Randy Jalem1 2 Yasuyuki Morishita3 Takashi Okajima3 Yuki Kondo3 Hayami Takeda4 Masanobu Nakayama2 3 4

1, Japan Science and Technology Agency (JST), PRESTO, Saitama, , Japan
2, National Institute for Materials Science – Global Research Center for Environment and Energy based on Nanomaterials Science (NIMS-GREEN), Tsukuba, , Japan
3, Nagoya Institute of Technology, Nagoya, , Japan
4, Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Kyoto, , Japan

The electrochemical stability of the solid electrolyte component is one of the very important criteria for consideration when developing solid-state Li ion batteries. For example, resistive interphase materials produced over the course of cycling operation can impede Li ion transport across grain boundary regions, severely compromising the overall battery performance. In this presentation, we report our results on combined experimental and first-principles DFT investigations on the cause of capacity fading at charging step of an air-isolated Li ion battery with the following components: a garnet solid electrolyte (with a nominal formula Li6.625La3Zr1.625Ta0.375O12, assigned as LLZrTaO), a LiFePO4 + carbon (LFP + C) cathode, and a Li metal anode. Our analysis revealed that the decomposition route may involve the formation of defective garnet and formation of products composed of light elements. Surveying by DFT approach the various known garnet compounds in the general formula Li5+xLa3M2O12 (M for x = 0: Nb, Ta; M for x = 2: Zr, Ti, Hf), we determined that the smaller the M cation electronegativity in the host framework, the more stable is the garnet material against our predicted decomposition route.1

Jalem et al., J. Mater. Chem. A 2016, 4, 14371–14379.