Use of Coal Gangue to Prepare Refractory Saggars with Superior Corrosion Resistance and Thermomechanical Properties for the Calcination of Li-Ion Battery Cathode Materials
Dafei Ding, Liu Guo, Yuandong Mu, Guotian Ye, Liugang Chen
Abstract
Mullite (3Al2O3·2SiO2) is commonly used as the basic component to prepare refractory saggars for the calcination of Li-ion battery (LIB) cathode materials. Coal gangue, basically treated as aluminosilicate solid waste/tailings, could be used as the starting material to synthesize mullite at elevated temperatures. However, high operation energy and additional high-quality alumina sources are required in this process. In addition, mullite is prone to corrosion by LIB cathode materials, which remains a major challenge. The present work reports the design and fabrication of refractory powders with a core–shell structure comprising calcined coal gangue (CCG) and a layer of in situ-generated KAlSi2O6 (KAS4) around CCG grains. The obtained CCG–KAS4 powders with a core–shell structure exhibit superior corrosion resistance against the Li(NixCoyMnz)O2 precursor/material during calcination compared with CCG or mullite. Materials prepared with CCG–KAS4 powders containing 4.2 and 8.4 wt % KAS4 possess better thermomechanical properties than those synthesized from mullite powders. This makes coal gangue a good candidate to prepare refractory saggars for the calcination of LIB cathode materials.