High rate capability of LiFePO 4 cathodes doped with a high amount of Ti

Abstract A Li-ion battery cathode with target stoichiometry LiTi 0.08 Fe 0.92 PO 4 was prepared by doping a high amount of Ti 4+ into the olivine structure using solid-state reaction at 700 °C. Synchrotron X-ray diffraction studies confirmed the presence of a major olivine phase and NASICON-type ion-conducting Li 3 Fe 2 (PO) 4 and Li 2 TiFe(PO 4 ) 3 impurities. Further, the calculated lattice parameter values appear to confirm Ti-doping in LiFePO 4 . Electron microscopy and particle distribution studies not only revealed a slightly increased average particle-size and particle fragmentation but also confirmed a fair distribution of Ti 4+ ions in the prepared sample. The LiTi 0.08 Fe 0.92 PO 4 cathode delivered high specific capacities and good capacity retentions (≤2% capacity loss after 50 cycles) for lithium battery applications. Besides, the cathode delivered impressive rate capabilities as specific capacities of 160 and 110 mA h g −1 at 0.2 and 11.4 C, respectively, were retained. Although the average particle-size was slightly higher, the presence of ion-conducting NASICON-type species appear to contribute to the enhanced electrical conductivity and hence to the cathode performance of LiTi 0.08 Fe 0.92 PO 4 .