Effects of Cr doping on the electrochemical properties of Li2FeSiO4 cathode material for lithium-ion batteries

Cr-doped Li2FeSiO4 was prepared by a sol–gel method. The effects of Cr doping on the characteristics of Li2FeSiO4 were carefully investigated. Compared with the XRD pattern of the Li2FeSiO4 sample, the XRD patterns of the Cr-doped samples have no extra reflections. This indicates that Cr enters the structure of Li2FeSiO4 rather than forming impurities. As indicated by the charge–discharge measurements, the highest capacity is obtained by 3% Cr doping. The particle size of the Li2Fe0.97Cr0.03SiO4 sample was smaller than that of the Li2FeSiO4 sample, and the BET surface area of the Li2Fe0.97Cr0.03SiO4 sample was more than twice as high as that of the Li2FeSiO4 sample. Compared with the Li2FeSiO4 sample, the Li2Fe0.97Cr0.03SiO4 sample shows faster activation, higher reversible capacity, and better rate capability, which can be attributed to the smaller particle size and larger surface area as well as the crystal defects induced by Cr doping.