Conductivity of the binary system iodine-phenazine

To improve the high-rate charging/discharging performance of a cell of laminated lithium iron phosphate (LiFePO4) cathodes/graphite anodes, micrometer-sized through-holes were formed on the electrode surfaces with a pico-second pulsed laser. The through-holes having 20 μm diameter were uniformly arranged with a hole opening rate of 1% as the ratio of the holed and un-holed areas on the cathode and anode surface. Compared with the cells fabricated from non-porous electrodes and electrodes prepared with the conventional porous current collectors, the present cell composed of the porous anode and cathode electrodes showed a large discharge capacity retention even at a high current density. The formation of through-holes on the electrodes provides a remarkable improvement in the high-rate charging/discharging performance as a result of the increased paths available in Li+ ion transfer from/to the active materials (LiFePO4 and graphite layers).