源于溪木贼的高性能锂离子电池三维多孔生物质硅/碳复合负极材料

Three-dimensional Porous Biogenic Si/C Composite for High Performance Lithium-ion Battery Anode Derived from Equisetum Fluviatile

锂离子电池硅基负极材料的理论比容量比传统石墨材料高10倍,是最有前途的锂离子电池负极材料之一。然而硅基纳米材料的制备工艺复杂、成本高昂,严重限制了锂离子电池硅负极的商业应用。本工作采用溪木贼为原料,通过深度还原、浅度氧化和碳包覆工艺制备了三维多孔生物质硅/碳复合材料(多孔3D-bio-Si/C)。三维多孔结构不仅有利于Li+的快速传输,而且提供足够的空隙缓解在脱-嵌锂过程中发生的体积变化。得益于三维结构中大量的孔隙和高强度的外部碳层,多孔3D-bio-Si/C制备的电极表现出优异的电化学性能。当电流密度为1 A/g时,多孔3D-bio-Si/C的可逆容量为1243.2 mAh/g,循环400次后仍可保持933.4 mAh/g,容量保持率高达89%。利用溪木贼作为生物质硅源制备高性能硅基负极材料,实现了低成本、可规模化、绿色和可持续的合成路线,有望为Si基锂离子电池负极材料的商业应用打下基础。

Silicon-based materials are one of the most promising anode materials for lithium-ion batteries(LIBs)because of their theoretical capacity which is ten times higher than that of conventional graphite.However,the complex fabrication process and the high cost of silicon-based nanomaterials limit their practical application.In this study,equisetum fluviatile was used as raw material to prepare a three-dimensional porous biogenic Si/C composite(3D-bio-Si/C)by deep reduction,mild oxidation and carbon coating processes.The three-dimensional porous structure not only allows rapid diffusion of Li+,but also provides enough voids to accommodate the volume change on Li+insertion and extraction.Benefiting from the abundant internal porosity and the high-strength outer carbon film of the three-dimensional porous structure,the obtained 3D-bio-Si/C shows remarkable electrochemical performance.This 3D-bio-Si/C can deliver reversible specific capacity of 1243.2 mAh/g at a current density of 1 A/g,and maintain 933.4 mAh/g after 400 cycles.This low-cost,scalable,green and sustainable route to synthesize high-performance silicon-based anode material derived from equisetum fluviatile lays a foundation for the commercial preparation of Si based lithium-ion battery anode materials.