Dual Electrostatic Assembly of Graphene Encapsulated Nanosheet-Assembled ZnO-Mn-C Hollow Microspheres as a Lithium Ion Battery Anode

Graphene encapsulated nanosheet-assembled ZnO-Mn-C hierarchical hollow microspheres are produced through a simple yet effective dual electrostatic assembly strategy, followed by a heating treatment in inert atmosphere. The modification of graphene sheets, metal Mn, and in situ carbon leads to form 3D interconnected conductive framework as electron highways. The hollow structure and the open configuration of hierarchical microspheres guarantee good structural stability and rapid ionic transport. More importantly, according to the density functional theory calculations, the oxygen vacancies in the hierarchical microspheres would cause an imbalanced charge distribution and thus the formation of local in-plane electric fields around oxygen vacancy sites, which is beneficial for the ionic/electronic transport during cycling. Due to this multiscale coordinated design, the as-fabricated graphene encapsulated nanosheet-assembled ZnO-Mn-C hierarchical hollow microspheres demonstrate good lithium storage properties in terms of high reversible capacity (1094 mA h g(-1) at 100 mA g(-1)), outstanding high-rate long-term cycling stability (843 mA h g(-1) after 1000 cycles at 2000 mA g(-1)), and remarkable rate capability (422 mA h g(-1) after total 1600 cycles at 5000 mA g(-1)).