Up‐Scaled Microspherical Aggregates of LiFe 0.4 V 0.4 PO 4 /C Nanocomposites as Cathode Materials for High‐Rate Li‐Ion Batteries

A series of microspherical LiFe x V 2/3−2 x /3 PO 4 /C (0< x <1) composites are successfully prepared using spray drying and the carbothermal reduction method. Compared with Li 3 V 2 (PO 4 ) 3 /C and LiFePO 4 /C, LiFe 0.4 V 0.4 PO 4 /C is a solid solution and has a microspherical morphology. The LiFe 0.4 V 0.4 PO 4 /C microspheres with an essentially log‐normal distribution around 18.2 μm consist of nanosized LiFe 0.4 V 0.4 PO 4 /C particles as building blocks, which have an average size of around 50 nm, a specific surface area of 11.3 m 2  g −1 , and a Barrett–Joyner–Halenda pore diameter of 21.9 nm. Moreover, LiFe 0.4 V 0.4 PO 4 /C delivers a discharge capacity of 144.8 mAh g −1 at C/10, which is close to the theoretical discharge capacity of 148.2 mAh g −1 in the insertion/extraction process at 2.5–4.3 V. Even at 10C and 20C, LiFe 0.4 V 0.4 PO 4 /C shows excellent specific capacities of 125.2 and 119.6 mAh g −1 , respectively, corresponding to excellent rate capacity retentions of close to 86.5 % and 82.6 %, respectively.