Synthesis of silicon nanosheets from kaolinite as a high-performance anode material for lithium-ion batteries

Because of the high theoretical capability surpassing other anode materials, silicon (Si) has been regarded as the most potential anode material for the next-generation lithium-ion batteries (LIBs). In this work, the amorphous SiO₂ precursors extracted from earth-abundant and silicon-rich clay mineral, kaolinite, have been applied to prepare Si nanosheets (k-Si) through a magnesiothermic reduction method. Benefiting from the special two-dimensional nanostructure, the problem caused by volume expansion can be greatly relieved. As an anode material of LIBs, the Si nanosheets deliver a high reversible specific capacity of 1909 mAh g⁻¹ at a low current density of 0.2 A g⁻¹ after 50 cycles, 1156 mAh g⁻¹ at a high current density of 2 A g⁻¹ after 500 cycles and excellent rate capability of 889 mAh g⁻¹ at a current density of 4 A g⁻¹, remarkably preceding the performance of Si material prepared by commercial SiO₂ powders. The strategy paves a promising way to the efficient production of electrode materials from the natural minerals.