Effect of Zn doping on the performance of LiMnPO4 cathode for lithium ion batteries

In this work, effect of Zn doping on the performance of LiMnPO4 is revisited. Samples of pure and Zn-doped LiMnPO4 are synthesized by a new solid-state method, and their structure, morphology and electrochemical behavior are characterized and compared. The results reveal that a small amount of Zn doping (2 at.%) is highly beneficial for the performance of LiMnPO4 due to the reduced charge transfer resistance, the increased lithium ion diffusion and phase conversion, but this effect is remarkably traded off at a high level of Zn doping (10 at.%). Compared with LiMnPO4, LiMn0.98Zn0.02PO4 has a much higher capacity and a much better rate capability. After 2 at.% Zn doping, the discharge capacity increases from 101 to 139 mAh g−1 at 0.1 C and 56 to 105 mAh g−1 at 2 C.