Lattice engineering of high-entropy olivine-type lithium metal phosphate as high-voltage cathodes

Engineering of high-entropy cathode materials for lithium-ion batteries has been actively pursued owing to the outstanding conductivity of high-entropy materials benefited from the maximum entropy and unique antisite disordering structure. Olivine lithium metal phosphates such as LiMnPO₄ and LiNiPO₄ feature high working voltages but low capacities due to their insulation nature. In this work, the synthesis of the high-entropy lithium metal phosphate materials (HELMPs) is realized by combining mechanochemistry with a calcination method. By regulating lattice of HELMPs, the high-entropy Li(Mn_0.35Fe_0.35Co_0.1Mg_0.1Ca_0.1)PO₄ reveals three typical high-voltage plateaus in charge-discharge curves corresponding to the redox of Fe, Mn, and Co in the voltage range of 2.0-4.9 V vs Li⁺/Li, and a much higher initial capacity than LiMnPO₄ (104 vs 15 mAh g⁻¹).