| 초록 |
The growing demand of global renewable energy sources for electric vehicles and consumer electronic devices have necessitated the need for innovations in energy storage devices. Moreover, conventional lithium ion batteries based on intercalation chemistry that are widely used in these applications have almost reached their practical limit. Most viable and promising option to meet these demands is to combine the high capacity, low voltage anodes with next-generation cathodes such as sulfur. Lithium metal with its high theoretical capacity of 3.86 Ah g-1 and an electrode potential of -3.04 V (vs. standard hydrogen electrode) is an ideal candidate for anode material. However, the safety issues caused by dendrite formation on the surface of lithium metal during repeated plating-stripping reactions limit the practical application of lithium metal anode. Herein, we demonstrate that 3-D porous graphene foam fabricated using a simple ice-template freezing technique can act as a lightweight, freestanding host that can accommodate a large amount of lithium and stabilize lithium metal plating/stripping reactions by homogenizing the lithium ion flux throughout the surface. These characteristics resulted in high areal capacity of 10 mAh cm-2. In addition, the 3-D porous graphene foam host delivered a stable coulombic efficiency of 99% over 140 cycles at a current density of 2 mA cm-2 and capacity of 4 mAh cm-2, which are far superior to the planar copper foil. Furthermore, the suitability of lithiated 3-D porous graphene foam host was verified by assembling full cell by coupling with sulfur cathode that showed typical voltage profile and stable cycle life. |
