Electrochemical characteristics of LiMn2O4-polypyrrole composite cathode for lithium polymer batteries

A LiMn2O4-PPy composite cathode for lithium polymer battery was developed. We investigated temperature dependence of ionic conductivity of PVDF-PC-EC-LiClO4 and PVDF-EC-DEC-LiClO4 electrolytes, AC impedance response and charge/discharge characteristics of LiMn2O4-PPy/MCMB in PVDF-based electrolyte. The ionic conductivity of PVDF-PC10EC10LiClO4 and PVDF-EC10DEC10LiClO4 with 25 wt.% PVDF electrolyte was 2.3 and 1.8×10−3 S/cm at room temperature. The first discharge capacity of LiMn2O4 added 15 wt.% SP270 was 123 mAh/g, while that of LiMnO2-PPy composite with 7 wt.% PPy and 10 wt.% SP270 was 135 mAh/g. The charge/discharge efficiency was above 98% after the 2nd cycle. The LiMn2O4-PPy composite cathode with 7 wt.% PPy–10 wt.% SP270 in PVDF-EC-DEC-LiClO4 electrolyte showed good capacity with cycling.