Yunhui Huang

Nitrogen-doped porous carbon nanofiber webs as anodes for lithium ion batteries with a superhigh capacity and rate capability.

Nitrogen-doped carbon nanofiber webs (CNFWs) with high surface areas are successfully prepared by carbonization-activation of polypyrrole nanofiber webs with KOH. The as-obtained CNFWs exhibit a superhigh reversible capacity of 943 mAh g(-1) at a current density of 2 A g(-1) even after 600 cycles, which is ascribed to the novel porous nanostructure and high-level nitrogen doping.

Synthesis of functionalized 3D hierarchical porous carbon for high-performance supercapacitors

Functionalized three-dimensional hierarchical porous carbon (THPC) is prepared via a facile modified chemical activation route with polypyrrole microsheets as precursor and KOH as activating agent. The as-obtained THPC presents a large specific surface area (2870 m2 g−1), high-level heteroatom doping (N: 7.7 wt%, O: 12.4 wt%), excellent electrical conductivity (5.6 S cm−1), and hierarchical porous nano-architecture containing macroporous frameworks, mesoporous walls and microporous textures. Such unique features make the THPC an ideal electrode material for electrochemical energy storage. As the electrode material for a supercapacitor, the THPC exhibits a high capacitance, excellent rate performance and long-term stability in both aqueous and organic electrolytes.

Self-assembled hierarchical MoO2/graphene nanoarchitectures and their application as a high-performance anode material for lithium-ion batteries.

Self-assembled hierarchical MoO(2)/graphene nanoarchitectures have been fabricated on a large scale through a facile solution-phase process and subsequent reduction of the Mo-precursor/graphene composite. The as-formed MoO(2)/graphene nanohybrid as an anode material for lithium-ion batteries exhibits not only a highly reversible capacity but also an excellent cycling performance as well as good rate capability. Results show that the hierarchical rods made of primary MoO(2) nanocrystals are uniformly encapsulated within the graphene sheets. The synergistic effect of the hierarchical nanoarchitecture and the conducting graphene support may contribute to the enhanced electrochemical performances of the hybrid MoO(2)/graphene electrode. This work presents a facile synthetic strategy that is potentially competitive for scaling-up industrial production. Besides, the MoO(2)/graphene hybrids with a well-defined hierarchical topology not only provide flexible building blocks for advanced functional devices, but are also ideal candidates for studying their nanoarchitecture-dependent performances in catalytic and electronic applications.

Na+ intercalation pseudocapacitance in graphene-coupled titanium oxide enabling ultra-fast sodium storage and long-term cycling

Sodium-ion batteries are emerging as a highly promising technology for large-scale energy storage applications. However, it remains a significant challenge to develop an anode with superior long-term cycling stability and high-rate capability. Here we demonstrate that the Na(+) intercalation pseudocapacitance in TiO2/graphene nanocomposites enables high-rate capability and long cycle life in a sodium-ion battery. This hybrid electrode exhibits a specific capacity of above 90 mA h g(-1) at 12,000 mA g(-1) (∼36 C). The capacity is highly reversible for more than 4,000 cycles, the longest demonstrated cyclability to date. First-principle calculations demonstrate that the intimate integration of graphene with TiO2 reduces the diffusion energy barrier, thus enhancing the Na(+) intercalation pseudocapacitive process. The Na-ion intercalation pseudocapacitance enabled by tailor-deigned nanostructures represents a promising strategy for developing electrode materials with high power density and long cycle life.

MOF‐Derived Porous ZnO/ZnFe2O4/C Octahedra with Hollow Interiors for High‐Rate Lithium‐Ion Batteries

Novel porous ZnO/ZnFe2O4/C octahedra with hollow interiors are fabricated by a facile self-sacrificing template method involving the refluxing synthesis of hollow, metal-organic framework octahedra in solution and subsequent thermal annealing in N2 . When evaluated as an anode material for lithium-ion batteries, these porous hollow ZnO/ZnFe2O4/C octahedra exhibit significantly enhanced electrochemical performances with high rate capability, high capacity, and excellent cycling stability.

Paper-Based Supercapacitors for Self-Powered Nanosystems†

Energy storage on paper: paper-based, all-solid-state, and flexible supercapacitors were fabricated, which can be charged by a piezoelectric generator or solar cells and then discharged to power a strain sensor or a blue-light-emitting diode, demonstrating its efficient energy management in self-powered nanosystems.

Electrospun porous ZnCo2O4 nanotubes as a high-performance anode material for lithium-ion batteries

Porous ZnCo2O4 nanotubes were synthesized for the first time by an easy single-nozzle electrospinning strategy combined with subsequent heating treatment. The ZnCo2O4 nanotubes are polycrystalline with diameters of 200–300 nm and lengths up to several millimeters. The walls are ∼50 nm thick, comprising interconnected ZnCo2O4 nanocrystals (∼30 nm) and numerous nanopores (∼3 nm). When tested as an anode material for lithium-ion batteries, the resulting ZnCo2O4 nanotubes exhibit superior electrochemical lithium-storage performances with high specific capacity, good cyclability, and excellent rate capability. A high reversible capacity of 1454 mAh g−1 at 100 mA g−1 is achieved, and even reaches 794 mAh g−1 at a current density as high as 2000 mA g−1 after 30 discharge/charge cycles, indicating a promising anode candidate for lithium-ion batteries.

A Solution-Phase Bifunctional Catalyst for Lithium–Oxygen Batteries

A lithium-oxygen battery would deliver the highest energy density of a rechargeable battery, but the multiphase electrochemical reaction on the air cathode has difficulty proceeding when operated with only solid catalysts. We report here the organic-electrolyte-dissolved iron phthalocyanine (FePc) as a shuttle of (O2)(-) species and electrons between the surface of the electronic conductor and the insulator Li2O2 product of discharge. The Li2O2 is observed to grow and decompose without direct contact with carbon, which greatly enhances the electrochemical performance. Our results signal that the use of molecular shuttles that are catalytically active may prove to be enablers of a practical lithium-air rechargeable battery.

Biomass derived hard carbon used as a high performance anode material for sodium ion batteries

A porous hard carbon material was synthesized by the simple pyrolysis of H3PO4-treated biomass, i.e., pomelo peels, at 700 °C in N2. The as-obtained hard carbon had a 3D connected porous structure and a large specific surface area of 1272 m2 g−1. XPS analysis showed that the carbon material was functionalized by O-containing and P-containing groups. The porous hard carbon was used as an anode for sodium ion batteries and exhibited good cycling stability and rate capability, delivering a capacity of 181 mA h g−1 at 200 mA g−1 after 220 cycles and retaining a capacity of 71 mA h g−1 at 5 A g−1. The sodium storage mechanisms of the porous hard carbon can be explained by Na+ intercalation into the disordered graphene layers, redox reaction of the surface O-containing functional groups and Na+ storage in the nanoscale pores. However, the porous hard carbon demonstrated a low coulombic efficiency of 27%, resulting from the formation of a solid electrolyte interphase film and the side reactions of surface phosphorus groups.

Morphosynthesis of a hierarchical MoO2 nanoarchitecture as a binder-free anode for lithium-ion batteries

A simple and cost-effective morphogenetic route has been developed for the fabrication of a hierarchically nanostructured “cellulose” MoO2 monolith in large qualities, whereby the cotton texture acts as both a template and a stabilizer. The MoO2 monolith possesses hierarchical porosity and an interconnected framework, which is demonstrated to be useful as a binder-free anode in rechargeable lithium-ion batteries with both high specific capacity of 719.1 mA h g−1 and good reversibility. Our single-component anode for lithium-storage devices also benefits from a simplified fabrication process and reduced manufacturing cost, in comparison with conventional multicomponent electrodes that are fabricated from a mixture of polymer binders and active materials. The present morphogenetic strategy is facile but effective, and therefore it is very promising for large-scale industrial production. It can be extended to prepare other metal oxides with elaborate textural characteristics.