Although silicon is a promising anode material for lithium-ion batteries, scalable synthesis of silicon anodes with good cyclability and low electrode swelling remains a significant challenge. Herein, we report a scalable top-down technique to produce ant-nest-like porous silicon from magnesium-silicon alloy. The ant-nest-like porous silicon comprising three-dimensional interconnected silicon nanoligaments and bicontinuous nanopores can prevent pulverization and accommodate volume expansion during cycling resulting in negligible particle-level outward expansion. The carbon-coated porous silicon anode delivers a high capacity of 1,271 mAh g −1 at 2,100 mA g −1 with 90% capacity retention after 1,000 cycles and has a low electrode swelling of 17.8% at a high areal capacity of 5.1 mAh cm −2 . The full cell with the prelithiated silicon anode and Li(Ni 1/3 Co 1/3 Mn 1/3 )O 2 cathode boasts a high energy density of 502 Wh Kg −1 and 84% capacity retention after 400 cycles. This work provides insights into the rational design of alloy anodes for high-energy batteries.

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Silicon-based nanomaterials are promising anode materials in lithium-ion batteries (LIBs) due to their high theoretical capacity of 4200 mA h g(-1), more than 10 times that of commercial graphite. Si nanoparticles (NPs) with a diameter of or below 10 nm generally exhibit enhanced lithium storage properties due to their small size and large surface area. However, it is challenging to generate such ultrafine Si NPs by a facile and scalable method. This paper reports a scalable method to fabricate ultrafine Si NPs 5-8 nm in size from dead bamboo leaves (BLs) by thermally decomposing the organic matter, followed by magnesiothermic reduction in the presence of NaCl as a heat scavenger. The ultrafine Si NPs show a high capacity of 1800 mA h g(-1) at a 0.2 C (1 C = 4200 mA g(-1)) rate and are thus promising anode materials in lithium-ion batteries. To achieve better rate capability, the BLs-derived ultrafine Si NPs are coated with a thin amorphous carbon layer (Si@C) and then dispersed and embedded in a reduced graphene oxide (RGO) network to produce Si@C/RGO nanocomposites by a layer-by-layer assembly method. The double protection rendered by the carbon shell and RGO network synergistically yield structural stability, high electrical conductivity and a stable solid electrolyte interface during Li insertion/extraction. The Si@C/RGO nanocomposites show excellent battery properties with a high capacity of 1400 mA h g(-1) at a high current density of 2 C and remarkable rate performance with a capacity retention of 60% when the current density is increased 20 times from 0.2 to 4 C. This work provides a simple, low cost, and scalable approach enabling the use of BL waste as a sustainable source for the production of ultrafine Si NPs towards high-performance LIBs.

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Recent research activities on the surface modification and biomedical applications of TiO2 NTAs are reviewed.

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