Mechanochemical synthesis of Li-rich (Li2Fe)SO cathode for Li-ion batteries

Li-rich antiperovskite (Li2Fe)SO with its high specific capacity is an attractive cathode material for Li-ion battery applications. While many battery materials depend on hazardous substances and their production is also rarely sustainable, we present an environmentally friendly and sustainable approach for the synthesis of Li-rich (Li2Fe)SO using mechanochemistry based on ball milling. This one step process enables preparing a large quantity of phase-pure (Li2Fe)SO using low-cost and non-toxic precursors, making it a viable alternative to current solid state synthetic method in terms of simplicity, laboratory safety and scalability. The obtained micro-sized particles are nearly spherical and have a small size distribution. To control the crystallinity and reduce the intrinsic defects of the ball-milled (Li2Fe)SO material, a post-heat treatment procedure was tested. Thermodynamic measurements confirmed the high thermal stability of the ball-milled (Li2Fe)SO material. Increasing the ball to powder weight ratio was found to be an effective strategy to decrease the milling time required for the synthesis, thus promoting energy saving. Overall, this work provides a practical guide for the green and scalable production of (Li2Fe)SO cathode material, as well as a method for particle modification for improved electrochemical properties.