Radical-oxidation coupled phosphate stabilization strategy: an aqueous and scalable route to mesoporous MnPO4∙H2O precursor for high-performance LiMnPO4 cathodes

MnPO 4 ∙H 2 O is an ideal precursor for the preparation of LiMnPO 4 . However, the instability of Mn 3+ in an aqueous solution necessitates the implementation of the existing preparation methods, which are carried out in ethanol and produce toxic gases such as NO and NO 2 . In this work, a radical-oxidation coupled phosphate stabilization strategy is proposed for synthesizing MnPO 4 ∙H 2 O in an aqueous solution. The strategy involves the initial oxidation of Mn 2+ to Mn 3+ by sulfate radicals, which are produced through the thermal activation of Na 2 S 2 O 8 . Subsequently, Mn 3+ is stabilized by H 3 PO 4 , leading to the formation of MnPO 4 ∙H 2 O. By implementing this strategy, the mesoporous MnPO 4 ∙H 2 O precursor can be readily obtained through a reaction at 90 °C for 5 h. Subsequently, the prepared LiMnPO 4 /C inherits the mesoporous structure of the MnPO 4 ∙H 2 O precursor, exhibiting excellent electrochemical performance. Specifically, the mesoporous LiMnPO 4 /C delivers an initial capacity of 115.8 mAh g −1 with a capacity retention of 83.1% after 100 cycles at 10 C. The enhanced performance is mainly attributed to the mesoporous structure, which facilitates electrolyte penetration, reduces interfacial charge transfer impedance, and accelerates Li + diffusion. The environmentally benign and scalable strategy presented here opens a new approach to the synthesis of high-performance LiMnPO 4 /C.