High performance potassium/sodium-ion storage enabled by anchoring cobalt atoms on sulfur vacancies in WS2 nanosheets

Abstract

Transition metal dichalcogenides (TMDs) as anodes have presented significant potential in alkali-ion batteries. Nevertheless, they are generally vulnerable to low conductivity and sluggish ion diffusion as well as severe volume variation. Here, a strategy of filling metal atoms into anion vacancies is proposed and applied to the example of WS2. More specifically, sulfur vacancies are produced and partially filled by Co atoms simultaneously in WS2 (denoted as Co@WS2-SV), creating a highly reactive micro-structure composed of Co-W-S, which can not only effectively provide more active sites, but also boost the charge transfer and reaction kinetics. Consequently, the as-prepared Co@WS2-SV exhibits superior K+ storage performance, which includes an ultrahigh reversible capacity of 382.9 mAh g−1 at 0.05 A g−1. Besides, Co@WS2-SV still maintain a capacity of 112.6 mAh g−1 after 1100 cycles at 2 A g−1 while the capacity fades to ∼0 mAh g−1 after only 800 cycles for WS2. Simultaneously, Co@WS2-SV also displays outstanding rate capability (338.7 mA h g−1 at 2 A g−1) and acceptable cycling performance (264.2 mA h g−1 at 1 A g−1 after 100 cycles) for sodium storage. The strategy in our study provides new way of precisely designing the other TMDs anodes for metal-ion batteries.