Huanyan Liu

Interfacial Constructing Flexible V2O5@Polypyrrole Core–Shell Nanowire Membrane with Superior Supercapacitive Performance

Flexible membrane consisting of ultralong V2O5@conducting polypyrrole (V2O5@PPy) core-shell nanowires is prepared by a facile in situ interfacial synthesis approach. The V2O5 is for the first time demonstrated to show versatile function of reactive template to initiate the uniform and conformal polymerization of PPy nanocoating without the need for extra oxidants. The freestanding PPy-encapsulated V2O5 nanowire membrane is of great benefit in achieving strong electrochemical harvest by increasing electrical conductivity, shortening ion/electron transport distance, and enlarging electrode/electrolyte contact area. When evaluated as binder- and additive-free supercapacitor electrodes, the V2O5@PPy core-shell hybrid delivers a significantly enhanced specific capacitance of 334 F g-1 along with superior rate capability and improved cycling stability. The present work would provide a simple yet powerful interfacial strategy for elaborate constructing V2O5/conducting polymers toward various energy-storage technologies.

Triaxial Nanocables of Conducting Polypyrrole@SnS2@Carbon Nanofiber Enabling Significantly Enhanced Li-Ion Storage

Two-dimensional (2D) SnS2 materials represent a class of high-capacity candidates as anodes of Li-ion batteries (LIBs); however, they are limited by inferior rate and cycling performance. Herein, we demonstrate unique triaxial nanocables of conducting polypyrrole@SnS2@carbon nanofiber (PPy@SnS2@CNF) prepared via a facile combination of hydrothermal method and vapor-phase polymerization. The PPy@SnS2@CNF manifests a strong synergistic effect from its hierarchical nanoarchitecture, which provides enlarged electrode/electrolyte contact interfaces, highly electrical conductive pathways, sufficient electrolyte ingress/transport channels, and an intimate mechanical/electrochemical safeguard for fast electrode kinetics and good structural stability. When evaluated as binder-free anodes of LIBs, the ternary nanocomposite delivers an ultrahigh reversible capacity of 1165 mAh g-1 after 100 cycles and outstanding rate/cycling performance (880 mAh g-1 at 2000 mA g-1), which are among the best results of the previously reported SnS2 electrodes. This work may pave a rational avenue of developing 2D materials with hierarchical structures for highly efficient energy-storage systems.

Facile Synthesis of V2O5 Hollow Spheres as Advanced Cathodes for High-Performance Lithium-Ion Batteries

Three-dimensional V2O5 hollow structures have been prepared through a simple synthesis strategy combining solvothermal treatment and a subsequent thermal annealing. The V2O5 materials are composed of microspheres 2–3 μm in diameter and with a distinct hollow interior. The as-synthesized V2O5 hollow microspheres, when evaluated as a cathode material for lithium-ion batteries, can deliver a specific capacity as high as 273 mAh·g−1 at 0.2 C. Benefiting from the hollow structures that afford fast electrolyte transport and volume accommodation, the V2O5 cathode also exhibits a superior rate capability and excellent cycling stability. The good Li-ion storage performance demonstrates the great potential of this unique V2O5 hollow material as a high-performance cathode for lithium-ion batteries.

Edge-oriented SnS2 nanosheet arrays on carbon paper as advanced binder-free anodes for Li-ion and Na-ion batteries

Two-dimensional SnS2 materials are promising for energy storage, but the specific capacity and cycling performance are still far from satisfactory. Herein, a rational design of edge-oriented SnS2 nanosheet arrays with vertical alignment on a carbon paper for Li-ion and Na-ion batteries is reported. The unique hybrid architecture provides sufficient electrode/electrolyte interaction areas, fast electron/ion transport and efficient volume accommodation, thereby enabling high and stable electrochemical utilization as well as fast reaction kinetics of SnS2. The as-prepared SnS2@C hybrid paper, when used as a binder-free anode for both Li-ion and Na-ion batteries, exhibits high specific capacity, superior rate capability and excellent cycling durability. The outstanding electrochemical performance suggests that the SnS2 nanosheet arrays with preferential edge orientation hold great potential serving as advanced anode materials for the use in energy storage applications.

Ultrafast lithium energy storage enabled by interfacial construction of interlayer-expanded MoS2/N-doped carbon nanowires

Two-dimensional (2D) molybdenum disulfide (MoS2) has been extensively regarded as a promising host material for lithium ion batteries due to the reversible insertion of Li+ into the layered structures. However, achieving ultrafast and durable Li+ storage has a challenge of designing largely exposed edge-oriented and kinetically favorable MoS2-based nanostructures. Herein, we report an interfacial synthesis strategy for facile construction of ultrathin MoS2/N-doped carbon nanowires (MoS2/N–C NWs) (ca. 10 μm in length) with a largely expanded (002) plane of MoS2 (d = 1.03 nm, vs. bulk 0.62 nm). This hierarchical nanowire configuration composed of edge-oriented and interlayer-expanded MoS2 nanosheets can not only effectively decrease the diffusion energy barriers for Li+ intercalation and improve the number of electrochemically active sites, but also provide fast electron pathways. As an anode for LIBs, the MoS2/N–C NWs demonstrate excellent rate capabilities (600 mA h g−1 at 5 A g−1 and 453 mA h g−1 at 10 A g−1) and long-term durability (86.7% retention at 5 A g−1 over 500 cycles). This study demonstrates the great potential of the MoS2/N–C NWs as promising anode materials for ultrafast lithium energy storage.

Self-Supported Ni(P, O)x·MoOx Nanowire Array on Nickel Foam as an Efficient and Durable Electrocatalyst for Alkaline Hydrogen Evolution

Earth-abundant and low-cost catalysts with excellent electrocatalytic hydrogen evolution reaction (HER) activity in alkaline solution play an important role in the sustainable production of hydrogen energy. In this work, a catalyst of Ni(P, O)x·MoOx nanowire array on nickel foam has been prepared via a facile route for efficient alkaline HER. Benefiting from the collaborative advantages of Ni(P, O)x and amorphous MoOx, as well as three-dimensional porous conductive nickel scaffold, the hybrid electrocatalyst shows high catalytic activity in 1 M KOH aqueous solution, including a small overpotential of 59 mV at 10 mA cm−2, a low Tafel slope of 54 mV dec-1, and excellent cycling stability.