Qinyou An

Hierarchical mesoporous perovskite La0.5Sr0.5CoO2.91 nanowires with ultrahigh capacity for Li-air batteries

Lithium-air batteries have captured worldwide attention due to their highest energy density among the chemical batteries. To provide continuous oxygen channels, here, we synthesized hierarchical mesoporous perovskite La0.5Sr0.5CoO2.91 (LSCO) nanowires. We tested the intrinsic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity in both aqueous electrolytes and nonaqueous electrolytes via rotating disk electrode (RDE) measurements and demonstrated that the hierarchical mesoporous LSCO nanowires are high-performance catalysts for the ORR with low peak-up potential and high limiting diffusion current. Furthermore, we fabricated Li-air batteries on the basis of hierarchical mesoporous LSCO nanowires and nonaqueous electrolytes, which exhibited ultrahigh capacity, ca. over 11,000 mAh⋅g –1, one order of magnitude higher than that of LSCO nanoparticles. Besides, the possible reaction mechanism is proposed to explain the catalytic activity of the LSCO mesoporous nanowire.

One-Pot Synthesized Bicontinuous Hierarchical Li3V2(PO4)3/C Mesoporous Nanowires for High-Rate and Ultralong-Life Lithium-ion Batteries

Lithium-ion batteries have attracted enormous attention for large-scale and sustainable energy storage applications. Here we present a design of hierarchical Li3V2(PO4)3/C mesoporous nanowires via one-pot synthesis process. The mesoporous structure is directly in situ carbonized from the surfactants (CTAB and oxalic acid) along with the crystallization of Li3V2(PO4)3 without using any hard templates. As a cathode for lithium-ion battery, the Li3V2(PO4)3/C mesoporous nanowires exhibit outstanding high-rate and ultralong-life performance with capacity retention of 80.0% after 3000 cycles at 5 C in 3-4.3 V. Even at 10 C, it still delivers 88.0% of its theoretical capacity. The ability to provide this level of performance is attributed to the hierarchical mesoporous nanowires with bicontinuous electron/ion pathways, large electrode-electrolyte contact area, low charge transfer resistance, and robust structure stability upon prolonged cycling. Our work demonstrates that the unique mesoporous nanowires structure is favorable for improving the cyclability and rate capability in energy storage applications.

Amorphous Vanadium Oxide Matrixes Supporting Hierarchical Porous Fe3O4/Graphene Nanowires as a High-Rate Lithium Storage Anode

Developing electrode materials with both high energy and power densities holds the key for satisfying the urgent demand of energy storage worldwide. In order to realize the fast and efficient transport of ions/electrons and the stable structure during the charge/discharge process, hierarchical porous Fe3O4/graphene nanowires supported by amorphous vanadium oxide matrixes have been rationally synthesized through a facile phase separation process. The porous structure is directly in situ constructed from the FeVO4·1.1H2O@graphene nanowires along with the crystallization of Fe3O4 and the amorphization of vanadium oxide without using any hard templates. The hierarchical porous Fe3O4/VOx/graphene nanowires exhibit a high Coulombic efficiency and outstanding reversible specific capacity (1146 mAh g(-1)). Even at the high current density of 5 A g(-1), the porous nanowires maintain a reversible capacity of ∼500 mAh g(-1). Moreover, the amorphization and conversion reactions between Fe and Fe3O4 of the hierarchical porous Fe3O4/VOx/graphene nanowires were also investigated by in situ X-ray diffraction and X-ray photoelectron spectroscopy. Our work demonstrates that the amorphous vanadium oxides matrixes supporting hierarchical porous Fe3O4/graphene nanowires are one of the most attractive anodes in energy storage applications.

Nanoscroll Buffered Hybrid Nanostructural VO2 (B) Cathodes for High‐Rate and Long‐Life Lithium Storage

Hybrid nanostructural VO2 (B) composed of nanoscrolls, nanobelts and nanowires is synthesized through a hydrothermal-driven splitting and self-rolled method. The hybrid nanostructure with nanoscroll buffered effect provides facile strain relaxation for swelling during lithiation/delithiation, resulting in the excellent structural stability and cyclability. The interior of nanoscrolls and the interconnected voids shorten the ion diffusion pathway, which greatly enhances the rate performance.

Cucumber-Like V2O5/poly(3,4-ethylenedioxythiophene)&MnO2 Nanowires with Enhanced Electrochemical Cyclability

Inspired by the cucumber-like structure, by combining the in situ chemical oxidative polymerization with facile soaking process, we designed the heterostructured nanomaterial with PEDOT as the shell and MnO(2) nanoparticles as the protuberance and synthesized the novel cucumber-like MnO(2) nanoparticles enriched vanadium pentoxide/poly(3,4-ethylenedioxythiophene) (PEDOT) coaxial nanowires. This heterostructured nanomaterial exhibits enhanced electrochemical cycling performance with the decreases of capacity fading during 200 cycles from 0.557 to 0.173% over V(2)O(5) nanowires at the current density of 100 mA/g. This method is proven to be an effective technique for improving the electrochemical cycling performance and stability of nanowire electrodes especially at low rate for application in rechargeable lithium batteries.

Hydrated vanadium pentoxide with superior sodium storage capacity

Sodium ion batteries (SIBs), as potential candidates for large-scale energy storage systems, have attracted great attention from researchers. Herein, a V2O5·nH2O xerogel composed of thin acicular interconnected nanowire networks has been synthesized via a facile freeze-drying process. The interlayer spacing of V2O5·nH2O is larger than that of orthorhombic V2O5 due to the intercalation of water molecules into the layer structure. As the cathode of a SIB, V2O5·nH2O exhibits a high initial capacity of 338 mA h g−1 at 0.05 A g−1 and a high-rate capacity of 96 mA h g−1 at 1.0 A g−1. On the basis of combining ex-situ XRD and FTIR spectroscopy, the Na+ ion intercalation storage reactions are discussed in detail. By modeling calculations, the pseudocapacitive behavior makes a great contribution to the high capacities. Our work demonstrates that V2O5·nH2O with large interlayer spacing is a promising candidate for high capacity sodium-based energy storage.

Nanoflakes-Assembled Three-Dimensional Hollow-Porous V2O5 as Lithium Storage Cathodes with High-Rate Capacity

Three-dimensional (3D) hollow-porous vanadium pentoxide (V2 O5 ) quasi-microspheres are synthesized by a facile solvothermal method followed by annealing at 450 °C in air. The interconnected hollow-porous networks facilitate the kinetics of lithium-ion diffusion and improve the performance of V2 O5 to achieve a high capacity and remarkable rate capability as a cathode material for lithium batteries.

Pore-controlled synthesis of Mn2O3 microspheres for ultralong-life lithium storage electrode

Mesoporous structures have attracted increasing interest in improving the cycling life and specific capacity of electrode materials. Mn2O3 microspheres with controlled pore size were successfully synthesized by morphology-conserved transformation at 500, 700 and 900 °C. Among them, mesoporous Mn2O3 microspheres annealed at 500 °C show the highest discharge capacity, the minor capacity fading per cycle and ultralong cycling life. It can realize 1000 stable charge/discharge processes with 125 mAh g−1 reversible capacity at current density of 1000 mA g−1. Meanwhile, at relatively low current density (200 mA g−1), it can deliver capacity of 524 mAh g−1 after 200 cycles. The remarkable electrochemical performance can result from the relatively high surface area and abundant surface active sites of mesoporous structure, which can enhance the continuous charge transfer kinetics, ion diffusion and capacity. The high cycling stability and long life span make mesoporous Mn2O3 microspheres promising electrode materials for electrochemical energy storage.

Substrate-Assisted Self-Organization of Radial β-AgVO3 Nanowire Clusters for High Rate Rechargeable Lithium Batteries

Rational assembly of unique complex nanostructures is one of the facile techniques to improve the electrochemical performance of electrode materials. Here, a substrate-assisted hydrothermal method was designed and applied in synthesizing moundlily like radial β-AgVO(3) nanowire clusters. Gravitation and F(-) ions have been demonstrated to play important roles in the growth of β-AgVO(3) nanowires (NWs) on substrates. The results of cyclic voltammetry (CV) measurement and X-ray diffraction (XRD) characterization proved the phase transformation from β-AgVO(3) to Ag(1.92)V(4)O(11) during the redox reaction. Further electrochemical investigation showed that the moundlily like β-AgVO(3) nanowire cathode has a high discharge capacity and excellent cycling performance, mainly due to the reduced self-aggregation. The capacity fading per cycle from 3rd to 51st is 0.17% under the current density of 500 mA/g, which is much better than 1.46% under that of 20 mA/g. This phenomenon may be related to the Li(+) diffusion and related kinetics of the electrode. This method is shown to be an effective and facile technique for improving the electrochemical performance for applications in rechargeable Li batteries or Li ion batteries.

Top-down fabrication of three-dimensional porous V2O5 hierarchical microplates with tunable porosity for improved lithium battery performance

Three-dimensional porous V2O5 hierarchical microplates have been fabricated by a one-step top-down strategy, and display an excellent rate capability and stable capacity of 110 mA h g−1 at 2000 mA g−1 after 100 cycles. We have demonstrated that the facile approach of a solid-phase conversion is promising for large-scale fabrication of highly porous micro/nano materials.