Reduced Grain Boundary Resistance by Surface Modification

Interfacial resistance is one of the severe problems in composite electrodes of all solid state batteries (ASSBs), especially oxide-type ASSBs. Conflicts between poor sinterability and possible unfavorable reaction with active materials limit applicable materials and processes. In this report, a novel approach is proposed to decrease grain boundary resistance among nonsintered solid electrolyte particles. The concept is successfully demonstrated, and the nonsintered grain boundary resistance of a highly conducting solid electrolyte (Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 ) was suppressed by being coated with poorly conducting solid electrolyte (Li 2 SiO 3 ). Increased total conductivity and variation of apparent activation energy are well explained from the viewpoint of defect chemistry.