Chemical intercalation of graphite using chromium trioxide for the anode application in rechargeable sodium-ion batteries

Abstract

Among naturally occurring graphite, Sri Lankan vein graphite (SLVG) is well known for its high initial purity in the range of 95 - 99% carbon, high crystallinity, extensive mineralization, and mode of occurrences. Due to its distinctive properties, Sri Lankan vein graphite has been proved to be a promising anode material for rechargeable Lithium-ion battery (LIB) applications. With the increasing demand for rechargeable energy sources, the supply of Lithium-ion batteries (LIB) could be hindered by the limited lithium reserves. Therefore, alternatives for Lithium in LIBs are being explored. In this context Sodium-ion batteries (SIB) have attracted much attention during the recent past. This study focused on studying the intercalation and deintercalation of Na+ ions into the domain of Graphite Intercalation Compound (GIC), fabricated from natural vein graphite, for the anode application of rechargeable SIBs. Graphite Intercalation Compounds with CrO3 (GIC-CO) were successfully synthesized using SLVG as the starting material. The synthesized GIC-CO exhibited an interlayer spacing of 4.02 Å which is regarded to be suitable for Na + ion intercalation. The anode material fabricated from GIC-CO showed a capacity of 26.9 mA h g-1 which is higher than that of pristine graphite (13 mA h g-1). This shows the potential of utilizing this GIC for anode applications in SIBs. The anode could be improved by optimizing the molar ratios of CrO 3 and the reaction time to obtain expanded graphite making it appropriate for high-capacity SIB application

Keywords

• sodium-ion battery
• graphite intercalation compound, interlayer expansion, graphite, chromium trioxide