A Robust Route to Co2(OH)2CO3 Ultrathin Nanosheets with Superior Lithium Storage Capability Templated by Aspartic Acid-Functionalized Graphene Oxide

Two-dimensional (2D) nanomaterials are widely recognized as an important class of functional materials possessing superior electrochemical reaction kinetics. Herein, an L-aspartic acid (AA)-modified graphene oxide (GO) templating strategy is developed to in situ yield ultrathin (i.e., approximate to 5 nm) cobalt carbonate hydroxide (Co-2(OH)(2)CO3) nanosheets as advanced anode materials of lithium ion batteries. Notably, the covalent tethering of AA on the GO surface renders a high density of carboxyl groups that impart effective loading of Co-containing precursors and subsequent growth into Co-2(OH)(2)CO3 nanosheets bridging adjacent GO layers. The lasagna-like Co-2(OH)(2)CO3-GO nanocomposites exhibit an ultrahigh lithium storage capacity of 1770 mAh g(-1) after 500 cycles at 100 mA g(-1). It is noteworthy that the cycled Co-2(OH)(2)CO3 phase separates into homogeneously dispersed Co(OH)(2) and CoCO3 phases with two different charge plateaus at approximate to 1.2 and 2.0 V, respectively, which effectively inhibit large-scale homophase coarsening of Co, Li2CO3, and LiOH. The much shortened Li+/e(-) transfer distance enabled by individual ultrathin Co-2(OH)(2)CO3 nanosheet together with robust layer-by-layer assembled nanostructure of Co-2(OH)(2)CO3-GO confers the superior electrochemical reactivity and mechanical stability. As such, the amino acid-modified GO templating strategy may represent a simple yet robust means of crafting a variety of 2D nanostructured composites of interest for energy storage applications.