Hybrid electrode materials built on vertically aligned carbon nanofibers arrays for high-performance electrical energy storage

Joint Conference: International Conference on DIAMOND AND CARBON MATERIALS & GRAPHENE AND SEMICONDUCTORS

July 17-18, 2017 Chicago, USA

Jun Li, Steven Klankowski, Gaind Pandey and James Emery Brown

Kansas State University, USA

Posters & Accepted Abstracts: J Material Sci Eng

Abstract :

Today�s high-performance electrochemical energy storage (EES) devices are represented by the high energy capacity of lithium-ion batteries (LIBs) and the high power and long cycle life of supercapacitors. At present, they are not able to be integrated into one system due to the distinct electrochemical mechanisms. The performance of the conventional electrodes is limited by the low electrical conductivity and slow ion diffusion in the electrode materials. In recent studies, we have demonstrated an effective approach to overcome these two issues using a three-dimensional nanostructured coreshell architecture consisting of ~100 � 200 nm thick coaxially coated electroactive materials (such as Si, TiO2, LiCoO2, V2O5, and MnO2) on a highly conductive nanostructured current collector, i.e. vertically aligned carbon nano fiber arrays. This hybrid electrode structure allows effectively mitigating the slow Li+ diffusion by shortening the diffusion length in solid electrode materials. With proper deposition techniques, the shell materials can form secondary mesoporous structures which further reduce the ion diffusion path length down to ~10 nanometers in solid electrode materials. In addition, it provides another benefit due to the significant pseudo capacitive contribution associated with fast faradaic reactions at or near the electrode surface. As a result, these electrodes present the features of a battery-super capacitor hybrid based on Li chemistry. The EES devices based on such hybrid materials offer high specific energy at very high power rates that are comparable to supercapacitors. These studies demonstrated the potential for multi-scale nanostructured EES electrodes to achieve stable long charge-discharge cycles in the super capacitor power regime (i.e. completing charging or discharging in less than 1 min.) while maintaining the battery-like high energy capacity. Such hybrid structure also significantly improves the mechanical stability of the electrode materials, particularly for future batteries involving larger ions such as Na+ and Mg2+.

Biography :

Email: junli@ksu.edu