A pinboard by
Cao Guan

Research Fellow, National University of Singapore


Rational design of functional materials from metal organic framework

In recent years, Metal Organic Frameworks (MOFs) and their derivatives have received considerable attention due to their unique structures and wide applications in catalysis, sensors as well as energy storage and conversion. However, most of the previous studies on MOF-based/derived materials were focused on particle-like structures, and there are few reports on one-dimensional (1D) or two-dimensional (2D) structured MOFs. In addition the electrode materials were prepared in powdered forms with polymer binder and carbon additives, which can hardly meet the application requirement for flexible and wearable devices. Thus it will be very promising to develop novel structured MOFs on flexible support for high-performance flexible energy storage and electrocatalysis.
In the present work, a novel hollowed NiCo2O4 nanobox arrays have been rational designed on flexible carbon cloth substrate from a 2D cobalt MOF precursor. The resulted hollow and porous structure can be directly used as a flexible electrode for both supercapacitor and oxygen evolution reaction catalyst. Due to the unique hollow and porous structure which can provide rich reaction sites and short ion diffusion length, and the direct electrical and mechanical contact with the conductive support, the unique NiCo2O4 nanobox arrays demonstrated high robust mechanical flexibility and outstanding electrochemical performance in both supercapacitor and oxygen evolution reaction tests.


High‐Performance Flexible Solid‐State Ni/Fe Battery Consisting of Metal Oxides Coated Carbon Cloth/Carbon Nanofiber Electrodes

Abstract: Aqueous Ni/Fe batteries have great potential as flexible energy storage devices, owing to their low cost, low toxicity, high safety, and high energy density. However, the poor cycling stability has limited the widely expected application of Ni/Fe batteries, while the use of heavy metal substrates cannot meet the basic requirement for flexible devices. In this work, a flexible type of solid‐state Ni/Fe batteries with high energy and power densities is rationally developed using needle‐like Fe3O4 and flake‐like NiO directly grown on carbon cloth/carbon nanofiber (CC–CF) matrix as the anode and cathode, respectively. The hierarchical CC–CF substrate with high electric conductivity and good flexibility serves as an ideal support for guest active materials of nanocrystalline Fe3O4 and NiO, which can effectively buffer the volume change giving rise to good cycling ability. By utilizing a gel electrolyte, a robust and mechanically flexible quasi‐solid‐state Ni/Fe full cell can be assembled. It demonstrates optimal electrochemical performance, such as high energy density (5.2 mWh cm−3 and 94.5 Wh Kg−1), high power density (0.64 W cm−3 and 11.8 KW Kg−1), together with excellent cycling ability. This work provides an example of solid‐state alkaline battery with high electrochemical performance and mechanical flexibility, holding great potential for future flexible electronic devices.

Pub.: 18 Jul '16, Pinned: 27 Jul '17