Potassium-ion hybrid capacitors (PIHCs) have received
extensive
attention due to combining the advantages of high energy density of
batteries and high power density of capacitors and are economically
advantageous alternatives to lithium-ion hybrid capacitors. Metal
phosphides are potential anode materials for K+-storage
with high theoretical capacity, relatively low working potential,
thermal stability, and metal characteristics. Nevertheless, high-performance
metal phosphide materials for PIHC applications have proven to be
challenging due in part to the dissatisfied electronic conductivity,
irreversible deterioration of the structure, and high electron transfer
resistance. In this work, we synthesize carbon nanotube (CNT)-wrapped
AgP2 via a wet-ball milling (WBM) approach to prepare the
electrode slurry. Simultaneously with electrode cycling, the in situ
formed Ag nanocrystals increased the electrical conductivity and formed
Ag-P composites that easily adsorbed more K+, the framework
of CNTs effectively reduced the capacity fading caused by material
refinement, and a large surface area is provided to facilitate electrolyte
penetration. Owing to these advantageous merits of AgP2/CNT electrodes, the assembled PIHC exhibits a high energy/power
density of 37.3 Wh kg–1/12207.3 W kg–1, respectively, and remarkable cycling life over 2000 cycles. These
promising results reveal that the design interfacial engineering of
the CNT-wrapped AgP2 scaffold provides a clue to propel
the development of metal phosphide-based hybrid capacitors.