Killing two birds with one stone: Constructing tri-elements doped and hollow-structured carbon sphere by a single template for advanced potassium-ion hybrid capacitors

Abstract

Integrating the merits of long lifespan and excellent energy as well as power densities, potassium-ion hybrid capacitors (PIHCs) exhibit great prospects for future energy storage devices. To boost comprehensive performance of PIHCs, heteroatom-doping and morphology-tuning as two comprehensive strategies have been devoted to designing uniquely structural carbon-based materials with favorable advantages. An ideal strategy for simultaneous atomic doping and structural regulation is expected to be developed. Herein, we propose a novel “Killing Two Birds with One Stone” strategy to prepare a tri-elements doped hollow carbon sphere (TED-HCS) as PIHCs anodes, that is, a single template of spherical CoP particles is rationally adopted, which not only provides both a P source for heteroatom-doping but also acts as a self-sacrificial template for hollow-structure engineering. The multifunctional TED-HCS presents a high capacity of 473.0 mAh g−1 and excellent rate performance of 212.5 mAh g−1 at 5.0 A g−1. Remarkably, the as-assembled PIHCs show outstanding energy/power density (40.4 Wh kg−1/10500 W kg−1) and remain high-capacity retention of 89.15% even cycling 12,000 times. The “Killing Two Birds with One Stone” strategy offers new insight into the search for the preparation of carbon-based materials with multi-elements doping and specific morphology structure.