Diamine molecules double lock-link structured graphene oxide sheets for high-performance sodium ions storage

Graphite has been commercialized as a material of lithium ions batteries because of its abundant source, low cost and excellent conductivity while the small interlayer spacing of graphite limits its application for Na+ insertion/extraction. Herein, an emerging and effective approach—chain-like H2N(CH2)xNH2 locked between graphene oxide (GO) sheets to expand the interlayer spacing of graphene with enhanced stability of layered structure was demonstrated by a dehydration condensation reaction. The as-obtained H2N(CH2)xNH2, which can link GO (xDM-GO), exhibits a lock-link structure, resulting in expanded interlayer spacing, with which the excellent Na+ storage performance with a high specific discharge capacity of 158.1 mAh g−1 at 0.1 A g−1 and outstanding capacity retention of 82.2% at a current density of 1 A g−1 can be achieved. The effects of interlayer spacing on Na+ diffusion coefficient and the rate capability were investigated, for which 0.95 nm is the most suitable interlayer spacing for the Na+ insertion/extraction. The novel strategy demonstrates an effective way to controllably tune the interlayer spacing with the improved structure stability of GO, resulting in the best Na+ insertion/extraction behavior with the excellent Na+ storage performance.