Effect of rhodium substitution on the electrochemical performance of LiFePO4/C

The effect of rhodium (Rh) substitution on the electrochemical properties of LiFePO4/C cathode materials was studied. The results of electrochemical measurement show that Rh substitution can improve the rate capability of LiFePO4/C. However, heavy Rh substitution causes a discharge capacity loss. The LiFe0.975Rh0.025PO4/C sample shows an excellent high rate performance and its discharge capacity at a 10 C rate is 117.0 mAh g−1 with a discharge voltage plateau of 3.31–3.0 V versus Li/Li+. LiFe0.975Rh0.025PO4/C also shows a noticeably better cycling life at high temperature than LiFePO4/C. It still remains a capacity of 135.4 mAh g−1 at the 300th cycle at 55 °C under a 1 C rate, which is 82.0% of its initial capacity.