Construction of Novel Bimetallic Oxyphosphide as Advanced Anode for Potassium Ion Hybrid Capacitor

Abstract

Potassium ion hybrid capacitors (PIHCs) have attracted considerable interest due to their low cost, competitive power/energy densities, and ultra‐long lifespan. However, the more sluggish insertion kinetics of battery‐type anodes than capacitor‐type cathodes in PIHCs seriously limits their practical application. Therefore, developing advanced anodes with high capacitor and suitable K+ intercalation is imperative and significant. A novel core–shell structure of NiCo oxide/NiCo oxyphosphide (NCOP) nanowires are designed and constructed in this study via efficient and facile strategy. Combining the merits of the core–shell structure and the massive active sites in the oxyphosphide layer, the as‐prepared NCOP composites manifest highly reversible capacitors and outstanding rate capability. Meanwhile, the insertion and conversion potassium storage mechanisms of the NCOP are successfully revealed through in situ X‐ray diffraction and density functional theory calculations, respectively. Furthermore, the PIHC was assembled with NCOP anode and borocarbonitride cathode, which displays a large energy density and high‐power density, along with an exceptional capacity retention of ≈90% over 10 000 cycles at 1.0 A g−1. This work provides the anion regulation strategy for modifying the transition metal oxide and constructing the advancing electrode materials for next‐generation energy storage and beyond.

Dimensional engineering of anode materials for high performance potassium ion hybrid capacitor—A review

“…Phan et al converted cotton‐rich textile waste into two different forms of sustainable carbon electrodes, which were used to assemble the PIHC and obtain a maximum energy density and power density of 181 Wh kg −1 and 4000 W kg −1 , 71 and is better than other reported devices (eg, Prussian blue//AC in PIHC 72 and peanut skin derived carbon nanosheets//SCN ‐ A in sodium‐ion hybrid capacitor [SIHC]) 73 . Wang et al design a novel core shell structure of Ni‐Co oxide/Ni‐Co oxyphosphide (NCOP) nanowires and construct in this work with a competent and simple strategy 70 . The electrochemical reaction mechanism of NCOP nanowires were well analyzed by in‐situ XRD test (Figure 3H).…”

“…73 Wang et al design a novel core shell structure of Ni-Co oxide/Ni-Co oxyphosphide (NCOP) nanowires and construct in this work with a competent and simple strategy. 70 The electrochemical reaction mechanism of NCOP nanowires were well analyzed by in-situ XRD test (Figure 3H). The XRD peaks appeared first and then weakened with the progress of potassiation and depotassiation, which proved that the reaction of ion insertion and extraction has good reversibility.…”

“…In summary, the unique linear structure of 1D nanostructured materials enables them to have high specific surface area, directional ionic conductivity, and defectability, which has good performance in PIHC anode materials. In this regard, we put forward several 70 Copyright 2022, WILEY-VCH optimization directions: (a) Suitable introduction of some heteroatoms or defects is helpful to achieve high performance PIHC anodes; (b) The formation direction of 1D nanostructured materials is slightly fixed, forming an array structure, which further improves the electron ion migration efficiency; (c) By controlling the length of 1D nanostructured materials, the solid-liquid region with electrolytes can be formed reasonably and evenly, which provides the possibility for the formation of uniform SEI phase.…”

“…(J and K) Cycling performance (left) at 1 A g −1 and contribution ratios (right) of the capacitive process at different scan rates of NCOP PIHC anode materials. (L) CV curves of the NCOP electrode at a scan rate of 0.1 mV s −1 70 . Copyright 2022, WILEY‐VCH…”

Novel semiconductor materials for advanced supercapacitors

“…21d) of 205.7 W h kg À1 and a power density of 22.5 kW kg À1 . Wang et al 217 also designed a novel nickel-cobalt-phosphorus oxide (NCOP) composite (Fig. 22a) that exhibits highly reversible capacitors and excellent rate performance (Fig.…”