CN-122016140-A - Lithium ion battery thermal runaway whole-process pressure testing method

CN122016140ACN 122016140 ACN122016140 ACN 122016140ACN-122016140-A

Abstract

The invention provides a lithium ion battery thermal runaway whole process pressure testing method, which relates to the technical field of lithium ion battery testing and comprises the steps of determining the required number of standby tank bodies based on the total gas production amount in the thermal runaway of a lithium ion battery to be tested, sequentially assembling the base tank bodies, the required number of standby tank bodies and a cover plate to form a current testing tank body, placing the lithium ion battery to be tested into the current testing tank body, then heating the lithium ion battery to be tested, continuously monitoring the real-time pressure in the current testing tank body, and further processing to obtain the thermal runaway whole process pressure change of the lithium ion battery to be tested. The method has the advantages of ensuring the sensitivity and accuracy of pressure data in the initial stage of thermal runaway, solving the difficult problem that the pressure is suddenly increased and the equipment range is exceeded due to insufficient volume in the later stage of mass gas production, and truly realizing the whole-process pressure data breakpoint-free acquisition from the triggering of the thermal runaway to the stable stage.

Inventors

DING LEI
JIN KAIQIANG
JI JINGJING
CHENG ZHIXIANG
LU XIAOAN
WANG QINGSONG

Assignees

上海轩邑新能源发展有限公司
中国科学技术大学

Dates

Publication Date: 20260512
Application Date: 20251223

Claims (10)

1. The method is characterized by adopting a variable volume test tank body for testing, wherein the variable volume test tank body comprises a base tank body with an opening at the top, a plurality of standby tank bodies with two openings at the two ends and a cover plate, and the method comprises the following steps: step S1, determining the required number of the standby tank bodies based on the total gas production amount when the lithium ion battery to be tested is in thermal runaway; s2, sequentially assembling the base tank body, the standby tank bodies with required numbers and the cover plate to form a current test tank body; And S3, placing the lithium ion battery to be tested into the current test tank body, then heating the lithium ion battery to be tested, continuously monitoring the real-time pressure in the current test tank body, and further processing to obtain the thermal runaway whole-process pressure change of the lithium ion battery to be tested.
2. The method according to claim 1, wherein the step S1 is further performed before the step S1 is performed, further comprising testing the total amount of generated gas, including: A1, calculating a predicted gas yield according to the capacity of the lithium ion battery to be tested; and step A2, placing the lithium ion battery to be tested into a large-sized closed tank body for thermal runaway test so as to obtain the actual total gas production amount, wherein the tank body volume of the large-sized closed tank body is larger than the estimated gas production amount.
3. The method according to claim 2, wherein in step S1, the required number is determined according to the following formula: ; Wherein, the In order to achieve the desired number of said units, For the total amount of gas produced in the process, 1 For the required volume of the current test tank body Is at a standard atmospheric pressure, and is at a pressure of one of the standard atmospheres, The tank body of the large-scale closed tank body is safe and pressure-resistant, For the volume of the base tank, Is the volume of the standby tank body.
4. The lithium ion battery thermal runaway whole process pressure testing method according to claim 1, wherein an external thread is arranged at the top opening of the base tank body, an internal thread is arranged at the opening at one end of the standby tank body, and an external thread is arranged at the opening at the other end of the standby tank body; a plurality of threaded holes are formed in the top opening of the base tank body, the opening of the standby tank body provided with the external threads and the cover plate; in step S2, the base tank body and the spare tank body are connected by threads, and then the cover plate is assembled to the top opening by passing through the threaded holes by corresponding bolts, so as to form the current test tank body.
5. The lithium ion battery thermal runaway whole process pressure testing method according to claim 4, wherein the ends of the base tank body and the standby tank body, on which the threaded holes are formed, are further provided with gasket openings; In the step S2, before the base tank body is assembled with the spare tank body, the spare tank body is assembled with the spare tank body and the cover plate, a gasket is placed into each corresponding gasket opening; the gasket is a fluorinated rubber ring.
6. The method for testing the thermal runaway whole process pressure of the lithium ion battery according to claim 1, wherein the cover plate is integrated with an inflation port, a pressure pipeline interface and a deflation port, and the method further comprises the step of performing pressure maintaining test on the current test tank body before executing the step S3: And installing a pressure sensor on the pressure pipeline interface, introducing nitrogen into the current test tank body through the inflation inlet, then monitoring the internal air pressure of the current test tank body acquired by the pressure sensor, and indicating that the pressure maintaining test is passed when the internal air pressure does not drop within a certain period of time, and then deflating the current test tank body to normal pressure through the deflation inlet, and then executing the step S3.
7. The method for testing the thermal runaway whole process pressure of the lithium ion battery according to claim 1, wherein the cover plate is integrated with a pole and a pressure pipeline interface, and the step S3 further comprises: and a heating component which is in contact with the lithium ion battery is arranged in the current test tank body, the heating component is electrically connected with the polar column, so that the polar column supplies power for the heating component, the lithium ion battery to be tested is heated, and the real-time pressure is continuously monitored through a pressure sensor arranged at a pressure pipeline interface.
8. The method for testing the thermal runaway overall process pressure of the lithium ion battery according to claim 1, wherein in the step S3, a thermocouple interface is integrated on the cover plate for accessing a thermocouple; In the step S3, the method further includes continuously monitoring the real-time temperature in the current test tank body through the thermocouple.
9. The method according to claim 1, wherein in step S3, before the lithium ion battery to be tested is placed in the current test can, the safety valve or the upper cover plate of the lithium ion battery to be tested is adjusted to a non-sealing state.
10. The method according to claim 1, wherein in step S3, the internal pressure of the lithium ion battery to be tested in the thermal runaway process is obtained by processing according to the following formula to characterize the pressure change: ; Wherein, the For the internal pressure of the battery, For the said real-time pressure to be applied, For the volume of the internal empty region of the lithium ion battery, Is the volume of the current test tank.

Description

Lithium ion battery thermal runaway whole-process pressure testing method Technical Field The invention relates to the technical field of lithium ion battery testing, in particular to a lithium ion battery thermal runaway whole-process pressure testing method. Background The square lithium iron phosphate battery is widely applied to a plurality of important fields such as new energy electric automobiles, electric commercial vehicles, large-scale energy storage power stations, portable electronic equipment and the like by virtue of excellent safety, cycle life and cost advantages, and becomes a core support for promoting transportation electrodynamic property and energy storage intellectualization. Meanwhile, with the continuous expansion of application scenes, the market puts forward increasingly stringent requirements on the energy density, the working multiplying power and the application scale of the lithium ion battery, and the stable operation of a large-scale battery pack under the high-multiplying power charge-discharge working condition becomes a focus of industry attention. However, in a high-rate working state of a large-scale lithium ion battery, the electrode reaction rate is rapidly accelerated, a large amount of joule heat and reaction heat can be generated, and if the heat dissipation system cannot timely conduct out the heat, the temperature of the battery can be rapidly increased, so that a heat accumulation effect is formed. The electrochemical performance of the lithium ion battery is extremely sensitive to temperature, the high-temperature environment can lead to rapid decay of the battery capacity and greatly shortened cycle life, and more seriously, when the temperature exceeds a critical threshold value, a series of severe side reactions can be initiated in the battery, including electrolyte decomposition, electrode material structure collapse and the like, so as to trigger a thermal runaway phenomenon. During thermal runaway, a large amount of inflammable and explosive gases (such as hydrogen, methane, carbon monoxide and the like) are generated, and the gases have strong corrosiveness and can accumulate in a closed space to form explosive mixed gas, so that serious safety accidents such as explosion, fire and the like can be caused once an ignition source is encountered, and great threat is caused to personnel life safety and property safety. Therefore, the gas production characteristics and the pressure change rule in the thermal runaway process of the lithium ion battery become core research hot spots in the field of new energy safety gradually. In order to reduce or even eliminate the damage caused by thermal runaway of lithium ion batteries, there is a need in the industry to design efficient and reliable pressure relief buffer measures and accurate early warning systems. The key premise of the method is to comprehensively and accurately master the gas production rule and pressure change characteristics of the target battery in the working process, especially in the whole thermal runaway process, including complete data of an extremely early trace gas production stage, an intermediate gas production acceleration stage and a later gas production stabilization stage, no matter the parameters of the pressure relief structure are optimized, or the pre-warning threshold is scientifically set. At present, a method for testing the thermal runaway pressure of a lithium ion battery in the industry mostly adopts a testing tank body with a fixed volume. However, in the practical testing process, the method has obvious technical bottlenecks that the gas yield of a battery is extremely small in the extremely early stage of thermal runaway, if the volume of a test tank body is excessively large, generated trace gas cannot enable the pressure in the tank body to form effective fluctuation which can be accurately captured by a sensor, so that extremely early pressure data is distorted or lost, if the tank body with the extremely small volume is selected for adapting to the extremely early testing requirement, the gas yield is rapidly increased along with the progress of the thermal runaway, the pressure in the tank body can rapidly rise in a short time, the measuring range of the pressure sensor is possibly exceeded, the test is interrupted, and the problem of safety risk and equipment damage is more likely to be caused by the fact that the sealing failure or even burst of the test tank body is caused by the excessively high pressure. Therefore, how to match the gas production characteristics of the whole thermal runaway process provides a testing scheme capable of flexibly adjusting the volume, and becomes a key technical problem to be solved in the field of the current thermal runaway pressure testing of lithium ion batteries. Disclosure of Invention The invention provides a method for testing the thermal runaway whole process pressure of a lithium ion battery, aiming at the problems existing