Improvement of Rate Performance of LiFePO4 Cathode with Porous LiFePO4/Activated Carbon Hybrid Electrode Structure

Abstract

After forming LiFePO4(LFP) and activated carbon (AC) layers on each face of an aluminium current collector, through-holes which have the design of the pore diameter (22 mm) and opening rate of the hole (0.5 %) were formed on the LFP/AC electrode with a system constructed with a pico-second pulse laser. A half cell was fabricated with the electrode having through holes and two lithium (Li) metal electrodes, where two Li metal sheets opposite the LFP side and AC side on the LFP/AC electrode by separating the Li metal and the LFP/AC electrode with polymer separators. The half-cell prepared with LFP/AC having through holes and Li metals exhibited much improvement of rate performance. Because the LFP/AC electrode having no through holes did not exhibit the improvement and LFP electrode did not exhibit better rate performance than one shown in LFP/AC electrode (0.5% opening rate), it was thought that both energy and Li+ transfer occurred between LFP and AC layers, and Li+passed through the holes from AC to LFP, as a result, the rate performance of the LFP/AC electrode was improved.