Polypyrrole‐Assisted Nitrogen Doping Strategy to Boost Vanadium Dioxide Performance for Wearable Nonpolarity Supercapacitor and Aqueous Zinc‐Ion Battery

Abstract

woven into the fabrics to solve the above challenges. [7][8][9] Recently, developed carbonbased fibers due to the merits of featuring light weight, superior conductivity, and omnidirectional flexibility are suitable as current collectors for realization of flexible energy-storage devices. [10][11][12][13][14][15] Therefore, the vast majority of spotlights mainly focused on exploring such fiber-shaped aqueous energy-storage devices including supercapacitors and aqueous ion batteries at present. [16][17][18][19][20][21][22] Unfortunately, the reported fiber-shaped electrodes are still inadequate for large-scale flexible energy storage, especially in practical applications. This may be ascribed to low specific capacitance, sluggish ionic diffusion, and poor electronic conductivity of the active material leading to suboptimal energy and power density, respectively. [23][24][25][26] Disadvantaged by these undesired outcomes, the development of flexible devices based on using carbonbased fibers as current collectors have been hampered for a long time.Numerous methodologies are undertaken by material chemists or energy experts to address the mentioned above shortcomings. [27][28][29][30][31][32][33][34] Among them, doping heteroatoms into active materials is the one effective solution, which can change their electronic distribution in molecular structure thereby enhancing the electronic conductivity. [18,[35][36][37] Another reported effective strategy is to load the active material onto a 3D scaffold, significantly increasing their load mass and specific surface area, which provide more Fiber-shaped energy-storage devices with high energy and power density are crucial for powering wearable electronics. However, the improvement of their energy and power density is limited by the low mass loading of active materials and slow diffusion of ions, which further hinders the application as flexible energy-storage devices. Herein, a facile and cost-effective strategy is proposed to fabricate polypyrrole (PPy)-assisted nitrogen-doped vanadium dioxide/ nitrogen-doped carbon (N-VO 2 @NC) heterostructures by the pyrolyzation of vanadium oxide (VO x )/PPy supported on carbon nanotube fiber (CNTF). The carbonization of PPy nanowire not only forms nitrogen-doped carbon 3D conductive scaffold for enhancing ion transport pathways and mass loading of N-VO 2 but also provides source of nitrogen in situ doping into VO x to produce N-VO 2 for improving electronic conductivity and energy-storage capacity. Consequently, the well-designed N-VO 2 @NC@CNTF electrode delivers impressive electrochemical performance and extraordinary mechanical flexibility both applied in all-solid-state fiber-shaped nonpolarity supercapacitors and aqueous zinc-ion batteries. Furthermore, the results of theoretical calculations discovered that the band gap of PPy-assisted N-VO 2 can be significantly reduced from 0.55 to 0.23 eV and thus its conductivity is greatly enhanced. This work sheds light on the construction of high-performance free-standing electrodes for n...

Flexible Quasi‐Solid‐State Aqueous Zinc‐Ion Batteries: Design Principles, Functionalization Strategies, and Applications

“…N-VO 2 nanosheets (NVNSs)@NC nanowires (NWs) heterostructure nanocomposites were prepared on CNTF using a three-step process that included electrochemical polymerization, a solvothermal procedure, and post-annealing established by Zhang group (Figure 2j). [57] With the fast ion transport and superb electronic conductivity of the binder-free cathode, the fabricated NVNSs@ NC@CNTF cathode delivered impressive electrochemical performance and extraordinary mechanical flexibility in FQAZIBs. Even though the direct growth of electrode active substances on soft current collectors possesses the advantage of without polymer binder, the successful acquires of this type of cathode are seriously limited by the varieties of electrode active substances and preparation approach.…”

Achieving high performance in aqueous iron-ion batteries using tunnel-like VO2 as a cathode material

“…Signals at 283 and 407 cm À1 represent the V-O bending modes, the signal at 526 cm À1 refers to the V 3 -O bending modes, the signal at 695 cm À1 represents the V-O-V stretching modes, and the last signal at 995 cm À1 refers to the shortest O-V stretching vibration modes. 33 The oxidation states of the sample are further confirmed by X-ray photoelectron spectra (XPS). For the V 2p curve (Fig.…”

Multiscale Dot‐Wire‐Sheet Heterostructured Nitrogen‐Doped Carbon Dots‐Ti3C2Tx/Silk Nanofibers for High‐Performance Fiber‐Shaped Supercapacitors

“…[10] Based on the energy-storage mechanism (electro-sorption ions of electrical double-layer capacitors [11] and the redox reactions of pseudocapacitors), [12] the micro-building blocks of fibers with large ion accessible surface, porous pathways, electroactivity and electrical conductivity are highly important. [13] In this regard, diverse nanocarbon-based (e.g., carbon nanotubes (CNT), [14] graphene [15] and activated carbon) [16] fibers, conductive material-coated yarn, [17] and pseudocapacitive active material-loaded metal wire [18] are constructed through dry spinning, [19] wet spinning, [20] hydrothermal self-assembly, [21] microfluidic spinning, [22] chemical/electrochemical deposition [23] and 3D printing [24] processes. For instance, the hierarchical-structured CNT-graphene [25] fibers presented good capacitance of 305 F cm À 3 due to enhanced ionic accessibility and filling density.…”