3D Ti3C2TX@PANI-reduced graphene oxide hydrogel and defective reduced graphene oxide hydrogel as anode and cathode for high-energy asymmetric supercapacitor

The rational constructions of asymmetric supercapacitors (ASCs) by extending the operating potential window has been verified as an effective tactic to break through the energy density of the device. In this work, Ti ₃C ₂T _X @polyaniline (PANI) heterostructure is successfully synthesized by uniformly depositing PANI nanorods onto the surface of Ti ₃C ₂T _X nanosheets through polymer polymerization, then via a low-temperature hydrothermal graphene oxide (GO)-gelation process, Ti ₃C ₂T _X @PANI is assembled into a three-dimensional (3D) porous hydrogel. The resultant Ti ₃C ₂T _X @PANI-reduced graphene oxide (RGO) hydrogel exhibits a high specific capacitance of 617.84 F g ⁻¹ at 0.5 A g ⁻¹ . Separately, a defective reduced graphene oxide (DRGO) hydrogel is prepared by a cost-effective cobalt-catalyzed gasification procedure, which shows a higher specific capacitance (237.62 F g ⁻¹ at 0.5 A g ⁻¹) than that of untreated RGO hydrogel (158 F g ⁻¹). Finally, Ti ₃C ₂T _X @PANI-RGO and DRGO are used as anode and cathode to construct the Ti ₃C ₂T _X @PANI-RGO//DRGO ASC device, which features a stable operating voltage (−1.6 to 0.2 V), an ultra-high energy density (269.18 Wh kg ⁻¹ at 527.72 W kg ⁻¹ and 77.90 Wh kg ⁻¹ at 12,409.04 W kg ⁻¹), and durable cycling property (retaining 92.52% capacitance after 10,000 cycles at 10 A g ⁻¹). This research emphasizes the extraordinary superiority of Ti ₃C ₂T _X-based structures for the construction of high-energy ASCs.