Coal-based kaolin derived porous silicon nanoparticles as anode materials for Li-ion batteries

Silicon is an attractive material for the next generation anode material of lithium ion batteries (LIBs), because of the advantages of high energy density, high safety and abundance in earth crust. However, it's the capacity attenuation caused by the volume expansion in lithiation, greatly limited its commercial application. Herein, the porous Si nanoparticles are prepared using abundant coal-based kaolin as raw materials, through ball grinding, calcination, selective leaching and magnesium thermal reduction processes. The porous silicon nanoparticles exhibit excellent electrochemical properties without any further modification, due to the unique porous nano-structures which buffer the volume expansion. The initial CE reaches up to 80.0%. After 100 cycle, the material still remains a discharge capacity of 546 mAh g(-1) at 100 mA g(-1) and a Coulombic efficiency (CE) of 98.8%. The porous Si nanoparticles are fabricated using abundant raw materials and via a facile procedure that is ready for scale-up to meet the large-scale energy storage application. At the same time, the work provides a value-added solution of coal-based kaolin.