Metal-organic framework derived CoSe2/N-doped carbon core-shell nanoparticles encapsulated in porous N-doped carbon nanotubes as high-performance anodes for sodium-ion batteries

Engineering ideal anode materials with low cost, considerable reaction kinetics and good structural stability are urgently needed for sodium-ion batteries (SIBs) toward large-scale applications. Here, a hierarchical peapod-like nanorod consisting of CoSe 2 /N-doped carbon (NC) core-shell nanoparticles (NPs) embedded into one-dimensional (1D) N-doped carbon nanotubes (CoSe 2 /NC@NCNTs) with inner void space is developed and fabricated by a self-template, dopamine-coating, and succeeding selenization strategy. In the cleverly designed CoSe 2 /NC@NCNTs composite, the 1D peapod-like structure provides high mechanical strength and allows for fast mass transport/electron transfer. The external NCNTs and inner void space can effectively accommodate volumetric undulation and restrain the aggregation of CoSe 2 NPs. Based on these advantages, the CoSe 2 /NC@NCNTs electrode exhibits excellent comprehensive sodium storage performance, e.g., good rate capability (386.3 mAh g −1  at 10.0 A g −1 ) and high cycling stability (394.2 mAh g −1 up to 4500 loops at 5.0 A g −1 ). Moreover, the SIB full cells (Na 3 V 2 (PO 4 ) 3 @C cathodes vs CoSe 2 /NC@NCNTs anodes) can achieve a reversible capacity of 75.6 mAh g −1 total after 200 cycles at 0.5 A g −1 . This work provides a feasible avenue to construct stable energy-storage materials.