Interface Design of Carbon Nano-Materials for Energy Storage

Lithium ion batteries (LIB) have been a forerunner and market leader since late 1990s in the field of rechargeable battery industry especially for portable electronic devices, and are also very attractive in electric vehicles and hybrid electric vehicles. In order to achieve high-performance LIB, developing novel electrode materials, on one hand, is pivotal; on the other hand, a deeper understanding of the related electrochemical phenomena along with electrode reactions is definitely necessary (Tarascon and Armand, 2001). It is well known that the interface between electrode materials and electrolytes plays an important role in affecting the first columbic efficiency, cyclability, rate capability, and safety of LIB (Aurbach, 2003). Especially for carbonaceous anode materials widely used in current LIB, there is a kind of solid electrolyte interphase (SEI) film formed on the surface due to electrolytes decomposition (Balbuena and Wang, 2004). The SEI film is insulating for electrons but conductive for Li ions, and can significantly influence the cyclability of carbon anode. Here, we introduce the formation and evolution of SEI film on the surface of natural graphite (NG) spheres, which show obvious advantages over artificially graphitized meso-phase carbon micro-beads owing to low cost and intrinsically high crystallinity (Vetter et al., 2005). Based on the interface results, we propose core-shell design to modify the electrode materials for LIB by the chemical vapour deposition process. We can obtain the full coating amorphous carbon core-shell structure without the catalyst and nanotube/nanofiber coating nano/micro urchin-like structure with catalyst by chemical vapor deposition (Zhang et al., 2005, 2006a,b).