Suppressing Manganese Dissolution via Ti-Doping in LiFe _0.4 Mn _0.6 PO ₄ : A Strategy for High-Temperature Battery Cycling Stability

LiFe1–xMnxPO4, which balances the high energy density of LiMnPO4 and excellent rate capacity of LiFePO4, is impeded by its sluggish kinetics of electron transport and severe Mn dissolution at elevated temperature. Herein, Ti doping was introduced to address the above obstacles, and Li(Fe0.4Mn0.6)1–yTiyPO4 cathodes were synthesized via the solid-state method. The SEM observation demonstrates that Ti doping leads to a diminution in the primary particle size, which contributes to shortening the transmission path of Li+ and improving the electrochemical performance. Additionally, reduced average Mn–O bond length originating from Ti doping is verified by XRD refinement, which facilitates the elevation of structural stability, thereby inhibiting Mn dissolution during high-temperature cycling. Under the optimized conditions, Li(Fe0.4Mn0.6)0.98Ti0.02PO4/C exhibits remarkable electrochemical performance: At room temperature, it delivers a discharge specific capacity of 154.41 mAh g–1 at 0.2 C and 134.98 mAh g–1 even at 10 C, accompanied by remarkable cycle stability with a capacity retention rate of 95.86% after 600 cycles at 2 C. At 50 °C, it possesses a discharge specific capacity of 160.68 mAh g–1 at 0.2 C and 148.80 mAh g–1 at 10 C, as well as the discharge specific capacity retaining 94.97% of the initial capacity after 300 cycles at 2 C.