Designed Redox‐Electrolyte Strategy Boosted with Electrode Engineering for High‐Performance Ti₃C₂T_x MXene‐Based Supercapacitors

Abstract

Ti3C2Tx MXene has shown remarkable potential for supercapacitors. However, its limited capacitance restrains the energy density. Here, a designed redox‐electrolyte strategy boosted with electrode engineering for Ti3C2Tx MXene is demonstrated, by which a record‐high specific capacitance of 788.4 F g−1 at 2 mV s−1 is achieved, accompanied by good rate capability and highly improved cyclic stability compared with the pristine MXene electrode. For the first time, redox additives with redox potentials falling in the Ti3C2Tx MXene's potential range and that can take full advantage of the characteristics of Ti3C2Tx MXene are investigated. CuSO4 and VOSO4 are screened as the hybrid redox additives; and it is revealed that copper and vanadium ions can bond with ═O terminals on the MXene surface and undergo redox reactions mainly via Cu2+/Cu+ and V3+/V2+. The electrode engineering significantly boosts the designed redox‐electrolyte strategy by enhancing ion dynamics and increasing electrochemically active sites. High energy density of 80.9 Wh kg−1 at a power density of 376.0 W kg−1 and high cyclic stability and improved self‐discharging behavior are obtained for the fabricated supercapacitor by applying this strategy. The strategy is also demonstrated for the performance improvement of MXene‐based flexible supercapacitors with hydrogel electrolytes.

A Ferricyanide Anion-Philic Interface Induced by Boron Species within Carbon Framework for Efficient Charge Storage in Supercapacitors

“…This favorable electrochemical performance originates from the enhanced electron/mass transfer process, which can be traced back to the formation of a ferricyanide anion-philic interface after B incorporation. Benefiting from the constructed ferricyanide anion-philic interface, the capacitance achieved by PC-3 in our study surpasses that of other reported carbon-based electrodes for R-SCs (Figure f). ,− Benefiting from the simultaneous promotion of mass/charge transfer, the asymmetric supercapacitor assembled with PC-3 can achieve excellent stability, maintaining capacitance retention of 98% even after undergoing 10,000 charge cycles (Figure S11 and Table S1), proving the potential of developed porous carbon which contains a high percentage of B species especially BC 2 O and BCO 2 units in practical energy storage applications.…”

A Ti3C2Tx@PANI core–shell heterostructure assembled into a 3D porous hydrogel as a free-standing electrode for high-energy supercapacitors

“…[31][32][33] In the MXene family, Ti 3 C 2 T x stands out for its high conductivity, excellent specific capacitance and abundant ion transmission channels. [34][35][36] Nevertheless, stacking of the Ti 3 C 2 T x layers may occur due to the van der Waals interactions, which can seriously limit the specific surface area and pore distribution and hence the electrochemical performance. [37][38][39] To mitigate this issue, aniline (ANI) monomers can be chemisorbed onto the surface of the Ti 3 C 2 T x nanosheets and in situ polymerized to prepare Ti 3 C 2 T x @PANI heterostructures.…”