Synergistic effect of ball milling time and Mn-Fe ratio on the electrochemical performance of paper-based LiMn1-XFeXPO4/C cathodes for Lithium-ion batteries

Abstract

In recent years, with the continuous development of high-voltage cathode materials for lithium-ion (Li⁺) batteries, the LiMn_1-XFe_XPO₄ solid solution obtained by using Mn element to replace part of Fe on the basis of LiFePO₄ (LFP) has received extensive attention. It shows significantly improved voltage and capacity than LFP, which is currently regarded as a leading update for the traditional LFP cathode. At present, preparation of high-performance LiMn_1-XFe_XPO₄ using common high-temperature solid-state method is still challenging and the basic intricate coupling of the Mn-Fe ratio and ball milling time parameters on its electrochemical performance is still need to be fully studied due to the parametric complexity. Herein, the carbon wrapped LiMn_1-XFe_XPO₄/C material was prepared by high-temperature solid-phase method, and paper-based LiMn_1-XFe_XPO₄/C electrodes were also fabricated to fully study the synergistic effects of ball milling times (0.5 h, 1 h, 2 h) and Mn-Fe ratios (5:5, 6:4, 7:3, 8:2) on their electrochemical performance. It was found that there happened to be optimized ball milling time for each Mn-Fe ratio based LiMn_1-XFe_XPO₄/C materials. The higher Mn-Fe ratio, the longer ball milling time that is needed to achieve high electrochemical performance of paper-based LiMn_1-XFe_XPO₄/C cathodes. Through detailed analysis of cyclic voltammetry (CV) curves, cycling and rate performance, it was found that LiMn_1-XFe_XPO₄/C cathode prepared by ball milling for 1 h and Mn-Fe ratio of 7:3 has the best optimized voltage, cycling and rate performance.