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

Abstract

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.

Construction of honeycomb porous silicon as a high-capacity and long-life anode toward Li-ion batteries

“…Wu et al succeeded in obtaining porous silicon by magnesium thermal reduction of treated bamboo leaves. 35 Park et al obtained coral-like porous silicon by magnesium thermal reduction of SiO 2 with a size of 10–20 nm as a raw material, which has a high SSA, and abundant pore structure, as well as a high reversible specific capacity and capacity retention rate. 36…”

High-Performance Porous pSi/Ag@C Anode for Lithium-Ion Batteries

“…However, the mass ratio of coating metals is too high and reduces the overall capacity of electrodes. Porous silicon allows room for its own volume expansion, and its interconnecting channels ensure efficient electrolyte penetration and shorten ionic transport paths [22,23]. However, the capacity degrades after a long cycling time owing to the intimate connection between nanostructures and electrolytes.…”