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

Abstract

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.

3D hierarchical core–shell spiny globe shaped Co2P@Ni2P/NiCo2O4@CoO for asymmetric supercapacitors

“…P 2p cannot be found in NCC-NF, and the peaks at 129.40 and 130.27 eV of CNNCC-NF are assigned to the M-P bond (M ¼ Co or Ni). 13 The peak at 133.75 eV is attributed to the P-O bond due to supercial oxidation of phosphorus in CNNCC-NF. 18 Furthermore, some of the Co 3+ ions were reduced to Co 2+ and some of the Ni 2+ ions were oxidized to Ni 3+ during the phosphatization process, indicating that the introduction of the P element causes the change of the local chemical state and adjusts the electronic structures.…”

“…The capacitance (areal capacitance or specic capacitance) of the CNNCC-NF electrode is found to be 10.11 F cm À2 (2641.15 F g À1 ), 9.63 F cm À2 (2528.23 F g À1 ), 9.35 F cm À2 (2466.03 F g À1 ), 9.15 F cm À2 (2415.31 F g À1 ), 8.95 F cm À2 (2363.63 F g À1 ) and 8.23 F cm À2 (2179.90 F g À1 ) at 2 mA cm À2 (0.52 A g À1 ), 4 mA cm À2 (1.05 A g À1 ), 6 mA cm À2 (1.57 A g À1 ), 8 mA cm À2 (2.1 A g À1 ), 10 mA cm À2 (2.63 A g À1 ) and 20 mA cm À2 (5.20 A g À1 ), respectively. For the CNNCC-NF electrode, the corresponding redox reactions are related to Co 2+ / Co 3+ and Ni 2+ /Ni 3+ associated with the OH anions as shown by the following eqn (1)-( 6): 13,[52][53][54] CoO + OH À 4 CoOOH + e À…”

“…Generally, the b values of most charge storage materials are between 0.5 and 1. 13 The b value of the CNNCC-NF electrode is calculated to be 0.89, 0.76, 0.91, and 0.74 at the peaks of 1, 2, 3, and 4 (Fig. S20 and S21 †), respectively.…”

“…Previous research studies demonstrated that a smaller band gap and higher electrochemical activity are obtained in TMPs. 13,14 There are several ways to achieve phosphatization, such as low-temperature plasma reduction, 15 metal phosphate reduction, 16 and wet chemical methods. 17 However, the higher activity of electrode materials is usually accompanied by worse cycle stability.…”

Effect of Manganese Valence on Specific Capacitance in Supercapacitors of Manganese Oxide Microspheres

“…The relationships between the scan rate and current density were used to investigate the reaction kinetics based on equation ( 3): [21] (…”