Yongling An

A controlled red phosphorus@Ni–P core@shell nanostructure as an ultralong cycle-life and superior high-rate anode for sodium-ion batteries

Sodium-ion batteries (SIBs), a potential alternative to lithium ion batteries (LIBs), have attracted remarkable attention recently due to the natural abundance and low-cost of sodium. Here, we have presented a comprehensive study on combining electroless deposition with chemical dealloying to control the shell thickness and composition of a red phosphorus (RP)@Ni–P core@shell nanostructure as a high performance anode for SIBs. For the first time depending on regulating the dealloying time (1 h, 4 h, 8 h, 10 h and 20 h) of RP@Ni–P synthesized by electroless deposition of Ni on RP, 1 h RP@Ni–P, 4 h RP@Ni–P, 8 h RP@Ni–P, 10 h RP@Ni–P and 20 h RP@Ni–P with different shell thicknesses and compositions were prepared. The in situ generated Ni2P on RP particle surfaces can facilitate intimate contact between RP and a mechanically strong amorphous Ni–P outer shell with a high electronic conductivity, which ensures strong electrode structural integrity, a stable solid electrolyte interphase and ultra-fast electronic transport. As a result, the 8 h RP@Ni–P composite presents a super high capacity (1256.2 mA h gcomposite−1 after 200 cycles at 260 mA gcomposite−1), superior rate capability (491 mA h gcomposite−1 at 5200 mA gcomposite−1) and unprecedented ultralong cycle-life at 5000 mA gcomposite−1 for an RP-based SIB anode (409.1 mA h gcomposite−1 after 2000 cycles). This simple scalable synthesis approach will provide a new strategy for the optimization of core@shell nanostructures, paving the way for mass production of high performance electrodes for SIBs and other energy storage systems.

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.

Metal–organic framework-derived graphene@nitrogen doped carbon@ultrafine TiO2 nanocomposites as high rate and long-life anodes for sodium ion batteries

Graphene@nitrogen doped carbon@ultrafine TiO2 nanoparticles (G-NC@TiO2) with porous structure are obtained through annealing the precursor of graphene oxide/metal-organic frameworks (MOFs) for the first time. As an anode material for sodium ion batteries (SIB), the G-NC@TiO2 composite can deliver an excellent capacity retention of 93% even after 5000 cycles, and a superior 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.

Nonflammable electrolyte for safer non-aqueous sodium batteries

Sodium batteries are now considered as promising low-cost alternatives for lithium batteries. However, safety problems such as fire and explosion during abuse-testing conditions hinder the development of room temperature sodium batteries. To address these issues, here we propose a nonflammable electrolyte system for sodium batteries. By introducing a high-efficiency flame-retarding additive, the carbonate based electrolyte becomes flame inhibiting. Moreover, the additive can improve the cyclability of both the acetylene black (AB) anode and the Na0.44MnO2 cathode.

Morphology- and Porosity-Tunable Synthesis of 3D Nanoporous SiGe Alloy as a High-Performance Lithium-Ion Battery Anode

The lithium storage performance of silicon (Si) can be enhanced by being alloyed with germanium (Ge) because of its good electronic and ionic conductivity. Here, we synthesized a three-dimensional nanoporous (3D-NP) SiGe alloy as a high-performance lithium-ion battery (LIB) anode using a dealloying method with a ternary AlSiGe ribbon serving as the precursor. The morphology and porosity of the as-synthesized SiGe alloy can be controlled effectively by adjusting the sacrificial Al content of the precursor. With an Al content of 80%, the 3D-NP SiGe presents uniformly coral-like structure with continuous ligaments and hierarchical micropores and mesopores, which leads to a high reversible capacity of 1158 mA h g-1 after 150 cycles at a current density of 1000 mA g-1 with excellent rate capacity. The strategy might provide guidelines for nanostructure optimization and mass production of energy storage materials.

MnO2 nanotubes with a water soluble binder as high performance sodium storage materials

Well dispersed MnO2 nanotubes were synthesized via a hydrothermal method. When tested as anode materials for sodium-ion batteries with sodium polyacrylate (PAANa) as the binder, for the first time, and aluminum as the current collector, the α-MnO2 nanotubes delivered an initial reversible capacity of 357 mA h g−1 and a capacity retention of 358 mA h g−1 after 40 cycles. Moreover, the α-MnO2 nanotubes showed a good rate capability. A capacity of 243 mA h g−1 could be obtained at the rate of 400 mA g−1. The sodium storage mechanism of MnO2 nanotubes and the effects of different binders were also probed through Cyclic Voltammetry (CV), ex situ Scanning Electron Microscope (SEM) and X-ray diffraction (XRD).

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.