In-situ CNT-loaded organic cathodes for sulfide all-solid-state Li metal batteries

Abstract

Organic cathodes show promising advantages of extensive resources, high theoretical specific capacity, and mild synthesis conditions, etc., but suffer from low density, poor electronic conductivity, and high solubility in liquid electrolytes. Herein, an in-situ coating method is developed to overcome the above issues by realizing high-performance sulfide all-solid-state batteries with organic Li₄C₈H₂O₆ cathode. Li₄C₈H₂O₆ composite cathodes with carbon nanotubes (CNTs) and vapor grown carbon fiber (VGCF) were systematically studied to reveal that CNTs accelerate the electrochemical decomposition of sulfide electrolyte, despite the effectively improved electronic conductivity, rate capability and active material utilization. Therefore, in-situ coating of Li₄C₈H₂O₆ onto CNTs (Li₄C₈H₂O₆@CNT) is developed to further improve the contact between Li₄C₈H₂O₆ and CNTs, but to reduce the contact of CNTs with sulfide solid electrolyte and its decomposition. As a result, the Li₄C₈H₂O₆@CNT electrode demonstrates a high capacity of 200.3 mAh/g, and a high active material utilization rate (83.4% at 0.1C). It also exhibits a specific capacity of 85.9 mAh/g at a high cathode loading of 40 wt% and a high rate of 1C.