RF Magnetron Sputtered LiCoP04 Cathodes for 4.8V Thin Film Batteries.

摘要

Thin film batteries employing sputtered LiCoPO4 cathode layers, Li3.3PO3.8N0.22 (LiPON) electrolyte and Li anode films have been successfidly fabricated and tested. The cells exhibit a high voltage charge/discharge plateau of 4.8V, with a lower plateau at 2.W corresponding to a much higher conductivity phase. Thin film batteries with asdeposited cathode layers are highly resistive and cannot be charged or discharged to appreciable capacities even at very low rates of approximately C/100. Upon annealing, the films sputtered from the LiCoPO4 target become discontinuous and take on a granular structure. These grains are well indexed to untextured crystalline LiCoPO4 on the Pt current collector, a finding further supported by the results from the electrochemical analyses. The thin film cells show no appreciable capacity fade or change in charge/discharge performance with increasing cycle number. The thin film cells employing the fully crystalline LiCoPO4 are among the highest voltage thin film batteries yet reported.