Hollow sea urchin-like microspheres of the dual transition metal oxides NiO/Co3O4 immobilized on rGO enhance lithium-ion battery cycling and rate performance

The serious volume expansion and unsatisfying electronic conductivity during charge/discharge of transition metal oxides with relatively high capacity and low cost have limited their development as anode materials for lithium-ion batteries (LIBs). Herein, elaborately designed dual transition metal oxides NiO/Co ₃O ₄ immobilized on reduced graphene oxide (NiO/Co ₃O ₄ @rGO) with unique hollow sea urchin-like microspheres are employed as a modulated material for satisfying structural integrity and high capacity. On the one hand, the radioactive spines outside of sea urchin material inhibit its’ agglomeration, enlarge surface area for electrolyte infiltration, and shorten the Li ⁺ transport path during the lithiation/delithiation process, but they also alleviate the side effects caused by volume change during cycling. On the other hand, rGO, with its good electronic conductivity and flexibility, provides physical protection for the material structure. Thanks to these merits, the NiO/Co ₃O ₄ @rGO anode exhibited a remarkable reversible discharge (1845 mAh g ⁻¹ upon 100 cycles at 0.1 A g ⁻¹), outstanding rate capacity, and desirable cycling stability (1252 mAh g ⁻¹ up to 400 cycles at 1 A g ⁻¹) in LIBs, demonstrating the enormous potential of NiO/Co ₃O ₄ @rGO for feasible synthesis, high performance, and inexpensive LIBs.