The advancement of lithium-ion battery (LIB) technology progressively demands innovations that increase energy density and reduce cost without compromising safety, mechanical resilience, and reliability. This requires innovation in the field of both battery materials and design. NextCell, as a part of an EU project, focuses on developing a gellified cell concept to provide a new 3b LIB generation. The innovation for this new cell is at the material level, by gellification of the electrode and separator, creating a hybrid system positioned between conventional liquid electrolyte (LE) and all-solid-state batteries. By combining the higher ionic conductivity of LE based system and enhanced safety and structural stability associated with solid-state batteries, the gellified cell concept tries to capture the strength of both technologies in a single safer and high-performance battery.

Gellified cells represent a compelling 3b-generation approach, promising advantages such as reduced leakage, enhanced structural stability, and potentially improved safety under abuse. According to the literature, the experiments indicated that the small gellified cells i.e., gel structure slowed down the thermal runaway mechanism [1],[2]. These tests were done on individual gellified components, and with systematic experimental validation. However, testing on higher capacity of such cells under severe conditions remains limited. Henceforth, in this work, the plan is to design a prototype of gellified LIBs and subject them to a comprehensive abuse testing protocol, including nail penetration, internal short circuit, overcharge, overdischarge, overheating, and mechanical crush. The test protocols will be designed according to relevant standards such as FreedomCAR and IEC 62660-2.

Expected results would be the evolution of current, voltage, and temperature of the device under test (DUT) during the mechanical, thermal, and electrical abuse. In addition, the condition of the DUT, including leakage, venting, rupture, fire, and explosion during the abuse tests, will be recorded. These observations will be used to assign an EUCAR hazard level (0-7), enabling direct comparison between gellified cells and conventional LE. A lower hazard level or a delayed onset of thermal runaway would indicate enhanced safety, reflected in an extended safety window during severe abuse and a longer available evacuation time for vehicle occupants in real scenarios. This improvement will support the potential of gellified architecture as a safer alternative to LE systems and highlight suitability for high-energy-density chemistries, including lithium-metal-based batteries.

References
[1] Wang, Chenlei and Zhou, Yifan and Wang, Xiaodong and Kan, Yongchun and Gui, Zhou and Hu, Yuan, Noncombustible gel polymer electrolyte inspired by bio-radical chemistry for high voltage and high safety Ni-rich lithium batteries, Journal of Colloid and Interface Science, 2024.
[2] Du, Yirou and Liu, Xianshuai and Chen, Lin and Yin, Sihao and Xie, Yuhui and Li, Ao and Liang, Xiaodong and Luo, Yong and Wu, Feng and Mei, Yi, 3D hierarchical fireproof gel polymer electrolyte towards high-performance and comprehensive safety lithium-ion batteries, Chemical Engineering Journal, 2023.