Lawrence Berkeley National Laboratory

LiFePO4/gel/natural graphite (NG) cells have been prepared and cycled under a fixed protocol for cycle and calendar life determination. Cell compression of 10 psi was found to represent an optimal balance between cell impedance and the first cycle losses on the individual electrodes with the gel electrolyte. Cells with a Li anode showed capacities of 160 and 78 mAh/g-LiFePO4 for C/25 and 2C discharge rates, respectively. Rapid capacity and power fade were observed in the LiFePO4/gel/NG cells during cycling and calanedar life studies. Diagnostic evaluations point to the consumption of cycleable Li though a side reaction as the reason for performance fade with minimal degradation of the individual electrodes.