Van der Waals Gap modulation of Graphene oxide through Mono-Boc ethylenediamine Anchoring for Li-ion Batteries

Abstract

Li-ion batteries stand out among energy storage systems due to their higher energy and power density, cycle life, and high-rate performance. Development of advanced, high-capacity anodes is essential for enhancing their performance, safety, and durability, and recently, two-dimensional materials have garnered extensive attention in this regard due to distinct properties, particularly their ability to modulate Van der Waal gap through intercalation. We have synthesised a crystalline covalently intercalated selectively protected mono-Boc-ethylenediamine into graphene oxide interlayer galleries (GO-EnBoc) via the epoxide ring opening, forming an amino alcohol moiety. This creates three coordination sites for Li ions exchange on the graphene oxide nanosheets' surface. Consequently, the interlayer d-spacing expands from 8.47 Å to 13.17 Å, as anticipated. When explored as an anode (Li-GO-En-Boc) show a significant enhancement in the stable and reversible capacity of 270 mA h g-1 at a current density of 25 mA g-1 compared to GO 80 mAh g-1, without compromising the mechanical or chemical stability. Through 13C, 7Li and 6Li MAS NMR, XPS, IR, Raman microscopy, and density functional theory (DFT) calculations, we confirm the positioning of Li+ ions at multiple sites of the interlayer gallery, which enhances the electrochemical performance. Our findings suggest that these novel systematically modulated Van der Waal gap GO-engineered materials hold promise as efficient anodes for Li-ion batteries.