不同封装条件下锂离子电池内部氢气泄漏行为的研究

Translated title of the contribution: Behaviors of Hydrogen Leakage in Lithium-Ion Batteries under Different Packing Conditions

Fuyi Yang, Siqi Lv, Na Li, Haosen Chen, Weili Song*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The growing demands for new energy vehicles, power grid energy storages and portable intelligent devices required more lithium-ion batteries (LIBs) with high specific capacity and outstanding safety standards coming into services. Ni-rich NCM (LiNixCoyMn1-x-y, Ni≧0.6) that the most promising materials had attracted the attention of many researchers and manufacturers. However, there were many undesirable and irreversible side reactions appearing in the cycles/storage process of NCM batteries, which originated from different parts inside batteries, including residual lithium compounds (RCLs), lattice oxygen vacancies and oxygen losses, gas evolution, intragranular and intergranular cracks et al. These problems were hugely influenced on the further applications of NCM positive materials. The chemical and electrochemical reactions at positive electrodes and positive electrode-electrolyte interface in lithium-ion batteries, which mainly resulted in the evolution of gases. In other words, the evolution and accumulation of hydrogen, methane, ethylene, carbon dioxide and other gases would affect not only the performance of batteries, but also the safety of batteries. Besides, these internal gases were crucial signals for evaluating health and safety of LIBs. Among these gases, the minimum combustible concentration of hydrogen was only 4%, that meant the safety of LIBs was vulnerable as hydrogen concentrated inside LIBs. As a consequence, detecting the leakage time and real-time concentration of hydrogen was very important to realize battery safety early warning. However, most of current researches and works focused on the evolution mechanism of hydrogen, and few on how to quantitatively detect the relationships between the leakage time of hydrogen and hydrogen concentration, hydrogen diffusion in batteries and differences of battery packaging configurations. In this work, a quantitative real-time detection method of hydrogen leakage in battery based on real packaging configurations was established by designing the operando detection tank and placing hydrogen sensor in the tank. (1) Different initial hydrogen concentrations were established by changing the volume of dilute sulfuric acid (1.0 mol·L-1) and the mass of zinc particles in the polytetrafluoroethylene column (replacement cells) placed inside battery configurations to study the effect of hydrogen concentration in different types of batteries on hydrogen leakage. When the initial concentration of hydrogen is the same(V=10 ml), hydrogen sensor detected hydrogen leakage outside battery configurations at time (t)=988, 1590, 1183 s (CC-2, PrC-2, PC-2). When the initial concentration of hydrogen was different (V=5, 10, 20, 50 ml), the higher concentration of hydrogen inside the same battery configuration, the more likely it was to leak and diffuse to the outside of the battery configuration. The results also showed that the hydrogen diffusion time in batteries decreased with the increasing concentration of hydrogen. The leakage of hydrogen was first detected outside the pouch battery configurations compared with the cylindrical and square battery configurations. (2) By increasing the amount of tab film in the packing process of pouch battery configuration to change the thickness of the packaging area, PC-1 rapidly diffused hydrogen inside the battery configuration from t=956 s to the outside of the battery after passing through the sealed area, and the hydrogen concentration outside the battery configuration did not change at about t=14400 s (4 h). Modified PC-1 after t=2929 s, the external hydrogen concentration slowly increased until t=11929 s, when the concentration did not change. At about t=4573 s, MPC-2 began to change the external hydrogen concentration and remained at a lower concentration (16×10-6), and the hydrogen leakage was delayed by 3582 s (about 10 min). Therefore, the hydrogen leakage problem of pouch battery configuration could be improved by increasing the thickness of the packaging area, i.e., extending the length of the diffusion path, by adding an additional 1~2 pieces of tab film. (3) A hydrogen diffusion configuration was constructed and compared with the experimental results of hydrogen leakage and diffusion in a flexible pouch battery configuration and a cylindrical battery configuration under the same initial conditions. The trend of hydrogen leakage and diffusion in the simulation results was similar to that in the experimental results of pouch battery configuration and cylindrical battery configuration. The internal hydrogen leakage diffusion rate of the battery changed with battery types changed. Within 4 h, the hydrogen accumulation outside the pouch battery configuration was about 25×10-6, while that of the cylindrical battery configuration was only about 3.2×10-6, which further indicated that the pouch battery configuration was more prone to hydrogen leakage and diffusion. Overall speaking, hydrogen leakage and diffusion occurred in different types of batteries, while the timing was different. Therefore, operando gas detection was very important for studying the gas evolution and safety warning in lithium-ion batteries. The in-situ gas leakage detection method established in this paper could also be combined with charge-discharge devices and gas chromatography-mass spectrometry devices to further quantitatively study the types of internal gas evolution and real-time concentration changes of lithium-ion batteries during cycles or storage. A new detection method for better studying the degradation mechanism of lithium-ion battery positive materials and realizing battery safety early warning was provided.

Translated title of the contributionBehaviors of Hydrogen Leakage in Lithium-Ion Batteries under Different Packing Conditions
Original languageChinese (Traditional)
Pages (from-to)813-820
Number of pages8
JournalXiyou jinshu
Volume46
Issue number6
DOIs
Publication statusPublished - Jun 2022

Fingerprint

Dive into the research topics of 'Behaviors of Hydrogen Leakage in Lithium-Ion Batteries under Different Packing Conditions'. Together they form a unique fingerprint.

Cite this

Yang, F., Lv, S., Li, N., Chen, H., & Song, W. (2022). 不同封装条件下锂离子电池内部氢气泄漏行为的研究. Xiyou jinshu, 46(6), 813-820. https://doi.org/10.13373/j.cnki.cjrm.XY21110021