Fast precipitation-induced LiFe0.5Mn0.5PO4/C nanorods with a fine size and large exposure of the (010) faces for high-performance lithium-ion batteries

Olivine-type LiFe x Mn 1- x PO 4 /C cathode materials are of great interest for lithium-ion batteries because of their higher lithium ion intercalation potential compared with that of LiFePO 4 . Two types of LiFe 0.5 Mn 0.5 PO 4 /C nanorods with different sizes and crystal structures were synthesized through a facile glycol-based solvothermal process with different precursor feeding sequences. The microstructural investigation revealed that the size and structure of the LiFe 0.5 Mn 0.5 PO 4 nanorods can be tuned by nucleation and crystal growth rates of the intermediate precipitates, which can be controlled by precursor feeding sequence. The LiFe 0.5 Mn 0.5 PO 4 nanorods obtained through the first feeding sequence (a solution of transition metal salts was added dropwise into the solution mixture of LiOH and H 3 PO 4 ) exhibited less exposure of the (010) crystal faces and had bigger sizes compared with those of the LiFe 0.5 Mn 0.5 PO 4 nanorods obtained through the second feeding sequence (a LiOH solution was added dropwise into the solution mixture of H 3 PO 4 and transition metal salts). Electrochemical investigations indicated that the LiFe 0.5 Mn 0.5 PO 4 nanorods obtained through the second feeding sequence showed substantially improved electrochemical performance, in which the discharge capacities reached 157 and 119 mAh g −1  at 0.2 and 5 C, respectively. Furthermore, a capacity retention of 89% was obtained after 500 cycles at 1 C, demonstrating excellent cyclic stability.