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(Ni
x
Co
y
Mn
z
)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.