Enhancement of Li2ZrO3 Modification of the Cycle Life of N/S-Doped LiMn0.5Fe0.5PO4/C Composite Cathodes for Lithium Ion Batteries

LiMn0.5Fe0.5PO4 cathodes have a high energy density but a poor rate and poor cycling performance. To this end, a series of N/S-doped LiMn0.5Fe0.5PO4/C composite cathodes modified with different contents of Li2ZrO3 were prepared by a solvothermal synthesis combined with calcination. The microstructure, chemical composition, and electrochemical properties are analyzed. Li2ZrO3 adsorbed on the LiMn0.5Fe0.5PO4 primary particles' surface in an amorphous state and on spherical particles (5-10 nm). The cycling life and rate performance of the cathodes are improved by the modification of a moderate amount of Li2ZrO3. The LMFP/NS-C/LZO1 shows available capacities of 166.8 and 118.9 mAh·g-1 at 0.1 and 5 C, respectively. The LMFP/NS-C/LZO1 shows no capacity loss after 100 cycles of charging/discharging (1 C), and still has a high capacity retention of 92.0% after 1000 cycles of charging/discharging (5 C). The excellent cycling performance of the LMFP/NS-C/LZO1 can be attributed to the improvement of the cathode microstructure and the electrochemical kinetics and the inhibition of Mn2+ dissolution by the moderate Li2ZrO3 modification.