Study on LiFe<inf>1 − x</inf>Sm<inf> x</inf>PO<inf>4</inf>/C used as cathode materials for lithium-ion batteries with low Sm component

LiFe<inf>1 − x</inf>Sm<inf>x</inf>PO<inf>4</inf>/C cathode materials were synthesized though a facile hydrothermal method. Compared with high-temperature solid-phase sintering, the method can allow for the fabrication of low Sm content (2 %), a scarce and expensive rare earth element, while the presence of an optimized carbon coating with large amount of sp²-type carbon sharply increases the material’s electrochemical performance. The high-rate dischargeability at 5 C, as well as the exchange current density, can be increased by 21 and 86 %, respectively, which were attributed to the fine size and the large cell parameter a/c as much. It should be pointed out that the a/c value will be increased for the LiFePO<inf>4</inf> Sm-doped papered by both of the two methods, while the mechanism is different: The value c is increased for the front and the value a is decreased for the latter, respectively.