Doping Induced Hierarchical Lattice Expansion of Cobalt Diselenide/Carbon Nanosheet Hybrid for Fast and Stable Sodium Storage

Abstract

Transition metal chalcogenides have received considerable attention in sodium-ion batteries. However, their practical application is greatly hindered by the low conductivity and sluggish kinetics. Here, we report a hierarchical structure, featuring carbon nanosheets grafted on carbon nanofibers, as a substrate that supports cobalt diselenide (CoSe 2 @ carbon nanosheets [CNS]/carbon nanofiber [CNF]) to boost the conductivity and prevent electrode pulverization. Moreover, we demonstrate that manganese doping can be used to expand the sodium-ion diffusion channels in Co 1-x Mn x Se 2 and induce the synergistic lattice expansion of carbon nanosheets, alleviating the sluggish kinetics. Exploiting this strategy, the Co 1-x Mn x Se 2 @CNS/CNF with pre-sodium treatment can deliver a high specific energy density of 409.4 Wh kg −1 at 0.1 C when paired with Na 2 V 1.85 Fe 0.15 (PO 4 ) 3 /C cathode in a full cell. This work may provide insights into how doping induces hierarchical lattice expansion of transition metal chalcogenide/carbon hybrids to alleviate sluggish kinetics and enhance sodium storage. A CNS/CNF hierarchical structure is constructed to prevent electrode pulverization Mn doping can simultaneously achieve lattice expansion of CoSe 2 and carbon nanosheets This hierarchical lattice expansion improves sodium-ion storage capacity and stability Full Na-ion battery can deliver a high specific energy density of 409.4 Wh kg −1 at 0.1 C Transition metal chalcogenides (TMCs) with decent working potential and high reversible theoretical capacity have received considerable attention in sodium-ion batteries. Sun et al. demonstrate that doping engineering is a suitable strategy to manipulate the diffusion channel, which alleviates the sluggish kinetics in intercalation-based electrode materials.