In this paper, we present the results of our current research in plastic-crystal-based lithium batteries. The N,N'-ringed pyrazolium. salts of tfifluoromethanesulfonimide (TFSI) are a new family of organic plastic crystals. Their exceptional properties have underlined their potential as new electrolyte materials for application in electrochemical devices such as lithium batteries. Both single-phase and multi-phase plastic crystals of the pyrazolium series were investigated. Battery results confirmed pyrazolium plastic crystals to be superior solid-state electrolyte materials. The rate capability and attainable capacity of the reported battery investigation demonstrate that plastic crystal pyrazoliums are excellent contenders as new solid-state electrolytes. (C) 2004 Elsevier B.V. All rights reserved.