Novel Skutterudite CoP3–Based Asymmetric Supercapacitor with Super High Energy Density

Skutterudite CoP3 holds a unique structural formation that exhibits much better electronic properties for obtaining high energy density supercapacitors. Herein, novel skutterudite Ni–CoP3 nanosheets are constructed by etching and coprecipitating at room temperature and subsequent low‐temperature phosphorization reaction. Benefiting from the enhanced electrical conductivity and more electroactive sites brought about by adjusting the electronic structure with Ni incorporating the Ni–CoP3 electrode with a battery‐type demonstrates an ultrahigh specific capacity of 0.7 mA h cm−2 and exceptional cycling stability. The asymmetric supercapacitor (ASC) device fabricated by employing Ni–CoP3 and activated carbon (AC) as positive and negative electrodes, resepectively, exhibits a remarkable high energy density of 89.6 Wh kg−1 at 796 W kg−1 and excellent stability of 93% after 10 000 cycles, due to the skutterudite structure. The skutterudite Ni–CoP3 shows a great potential to be an excellent next‐generation electrode candidate for supercapacitors and other energy storage devices. A skutterudite structure of Ni‐doped CoP3 nanosheets is designed via etching and coprecipitating at room temperature and subsequent low‐temperature phosphating treatment. The incorporation of Ni ensures higher electrical conductivity and richer electrochemical active sites, which results in ultrahigh high energy density when Ni–CoP3 electrode is assembled into asymmetric supercapacitors.