Architecturally Robust Graphene-Encapsulated MXene Ti₂CT_x@Polyaniline Composite for High-Performance Pouch-Type Asymmetric Supercapacitor

Abstract

A harmonized three-component composite system which preserves the characteristics of individual components is of interest in the field of energy storage. Here, we present a graphene-encapsulated MXene Ti 2 CT x @ polyaniline composite (GMP) material realized in a systematically stable configuration with different ternary nanomaterials for supercapacitor electrodes. Due to the different ζpotentials in a high-pH solution, chemically converted graphene (negatively charged) is thoroughly unfolded to allow full encapsulation, but the MXene Ti 2 CT x @polyaniline composite with a low positive ζ-potential is easily attracted toward a counter-charged substance. The obtained GMP electrode exhibits improved cycling stability and better electrochemical performance owing to the use of mechanically robust and chemically inert graphene and the densely intercalated conductive polyaniline between the multilayer MXenes. The GMP electrode has a high gravimetric capacitance of 635 F g −1 (volumetric capacitance of 1143 F cm −3 ) at a current density of 1 A g −1 with excellent cycling stability of 97.54% after 10 000 cycles. Furthermore, the asymmetric pouch-type supercapacitor assembled using the GMP as a positive electrode and graphene as a negative electrode yields a high energy density of 42.3 Wh kg −1 at a power density of 950 W kg −1 and remarkable cycling stability (94.25% after 10 000 cycles at 10 A g −1 ).

A MXene‐Coated Activated Carbon Cloth for Flexible Solid‐State Supercapacitor

“…Meanwhile, the available active sites will be greatly reduced due to the restacking of Ti 3 C 2 T X layers, which causes inferior performance when charge/discharge under large current. Therefore, among the series of samples, the HHK‐CC@Ti 3 C 2 T X ‐3 with a uniform morphology can be expected to have the best electrochemical performance …”

Two‐Dimensional Ti3C2TX/Polyaniline Nanocomposite from the Decoration of Small‐Sized Graphene Nanosheets: Promoted Pseudocapacitive Electrode Performance for Supercapacitors

“…Ti 3 C 2 T X displays two strong peaks at about 400 and 600 cm −1 , which are related to the vibration of nonstoichiometric Ti−C. And two week peaks at 1340 and 1570 cm −1 are coded as the D and G bands of carbon in MXene . As for TP and GTP, new peaks at 767, 1248, 1355, 1402 and 1485 cm −1 can associate with the imine deformation, in plane C−H bending of quinoid, in plane ring deformation, C=N stretching and C=C stretching vibration, respectively, further confirmed the presence of PANI .…”

“…The main peak located at 284.7 eV is related to the C−C bonding in graphene. The Ti 2p spectrum (Figure d) consisted of Ti 2p 1/2 and Ti 2p 3/2 peaks with an area ratio of 2 : 1 and energy separation value of 5.7 eV, and it can be further divided into Ti−F, TiO 2 , Ti−C and, Ti−O, respectively …”

“…Fu et al. reported a graphene‐encapsulated (more than 10 μm) MXene Ti 2 CT X /polyaniline composite electrode with potential range of 1.0 V (larger than pristine Ti 2 CT X of 0.8 V) . Our previous study also showed that the introduction of sulfonic polyaniline (PANI) into the graphene nanosheets could greatly improve its performance as an electrode for efficient electrochemical supercapacitor …”

“…As we all know, self‐polymerization polyaniline nanorods are normally thought to possess worse performance in rate performance and cycling stability . Enhanced performances of Ti 3 C 2 T X /PANI composites can be obtained only if polyanilines grow on Ti 3 C 2 T X layered structure uniformly . On the other hand, chemically prepared polyanilines are usually available in powder form and insulating in dedoped states .…”