Effect of hybrid conductive additives on all-solid-state lithium batteries using Li2S–P2S5 glass-ceramics

Abstract

In order to enhance the electrochemical performance of all-solid-state composite cathodes, a hybrid of conductive additives consisting of Vapor Grown Carbon Fiber (VGCF), which had a high aspect ratio, and Super P carbon with a high surface area, were employed in all-solid-state composite cathodes. The effect of these additives on the electrochemical properties and microstructure was investigated. Microstructures that had valid electron conducting networks consisting of short-range conducting paths crossing the surfaces of individual LiCoO2 particles and long-range conducting paths linking neighboring LiCoO2 particles were obtained by blending of fibrous VGCF with nano-sized spherical Super P carbon particles. As a result, the all-solid-state composite cathodes using hybrid conductive additives showed a higher electronic conductivity and lower charge-transfer resistance compared with those using single conductive additives, which resulted in the highest discharge capacity of 68mAhg−1 at 1C and 38mAhg−1 at 2C when using the all-solid-state composite cathode with 2wt% of VGCF and 1wt% of Super P carbon. This indicated that the use of a hybrid conductive additive was a suitable and effective method to enhance the reversible capacity of the all-solid-state composite cathode at high current densities.