Vacancy engineering in WS2 nanosheets for enhanced potassium‐ion storage

As a promising energy storage technology, potassium-ion batteries (PIBs) have received extensive attention because of the cheap and abundant potassium resources. To date, developing anodes for fast and reversible potassiation/depotassiation is in its infancy. This study reports WS2 nanosheets modified by abundant sulfur vacancies (denoted as Sv-WS2) as anode for PIBs for the first time. Benefiting from the synergistic effects of improved electronic conductivity and more active sites produced by sulfur vacancies, and rich interspace acquired by the connection of adjacent nanosheets, the Sv-WS2 anode displays a high reversible capacity of 303.3 mAh g−1 at 0.05 A g−1 and a high rate performance of 136.6 mAh g−1 at 2.0 A g−1, as compared with that (216.5 and 45.5 mAh g−1) of pristine WS2 (P-WS2). Ex situ characterizations confirm that the Sv-WS2 anode undergoes an intercalation-conversion reaction mechanism. First principles calculations further reveal that the creation of sulfur vacancies can availably lower K-insertion energy barriers and increase the electrical conductivity. This study demonstrates a further direction to effectively enhance the potassium storage capability of transition metal dichalcogenides.