Yalan Xing

Carbon nanofibers/nanosheets hybrid derived from cornstalks as a sustainable anode for Li-ion batteries

A porous carbon nanofibers/nanosheets hybrid (CNFS) is converted from cornstalk waste by a simple treatment. The resulting material displays a superhigh surface area and rich porosity. Benefiting from unique structural features, the evolved CNFS possesses an ultrahigh rate capability of 454 mA h g−1 at 3 A g−1.

Formation of a stable carbon framework in a MnO yolk–shell sphere to achieve exceptional performance for a Li-ion battery anode

A 3D carbon framework has been introduced into a MnO yolk–shell structure, which functions as an electrical highway and a mechanical framework that improves the reaction kinetics, prevents MnO from fracturing and agglomerating, and limits most SEI formation to the carbon surface instead of on the MnO–electrolyte interface. As a result of this arrangement, the sample demonstrates a maximum reversible specific capacity of 1040 mA h g−1 at rate of 0.2 A g−1 with a long cycle life (without any decrease after 500 cycles), and an outstanding charge/discharge rate capability (513 mA h g−1 at 4 A g−1).

Dealloying Behavior of Dual-Phase Al 40 atom % Cu Alloy in an Alkaline Solution

To further understand the underlying physical mechanisms of dealloying of multiphase alloys and control dissolution processes among different phases, the dealloying behavior of melt-spun Al 40 atom % Cu alloy comprising Al 2 Cu and AlCu intermetallic compounds in a 10 wt % sodium hydroxide (NaOH) aqueous solution was studied. The microstructure of as-dealloyed samples was characterized using x-ray diffraction, scanning electron microscopy, and energy dispersive x-ray analysis. The experimental results show that the alloy with the amount of Al 2 Cu comparable to that of AlCu can be partially dealloyed, which eventually results in the formation of a unique kind of nanoporous copper/AlCu composite. Additionally, the formation mechanism has been well established to describe the morphology and composition evolutions during the dealloying process based upon kinetic competitions between dissolution of Al atoms and diffusion-rearrangement of Cu atoms, which includes three stages, sequentially, defined as Al 2 Cu dealloying, AlCu dealloying, and coarsening accompanying underlying AlCu re-dealloying..

Hollow carbon-shell/carbon-nanorod arrays for high performance Li-ion batteries and supercapacitors

N-doped hollow hierarchical peanut-like carbon-shells with nanorod arrays on the surface and interconnected networks in the core are prepared, which display rich porosity, superhigh specific surface area and a high degree of graphitization. The unique composition and hierarchical structure of the carbon resulted in very promising electrochemical energy storage performance.

MOF-derived, N-doped porous carbon coated graphene sheets as high-performance anodes for lithium-ion batteries

N-doped porous carbon coated graphene (rGO) sheets (denoted as NPCGS) have been synthesized through a facile pyrolysis of an in situ grown zeolitic imidazolate framework (ZIF) on graphene oxide (GO). When tested as an anode material for lithium-ion batteries, the NPCGS exhibited superior electrochemical performance with a specific capacity of 1040 mA h g−1 after 200 cycles at a discharging current density of 0.5 A g−1 and excellent rate performance. The fascinating electrochemical performance of the NPCGS can be attributed to the synergistic effect of NPC and graphene in terms of N-doping, rich porosity and high electrical conductivity. The novel N-doped porous carbon coated graphene sheet material can be extended for application in sensors, electronic devices, catalysts, hydrogen storage and other systems.

Synthesis of Cu@Fe3O4 nanowire arrays electrode for Li-ion batteries

Three-dimensional (3D) electrodes of Cu@Fe3O4 nanowire arrays for Li-ion batteries are prepared by an electrochemical route. XRD, SEM, TEM and HRTEM are used to characterize the micromorphology. The structures are improved, which is beneficial for the electrochemical performances. The obtained electrodes show a higher initial capacity than the traditional Cu@Fe3O4 planar electrodes. Moreover, the 3D electrodes exhibit better long-term cycling stability and an appealing rate capability.

Synthesis, structure and electrochemical properties of lithium-rich cathode material Li1.2Mn0.6Ni0.2O2 microspheres

Lithium-rich Li1.2Mn0.6Ni0.2O2 microspheres with a few mesopores have been successfully obtained. The results show that the Li1.2Mn0.6Ni0.2O2 material exhibits excellent cycling capability and rate performance. The microsphere morphology with a few mesopores could play a significant role in improving electrochemical performance.

The closed-environment CVD method for preparing three-dimensional defect controllable graphene foam with a conductive interconnected network for lithium-ion battery applications

A 3D defect controllable graphene foam (GF) with a conductive interconnected network is prepared by a CVD process in a closed environment, which we refer to as the closed-environment CVD method. The resulting GF is not only high quality, but is also provided with controllable defect density, offering a great potential in Lithium-ion battery (LIB) applications. When ZnO is anchored on the 3D GF to construct a ZnO/GF composite as the anode for LIBs, benefiting from the advantages of graphene and unique structural features, it exhibits a high reversible capacity of 851.5 mA h g−1 at 0.2 A g−1, good cycling performance and excellent rate capability. Notably, the higher defect density of GF leads to an increase in the capacity of ZnO/GF, meanwhile, it maintains an excellent rate performance.

Facile shape control of nano-coaxial Co3O4/TiO2 arrays and the effect of the microstructure on lithium storage capability

Arrays of self-supported core–shell nanowire have attracted considerable attention with respect to improved capability for electrochemical energy storage. Herein, we report a facile strategy, involving hydrothermal and liquid phase deposition (LPD) routes, to fabricate nano-coaxial Co3O4/TiO2 arrays with intriguing morphologies, architectures, and chemical compositions. When tested as anode materials for lithium ion batteries, these nanohybrids exhibited high reversible capacity, excellent cycling stability and good rate capability. It is assumed that the excellent electrochemical performance originates from the intricate core–shell nanoarchitecture and the coating effect of TiO2, including improved mechanical/chemical stability and good strain accommodation. The improved lithium ion storage performance of the Co3O4/TiO2 nanostructure indicates its potential application as an anode material for electrochemical energy storage and the potential use of TiO2 coating for modification of other anode materials.

Preparation and characterization of nanoporous Cu6Sn5/Cu composite by chemical dealloying of Al–Cu–Sn ternary alloy

In this article, a new ternary Al–Cu–Sn alloy system has been exploited to fabricate nanoporous Cu6Sn5/Cu composite slices through chemical dealloying in a 20xa0wt% NaOH solution at an elevated temperature. The microstructure of the sliced nanoporous Cu6Sn5/Cu composite was characterized using x-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, and transmission electron microscopy. The experimental results show that multi-phase precursor alloy comprises α-Al, Sn, and θ-Al2Cu phases. The new phase Cu6Sn5 emerges through dealloying, and the as-dealloyed samples have three-dimensional (3D) structure composed of large-sized channels (hundreds of nanometers) and small-sized channels (tens of nanometers). Both the large- and small-sized pores are 3D, open and bicontinuous. The synergetic dealloying of α-Al and θ-Al2Cu in the three-phase Al–Cu–Sn alloy and fast surface diffusion of Cu atoms and Sn atoms result in the formation of Cu6Sn5/Cu composite with bimodal channel size distributions. In addition, the dealloying duration plays a significant role in the formation of Cu6Sn5 and the length scales of the small-sized ligament/channels at a settled temperature.