CoSe2 nanodots confined in multidimensional porous nanoarchitecture towards efficient sodium ion storage

Sodium ion batteries (SIBs) are a low-cost and promising alternative to lithium ion batteries, however, due to the large sodium ion size (Na+ vs Li+: 1.02 Å vs 0.76 Å), high ion diffusion barrier and huge volume variation of electrode materials, it remains a challenge to achieve satisfactory Na+ storage performance. To address these issues, herein, we deliberately designed a multidimensional porous anode for SIBs, which was constructed by zero-dimensional (0D) ultrasmall CoSe2 nanodots confined in one-dimensional (1D) porous carbon nanowires (CNWs) and well encapsulated within three-dimensional (3D) graphene (3DG/CoSe2@CNWs). The fabricated 3DG/CoSe2@CNWs nanoarchitecture exhibits plentiful reactive sites, interconnected conductive network, abundant ion transport channels, and double protective structure. Thus, it showed enhanced Na+ storage performance with high reversible capacities (543 mA h g−1 at 0.1 A g−1) and superior long-term cycling performance with a capacity retention of 86.1% at 2 A g−1, and when coupled with 3D graphene/Prussian blue (3DG/PB) cathodes, the full batteries also delivered enhanced electrochemical performance. Furthermore, its efficient Na+ storage mechanisms were proved by the reaction kinetics analysis and density functional theory calculations. Our work provides a new electrode design strategy based on multidimensional nanoarchitecture for high-performance energy storage devices.