Synthesis of Stacked Graphene-Sn Composite as a High-Performance Anode for Lithium-Ion Capacitors
Seongki Ahn, Yamato Haniu, Hiroki Nara, Toshiyuki Momma, Wataru Sugimoto, Tetsuya Ōsaka
Abstract
A Lithium-ion capacitor (LIC) is composed of an electrochemical capacitor-like cathode and battery-like anode which store charge based on non-faradaic and faradaic processes, respectively. As an anode material for LIC, graphite is widely used because of its physical and electrochemical advantages. In the LIC system, stable cyclability at the high rate conditions is essential for bridging the gap between lithium-ion batteries and supercapacitors. However, there have been reported that the low working potential of graphite (close to 0.05 V vs Li/Li+) causes Li plating on the graphite surface and non-unity coulombic efficiency at high current charge/discharge results in degradation of cycle performance. To overcome this issue, stacked reduced graphene oxide-tin (SrGO-Sn) composite by co-reduction of graphene oxide and Sn2+ are studied in this work. The LIC consisting of SrGO-Sn anode shows good long-term cyclability with a remarkable capacity retention of 85, 77, and 60% at 10,000, 50,000, and 100,000th cycle and coulombic efficiency of 98% after 120,000 cycles. We believe that this study presents a new approach to the design of the high-performance LIC using an alternative to conventional graphite-based anode materials.