Densified Metallic MoS2/Graphene Enabling Fast Potassium-Ion Storage with Superior Gravimetric and Volumetric Capacities

The potassium-ion battery (PIB) is an attractive energy storage device that possesses the potential advantages of high energy density and low cost. Herein, a pure 1T-MoS 2 is synthesized on graphene oxide and assembled into a hydrogel. The hydrogel is further tightened to a compact 1T-MoS 2 /graphene (CTMG) bulk by a densifying strategy of capillary tension. When employed as an anode for PIBs, the CTMG electrode can store K + through reversible intercalation and conversion electrochemistry, accompanied with fast kinetics since the 1T-MoS 2 induces a pseudocapacitive storage mechanism and the extraordinary K + transportation ability. Consequently, the CTMG electrode delivers the high and reversible rate capacities of 511 and 327 mAh g -1 at 0.1 and 1 A g -1 , respectively. Moreover, the compact architecture reduces the electrode thickness by ≈33% enabling a high volumetric capacity (512 mAh cm -3 at 0.1 A g -1 after 100 cycles), as well as holding a promising application in thick electrode.