Lithium Ionic Conductor Thio-LISICON: The Li[sub 2]S-GeS[sub 2]-P[sub 2]S[sub 5] System

Abstract

The new crystalline material family, lithium superionic conductor (thio-LISICON), was found in the Li2S­GeS2­P2S5Li2S­GeS2­P2S5 system. The solid solution member x=0.75x=0.75 in Li4−xGe1−xPxS4Li4−xGe1−xPxS4 shows the highest conductivity of 2.2×10−32.2×10−3 Scm−1Scm−1 at 25°C of any sintered ceramic, together with negligible electronic conductivity, high electrochemical stability, no reaction with lithium metal, and no phase transition up to 500°C. Its material design concepts of changing constituent ions with various ionic radii, valence, and polarizability are described. © 2001 The Electrochemical Society. All rights reserved.