Transport properties of LiMn2O4 electrode materials for lithium-ion batteries

Transport properties of LiMn2O4 prepared under different conditions are characterized using impedance spectroscopy and 4-probe DC techniques. Results indicate that LiMn2O4 is a mixed ionic-electronic conductor with lithium-ion transference number varying from about 0.67 to 0.92, depending on conditions of preparation. It is observed that LiMn2O4 powders synthesized at low temperatures exhibit higher total conductivities than those synthesized at high temperatures. Among the LiMn2O4 powders synthesized at high temperatures, the ones quenched in liquid nitrogen have lower activation energy than the ones cooled down slowly. Further, cycling of Li \ P(EO)(8)LICF3SO3 \ LixMn2O4 cells indicates that the LiMn2O4 powders synthesized at a low temperature exhibit much higher obtainable capacity than those synthesized at high temperatures under the same cycling conditions. (C) 1998 Elsevier Science B.V. All rights reserved.