Highly dispersive CoSe2 nanoparticles encapsulated in carbon nanotube-grafted multichannel carbon fibers as advanced anodes for sodium-ion half/full batteries

Abstract

Transition metal selenides hold great promise as anode materials for obtaining excellent sodium ion batteries. However, the volume expansion effect during charging and discharging severely affects its application. In response, we propose a method to limit the volume expansion of cobalt selenide with carbon nanotubes and enhance electron and sodium ion conductivity by carbon and nitrogen doping. Excellent cycling stability and multiplicative performance were eventually achieved. Specifically, the CoSe₂@NC/CNTs have a capacity of 480 mA h g⁻¹ at 1 A g⁻¹ after 200 cycles. In addition, a capacity of 369 mA h g⁻¹ at 10 A g⁻¹ can be provided after 800 cycles. Impressively, the CoSe₂@NC/CNTs//NVPOF full cell was assembled by combining a CoSe₂@NC/CNT anode with a Na₃V₂(PO₄)₂O₂F (denoted as NVPOF) cathode with a high capacity of 233 mA h g⁻¹ at 0.1 A g⁻¹. In addition, the assembled full sodium ion cell had a maximum energy density of 113 W h kg⁻¹ and a peak power density of 207 W kg⁻¹, making CoSe₂@NC/CNTs a promising anode material for high performance sodium ion batteries.