Huifang Fei

Ultrafine TiO2 Confined in Porous-Nitrogen-Doped Carbon from Metal–Organic Frameworks for High-Performance Lithium Sulfur Batteries

Ultrafine TiO2 confined in porous-nitrogen-doped carbon is synthesized from a single metal-organic framework precursor. As a novel interlayer for lithium-sulfur batteries, the TiO2@NC composite can act as both a high efficiency lithium polysulfide barrier to suppress the side reactions and an additional current collector to enhance the polysulfide redox reactions. The lithium-sulfur battery with a TiO2@NC interlayer delivers a high reversible capacity of 1460 mAh g-1 at 0.2 C and capacity retention of 71% even after 500 cycles with high rate capability.

Self-templated biomass-derived nitrogen-doped porous carbons as high-performance anodes for sodium ion batteries

Abstract Nitrogen-doped porous carbon is synthesised from mineral-rich egg yolks. Pores are produced via successive chemical etching. As anode for sodium ion batteries, the as-prepared carbon showed an initial reversible capacity of 208 mAh g−1 and a high capacity retention of 86% after 200 cycles with good rate capability.

Facile hydrothermal growth of VO2 nanowire, nanorod and nanosheet arrays as binder free cathode materials for sodium batteries

Owing to the natural abundance and low standard potential of sodium, sodium-ion batteries are now considered to be promising power systems for electric vehicles and stationary energy storage. Herein, for the first time, we report the synthesis of VO2 nanowire, nanobelt and nanosheet arrays with preferential (110) orientation on conductive titanium foil by a simple time-dependent hydrothermal method. The morphological and crystallization evolution processes of these products are investigated via XRD, SEM, Raman and TEM in detail. The effect of VO2 morphology on sodium storage performance is also probed by charge–discharge and EIS. Benefiting from the unique morphological features, the VO2 nanowire array shows a superior cycle ability of 160 mA h g−1 after 200 cycles and high rate ability even at 1 A g−1.

Enhancing the safety and electrochemical performance of ether based lithium sulfur batteries by introducing an efficient flame retarding additive

Lithium sulfur batteries have been considered as a promising candidate for use as next generation high energy power sources. However, safety problems could be one key problem that hinders the development of lithium sulfur batteries. In this study, a novel flame retarding additive, hexafluorocyclotriphosphazene (HFPN), is investigated for the construction of an ether based (1,3-dioxolane and dimethoxyethane) nonflammable electrolyte for lithium sulfur batteries. A 20% addition could render the electrolyte nonflammable. Moreover, this additive could enhance the electrochemical properties of lithium sulfur batteries by reducing the solubility of polysulfides and reducing the electrode interphase resistance. These results suggest that HFPN could be considered as a useful additive for safer lithium sulfur batteries.

A novel Lithium/Sodium hybrid aqueous electrolyte for hybrid supercapacitors based on LiFePO4 and activated carbon

A novel low cost Na+/Li+ hybrid electrolyte was proposed for hybrid supercapacitor. By partly substituting Lithium salt with Sodium salt, the Li+/Na+ hybrid electrolyte exhibits synergic advantages of both Li+ and Na+ electrolytes. Our findings could also be applied to other hybrid power sources.

Green, Scalable, and Controllable Fabrication of Nanoporous Silicon from Commercial Alloy Precursors for High-Energy Lithium-Ion Batteries

Silicon is considered as one of the most favorable anode materials for next-generation lithium-ion batteries. Nanoporous silicon is synthesized via a green, facile, and controllable vacuum distillation method from the commercial Mg2Si alloy. Nanoporous silicon is formed by the evaporation of low boiling point Mg. In this method, the magnesium metal from the Mg2Si alloy can be recycled. The pore sizes of nanoporous silicon can be secured by adjusting the distillated temperature and time. The optimized nanoporous silicon (800 °C, 0.5 h) delivers a discharge capacity of 2034 mA h g-1 at 200 mA g-1 for 100 cycles, a cycling stability with more than 1180 mA h g-1 even after 400 cycles at 1000 mA g-1, and a rate capability of 855 mA h g-1 at 5000 mA g-1. The electrochemical properties might be ascribed to its porous structure, which may accommodate large volume change during the cycling process. These results suggest that the green, scalable, and controllable approach may offer a pathway for the commercialization of high-performance Si anodes. This method may also be extended to construct other nanoporous materials.