Enhanced electrochemical performance of Ni2+ doped carbon coated LiMn0.5Fe0.5PO4 nanocomposites as cathode materials for lithium-ion batteries
Qi Chen, Junjie You, Chuanqing Du, Yourong Wang, Siqing Cheng
Abstract
To highlight the complementary advantages between LiFePO 4 and LiMnPO 4 , the orthorhombic phosphor-olivine structured LiMn 1-x Fe x PO 4 (0<x<1) has been attracting significant attention as cathode material for lithium ion battery due to its series of appealing features. However, LiMn 1-x Fe x PO 4 (0<x<1) suffers from low electronic and ionic conductivity and slow lithium ion diffusion. Therefore, in this work, Ni 2+ doped carbon coated LiMn 0.5 Fe 0.5 PO 4 nanocomposites were synthesized by a facile solvothermal method followed by calcination under an Ar atmosphere with 10% (v/v) H 2 and investigated electrochemically. The results show that Ni 2+ doping could tune the morphology and cell parameters of carbon coated LiMn 0.5 Fe 0.5 PO 4 crystal composites to form carbon coated LiMn 0.5 Fe 0.5-x Ni x PO 4 solid solution, thus affect its electrochemical performance. In comparison, carbon coated LiMn 0.5 Fe 0.499 Ni 0.01 PO 4 nanocomposite exhibits excellent rate capability and superb cycle stability due to its reinforced crystal structure stability, improved electrical conductivity and fast lithium ion diffusion rate, indicating that the appropriate amount of Ni 2+ doping could greatly ameliorate the electrochemical performance of carbon coated LiMn 0.5 Fe 0.5 PO 4 cathode material. This offers the guidance of designing the stable structurally LiMn 1-x Fe x PO 4 composite cathode for the next generation of lithium ion battery.