Superior electrochemical performance of layered WTe₂ as potassium-ion battery electrode

Potassium-ion batteries or KIBs are prominent candidates among research involving post lithium-ion batteries due to abundant availability, low-cost, and low standard reduction potential of potassium metal. Although some chemistry correlation with other monovalent alkali metal-ion batteries may exist, research on KIB chemistry is still in its infancy. A relevant research aspect of KIB is the development of a stable anode material that can efficiently cycle the large K⁺ ions in its crystal structure within the 0 to 3 V potential window range; providing reasonable charge capacity and high reversibility. To this end, transition metal dichalcogenides or TMDs are promising electrode materials because of their favorable electrochemical properties. In this work, we study electrochemical performance of tungsten ditelluride (WTe₂) TMD as working electrode in a KIB half-cell. Results show that WTe₂, a telluride-based TMD, has high first cycle specific charge capacity-with up to 3.3 K⁺ stored per WTe₂ molecule (at least 4 times that of WS₂ electrode)-stable capacity of 143 mAh g^-1 at 10th cycle number-outperforming WS₂ (66 mAh g^-1) and graphite (95 mAh g^-1)-good reversibility, reasonable cycling stability, and low charge transfer resistance.