Effect of Mn content on electrochemical performance and energy density of LiFe1-xMnxPO4/C

In this work, LiFe1-xMnxPO4/C (x = 0, 0.2, 0.5) composite materials are synthesized to obtain high energy density lithium ion battery cathode materials. The prepared materials were characterized by XRD, XPS, SEM, TEM, CV, EIS and galvanostatic charge-discharge testing. The effect of the Mn content on the structure, morphology and electrochemical performance of LiFe1-xMnxPO4/C is studied in detail. It is found that LiFe0.5Mn0.5PO4/C not only possesses the highest specific energy, but also has the best rate performance. The discharge capacities at 5C of LiFe1-xMnxPO4/C (x = 0, 0.2, 0.5) are 97.2, 98.8, 107.8 mAh g−1, and the specific energies are 235.0, 248.5 and 299.3 Wh kg−1, respectively. It is calculated that LiFe0.5Mn0.5PO4/C has the highest conductivity and lithium ion diffusion coefficient because of its dispersed particle state and suitable carbon layer thickness. The analysis of the influence of different Mn contents on the electrochemical performance and energy density of LiFe1-xMnxPO4/C solid solution materials carried out based on the difference in material structure and morphology provides guidance for the subsequent research and industrial production of these materials.