Facile solvothermal synthesis of ultrathin LiFe_xMn_1-xPO₄ nanoplates as advanced cathodes with long cycle life and superior rate capability

Fe doping is widely used to improve the electrochemical performance of LiMnPO₄ by "implanting" the merits of high rate capability and long cycle life of LiFePO₄ into LiMnPO₄. Nevertheless, great challenges still remain to obtain high-performance LiFe_xMn_1-xPO₄ at a low x value. In this work, we synthesized ultrathin LiFe_xMn_1-xPO₄ (x ≤ 0.15) nanoplates by a facile, controllable method. The plate-like LiFe_xMn_1-xPO₄ with a small lateral size (40-100 nm) and thickness (10-20 nm) exhibits high electrochemical activity, excellent rate capability and superior cycling stability after carbon coating. At a rate as high as 50C (8.5 A g^-1), the LiFe_0.15Mn_0.85PO₄/C composite can still yield a high discharge capacity of 96.2 mA h g^-1 where the discharge process can be completed in only 40 s. LiFe_0.15Mn_0.85PO₄/C can sustain a long-term cycling up to 1000 cycles at 10C with a capacity retention close to 70%. The fast and stable cycling ability of LiFe_xMn_1-xPO₄ makes it promising for applications in electric vehicles and hybrid electric vehicles.