Achieving Ultrahigh Energy Densities of Supercapacitors with Porous Titanium Carbide/Boron‐Doped Diamond Composite Electrodes

Abstract

The energy densities of most supercapacitors (SCs) are low, hindering their practical applications. To construct SCs with ultrahigh energy densities, a porous titanium carbide (TiC)/boron‐doped diamond (BDD) composite electrode is synthesized on a titanium plate that is pretreated using a plasma electrolytic oxidation (PEO) technique. The porous and nanometer‐thick TiO2 layer formed during PEO process prevents the formation of brittle titanium hydride and enhances the BDD growth during chemical vapor deposition processes. Meanwhile, the in situ conversion of TiO2 into TiC is achieved. Combination of this capacitor electrode with soluble redox electrolytes leads to the fabrication of high‐performance SCs in both aqueous and organic solutions. In 0.05 m Fe(CN)63−/4− + 1 m Na2SO4 aqueous solution, the capacitance is as high as 46.3 mF cm−2 at a current density of 1 mA cm−2; this capacitance remains 92% of its initial value even after 10 000 charge/discharge cycles; the energy density is up to 47.4 Wh kg−1 at a power density of 2236 W kg−1. The performance of constructed SCs is superior to most available SCs and some electrochemical energy storage devices like batteries. Such a porous capacitor electrode is thus promising for the construction of high‐performance SCs for practical applications.

Ultra-high energy density supercapacitors using a nickel phosphide/nickel/titanium carbide nanocomposite capacitor electrode

“…It is believed that the electrolyte components can be dissociated to active ion-or atomspecies due to the high energy discharges during the PEO. 17,18 This is confirmed by the EDX analysis of the PEO sample before the growth of the Ni 5 TiO 7 nanowires (Fig. S2a †).…”

Photocatalysis‐Assisted Co3O4/g‐C3N4 p–n Junction All‐Solid‐State Supercapacitors: A Bridge between Energy Storage and Photocatalysis

“…Such an energy density could be obtained without sacrificing its power density. [ 63 ] Ragone plot is essential to assess the overall performance of supercapacitor device by energy density ( E ) and power density ( P ) indexes [ 64 ] (Figure S30, Supporting Information). Compared with the results in previous literatures, the as‐prepared device demonstrates an excellent E–P performance with photoirradiation, which is better than some carbon‐based asymmetric supercapacitor devices, proving that photoirradiation is an efficient approach to enhance energy density of supercapacitors.…”

3D Carbon Frameworks for Ultrafast Charge/Discharge Rate Supercapacitors with High Energy-Power Density

“…However, high surface oxygen content will decrease the electric conductivity of carbon electrodes, cause rapid capacity loss at high current density and generate polarization reaction at high voltage during the charge/discharge process, which should be avoided [23]. All in all, the understanding of the relationship between surface properties of carbon electrodes and electrochemical performance is critical for the development of SCs [24][25][26].…”