Atomic-interface strategy and N,O co-doping enable WS2 electrodes with ultrafast ion transport rate in sodium-ion batteries

Abstract

The high theoretical capacity and graphene-like structure enable WS₂ to be a promising anode material for fast-charging sodium-ion batteries. However, poor intrinsic electrical conductivity and large Na⁺-diffusion energy barrier limit its practical applications. Here, an atomic-interface strategy and N,O co-doping were first introduced for WS₂ electrodes to obtain a unique WS₂/C nanocomposite. The atomic-interface strategy that allowed the construction of a unilamellar interoverlapped superstructure maximized the contact area of WS₂ and C, thus significantly improving the electrical conductivity and decreasing the Na⁺-diffusion energy barrier of WS₂ electrodes during cycling. More importantly, the atomic-interface strategy suppressed the growth of superparamagnetic W metallic nanoparticles during conversion reactions, resulting in a strong surface-capacitance effect to boost the Na⁺ transport. Besides, N,O co-doping changed the electronic structure of WS₂ to decrease the bandgap from 1.6 to 0 eV and enlarged the interlayer spacing between WS₂ and C, thus boosting the electron and ion transport. Consequently, WS₂/C exhibited an ultrafast Na⁺-storage capability (450.8 mA h g⁻¹ at 13 A g⁻¹), with an ultrahigh capacity of 669.2 mA h g⁻¹ at 0.065 A g⁻¹ and an ultralong lifetime of over 3000 cycles at 6.5 A g⁻¹ in half-cells. Further, the full-cells showed superior fast-charging capability with an 80.6% capacity retention at 1.95 A g⁻¹.