Spray-Dried Mesoporous Mixed Cu-Ni Oxide@Graphene Nanocomposite Microspheres for High Power and Durable Li-Ion Battery Anodes

Exfoliated graphene-wrapped mesoporous Cu-Ni oxide (CNO) nanocast composites are developed using a straightforward nanostructure engineering strategy. The synergistic effect of hierarchical mesoporous CNO nanobuilding blocks that are homogeneously wrapped by graphene nanosheets (GNSs) using a rapid spray drying technique effectively preserves the electroactive species against the volume changes resulting from the charge/discharge process. Owing to the intriguing structural/morphological features arising from the caging effect of exfoliated graphene sheets, these 3D/2D CNO@GNS nanocomposite microspheres are promising as high-performance Li-ion battery anode materials. They exhibit unprecedented electrochemical behavior, such as high reversible specific capacity (initial discharge capacities exceeding 1700 mAh g⁻¹ at low 0.1 mA g⁻¹, stable 850 and 730 mAh g⁻¹ at 1 and 5 mA g⁻¹ after 800 and 1300 cycles, respectively, and higher than 400 mAh g⁻¹ at very high current density of 10 mA g⁻¹ after more than 2000 cycles), excellent coulombic efficiency and long-term stability (more than 3000 cycles with >55% capacity retention) at high current density that are remarkable compared to most transition metal oxides and nanocomposites prepared by conventional techniques. This simple, yet innovative, material design is inspiring to develop advanced conversion materials for Li-ion batteries or other energy storage devices.