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

Abstract 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., ≈5 nm) cobalt carbonate hydroxide (Co 2 (OH) 2 CO 3 ) 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 CO 3 nanosheets bridging adjacent GO layers. The lasagna‐like Co 2 (OH) 2 CO 3 ‐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 CO 3 phase separates into homogeneously dispersed Co(OH) 2 and CoCO 3 phases with two different charge plateaus at ≈1.2 and 2.0 V, respectively, which effectively inhibit large‐scale homophase coarsening of Co, Li 2 CO 3 , and LiOH. The much shortened Li + /e − transfer distance enabled by individual ultrathin Co 2 (OH) 2 CO 3 nanosheet together with robust layer‐by‐layer assembled nanostructure of Co 2 (OH) 2 CO 3 ‐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.