A High‐Performance, Tailorable, Wearable, and Foldable Solid‐State Supercapacitor Enabled by Arranging Pseudocapacitive Groups and MXene Flakes on Textile Electrode Surface

Abstract

The challenges of solid‐state supercapacitors (SCs) for flexible and wearable electronics still remain in well balancing the electrochemical performance, mechanical stability, and processing technologies. Herein, a high‐performance, tailorable and foldable solid‐state asymmetric supercapacitor is developed via one‐step scalable chemical oxidization and MXene ink painting of N‐doped carbon fiber textile (NCFT) substrate. The employed O/N‐functionalized NCFT (ONCFT) and MXene materials under opposite potentials both incorporate excellent electrochemical behaviors of carbon‐like materials and pseudocapacitive materials, namely high rate capability and pseudocapacitance. By regulating oxidization time and MXene loading, the active layer of MXene decorated NCFT (MNCFT) and ONCFT electrodes analogously present tight skin structure, fundamentally avoiding the risk of active materials detaching from the support during mechanical deformation. As a result, the assembled MNCFT//ONCFT device not only achieves an extended voltage window of 1.6 V, high areal energy density of 277.3 μWh cm−2 and 90% capacitance retention after 30 000 cycles, but also experiences repeated folding tests. Additionally, the design makes it possible to tailor the textile‐based energy storage device (TEESD) into a designed size or shape without impairing its performance for device integration or shape conformable integration. Owing to the whole component fabrication being simple and scalable, the TEESD shows potential practical application.

Foldable batteries: from materials to devices

“…Yuan and coworkers fabricated tailorable, wearable, and foldable solid-state asymmetric supercapacitors (ASCs) based on CFTs. 113 The suggested positive and negative electrodes of the ASCs were O/N-functionalized CFTs (ONCFT) and N-doped CFT with MXene ink (MNCFT), respectively, and polyvinyl alcohol (PVA)/H 2 SO 4 gel electrolytes were inserted between the electrodes. Figure 9g shows a 10 × 10 cm 2 region of the MNCFT electrodes with different folded shapes.…”

“…Transition-metal oxides are one of the most promising candidates, for pseudocapacitors, because they provide high energy density through the redox reactions occurring within the bulk material. 19,[112][113][114][115][116][117][118][119] Conductive polymers are also promising candidates. 120 However, for EDLCs, the electrical energy is stored by electrostatic accumulation on the interfacial electrolyte/electrode surface, mainly for carbon-based materials with a high specic surface area.…”

Soft materials for wearable supercapacitors

“…For instance, Yuan and co-workers [13] developed a tailorable and foldable solid-state asymmetric supercapacitor through a one-step scalable chemical oxidization and Ti3C2Tx MXene ink painting of N-doped carbon fiber textile (NCFT) substrate. By regulating the oxidization time and MXenen loading, the active layer of MXenen decorated NCFT (MNCFT) and O-functionalized NCFT (ONCFT) electrodes analogously presented tight skin structure, avoiding the risk of active materials detaching from the support during mechanical deformation.…”

High‐Energy Aqueous Asymmetric Supercapacitors via Synergistic Design of Electrodes Derived from Hierarchical Vanadium Dioxide Nanocomposites

“…[5] Nevertheless, the energy density is still astricted depending on the formula of E ¼ 1 2 CV 2 , thus it is imperative to provoke the energy density by improving the specific capacitance (C) and extending the working voltage (V) without sacrificing power density. [6,7] Obviously, improving the voltage window by constructing asymmetric supercapacitors (ASCs) is an available strategy. Therefore, extensive efforts have been dedicated to assemble ASCs such as NSs/CNTF, [8] rGO@VO 2 //rGO@Mn 3 O 4 [9] and FeOOH//NMO-NDs@NG.…”