CoSe2-Modified multidimensional porous carbon frameworks as high-Performance anode for fast-Charging sodium-Ion batteries

Multidimensional porous carbon nanosheet frameworks decorated with CoSe2 nanoparticles (CoSe2-CNF) was produced by a metal salt-assisted polymer-blowing method. Unique structure endows CoSe2-CNF with exceptional battery capacity and fast-charging capability as anode for sodium-ion batteries in various electrolyte systems. In situ techniques and DFT calculations further investigate the sodium storage mechanism and excellent electrochemical properties. [Display omitted] •A metal salt-assisted polymer-blowing method is proposed to construct CoSe2-CNF.•Unique nanoarchitecture offers more active sites for Na+ storage and transmission.•The CoSe2-CNF as anode exhibits exceptional battery capacity and fast-charging capability in diverse electrolyte systems.•Sodium storage mechanism and fast electrochemical kinetics are investigated. Transition metal selenides (TMSs) possess relatively high theoretical capacity and unique structures emerge as promising anode materials for sodium-ion batteries (SIBs). However, TMSs anode materials suffer from challenges such as substantial volume expansion, undesired side reactions, and poor active reaction dynamics. Herein, we propose a novel synthesis method that integrates metal salt-assisted polymer-blowing technique with in situ selenization strategy to fabricate multidimensional porous 3D carbon nanosheet frameworks modified by cobalt diselenide nanoparticles (CoSe2-CNF). Such unique architecture bestows intimate structural interconnectivity with high mechanical strength and abundant ion diffusion channels on CoSe2-CNF, exhibiting remarkable reversible capacity and fast-charging capability within diverse electrolyte systems. For instance, the CoSe2-CNF anode in ether electrolyte exhibits prominent rate performance of 349 mAh/g at 15 A/g. Sodium storage mechanism and fast electrochemical kinetics in the discharge/charge processes are investigated by in situ XRD and in situ EIS techniques. Additionally, DFT calculations are utilized to analyze the electrochemical differences observed in various electrolyte systems. When coupled with Na3V2(PO4) (NVP) cathodes, the full batteries also afford enhanced reversible capacity of 105 mAh/g over 100 cycles. The proposed structural engineering for CoSe2-CNF is beneficial for designing fast-charging energy storage devices.