Wet Mechanical Route To Synthesize Morphology-Controlled NH₄MnPO₄·H₂O and Its Conversion Reaction into LiMnPO₄

A mechanical route using a grinding apparatus such as a planetary ball mill is a simple and scalable method to produce powder materials. However, the control of the particle shapes is difficult. In this paper, we report a wet mechanical process in water to synthesize NH₄MnPO₄·H₂O (AmMnP) with various shapes (plates, flakes, rods, and nanoparticles). This process involves planetary ball milling of inexpensive raw materials (NH₄H₂PO₄ and MnCO₃) at room temperature. Morphology-controlled AmMnP particles can be obtained by only adjusting the milling conditions such as milling time, ball size, and centrifugal acceleration. Furthermore, the conversion of AmMnP into LiMnPO₄ with two different approaches (solid-state and hydrothermal reactions) has been investigated to evaluate its future applicability as a cathode for lithium-ion batteries. As a particle synthesis with a unique morphology can be attained based on a dissolution-precipitation mechanism in a solution via a suitable combination of raw materials, the study results will promote wet mechanical processes to be widely used as classic but advanced particle synthesis method.