Yanbiao Ren

Copper nanowires based current collector for light-weight and flexible composite silicon anode with high stability and specific capacity

A metal network fabricated by copper nanowires (CuNWs), synthesized in a facile way, is introduced to silicon composite anode as current collector for lithium-ion battery. The light and flexible sheet can act as the collector and the substrate, and improve the kinetic electron transport and the stability of composite anode. In this configuration, the composite anode exhibits a better capacity retention of 89.4% and a coulombic efficiency of ∼93% after 60 cycles (rate = 0.2C) compared to conventional composite thin film anode in which CuNWs are beneficial for electrochemical performances. There appears to be a promising improvement that the light-weighted anode can also be applied to meet the commercial requirement.

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.

Investigation of Co3O4 nanorods supported Pd anode catalyst for methanol oxidation in alkaline solution

Abstract A Co 3 O 4 nanorod supported Pd electro-catalyst for the methanol electro-oxidation (MEO) has been fabricated by the combination of hydrothermal synthesis and microwave-assisted polyol reduction processes. The crystallographic property and microstructure have been characterized using XRD, SEM and TEM. The results demonstrate that Pd nanoparticles (PdNPs) with a narrow particle size distribution (3–5 nm) are uniformly deposited onto the surface of Co 3 O 4 nanorods. Electrochemical measurements show that this catalyst having a larger electrochemically active surface area and a more negative onset-potential exhibits enhanced catalytic activity of 504 mA/mg Pd for MEO comparing with the Pd/C catalyst (448 mA/mg Pd). The dependency of log I against log v reveals that MEO on Pd-Co 3 O 4 electrode is under a diffusion control. Electrochemical impedance spectroscopy (EIS) measurement agrees well with the CV results. The minimum charge transfer resistance of MEO on Pd-Co 3 O 4 is observed at −0.05 V, which coincides with the potential of MEO peak.

Ru effect on the catalytic performance of Pd@Ru/C catalysts for methanol electro-oxidation

Abstract Pd@Ru bimetallic nanoparticles deposited on carbon black electro-catalysts have been fabricated by microwave-assisted polyol reduction method and investigated for methanol electro-oxidation (MEO). The structure and electro-catalytic properties of the as-prepared catalysts were characterized by XRD, SEM, TEM and cyclic voltammetry (CV) techniques. The results showed that the introduction of Ru element (2–10 wt%) into Pd 20 wt%/C (hereafter, denoted as Pd/C) produced a series of core-shell structured binary catalysts. Pd@Ru 5 wt%/C (hereafter, denoted as Pd@Ru 5 /C) catalyst displayed the highest catalytic activity towards MEO. And the mass activity of Pd@Ru 5 /C electrode catalyst at E = −0.038 V (vs. Hg/HgO) was 1.42 times higher than that of Pd/C electrode catalyst. In addition, the relationship between the catalytic stability for MEO on Pd@Ru/C catalysts and the value of J bp / J fp (the ratio of MEO peak current density in the negative scan and positive scan) were also investigated. The result demonstrated that Pd@Ru 5 /C offering the smallest value of J bp / J fp displayed the best stable catalytic performance.

Hierarchical porous ZnMn2O4 microspheres assembled by nanosheets for high performance anodes of lithium ion batteries

Hierarchical porous ZnMn2O4 microspheres assembled by nanosheets with an average thickness of several nanometers are successfully synthesized by a facile hydrothermal method and subsequent calcination at 500 °C in air. When used as an anode electrode of lithium ion batteries (LIBs), the ZnMn2O4 microspheres exhibit a high discharge capacity of 1132 mA h g−1 after 500 cycles at a current density of 500 mA g−1 and excellent rate capability. It is believed that the outstanding electrochemical performance benefits from the hierarchical porous structure that can not only increase the contact area between the electrode and the electrolyte to facilitate the transfer of Li+ ions, but also provide sufficient space for volume expansion of the electrode during the cycling process.

Cu@Sn nanostructures based on light-weight current collectors for superior reversible lithium ion storage

A binder-free method is applied to avoid the huge irreversible capacity of Sn-based composite anodes in this paper. We report two types of copper-based current collector: (i) a light and flexible current collector, which is fabricated from copper nanowires (CuNWs), and (ii) Cu foam with copper nanowires grown on it. The charge capacity of the thin CuNW sheet based Sn–Cu composite anode remains above 760 mA h g−1 after 60 cycles with a relatively stable coulombic efficiency fluctuating around 97%. The Cu foam based composite anode also shows a good capacity retention of 79.8% after the same test, compared with the Cu foil based anode. According to the good rate performance and the light weight of the composite electrode, the CuNW sheet based current collector may be a promising material in energy fields in the future.