Sea Sand-Derived Magnesium Silicide as a Reactive Precursor for Silicon-Based Composite Electrodes of Lithium-Ion Battery

Engineering Bamboo Leaves Into 3D Macroporous Si@C Composites for Stable Lithium-Ion Battery Anodes

Silicon is considered as the most promising candidate for anodes of next generation lithium-ion batteries owing to its natural abundance and low Li-uptake potential. Building a macroporous structure would alleviate the volume variation and particle fracture of silicon anodes during cycling. However, the common approaches to fabricate macroporous silicon are complex, costly, and high energy-consuming. Herein, bamboo leaves are used as a sustainable and abundant resource to produce macroporous silicon via a scalable magnesiothermic reduction method. The obtained silicon inherits the natural interconnected network from the BLs and the mesopores from the BL-derived silica are engineered into macropores by selective etching after magnesiothermic reduction. These unique structural advantages lead to superior electrochemical performance with efficient electron/ion transport and cycling stability. The macroporous Si@C composite anodes deliver a high capacity of 1,247.7 mAh g⁻¹ after 500 cycles at a current density of 1.0 A g⁻¹ with a remarkable capacity retention of 98.8% and average Coulombic efficiency as high as 99.52% for the same cycle period. Furthermore, the rate capabilities of the Si@C composites are enhanced by conformal carbon coating, which enables the anode to deliver a capacity of 538.2 mAh g⁻¹ at a high current density of 4.0 A g⁻¹ after 1,000 deep cycles. Morphology characterization verifies the structural integrity of the macroporous Si@C composite anodes. This work demonstrated herein provides a simple, economical, and scalable route for the industrial production of macroporous Si anode materials utilizing BLs as a sustainable source for high-performance LIBs.

When Silicon Materials Meet Natural Sources: Opportunities and Challenges for Low-Cost Lithium Storage

The manipulation of progressive lithium-ion batteries (LIBs) with high energy density, low cost, and long-term cycling stability is of high priority to meet the growing demands for next-generation energy storage devices. Silicon (Si) has been receiving marvelous attention as a promising anode material for rechargeable LIBs, due to its high theoretical gravimetric capacity and low cost. Si is the second most abundant element in the earth crust in the form of silicates, so it is the most cost-effective element as an anode material in next-generation LIBs. In this review, different natural sources such as rice husk, sugar cane bagasse, bamboo, reed plant, sand, halloysite, and different waste sources such as waste of the solar power industry, fly ash, straw ash, and other industrial waste that can give rise to different nanostructured Si are systematically summarized. In addition, different synthesis methods of fabricating nanostructured Si are reviewed as well as including magnesiothermic reduction, etching methods, ball milling, and chemical vapor deposition. The advantages and disadvantages of these kind of synthesis methods are discussed as well. Furthermore, the opportunities and challenges of nano-Si are also discussed.