posted on 2021-02-05, 00:13authored byAsif Raza, Jae Yup Jung, Cheol-Ho Lee, Byung Gon Kim, Jeong-Hee Choi, Min-Sik Park, Sang-Min Lee
Si-based
anode materials are considered as potential materials
for high-energy lithium-ion batteries (LIBs) with the advantages of
high specific capacities and low operating voltages. However, significant
initial capacity loss and large volume variations during cycles are
the primary restrictions for the practical application of Si-based
anodes. Herein, we propose an affordable and scalable synthesis of
double-layered SiOx/Mg2SiO4/SiOx composites through the magnesiothermic
reduction of micro-sized SiO with Mg metal powder at 750 °C for
2 h. The distinctive morphology and microstructure of the double-layered
SiOx/Mg2SiO4/SiOx composite are beneficial as they remarkably
improve the reversibility in the first cycle and completely suppress
the volume variations during cycling. In our material design, the
outermost layer with a highly porous SiOx structure provides abundant active sites by securing a pathway for
efficient access to electrons and electrolytes. The inner layer of
Mg2SiO4 can constrain the large volume expansion
to increase the initial Coulombic efficiency (ICE). Owing to these
promising structural features, the composite prepared with a 2:1 molar
ratio of SiO to Mg exhibited initial charge and discharge capacities
of 1826 and 1381 mA h g–1, respectively, with an
ICE of 75.6%. Moreover, it showed a stable cycle performance, maintaining
high capacity retention of up to >86.0% even after 300 cycles.
The
proposed approach provides practical insight into the mass production
of advanced anode materials for high-energy LIBs.