In situ conductivity measurements of LiMn₂O₄thin films during lithium insertion/extraction by using interdigitated microarray electrodes

Thin films of LiMn₂O₄ have been prepared by RF magnetron sputtering on interdigitated microarray electrodes. In situ conductivity-potential profiles and cyclic voltammograms during extraction/insertion processes of Li ions were obtained simultaneously in nonaqueous and aqueous electrolyte solutions (1 M LiClO₄/ propylene carbonate and 1 M LiCl/water). The electronic conductivity of Li_1-xMn₂O₄ was found not to show metallic transition and maintain its semiconducting state during the extraction/insertion of Li ion. A slight decrease in conductivity was observed with increasing the anodic potential, i.e., with increasing x (lithium extraction) and recovered reversibly when the potential returned to the cathodic side (re-insertion of Li ions). Similar results were obtained in both aqueous and nonaqueous electrolyte solutions.