Rational design of the micron-sized particle size of LiMn0.8Fe0.2PO4 cathode material with enhanced electrochemical performance for Li-ion batteries

Abstract

Recently, micron-sized LiMn1-xFexPO4 cathode materials have attracted attention due to its better rate capability and higher tap density than the nano-sized ones. However, the influence of the particle size on the energy density of micron-sized LiMn1-xFexPO4 is still unknown. In this paper, we report the optimal particle size of the micron-sized LiMn0.8Fe0.2PO4 with enhanced electrochemical performance as cathode material in lithium-ion batteries (LIBs). The LiMn0.8Fe0.2PO4 sample with the particle size of ∼9.39 μm delivers the initial discharge capacity of 124 mAh g-1 at 0.2 C rate with high capacity retention of 94.35% after 100 cycles, which is higher than that with the particle sizes of ∼2.71 μm, ∼3.74 μm, ∼6.41 μm or ∼16.31 μm. This structure with the specific capacity of 122 mAh g-1 at 0.5 C rate and 106 mAh g-1 at 3 C rate also exhibits excellent rate performances. The improved electrochemical performances are mainly derived from its fast Li+ diffusion, which causes the higher ionic conductivity. The LiMn0.8Fe0.2PO4 sample with the particle sizes of ∼9.39 μm also shows the highest tap density (0.68 g cc-1) among the as-prepared samples. This finding provides a new way to enhance the energy density of other cathode materials.