Electrochemical Performance Of LiFePO₄ Synthesized By 3-D Mesopous Hard Template

LiFePO₄ is currently one of the most promising lithium-ion battery cathodematerials due to incomparable advantages. Compared to other options for lithium-ionbattery cathode materials, LiFePO₄ has its own advantages: a relatively hightheoretical capacity; flat charge-discharge voltage plateau; good reversibility;excellent chemical stability and thermal stability; and environment-benign.The periodic structure, uniform pore size of porous materials and uniform porewall thickness enable the resistance of liquid transfer by the same everywhere, ionsand electrons would be transport timely even in the case of large current densities. Inspite of many studies that centered on the preparation of metal oxide derivatives usinga hard-template, nano-porous structure of electrode materials is still lack of systemicstudy. From this perspective, we try to synthesize LiFePO₄ via a template method toimprove electrochemical propertiesOn previos works of mesoporous metal oxieds, mesoporous template KIT-6 wasfirst synthsized, then the precursor of Li(CH₃COO)₂·H₂O, Fe(NO₃)₃·9H₂O, H₃PO₄ wasincorporated into KIT-6 silica powder using a wetness impregnation technique. Aftermuti-step reactions, the template was removed and the composite would beheat-treated, finally we got three-dimensional porous LiFePO₄. The results showedthat the mesostructure of LiFePO₄ replicated successfully from the mesoporous KIT-6,and exhibited good electrochemical performance. After synthesis in differentconditions such as precursor concentration, pre-heated temperature and the choice ofprecursor, morphology and electrochemical tests were carried out to get the mostoptimal conditions. This is the first synthesisat home and abroad. The TEM imagesshow clearly the periodic ordered channels of LiFePO₄, confirming that the orderedpore structure replicates successfully from the mesoporous KIT-6. EDX spectra showsno trace of Si.The initial discharge capacity is 158 mAh/g at a 0.1C rate. When therate increases to 5C, the discharge capacity shows 110 mAh/g. From the second to the50th cycle, the ratio of discharge/charge is larger than 98%, illuminating thatelectrochemical reversibility was established after the initial cycle.