Customizing CoSe2/Ti3C2Tn MXene hybrid inks toward high-energy-density 3D-printed K-ion hybrid capacitors

Potassium-ion hybrid capacitor (PIHC) has been deemed as an appealing energy storage system thanks to its low cost and reconciled energy/power density. Nevertheless, the rapid capacity deterioration, sluggish anode kinetics and unsatisfied energy output greatly impede its practical implementation. Herein, a fully 3D-printed (3DP) PIHC affording high-energy–density and long-lifetime is conceptually demonstrated based on a 3DP CoSe2@Ti3C2Tn MXene anode and a 3DP activated carbon cathode, which can harvest a gravimetric energy density of 199 Wh kg−1 and a 6000-cycled lifespan with a capacity retention of 84.8%. Our 3D-printable CoSe2@Ti3C2Tn MXene hybrid ink with desirable rheological property is customized to derive 3DP electrode with facilitated ion diffusion and mass transport, thereby enabling impressive K-ion storage performances. This work would open up a new and facile avenue for the development of stable, safe and credible PIHCs, which could be readily extended to other metal-ion hybrid capacitors.