Doping Effects on the Crystal Structure and Electrochemical Performance of LiFePO 4 /C

LiFe 0.98 M 0.02 PO 4 /C ( M  =  M g, N i, C o, S r) composite materials were prepared by solid‐state synthesis method using F e 2 O 3 as one of the starting materials. The structures and electrochemical performance of samples were carried out by means of XRD , SEM , TEM , and constant‐current charge–discharge method. The results showed that the ion doping did not change the crystal structure and morphology of L i F e P O 4 . Unit‐cell volume gradually increased, which was good for embedding and disembedding of L i + , and improving conductivity and charge–discharge performance. The electrical conductivity of powders was increased by carbon coating and ion doping. The initial discharge capacity of N i 2+ ‐doped sample reached 156.6 mA·h/g and 149.4 mA·h/g at 0.2C and 1C rate. After 30 cycles, the capacity retention rate was still 98.8% and 97.2%.