Enhancement of Li₂ZrO₃ Modification of the Cycle Life of N/S-Doped LiMn_0.5Fe_0.5PO₄/C Composite Cathodes for Lithium Ion Batteries

LiMn_0.5Fe_0.5PO₄ cathodes have a high energy density but a poor rate and poor cycling performance. To this end, a series of N/S-doped LiMn_0.5Fe_0.5PO₄/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 LiMn_0.5Fe_0.5PO₄ 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.