Experimental Corroboration of Lithium Orthothioborate Superionic Conductor by Systematic Elemental Manipulation
Xiang Zhu, Pushun Lu, Dengxu Wu, Qifa Gao, Tenghuan Ma, Yang Ming, Liquan Chen, Hong Li, Fan Wu
Abstract
The Li superionic conductor Li 3 BS 3 has been theoretically predicted as an ideal solid electrolyte (SE) due to its low Li + migration energy barrier and high ionic conductivity. However, the experimentally synthesized Li 3 BS 3 has a 10 4 times lower ionic conductivity. Herein, we investigate the effect of a series of cation and anion substitutions in Li 3 BS 3 SE on its ionic conductivity, including Li 3– x M 0.05 BS 3 (M = Cu, Zn, Sn, P, W, x = 0.05, 0.1, 0.2, 0.25), Li 3– y BS 2.95 X 0.05 (X = O, Cl, Br, I, y = 0.05, 0.1) and Li 2.75– x P 0.05 BS 3– x Cl x ( x = 0.05, 0.1, 0.15, 0.2, 0.4, 0.6). Amorphous ionic conductor Li 2.55 P 0.05 BS 2.8 Cl 0.2 has a high ion conductivity of 0.52 mS cm –1 at room temperature with an activation energy of 0.41 eV. The electrochemical performance of all-solid-state batteries with Li 2.55 P 0.05 BS 2.8 Cl 0.2 SEs show stable cycling with a discharge capacity retention of >97% after 200 cycles at 1 C under 55 °C.