Interlayer, gallery-engineered graphene oxide using selective protection of mono-Boc-ethylenediamine as anode for sodium ion batteries

The enormous demand for Lithium urges researchers to look for alternatives. Sodium can play a critical role in a plethora of rechargeable batteries as they are more abundant, economical, have better safety characteristics, and have similar power delivery possibilities. In this work, we established the intercalation of the sodium ions in between selectively functionalized graphene oxide (GO) layers for a Na-ion battery with enhanced performance. GO was functionalized by reacting with N-Boc-ethylenediamine (EnBoc) which resulted in the formation of amino alcohol moieties offering three coordination sites for sodium ions. This synthetic approach led to the formation of Na-GO-EnBoc material by increasing the interlayer d-spacing from 9.7 Å to 13.17 Å (2θ = 6.7 deg.) which facilitated more Na⁺ ions to intercalate efficiently in between GO nanosheets. The insertion of sodium ions on the surface of intercalated GO-EnBoc nanosheets was performed by the precursor sodium perchlorate in ethylene carbonate. The resultant Na-GO-EnBoc material was characterized by using solid state MAS NMR, XPS, XRD, IR, Raman, and microscopy. The analysis suggested different types of Na⁺ ions on the interlayer gallery which was also substantiated by DFT calculations. The coin cell fabricated with Na intercalated GO-EnBoc-based anode exhibited a consistent reversible capacity of 170 mAhg⁻¹ at 25 mAg⁻¹ rate, suggesting the promise of Na-GO-EnBoc for building future rechargeable batteries.