Enhanced Air and Electrochemical Stability of Li7P2.9Ge0.05S10.75O0.1 Electrolytes with High Ionic Conductivity for Thiophosphate-Based All-Solid-State Batteries

Lu Lv; Niaz Ahmad; Chaoyuan Zeng; Peiwen Yu; Tinglu Song; Qinxi Dong; Wen Yang

doi:10.1021/acsami.2c09717

Enhanced Air and Electrochemical Stability of Li₇P_2.9Ge_0.05S_10.75O_0.1 Electrolytes with High Ionic Conductivity for Thiophosphate-Based All-Solid-State Batteries

ACS Appl Mater Interfaces. 2022 Sep 7;14(35):39985-39995. doi: 10.1021/acsami.2c09717. Epub 2022 Aug 24.

Authors

Lu Lv^{1

2}, Niaz Ahmad^{1

2}, Chaoyuan Zeng¹, Peiwen Yu², Tinglu Song³, Qinxi Dong¹, Wen Yang²

Affiliations

¹ Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, Collaborative Innovation Center of Ecological Civilization, Hainan University, Haikou 570228, China.
² Key Laboratory of Cluster Science of Ministry of Education Beijing and Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 5# Zhongguancun Road, Haidian District, Beijing 100081, P. R. China.
³ Experimental Center of Advanced Materials, School of Material Science and Engineering, Beijing Institute of Technology, 5# Zhongguancun Road, Haidian District, Beijing 100081, P. R. China.

PMID: 36000918
DOI: 10.1021/acsami.2c09717

Abstract

Sulfide solid electrolytes (SSEs) show tremendous potential to realize high-energy-density secondary batteries and offer distinguishing safety features over the traditional liquid-electrolyte-based system. However, their installation is hindered by the air sensitivity and substandard interfacial compatibility with Li-metal anodes. Herein, an aliovalent P⁵⁺/Ge⁴⁺ and isovalent S^2-/O^2- cosubstitution strategy increases the σ_Li+ to 4.77 mS cm^-1, which is associated with the lowest activation energy (18.66 kJ mol^-1). Impressively, with limited substitution of P/Ge and S/O in Li₇P₃S₁₁, the derived electrolytes largely suppressed the structural hydrolysis in the air. Furthermore, the Li//Li cell with novel Li₇P_2.9Ge_0.05S_10.75O_0.1 SSEs realized Li plating/stripping over 100 h at 0.1 mA cm^-2/0.1 mAh cm^-2 @ RT, with the lowest overpotential at ∼5 mV. Next, ex situ X-ray photoelectron spectroscopy (XPS) quantified the electrochemical decomposition of the Li₇P₃S₁₁/LiNbO₃@NCA interface during cell operation. XPS results confirmed better thermodynamic stability between LiNbO₃@NCA and L₇P₃S₁₁ after GeO₂ substitution. Accordingly, the LiNbO₃@NCA/Li₇P_2.9Ge_0.05S_10.75O_0.1/Li-In cell performed remarkably; first discharge capacity, 158.9 mAh g^-1; capacity retention, 89%; and Coulombic efficiency, ∼100% after 50 cycles @ 0.064 mA cm^-2 and even at 0.3 mA cm^-2 versus the first discharge capacity and retention (129.4 mAh g^-1 and 75.73%) after 70 cycles @ RT. These remarkable results could be attributable to the excellent σ_Li+, chemical/electrochemical stability toward LiNbO₃@NCA, and meager interfacial resistance, essential for the practical application of sulfide-based batteries.

Keywords: Li7P2.9Ge0.05S10.75O0.1 SSE; air stable; low Li7P2.9Ge0.05S10.75O0.1/LiNbO3@NCA interface resistance; low activation energy; stable anionic functional units.