Uncovering LiH Triggered Thermal Runaway Mechanism of a High‐Energy LiNi0.5Co0.2Mn0.3O2/Graphite Pouch Cell

• Published in: Advanced science Vol. 8; no. 14
• Main Authors: Huang, Lang, Xu, Gaojie, Du, Xiaofan, Li, Jiedong, Xie, Bin, Liu, Haisheng, Han, Pengxian, Dong, Shanmu, Cui, Guanglei, Chen, Liquan
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.07.2021; John Wiley and Sons Inc; Wiley
• Subjects: batteries; Corrosion; Efficiency; Electric vehicles; Electrolytes; Energy resources; Energy storage; Graphite; Heat; heat generation; Lithium; Renewable resources; Retention; Solvents; Temperature; thermal safety
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202100676

The continuous energy density increase of lithium ion batteries (LIBs) inevitably accompanies with the rising of safety concerns. Here, the thermal runaway characteristics of a high‐energy 5 Ah LiNi0.5Co0.2Mn0.3O2/graphite pouch cell using a thermally stable dual‐salt electrolyte are analyzed. The existence of LiH in the graphite anode side is innovatively identified in this study, and the LiH/electrolyte exothermic reactions and H2 migration from anode to cathode side are proved to contribute on triggering the thermal runaway of the pouch cell, while the phase transformation of lithiated graphite anode and the O2‐releasing from cathode are just accelerating factors for thermal runaway. In addition, heat determination during cycling at two boundary scenarios of adiabatic and isothermal environment clearly states the necessity of designing an efficient and smart battery thermal management system for avoiding heat accumulation. These findings will shed promising lights on thermal runaway route map depiction and thermal runaway prevention, as well as formulation of electrolyte for high energy safer LIBs. During elevated temperatures, pouch cell starts the heat accumulation process from the anode/electrolyte interfacial reactions, accompanied with a large amount of H2 producing. The anode‐liberated H2 then migrates to cathode side, cross‐interacting with the delithiated cathode to induce O2 releasing and tremendous heat generation, which further accelerates the exothermic chain reactions and leads to severe thermal runaway.