Bismuth dots imbedded in ultralong nitrogen-doped carbon tubes for highly efficient lithium ion storage

Abstract

Bismuth (Bi) is a prospective alloying-type anode material for rechargeable lithium-ion batteries (LIBs) on account of its high theoretical gravimetric capacity. The main challenge faced with Bi-based anode materials, however, is the extremely severe volume expansion during charge/discharge, which generally causes severe structural degradation and an unstable solid–electrolyte interphase (SEI). Herein, a nanotube-shaped porous Bi–carbon hybrid is designed and fabricated through a facile template synthesis strategy. Ultrafine Bi nanodots are uniformly embedded and space-confined in nitrogen-doped hollow carbon nanotubes (referred to as Bi@NC), which are constructed employing MnO₂ nanowires as a template followed by selective etching. The architecture of this unique Bi@NC nanostructure with ample internal voids gives a stable SEI during cycling and accommodates the volume variation of the entrapped Bi, while the ultralong tubular carbon framework with a large aspect ratio can provide continuous longitudinal conductive channels for rapid electron transfer. Benefiting from these features, the as-built Bi@NC composite exhibits superior Li-storage performance, as reflected by the outstanding high rate capability and durable cycling lifespan in LIBs (117 mA h g⁻¹ at 10 A g⁻¹; 470 mA h g⁻¹ at 1.0 A g⁻¹ after 2000 cycles). The excellent Li-storage property of Bi@NC associated with its structural advantages could provide inspiration for the rational design of other nanostructured alloying-based anode materials toward multifunctional electrochemical energy storage.