Important Consideration for Interface Engineering of Carbon-Based Materials in Sulfide All-Solid Lithium-Ion Batteries

Abstract

Recently, an issue has emerged in ASSLBs in which carbon materials accelerate the deterioration of the sulfide solid electrolytes (SSEs), thereby reducing electrochemical performance. In this paper, we present approach for carbon materials that can enhance compatibility with solid electrolytes in ASSLBs. The compatibility between carbon and solid electrolyte is improved by removing amorphous carbon on the carbon surface, which unavoidably forms on the surface during carbon material synthesis, covering about 5~7 nm on the highly crystalline graphite surface. The evaluation of ASSLBs revealed significant differences in electrochemical performance depending on pristine graphite (P-Gr), which had amorphous carbon adsorbed on the surface, and surface-crystallized graphite (SC-Gr), from which amorphous carbon was removed, despite showing no significant difference in electrochemical performance LIBs. The improved electrochemical properties were closely associated with the quantity of Li2S, Li- phosphide, and SEI layer formed by the decomposition of the solid electrolyte during charging and discharging, subsequently affecting interfacial resistance between graphite and SSEs. In addition, the suppressed degradation of the solid electrolyte and the stable interface have enabled stable electrochemical performance in the half-cell and full-cell evaluation, even with a reduced proportion of the solid electrolyte within the anode composite, decreasing from 40% to 20%. We anticipate that improving the interface compatibility between crystalline carbon and the solid electrolyte will broaden the applications of carbon materials in solid-state electrolytes, advancing the development of ASSLBs that meet specific electrochemical performance criteria.

Keywords: Sulfide All-Solid Lithium-Ion Batteries, interface engineering, Carbon-Based Materials, Amorphous carbon, Graphite