High‐performance LiMn 0 . 8 Fe 0 . 2 PO 4 /C cathode prepared by using the toluene‐soluble component of pitch as a carbon source

The nanocrystalline material LiMn0.8Fe0.2PO4/C was prepared by the solvothermal method using the toluene-soluble component of pitch or sucrose as a carbon source. The effects of carbon source types and contents, and the carbonization-heating rate between 350°C and 500°C on the physicochemical and electrochemical properties of the obtained materials were investigated. When the carbonization heating rate was between 350°C and 500°C is 0.5°C·min−1, cathode TS-200-0.5 coated by 200 mg toluene-soluble component of pitch showed the optimum electrochemical performance with discharge specific capacity of 156.4, 149.2, and 116.4 mAh·g−1 at 0.1, 1, and 5 C, respectively. After 150 cycles at 1 C, the specific discharge capacity was still 135.1 mAh·g−1, and the capacity retention rate was 92.7%. Compared with sucrose, the toluene-soluble component of pitch is an aromatic compound, and its pyrolytic carbon has streamlined structure with high graphitization. Moreover, small amounts of sulfur and nitrogen doped exist in pyrolysis carbon of the toluene-soluble component of pitch. Cathode TS-200-0.5 exhibits high ionic and electronic conductivity and stability.