Al₂O₃‐Assisted Confinement Synthesis of Oxide/Carbon Hollow Composite Nanofibers and Application in Metal‐Ion Capacitors

Abstract

Hollow micro-/nanostructures are widely explored for energy applications due to their unique structural advantages. The synthesis of hollow structures generally involves a "top-down" casting process based on hard or soft templates. Herein, a new and generic confinement strategy is developed to fabricate composite hollow fibers. A thin and homogeneous atomic-layerdeposition (ALD) Al 2 O 3 layer is employed to confine the pyrolysis of precursor fibers, which transform into metal (or metal oxide)-carbon composite hollow fibers after removal of Al 2 O 3. Because of the uniform coating by ALD, the resultant composite hollow fibers exhibit a hollow interior from heads to ends even if they are millimeter long. V, Fe, Co, and Ni-based hollow nanofibers, demonstrating the versatility of this synthesis method, are successfully synthesized. Because of the carbon constituent, these composite fibers are particularly useful for energy applications. Herein, the as-obtained hollow V 2 O 3-C fiber membrane is employed as a freestanding and flexible electrode for lithium-ion capacitor. The device shows an impressive energy density and a high power density.

Boosting Zn2+ and NH4+ Storage in Aqueous Media via In‐Situ Electrochemical Induced VS2/VOx Heterostructures

“…[ 34 ] After experiencing the initial charging, apart from the retaining VSV vibrational mode, three new peaks at around 600, 656, and 995 cm −1 appear, corresponding to the stretching vibrations of the vanadyl group, VOV and VO vibrational modes, respectively. [ 17,35 ] X‐ray photoemission spectra (XPS) confirms that the pristine VS 2 powder demonstrates two peaks at 524.5 and 516.4 eV (Figure 2d), corresponding to V 4+ 2p1/2 and V 4+ 2p3/2, respectively. Another deconvoluted peak at 517.65 eV can be ascribed to the V 5+ 2p3/2, which can be attributed to the partial surface oxidation.…”

Aligned Arrays of Na2Ti3O7 Nanobelts and Nanowires on Carbon Nanofiber as High‐Rate and Long‐Cycling Anodes for Sodium‐Ion Hybrid Capacitors

“…The first discharge and charge capacity is 575.4 and 234.2 mAh g −1 , respectively, leading to a low initial coulombic efficiency (ICE) of 40.7% in the initial cycle. This low ICE is mainly caused by the decomposition of electrolyte and the generation of solid‐electrolyte interfacial film [ 39–41 ] and can be improved by presodiation. [ 42 ] Based on the GCD curves at different current densities (Figure 4b, and Figure S4, Supporting Information), we can calculate the specific capacity.…”

Two-dimensional SnO2 anchored biomass-derived carbon nanosheet anode for high-performance Li-ion capacitors

“…5d, Table S1 †). [72][73][74][75][76][77][78][79][80] The LICs with SnO 2 /PCN anode and PCN capacitive cathode overcome intrinsic sluggish kinetics, the reasons can be summarized as follows: (1) the conductivity of SnO 2 is improved by N-doped PCN nanosheets, and the mesoporous-dominated structure is conductive to the penetration and migration of the electrolyte. (2) SnO 2 nanoparticles can not only inhibit the close packing of PCN nanosheets, but also shorten the length of Li + /electron diffusion path; (3) the intrinsic heteroatom doped PCN cathode favors adsorption/desorption of electrolyte ions, which further increases pseudo-capacitance and provides more active sites for lithium ions storage.…”