(376o) First-Principles Study on Developing Li10-XSnP2S12-XClx Electrolyte with Outstanding Li-Ion Conductivity for High-Voltage Solid State Batteries

line-height:115%;font-family:" times new roman>First-Principles Study on
Developing Li_10-xSnP₂S_12-xCl_x Electrolyte
with Outstanding Li-ion Conductivity for High-Voltage Solid State Batteries

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font-family:" times new roman>Kyungju
Nam¹, Jeemin Hwang², Byungchan Han^1,2,*

¹
Department of Vehicle Convergence Engineering, Yonsei University, Seoul 03722,
Republic of Korea

²
Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul
03722, Republic of Korea

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line-height:115%"> font-family:" times new roman>Using
first-principles density functional theory calculations (DFT) and ab-initio
molecular dynamics (AIMD) simulations, we suggest Li_10-xSnP₂S_12-xCl_x
(LSPSC) for the first time as solid electrolyte with supreme ionic conductivity:
the substitution of Sn⁴⁺ for Ge⁴⁺ and the partial
substitution of Cl^- for S^2- to a Li₁₀GeP₂S₁₂
(LGPS) electrolyte which is well-known sulfide electrolyte. The crystal
structure of the LSPSC has a similar symmetry as LGPS, 1 dimensional ion
diffusion channels, but further improves on the Li-ion conductivity at room
temperature. The main reason of the improvement is chlorine ions that enlarge diffusion
channels; however, excess amount of Cl doping degrades the transport of Li ion
due to attractive interaction of Cl with Li. The key is to find an optimum
halide doping concentration that can maximize the Li-ion conductivity. Calculated
density of states (DOS) for LSPSC shows electrochemical instability with
approximately 3eV band gap, an insufficient value for the electrolyte material.
However, the halides near anode react with Li metal and form LiCl thin layer which
demonstrates high bandgap (about 8eV). The computational design concept for a
sulfide solid electrolyte with halide doping is a promising for high-voltage solid
state batteries font-family:" times new roman>.

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normal"> " times new roman>Figure. The model systems of (a) pristine LGPS, (b) LSPS and (c) LSPSC,
the partial substitutional doping of Cl to S for LSPS. All model systems have
the BCC structure with 1 dimensional diffusion path for Li ions.