The safety of Lithium ion battery (LIB) is recently a hot topic due to their increased use by the electric vehicles. Energy density has become more and more important to solve the range anxiety. However, thermal behavior becomes more unstable due to this increase in energy density. Several studies have claimed that the main reason batteries have thermal runaway events are the reactions between the intercalated lithium in the anode and the liquid electrolytes [1] [2]. Therefore, solid state electrolytes are proposed [3] [4] to be an option to increase the thermal stability of LIBs.

In this work, thermal evaluation of Solid state battery materials will first be defined by a differential scanning calorimeter to understand the thermal stability of the different materials that might be used in different types of solid state cells. Materials tested include layered oxide cathodes with different Ni content, pure lithium metal and several types of solid electrolytes such as sulfides, polymers and oxides. Heat flow test with different combinations of the materials, such as cathode with anode, cathode with electrolytes and anode with electrolytes were conducted to isolate reaction mechanisms between the different materials. The results show, that compared to the thermal runaway paths of cell with liquid electrolytes, sulfide and oxide electrolytes show the possibility of improved thermal stability. However, polymer electrolytes might have the similar, or even worse, thermal behavior as liquid electrolytes.

Reference

[1] Ren, X. Feng, L. Liu, H. Hsu, L. Lu, L. Wang, X. He and M. Ouyang. "Investigating the relationship between internal short circuit and thermal runaway of lithium-ion batteries under thermal abuse condition." Energy Storage Materials, 2021.

[2]Mukai, T. Inoue and K. "Are All-Solid-State Lithium-Ion Batteries Really Safe?−Verification by Differential Scanning Calorimetry with an All-Inclusive Microcell." ACS Applied Materials & Interfaces, 2016.

[3]Chen, A. M. Nolan, J. Lu, J. Wang, X. Yu, Y. Mo, L. Chen, X. Huang and H. Li. "The Thermal Stability of Lithium Solid Electrolytes with Metallic Lithium." Joule, 2020.

[4]Feng, M. Ouyang, X. Liu, L. Lu, Y. Xia and X. He. "Thermal runaway mechanism of lithium ion battery for electric vehicles: A review." Energy Storage Materials, 2018.