Influence of Electronic Conducting Additives on Cycle Performance of Garnet-based Solid Lithium Batteries

Abstract

Solid state lithium batteries based on garnet-type solid electrolytes face the problem of contact between the solid electrolytes and the solid cathodes, which deteriorates the cycle performance. Aiming to overcome such problem, the solid state batteries with the LiNi1/3Co1/3Mn1/3O2-based cathodes, the Li6.4La3Zr1.4Ta0.6O12 ceramic electrolytes, and the lithium metal anodes were studied. For constructing the LiNi1/3Co1/3Mn1/3O2-based composite cathodes, three-kind carbons were used as electronic conducting additives. It is found that the batteries with cathodes containing vapor grown carbon fibers (VGCFs) show better cycle performance than those with granular Ketjen Black as well as Super P carbons. Analysis indicates that the VGCFs result in less side reaction at high charge potential than do other two electronic additives, leading to reduced carbonates that cause the increase of the internal cell resistance. These results suggest that stability of electronic additives has important influence on cycle performance of solid state lithium batteries.