No abstract

safe, environmentally friendly, and costefficient energy storage technologies. Since renewable and green energy sources such as solar, wind, and tide are available only intermittently, batteries are an exceptionally promising technology to store electricity generated from such sources for later use at the peak consumption times in large scale networks. [1][2][3][4] Commercial lithium-ion batteries (LIBs) with high energy density, cycle stability, and energy efficiency have dominated the energy storage field, and they provide a great convenience for our modern lives. [5,6] However, their further applications are hindered by safety concerns involving the use of harmful organic electrolytes and by the high cost of the appropriate electrode materials. [7,8] Lately, abundant sodium and potassium resources in nature have attracted much attention because of their similar chemical properties to lithium, where sodium-ion batteries and potassium-ion batteries have, thus, become promising alternatives for LIBs. [9][10][11][12] Although the issue of high cost can be solved using such novel battery materials, the usage of conventional organic electrolytes that are toxic and flammable still affects the safety of battery operation. Therefore, in recent years, large researchThe ORCID identification number(s) for the author(s) of this article can be found under

A cascade three-component iodoazidation of para-quinone methides to construct spiro[4.5]deca-6,9-dien-8-ones under mild conditions has been developed. The chemoselective 1,6-addition of azide radical triggered a regioselective 5-exo-dig cyclization/radical coupling sequence, enabling C-N, C-C, and C-I bond formations in a one-pot procedure with high efficiency.

and [2+4] cycloaddition reactions of benzofuran-derived azadienes have been developed. Taking advantage of chiral P,Nligand (S,R p )-PPFA, we obtained a variety of benzofuro [2,3-c][1,5] oxazocines in good yields with excellent enantioselectivities via [4+4] cycloaddition reactions. Employing chiral P,P-ligand (S)-Cl-MeO-BIPHEP, the chemo-and regioselectivities were switched to synthesize tetrahydropyran-fused spirocyclic compounds in good efficiency via [2+4] cycloaddition reactions.

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...