Intrinsically Coupled 3D nGs@CNTs Frameworks as Anode Materials for Lithium-Ion Batteries

Acquiring high-quality integrated nanographene sheets (nGs) and mitigating their self-aggregation are highly essential to achieving their full potential in energy related applications. The insertion of enthetic spacers into nGs layers can relieve the stacking problems but always results in a change in the intrinsic properties of the nGs and/or the introduction of complexity at the interfaces. In this work, a facile and scalable strategy is used to construct highly integrated, intrinsically coupled, N, S-doped 3D nanographene sheets trapped within carbon nanotubes (nGs@CNTs) through a modified counterion intercalation. The as-obtained nGs@CNTs are composed of two building blocks, in which large amounts of integrated unzipped nanoscale graphene sheets are tightly attached to the intact inner walls of the CNTs. The remaining CNTs serve as inherent spacers to prevent the self-stacking of nGs. Benefiting from the permanent and robust column bracing frameworks, the resultant 3D aerogels are expected to act as effective electrode materials for lithium-ion batteries with superior cyclic performance, delivering a reversible capacity as high as 1089 mAh g –1 at a current density of 2 A g –1 even after 300 cycles. The good lithium-ion storage performance is attributed to the hierarchical porous feature, the intrinsically unstacked bridged structure, and the synergistic effects between the N and S. This promising strategy represents a new concept for mitigating the self-aggregation of nGs by using autologous spacers.