Synthesis of nanowire and hollow LiFePO4 cathodes for high-performance lithium batteries

Abstract

The synthesis of nanowire and hollow LiFePO4 cathodes using the hard templates KIT-6 and SBA-15 is reported for high-performance lithium batteries. The two-dimensional hexagonal SBA-15 silica template with P(mm symmetry is used for the template that contains parallel cylindrical pores arranged with hexagonal symmetry, which serves to organize the wires into parallel bundles. On the other hand, three-dimensional cubic arrangement of pores in KIT-6 silica with Ia3d symmetry yields hollow morphology with mesopores. After impregnation of the template into a solution or after coating on the template with a solution consisting of LiFePO4 precursors, the silica template is removed and is subsequently fired at 700 degrees C. Electrochemical cycling of both the nanowire and hollow LiFePO4 cathodes demonstrates excellent rate capability even above 10C rate, showing > 89% capacity retention of the initial capacity. Among them, the rate capability of the hollow cathode at 15C is higher than that of the nanowire cathode, showing 6% improvement due to its higher Brunauer-Emmett- Teller surface area.