Ternary Molybdenum Sulfoselenide Based Hybrid Nanotubes Boosts Potassium-Ion Diffusion Kinetics for High Energy/Power Hybrid Capacitors
Potassium-ion based energy storage technology could possess unique advantages for grid-level applications owing to its abundance and low cost, while the intrinsically sluggish kinetics and large ion radius raise harsh requirement on electrode materials, which severely limits the practical applications. Herein, the ternary MoS2-xSex/carbon hybrid nanotubes (denoted as MoS2-xSex/C-HNTs) with unique disordered layer structure and expanded interplanar spacing was synthesized through the facile two-step method involving oxidative polymerization coating and subsequent thermal annealing treatment using Sb2S3 nanowire template. Impressively, when evaluated as anode for K+ storage, it can maintain a decent specific capacity of 237.0 mAh g−1 after 300 cycles at 0.5 A g-1, delivering a high capacity retention rate of 80.2%. The ex-situ XRD, Raman spectroscopy and GITT measurements are conducted to unravel the energy storage mechanism and the possible origins for the enhanced performance, which supports that the higher diffusion coefficient, excellent structural robust and disordered layer structure could be the combined factors. More importantly, the potassium-ion hybrid capacitor (KIHCs) based on MoS2/3Se4/3/C-HNT anode and commercial activated carbon (AC) cathode can achieve a decent energy density of 44.1 Wh kg−1 at an ultrahigh power density of 15414.0 W kg−1, which demonstrates its great potential for future practical applications.