Dynamic template directed construction of three-dimensional porous bismuth aerogels for high-rate Na-ion storage

Abstract

Aiming to achieve a metallic bismuth (Bi) anode with constant accommodation of volume change, a dynamic template strategy is proposed for fabrication of a highly adjustable Bi aerogel anode. In the presence of the NaBH₄ reductant, the in situ generated hydrogen bubbles served as dynamic templates to direct the reduction, nucleation and growth of Bi nanoparticles, which are subsequently merged into a three-dimensional porous skeleton. The unique 3D porous Bi skeleton ensures the rapid alloying/dealloying of sodium ions and efficient electrolyte infiltration. Its excellent structural integrity and buffering capacity for volume fluctuation lead to superior rate performance (330.6 mA h g⁻¹ at 30C) and long-term stability (339.1 mA h g⁻¹ after 2000 cycles at 10C) in a half cell. When coupled with a Na₃V₂(PO₄)₃ cathode, the Na₃V₂(PO₄)₃//Bi full cell exhibits appealing energy density and power density. This work demonstrates a new idea for constructing highly reliable alloy-type anodes for high-rate energy storage systems.