Towards Excellent Anodes for Li-Ion Batteries with High Capacity and Super Long Lifespan: Confining Ultrasmall Sn Particles into N-Rich Graphene-Based Nanosheets

摘要

Sn is regarded as a promising anode material for Li-ion batteries due to high capacity and cost effectiveness. Hitherto large-scale fabrication of Sn-based materials while achieving both high capacity and long cycle life remains challenging, but it is highly required for its realization in practical applications. Furthermore, low melting point always casts shadow over the morphology-controllable preparation, and leads to multistep or high-cost processes. Here, a facile and scalable method is devised for a 2D hybrid structure of Sn@ graphene-based nanosheets incorporating of optimized nitrogen species (approximate to 13 wt%). Distinct from conventional Sn-C composites, the fairly N-rich carbon nanosheets liberate limited potential of low N doping, induce massive extra Li-storage sites, and encourage a high capacity significantly. In addition, these abundantly anchored heteroatoms also promote the homogeneous dispersion and robust confinement of ultrasmall Sn nanoparticles into the flexible graphene-based nanosheets. This elastic encapsulation towards Sn nanoparticles admirably maintains structural integrity through effective remission of volume expansion, demonstrating a super long-term cyclic stability for 1000 cycles. This structural and componential engineering offers a signifi cant implication for rational design of materials in extended areas of energy conversion and storage.