Mechanochemical Synthesis of Shape-Anisotropic Particles through Wet Milling Using High-Energy Mills

Abstract

A high-energy ball mill, such as a planetary ball mill, is widely used for preparing a homogeneously mixed powder and reducing particle size. Because of the high impact energy generated by the collision of ball media, the planetary ball milling is expected to produce local high-temperature and high-pressure zones. In wet milling, the solubility of the material varies owing to the local and instantaneous changes caused by the collision. Consequently, mechanochemical reactions through a dissolution–precipitation mechanism can be attained without external heating. In this paper, we show the wet mechanochemical process in water to synthesize functional hydrous or hydrate materials with various shapes, including nanosheets, nanotubes, plates, flakes, rods, and nanoparticles. Morphology-controlled particles can be obtained by only adjusting the milling conditions, such as milling time, ball size, and centrifugal acceleration. Further, the products can be converted into electrode materials for Li-ion batteries, retaining the precursor morphologies. This wet mechanochemical synthesis can be also applied in a bead mill, where mass production and continuous processing are possible. The wet mechanochemical process is a new particle synthesis method that can achieve both grinding and crystal growth.