Rapid CO2 exfoliation of Zintl phase CaSi2-derived ultrathin free-standing Si/SiOx/C nanosheets for high-performance lithium storage

Semiconducting silicon (Si) nanomaterials have great potential for the applications in electronics, physics, and energy storage fields. However, to date, it is still a challenge to realize the batch production of Si nanomaterials via efficient and low-cost approaches, owing to some long-standing shortcomings, e.g., complex procedures and time and/or energy consumption. Herein, we report a green and inexpensive method to rapidly obtain two-dimensional (2D) free-standing Si/SiOx nanosheets via the rapid thermal exfoliation of layered Zintl compound CaSi2. With the help of the rapid exfoliation reaction of CaSi2 in the atmosphere of greenhouse gas CO2, and the following mild sonication, 2D free-standing Si/SiOx nanosheets can be produced with very high yield. After applying the coating of a thin carbon outer layer, the electrodes of Si/SiOx/C nanosheets serving as the anodes for lithium-ion batteries exhibit ultrahigh reversible capacity and outstanding electrochemical stability. We expect this study will provide new insights and inspirations for the convenient and batch production of nanostructural Si-based anode materials towards high-performance lithium-ion batteries.