Reduced Graphene Oxide Encapsulated Phosphorus-Carbon Composite with Improved Reversibility of Sodium-Ion Storage

Thursday, 23 June 2016
Riverside Center (Hyatt Regency)
G. H. Lee, M. R. Jo (Dept. of Energy and Materials Eng., Dongguk University), S. Y. Kim (School of Chem. Eng. and Mater. Sci., Chung-Ang University), and Y. M. Kang (Dept. of Energy and Materials Eng., Dongguk University)
Recently, Na ion battery systems came to the fore again because of their high cost-effectiveness compared to the widely used Li ion battery systems. However, representative Li ion battery anode materials such as graphite and silicon cannot adapt to Na ion battery. So, many researchers have tried to find new anode materials for Na ion battery, and phosphorus has emerged as one of the promising materials. Phosphorus is a prospective anode material substitute for silicon as a high capacity material in Na ion battery. But similar to silicon, poor intrinsic electric conductivity and high volume expansion ratio of phosphorus makes it challenging to be applied as an anode material. To overcome the problems, numerous synthesis processes such as mechanical milling of phosphorus with carbon or other metals, and insertion of phosphorus inside the active carbon by evaporating process have been conducted. However, cyclability and coulombic efficiency of previous materials still needs to be improved in order to make NIB commercially viable. In this study, we encapsulated mechanically milled P/C composite into reduced graphene oxide (rGO) by simple spray-drying to prevent deterioration of the P/C composite. Specifically, we tried to reduce the surface side reaction and volume expansion problem by our design strategy which was helpful to solve the problem due to the outstanding mechanical strength and electric conductivity of rGO. Consequently, rGO encapsulated P/C composite shows improved performance by rGO coating effect in terms of cyclability, rate capability and coulombic efficiency.