container of the adiabatic accelerating calorimeter is 4 - 6 °C; and / or,

[0030] The holding time for each temperature in the test container of the adiabatic accelerating calorimeter is 25 - 35 min.

[0031] In a preferred embodiment of the present invention, in step S2,

[0032] The test container of the adiabatic accelerating calorimeter is evacuated and replaced with an inert gas;

[0033] Preferably,

[0034] the inert gas is nitrogen or argon; and / or,

[0035] the pressure in the test container of the adiabatic accelerating calorimeter is 0.8 - 1.2 bar.

[0036] In a preferred embodiment of the present invention, in step S3,

[0037] the target gas is at least one of carbon monoxide, hydrogen, oxygen, and methane.

[0038] In a preferred embodiment of the present invention,

[0039] Step S1 further includes: preparing one of the isotope - labeled battery components into an isotope - labeled battery cell; preparing one of the unlabeled battery components into an unlabeled battery cell;

[0040] Step S2 further includes: respectively performing adiabatic thermal runaway experiments on the isotope - labeled battery cell and the unlabeled battery cell to obtain the gas - generating composition of the isotope - labeled battery cell and the gas - generating composition of the unlabeled battery cell;

[0041] Step S3 further includes: comparing the gas - generating composition of the isotope - labeled battery cell and the gas - generating composition of the unlabeled battery cell to obtain the gas - generating source of the target gas.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] The method for testing the gas - generating source tracing of battery thermal runaway in the present invention uses the isotope calibration method to prepare batteries at the material level and / or cell level. After preparation, adiabatic thermal runaway tests and gas - generating composition tests are carried out. By comparing and analyzing the ratio of the labeled element to the unlabeled element, the tracing of the gas - generating components of lithium - ion batteries is realized, revealing the mechanism of gas generation during lithium - ion battery thermal runaway, and further providing guidance for optimizing the battery material ratio, achieving the purpose of reducing the risk of battery thermal runaway and improving battery safety. Description of the Drawings

[0044] Figure 1 is a schematic diagram of a lithium - ion battery thermal runaway gas - generating test platform in the prior art;

[0045] Figure 2 is a schematic flow diagram of the method for testing the gas - generating source tracing of battery thermal runaway in the present invention;

[0046] Figure 3 is a schematic flow diagram of the method for testing the gas - generating source tracing of battery thermal runaway in the present invention;

[0047] Figure 4 Exemplary isotope labeling for the method of tracing the origin of gas generated during thermal runaway of the battery of the present invention;

[0048] Figure 5 Isotope labeling method for the method of tracing the origin of gas generated during thermal runaway of the battery of the present invention;

[0049] Figure 6 Analysis method for the gas generation mechanism of the method of tracing the origin of gas generated during thermal runaway of the battery of the present invention. Detailed implementation manners

[0050] The present invention will be further described in detail below with reference to the accompanying drawings:

[0051] As Figures 2 to 6 shown, the present invention provides an isotope-based method for tracing the origin of gas generated during thermal runaway of a battery, which specifically includes the following steps:

[0052] S1: Isotopically label one of the battery materials, and prepare the isotopically labeled battery material into one of the isotopically labeled battery components; prepare the unlabeled battery material into one of the unlabeled battery components; wherein, the battery material is the material for preparing the battery positive electrode or the material for preparing the battery electrolyte; one of the battery components is the battery electrolyte or the battery positive electrode;

[0053] S2: Conduct adiabatic thermal runaway experiments on one of the isotopically labeled battery components and one of the unlabeled battery components respectively to obtain the gas generation composition of one of the isotopically labeled battery components and the gas generation composition of one of the unlabeled battery components;

[0054] S3: Compare the gas generation composition of one of the isotopically labeled battery components with the gas generation composition of one of the unlabeled battery components to obtain the gas generation source of the target gas.

[0055] In a preferred implementation manner of the present invention,

[0056] S1: Isotopically label the material for preparing the battery electrolyte, and prepare the isotopically labeled material for preparing the battery electrolyte into an isotopically labeled battery electrolyte; prepare the unlabeled material for preparing the battery electrolyte into an unlabeled battery electrolyte;

[0057] S2: Conduct adiabatic thermal runaway experiments on the isotopically labeled battery electrolyte and the unlabeled battery electrolyte respectively to obtain the gas generation composition of the isotopically labeled electrolyte and the gas generation composition of the unlabeled battery electrolyte;

[0058] S3: Compare the gas generation composition of the isotopically labeled battery electrolyte with the gas generation composition of the unlabeled battery electrolyte to obtain the gas generation source of the target gas.

[0059] Taking ethylene carbonate (EC), a common organic solvent for battery electrolytes, as an example, the aforementioned steps S1 to S3 will be exemplarily described.

[0060] In step S1, 13 C is used to replace 12 C in the organic solvent EC to obtain isotope-labeled 13 C-EC; this isotope-labeled 13 C-EC and other substances that make up the battery electrolyte are jointly prepared into a battery electrolyte to obtain an isotope-labeled battery electrolyte ( 13 C-EC). As a control, unlabeled EC and other substances that make up the battery electrolyte are jointly prepared into an unlabeled battery electrolyte ( 12 C-EC). The difference between the isotope-labeled battery electrolyte ( 13 C-EC) and the unlabeled battery electrolyte ( 12 C-EC) lies only in whether 12 C in EC is replaced by 13 C.

[0061] In step S2, an adiabatic thermal runaway experiment is carried out on the isotope-labeled battery electrolyte ( 13 C-EC), the gas is collected and detected to obtain the gas production composition of the isotope-labeled battery electrolyte ( 13 C-EC); an adiabatic thermal runaway experiment is carried out on the unlabeled battery electrolyte ( 12 C-EC), the gas is collected and detected to obtain the gas production composition of the unlabeled battery electrolyte ( 12 C-EC). When the isotope-labeled battery electrolyte ( 13 C-EC) and the unlabeled battery electrolyte ( 12 C-EC) are subjected to the adiabatic thermal runaway experiment, all the condition parameters during the experiment are exactly the same. The test process for analyzing the gas production composition of the isotope-labeled battery electrolyte ( 13 C-EC) and the unlabeled battery electrolyte ( 12 C-EC) is also exactly the same.

[0062] In step S3, the gas production composition of the isotope-labeled battery electrolyte ( 13 C-EC) is compared with the gas production composition of the unlabeled battery electrolyte ( 12 C-EC) to obtain the gas production source of the target gas. Assuming the target gas is CO, in the gas production composition of the isotope-labeled battery electrolyte ( 13 C-EC), 13 CO accounts for that in the unlabeled battery electrolyte ( 12The proportion of CO in the gas production composition of C-EC is the proportion of CO produced by EC in the battery electrolyte. By isotopically labeling each component of the battery electrolyte and the battery positive electrode respectively, the source of CO and the proportion of each source can be finally obtained, and then technicians can be guided to reduce the dosage of the component with a high CO production rate.

[0063] In a preferred embodiment of the present invention,

[0064] S1: Isotopically label the materials for preparing the battery positive electrode, and prepare the isotopically labeled materials for preparing the battery positive electrode into an isotopically labeled battery positive electrode; prepare the materials for preparing the battery positive electrode without isotopic labeling into an unlabeled battery positive electrode;

[0065] S2: Conduct adiabatic thermal runaway experiments on the isotopically labeled battery positive electrode and the unlabeled battery positive electrode respectively to obtain the gas production composition of the isotopically labeled positive electrode and the gas production composition of the unlabeled battery positive electrode;

[0066] S3: Compare the gas production composition of the isotopically labeled battery positive electrode with the gas production composition of the unlabeled battery positive electrode to obtain the gas production source of the target gas.

[0067] Taking the commonly used material of the battery positive electrode, polyvinylidene fluoride (abbreviated as PVDF) for example, the foregoing steps S1 to S3 are illustratively described.

[0068] In step S1, replace H in PVDF with D to obtain isotopically labeled D-PVDF; prepare the isotopically labeled D-PVDF and other substances constituting the battery positive electrode into a battery positive electrode together to obtain an isotopically labeled battery positive electrode (D-PVDF). As a control, prepare the unlabeled PVDF and other substances constituting the battery positive electrode into an unlabeled battery positive electrode (H-PVDF). The difference between the isotopically labeled battery positive electrode (D-PVDF) and the unlabeled battery positive electrode (H-PVDF) is only whether H in PVDF is replaced by D.

[0069] In step S2, an adiabatic thermal runaway experiment is carried out on the positive electrode of the isotope-labeled battery (D-PVDF), the gas is collected and detected to obtain the gas production composition of the positive electrode of the isotope-labeled battery (D-PVDF); an adiabatic thermal runaway experiment is carried out on the positive electrode of the unlabeled battery (H-PVDF), the gas is collected and detected to obtain the gas production composition of the positive electrode of the unlabeled battery (H-PVDF). When the positive electrode of the isotope-labeled battery (D-PVDF) and the positive electrode of the unlabeled battery (H-PVDF) are subjected to the adiabatic thermal runaway experiment, all the condition parameters during the experiment are exactly the same. The test processes for analyzing the gas production compositions of the positive electrode of the isotope-labeled battery (D-PVDF) and the positive electrode of the unlabeled battery (H-PVDF) are also exactly the same.

[0070] In step S3, the gas production compositions of the positive electrode of the isotope-labeled battery (D-PVDF) and the positive electrode of the unlabeled battery (H-PVDF) are compared to obtain the gas production source of the target gas. Assuming the target gas is HF, the ratio of DF in the gas production composition of the positive electrode of the isotope-labeled battery (D-PVDF) to HF in the gas production composition of the positive electrode of the unlabeled battery (H-PVDF) is the proportion of HF produced by PVDF in the positive electrode of the battery. By isotope-labeling each constituent substance of the battery electrolyte and the battery positive electrode respectively, the source of HF and the proportion of each source can be finally obtained, and then technicians can be guided to reduce the dosage of the constituent substance with a higher HF production.

[0071] It can be seen from the above exemplary description that when each constituent in the battery electrolyte and the battery positive electrode is isotope-labeled, the main gas production source and the secondary gas production source of the target gas can be obtained, and the main release source of the toxic and harmful gas can be found, which can be used to guide the material ratio scheme during the preparation of lithium-ion batteries, reduce the proportion of this material or replace this material. By using isotopes to label the battery electrolyte material or the battery positive electrode material, the movement and transformation of these labeled elements can be traced, the specific path of gas generation can be traced back, so as to determine the chemical reactions participated by the battery electrolyte material or the battery positive electrode material during the thermal runaway process, reveal the chain reaction mechanism of gas production during the thermal runaway of lithium-ion batteries, achieve the precise traceability of the gas production components, and further be used to guide the material ratio scheme during the preparation of lithium-ion batteries, thereby reducing the risk of gas production during thermal runaway and achieving the ultimate goal of improving battery safety.

[0072] In a preferred embodiment of the present invention, in step S1, select 13 C, D, 18 any one of O to isotope-label the battery material (such as Figure 6)。More preferably, the material for preparing the battery electrolyte is an organic solvent; and / or, the material for preparing the battery positive electrode is a binder; therefore, one of the organic solvents of the battery electrolyte is isotope-labeled; and / or, one of the binders of the battery positive electrode is isotope-labeled.

[0073] Exemplarily, the electrolyte part is with 13 C replacing 12 C in the organic solvent, which is "isotope-labeling the organic solvent of the electrolyte part". Preferably, the organic solvents of the battery electrolyte include but are not limited to any one of ethylene carbonate (abbreviated as EC), dimethyl carbonate (abbreviated as DMC), and ethyl methyl carbonate (abbreviated as EMC). Taking EC and DMC as examples, the labeled chemical substances are as Figure 4 shown. Specifically in this embodiment, the positive electrode part is with 13 C replacing 12 C in the binder, which is "isotope-labeling the binder of the positive electrode part". Preferably, the binder is polyvinylidene fluoride or sodium carboxymethyl cellulose.

[0074] In a preferred embodiment of the present invention, in step S2, an adiabatic thermal runaway experiment is carried out in an accelerating rate calorimeter (ARC), specifically in the test container of the accelerating rate calorimeter for the adiabatic thermal runaway experiment, and the test container is generally a sealed metal can. Preferably, when carrying out the adiabatic thermal runaway experiment, the test container is evacuated and replaced with an inert gas; and / or, the initial temperature of the test container is 40 - 50 °C; and / or, the step temperature is 4 - 6 °C; and / or, the holding time at each temperature is 25 - 35 min; and / or, the time for collecting gas is after the battery thermal runaway until it returns to the ambient temperature; and / or, gas chromatography-mass spectrometry (GC-MS) is used to detect the collected gas. More preferably, the inert gas in the test container is nitrogen or argon; the pressure of the test container is 0.8 - 1.2 bar.

[0075] In a preferred embodiment of the present invention, the target gas is at least one of carbon monoxide, hydrogen, oxygen, and methane. The following will exemplarily illustrate "comparing the gas production composition of the isotope-labeled battery electrolyte or the isotope-labeled battery positive electrode, and the gas production composition of the unlabeled battery electrolyte or the unlabeled battery positive electrode to obtain the gas production source of the target gas" in step S3. Assume that the isotope-labeled material is prepared as an isotope-labeled battery electrolyte, and 13 C is used to replace 12 C in the organic solvent of the electrolyte part, and the target gas is CO. First, 13 C is used to replace 12 C in EC, and after preparing it into a battery electrolyte, an adiabatic thermal runaway experiment is carried out, the gas is collected and detected to obtain 13 the gas production composition of the battery electrolyte made of 12 C-EC. Secondly, after preparing the unlabeled EC into a battery electrolyte, an adiabatic thermal runaway experiment is carried out, the gas is collected and detected to obtain the gas production composition generated by the battery electrolyte made of EC. It should be noted that this battery electrolyte is basically the same as the previous battery electrolyte, except that 13 C in its EC is not replaced with 13 CO / 12 CO ratio ( 13 C-EC). Similarly, using 13 C to replace 12 C in DMC, the 13 CO / 12 CO ratio ( 13 C-DMC) can be obtained; using 13 C to replace 12 C in EMC, the 13 CO / 12 CO ratio ( 13 C-EMC) can be obtained. Comparing the 13 CO / 12 CO ratio ( 13 C-EC), 13 CO / 12 CO ratio ( 13 C-DMC), 13 CO / 12 CO ratio ( 13 C-EMC) can obtain the ratio of CO generated by different organic solvents in the electrolyte part. Assume that the electrolyte part labeled 13 C-EC generates 13 CO at a ratio of 90 / 10, and the electrolyte part labeled 13 C-DMC generates 13The proportion of CO is 10 / 90, and the electrolyte part is marked 13 C-EMC is generated 13 If the proportion of CO is 90 / 10, it means that the main source of CO generated in the electrolyte part is EC.

[0076] In a preferred embodiment of the present invention, as Figure 5 shown, step S1 further includes: preparing one of the isotope-labeled battery components into an isotope-labeled battery cell; preparing one of the unlabeled battery components into an unlabeled battery cell; step S2 further includes: performing adiabatic thermal runaway experiments on the isotope-labeled battery cell and the unlabeled battery cell respectively to obtain the gas generation components of the isotope-labeled battery cell and the gas generation components of the unlabeled battery cell; step S3 further includes: comparing the gas generation components of the isotope-labeled battery cell and the gas generation components of the unlabeled battery cell to obtain the gas generation source of the target gas. This embodiment is the battery thermal runaway gas generation traceability test method at the battery cell level.

[0077] Taking ethylene carbonate (EC), a common organic solvent in battery electrolytes, as an example, steps S1 to S3 of this embodiment are exemplarily described.

[0078] In step S1, use 13 C to replace 12 C in the organic solvent EC to obtain isotope-labeled 13 C-EC; use this isotope-labeled 13 C-EC and other substances constituting the battery electrolyte to jointly prepare a battery electrolyte to obtain an isotope-labeled battery electrolyte ( 13 C-EC); combine the isotope-labeled battery electrolyte ( 13 C-EC) with the battery positive electrode and the battery negative electrode to jointly prepare an isotope-labeled battery cell ( 13 C-EC). As a control, EC without isotope labeling and other substances constituting the battery electrolyte are jointly used to prepare an unlabeled battery electrolyte ( 12 C-EC), and the unlabeled battery electrolyte ( 12 C-EC) is combined with the battery positive electrode and the battery negative electrode to jointly prepare an unlabeled battery cell ( 12 C-EC). The difference between the isotope-labeled battery cell ( 13 C-EC) and the unlabeled battery cell ( 12 C-EC) is only whether the 12 C in EC is replaced by 13 C.

[0079] In step S2, perform an adiabatic thermal runaway experiment on the isotope-labeled battery cell ( 13 C-EC), collect the gas and perform detection to obtain the isotope-labeled battery cell (13 The gas production composition of (C-EC); for the unlabeled battery cell ( 12 (C-EC) was subjected to an adiabatic thermal runaway experiment, the gas was collected and detected, and the gas production composition of the unlabeled battery cell ( 12 (C-EC) was obtained. The isotope-labeled battery cell ( 13 (C-EC) and the unlabeled battery cell ( 12 (C-EC), when both were subjected to an adiabatic thermal runaway experiment, all the condition parameters during the experiment were exactly the same. The gas production composition of the isotope-labeled battery cell ( 13 (C-EC), and the gas production composition of the unlabeled battery cell ( 12 (C-EC), the test processes for analyzing their gas production compositions were also exactly the same.

[0080] In step S3, by comparing the gas production composition of the isotope-labeled battery cell ( 13 (C-EC) with the gas production composition of the unlabeled battery cell ( 12 (C-EC), the gas production source of the target gas was obtained. Assuming the target gas is CO, in the gas production composition of the isotope-labeled battery cell ( 13 (C-EC) 13 the proportion of CO in the gas production composition of the unlabeled battery cell ( 12 (C-EC) is the proportion of CO produced by EC in the electrolyte of the battery cell.

[0081] Taking the commonly used material for the battery positive electrode, polyvinylidene fluoride (Polyvinylidene fluoride, abbreviated as PVDF) as an example, steps S1 to S3 of this embodiment will be exemplarily described.

[0082] In step S1, H in PVDF was replaced with D to obtain the isotope-labeled D-PVDF; the isotope-labeled D-PVDF and other substances constituting the battery positive electrode were used to prepare the battery positive electrode together, and the isotope-labeled battery positive electrode (D-PVDF) was obtained; the isotope-labeled battery positive electrode (D-PVDF), the battery electrolyte, and the battery negative electrode were used to prepare the isotope-labeled battery cell (D-PVDF) together. As a control, the unlabeled PVDF and other substances constituting the battery positive electrode were used to prepare the unlabeled battery positive electrode (H-PVDF); the unlabeled battery positive electrode (H-PVDF), the battery electrolyte, and the battery negative electrode were used to prepare the unlabeled battery cell (H-PVDF) together. The difference between the isotope-labeled battery cell (D-PVDF) and the unlabeled battery cell (H-PVDF) is only whether H in PVDF is replaced by D.

[0083] In step S2, an adiabatic thermal runaway experiment is carried out on the isotope-labeled battery cell (D-PVDF), the gas is collected and detected to obtain the gas production composition of the isotope-labeled battery cell (D-PVDF); an adiabatic thermal runaway experiment is carried out on the unlabeled battery cell (H-PVDF), the gas is collected and detected to obtain the gas production composition of the unlabeled battery cell (H-PVDF). When the isotope-labeled battery cell (D-PVDF) and the unlabeled battery cell (H-PVDF) carry out the adiabatic thermal runaway experiment, all the condition parameters during the experiment are exactly the same. The test process of the gas production composition analysis of the gas production composition of the isotope-labeled battery cell (D-PVDF) and the unlabeled battery cell (H-PVDF) is also exactly the same.

[0084] In step S3, the gas production composition of the isotope-labeled battery cell (D-PVDF) is compared with the gas production composition of the unlabeled battery cell (H-PVDF) to obtain the gas production source of the target gas. Assuming that the target gas is HF, the proportion of DF in the gas production composition of the isotope-labeled battery cell (D-PVDF) to HF in the gas production composition of the unlabeled battery cell (H-PVDF) is the proportion of PVDF producing HF in the positive electrode of the battery cell.

[0085] In a preferred embodiment of the present invention, the battery thermal runaway gas production traceability test method further includes the following steps:

[0086] S4: Each organic solvent in the material for preparing the battery electrolyte is respectively isotope-labeled and then respectively prepared into battery cells, and each binder in the material for preparing the battery positive electrode is respectively isotope-labeled and then respectively prepared into battery cells to obtain the gas production source of each target gas.

[0087] S5: Based on the gas production composition of the unlabeled battery cell in step S3, the risk level of the battery cell is obtained. If the risk level of the battery cell is high risk, the amount of the organic solvent and / or the binder is adjusted based on the gas production source of each target gas in step S4.

[0088] S6: After adjusting the battery materials, they are prepared into battery cells and subjected to adiabatic thermal runaway to obtain the gas production composition (unlabeled) of the adjusted battery cells. After adjusting the battery materials, each organic solvent in the material for preparing the battery electrolyte is respectively isotope-labeled and then respectively prepared into battery cells, and each binder in the material for preparing the battery positive electrode is respectively isotope-labeled and then respectively prepared into battery cells to obtain the gas production source of each target gas in the adjusted battery cells.

[0089] S7: Obtain the risk level of the adjusted battery cell based on the gas production composition of the adjusted battery cell. If the risk level of the battery cell is low risk, determine the battery materials and their ratios of the battery cell. If the risk level of the battery cell is high risk, adjust the dosage of the organic solvent and / or binder based on the gas production source of each target gas in the adjusted battery cell.

[0090] Repeat steps S6 - S7 until the risk level of the adjusted battery cell is low risk, then determine the battery materials and their ratios of the battery cell.

[0091] It should be noted specifically that the methods for preparing the battery electrolyte, the battery positive electrode, and the battery cell are exactly the same as the prior art, except that one of the materials is isotope - labeled before preparing the battery. Those skilled in the art can prepare according to the original method of the battery. Exemplarily, the method of "Electrode Preparation and Battery Assembly" in "Preparation and Performance Research of New Type Power Lithium - Ion Electrode Materials" (Doctoral Dissertation of Liu Jianhong from Beijing Institute of Technology, published in 2015) can be referred to.

[0092] Example 1

[0093] For the ternary / graphite system lithium - ion battery, the gas production source tracing test method of the invented battery is used for testing. The specific steps include:

[0094] (1) Prepare the battery electrolyte with un - isotope - labeled EC. The battery electrolyte is specifically: 1M LiPF6 / (EC:EMC:DMC = 1:1:1 wt%). Put the battery electrolyte into the sealed metal can of the ARC for adiabatic thermal runaway experiment. Before the test, evacuate the air in the metal can and then replace it with nitrogen to 1 bar. Set the starting temperature of the ARC to 50 °C, and the step temperature to 5 °C until the battery undergoes thermal runaway (in this example, the battery thermal runaway means that the temperature of the battery increases rapidly at a rate higher than 1 °C / s). After the battery undergoes thermal runaway, collect the gas when the temperature returns to room temperature, and send the gas into the GC - MS for gas component and content detection to obtain 12 The gas types and contents produced by the battery electrolyte made of EC (as shown in Table 1). It should be noted that N2 is the protective gas introduced in the adiabatic thermal runaway experiment and is not the thermal runaway gas produced by the battery materials.

[0095] Table 1 Gas production composition of the un - isotope - labeled battery electrolyte

[0096]

[0097] (2) Replace 13 C in EC with 12 C to obtain 13 C - EC. Put 13C-EC is prepared as a battery electrolyte. The battery electrolyte is specifically: 1M LiPF6 / ( 13 C-EC:EMC:DMC = 1:1:1 wt%), abbreviated as 13 C-EC battery electrolyte. Put this battery electrolyte into a sealed metal can of ARC for an adiabatic thermal runaway experiment. Before the test, evacuate the air in the metal can and then replace it with nitrogen to 1 bar. Set the starting temperature of ARC to 50 °C and the step temperature to 5 °C until the battery undergoes thermal runaway (in this example, the thermal runaway of the battery means that the temperature of the battery increases rapidly at a rate higher than 1 °C / s). After the battery undergoes thermal runaway, collect the gas when the temperature returns to room temperature, and send the gas to GC-MS for gas component and content detection to obtain 13 the gas types and contents generated by the battery electrolyte prepared from C-EC (as shown in Table 2). It should be noted that N2 is the protective gas introduced in the adiabatic thermal runaway experiment and is not the gas generated by the thermal runaway of the battery material.

[0098] Table 2 Gas production composition of the battery electrolyte with isotope labeling

[0099]

[0100] (3) Analyzing the data in Table 1 and Table 2, it can be seen that in the gas production composition of the battery electrolyte ( 13 C-EC), the proportion of labeled 13 C-EC generating 13 CO is 86 / 14.

[0101] (4) Repeat steps (1) to (3), with the only difference being that 13 C is used to replace 13 C in 12 C-DEC. The results show that in the gas production composition of the battery electrolyte ( 13 C-DEC), the proportion of labeled 13 C-DEC generating 13 CO is 3 / 97.

[0102] (5) Repeat steps (1) to (3), with the only difference being that 13 C is used to replace 13 C in 12 C-EMC. The results show that in the gas production composition of the battery electrolyte ( 13 C-EMC), the proportion of labeled 13 C-EMC generating 13 CO is 8 / 92.

[0103] It can be seen that when the battery electrolyte is labeled 13 C-EC, the 13The CO ratio is the highest. In other words, the main source of CO generated by the battery electrolyte is EC.

[0104] It should be noted that the analysis methods for the remaining carbon-containing target gases are basically the same as those in this embodiment, except that the substances for isotope labeling and the target gases are different. Similarly, for target gases such as H2, CH4, and O2, D or 18 O labeling can be used to detect the source. Therefore, the method of this embodiment can be used to perform isotope labeling on different battery components (battery electrolyte or battery positive electrode), and then obtain the ratio of target gases generated by different battery materials.

[0105] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0106] In the description of the present invention, unless otherwise specified, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0107] The above technical solution is only one implementation manner of the present invention. For those skilled in the art, based on the disclosed principle of the present invention, it is very easy to make various types of improvements or deformations, not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the foregoing description is only preferred and does not have a restrictive meaning.

Claims

1. An isotope-based method for tracing the gas generation during battery thermal runaway, characterized in that, Comprising: S1: Isotopically label one of the battery materials, and prepare the isotopically labeled battery material as one of the isotopically labeled battery components; prepare the unlabeled battery material as one of the unlabeled battery components; wherein, the battery material is a material for preparing a battery positive electrode or a material for preparing a battery electrolyte; one of the battery components is a battery electrolyte or a battery positive electrode; S2: Conduct adiabatic thermal runaway experiments on one of the isotopically labeled battery components and one of the unlabeled battery components respectively, to obtain the gas generation composition of one of the isotopically labeled battery components and the gas generation composition of one of the unlabeled battery components; S3: Compare the gas generation composition of one of the isotopically labeled battery components with the gas generation composition of one of the unlabeled battery components to obtain the gas generation source of the target gas.

2. The battery thermal runaway gas generation traceability test method according to claim 1, wherein Comprising: S1: Isotopically label the material for preparing the battery electrolyte, and prepare the isotopically labeled material for preparing the battery electrolyte as an isotopically labeled battery electrolyte; prepare the unlabeled material for preparing the battery electrolyte as an unlabeled battery electrolyte; S2: Conduct adiabatic thermal runaway experiments on the isotopically labeled battery electrolyte and the unlabeled battery electrolyte respectively, to obtain the gas generation composition of the isotopically labeled electrolyte and the gas generation composition of the unlabeled battery electrolyte; S3: Compare the gas generation composition of the isotopically labeled battery electrolyte with the gas generation composition of the unlabeled battery electrolyte to obtain the gas generation source of the target gas.

3. The method for testing the origin tracing of gas generated by battery thermal runaway according to claim 1, characterized in that, Comprising: S1: Isotopically label the material for preparing the battery positive electrode, and prepare the isotopically labeled material for preparing the battery positive electrode as an isotopically labeled battery positive electrode; prepare the unlabeled material for preparing the battery positive electrode as an unlabeled battery positive electrode; S2: Conduct adiabatic thermal runaway experiments on the isotopically labeled battery positive electrode and the unlabeled battery positive electrode respectively, to obtain the gas generation composition of the isotopically labeled positive electrode and the gas generation composition of the unlabeled battery positive electrode; S3: Compare the gas generation composition of the isotopically labeled battery positive electrode with the gas generation composition of the unlabeled battery positive electrode to obtain the gas generation source of the target gas.

4. The battery thermal runaway gas generation traceability test method according to any one of claims 1 to 3, characterized in that, In step S1, choose 13 C、D、 18 Any one of O isotopically labeled the battery material.

5. The battery thermal runaway gas generation traceability test method according to any one of claims 1 to 3, characterized in that, In step S1, The material for preparing the battery electrolyte is an organic solvent; and / or, The material for preparing the battery positive electrode is a binder; Preferably, The organic solvent is any one of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate; and / or, The binder is polyvinylidene fluoride or sodium carboxymethyl cellulose.

6. The battery thermal runaway gas generation traceability test method according to any one of claims 1 to 3, characterized in that, In step S2, conduct the adiabatic thermal runaway experiment in an adiabatic accelerating calorimeter.

7. The battery thermal runaway gas generation traceability test method according to claim 6, wherein, In step S2, The initial temperature in the test container of the adiabatic accelerating calorimeter is 40 - 50 °C; and / or, The step temperature in the test container of the adiabatic accelerating calorimeter is 4 - 6 °C; and / or, The holding time for each temperature in the test container of the adiabatic accelerating calorimeter is 25 - 35 min.

8. The battery thermal runaway gas generation traceability test method according to claim 6, wherein In step S2, The test container of the adiabatic accelerating calorimeter is evacuated and replaced with an inert gas; Preferably, The inert gas is nitrogen or argon; and / or, The pressure in the test container of the adiabatic accelerating calorimeter is 0.8 - 1.2 bar.

9. The battery thermal runaway gas generation traceability test method according to any one of claims 1 to 3, characterized in that, In step S3, The target gas is at least one of carbon monoxide, hydrogen, oxygen, and methane.

10. The method for tracing the origin of gas generated during thermal runaway of a battery according to any one of claims 1 to 3, characterized in that Step S1 further includes: preparing one of the isotope-labeled battery components into an isotope-labeled battery cell; preparing one of the unlabeled battery components into an unlabeled battery cell; Step S2 further includes: respectively performing adiabatic thermal runaway experiments on the isotope-labeled battery cell and the unlabeled battery cell to obtain the gas generation composition of the isotope-labeled battery cell and the gas generation composition of the unlabeled battery cell; Step S3 further includes: comparing the gas generation composition of the isotope-labeled battery cell and the gas generation composition of the unlabeled battery cell to obtain the gas generation source of the target gas.

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