Electrochemically exfoliated WS2 in molten salt for sodium-ion battery anode

The poor crystallinity and unstable crystal structure of tungsten disulfide (WS2) limit its application in practice. In this paper, a molten salt electrolysis method is proposed to intercalate metal ions into the interlayers of layered WS2 to obtain few-layer sheetlike structures. The effect of the molten salt system, applied constant current and electrolysis duration on the exfoliation degree of WS2 bulk has been investigated. The results show that the products electrolyzed in molten LiCl-NaCl-KCl and NaCl-KCl salts under 25 mA were more transparent and thinner flakes sheets due to the uniform intercalation of Li+ and Na+ with smaller size. The exfoliated WS2 was used as an anode material for sodium-ion batteries with a potential of 0.01-2.50 V. In comparison, the WS2-NaCl-25 mA electrode displays a high reversible capacity of 373 mAh & BULL;g(-1) at 0.1 A & BULL;g(-1) after cycling for 100 cycles at the same time showing great rate and cycle performance. It also presents a high capacitive ratio of 90.65% at 1.0 mV & BULL;s(-1). The molten salt electrolysis provides a new perspective on the exfoliation of layered material, while demonstrating the great potential of WS2 as an anode material for sodium-ion battery.