A Solid‐State Fibriform Supercapacitor Boosted by Host–Guest Hybridization between the Carbon Nanotube Scaffold and MXene Nanosheets

Abstract

Fiber-shaped supercapacitors with improved specific capacitance and high rate capability are a promising candidate as power supply for smart textiles. However, the synergistic interaction between conductive filaments and active nanomaterials remains a crucial challenge, especially when hydrothermal or electrochemical deposition is used to produce a core (fiber)-shell (active materials) fibrous structure. On the other hand, although 2D pseudocapacitive materials, e.g., Ti C T (MXene), have demonstrated high volumetric capacitance, high electrical conductivity, and hydrophilic characteristics, MXene-based electrodes normally suffer from poor rate capability owing to the sheet restacking especially when the loading level is high and solid-state gel is used as electrolyte. Herein, by hosting MXene nanosheets (Ti C T ) in the corridor of a scrolled carbon nanotube (CNT) scaffold, a MXene/CNT fiber with helical structure is successfully fabricated. These features offer open spaces for rapid ion diffusion and guarantee fast electron transport. The solid-state supercapacitor based on such hybrid fibers with gel electrolyte coating exhibits a volumetric capacitance of 22.7 F cm at 0.1 A cm with capacitance retention of 84% at current density of 1.0 A cm (19.1 F cm ), improved volumetric energy density of 2.55 mWh cm at the power density of 45.9 mW cm , and excellent mechanical robustness.

Highly Conductive Ti3C2Tx MXene Hybrid Fibers for Flexible and Elastic Fiber‐Shaped Supercapacitors

“…This method is simple and scalable to achieve FSC electrodes with active material loading of up to ≈30 wt% . Another fiber fabrication example is biscrolling technique, which can trap active materials onto the helical corridors of carbon nanotube (CNT) sheets . This method is suitable for making tens of centimeters long fiber electrodes with very high active material loadings (>90 wt%).…”

Interlayer Hydrogen‐Bonded Metal Porphyrin Frameworks/MXene Hybrid Film with High Capacitance for Flexible All‐Solid‐State Supercapacitors

“…Unfortunately, the compact self‐stacking of MXene nanosheets limits the abundant accessibility of electrolyte ions, thus preventing the further enhancement of the energy storage ability. To overcome this problem, various electrochemically active materials, such as, C 3 N 4 , graphene, carbon nanotubes, activated carbon, nickel‐aluminum‐layered double hydroxides, and polymer, were intercalated, aligned, and integrated with MXene to increase the interlayer spacing and facilitate ion/electrolyte transport. However, these materials usually have low specific surface area and nonporous nature to limit theoretical capacitance.…”

MXene‐Based Composites: Synthesis and Applications in Rechargeable Batteries and Supercapacitors

“…Mater. [294] Copyright 2018, John Wiley and Sons. a) Schematic of the preparation process of the Ti 3 C 2 T x /CNT fiber-based supercapacitor by rolling.…”

“…Interfaces 2019, 6, 1802004 Figure 13. [294] Copyright 2018, John Wiley and Sons. Reproduced with permission.…”

“…For example, Ti 3 C 2 T x / CNTs film has been rolled into a fiber (Figure 13a), which is assembled into a special supercapacitor (Figure 13d), and the capacity retention is 99% without bending, and 98% under bending after 1500 cycles (Figure 13e,f). [294] It is also possible to spray Ti 3 C 2 T x onto polyester (PET) fibers by electrospinning (Figure 13b). Ti 3 C 2 T x can be uniformly deposited on PET (Figure 13c), which produces a high capacity retention under different bending conditions (Figure 13g).…”