context: In this work, we developed lithium-ion cathodes based on 3D-interconnected Ni nanowire current collectors and a lithiated manganese oxide active material, which combine high volumetric capacity and good rate performance. The 3D-nanowire current collector exhibits high porosity and a very high surface-to-volume ratio. Consequently, upon conformally coating it with the active material, the energy-storing component is distributed over a few nanometer-thick layer. Since the Ni nanowire network provides access of electrons to the entire volume of the active material and the ionic transport in the thin active layer is unimpeded, the cathode reached very high utilization of the active material, which is typically inaccessible in bulk cathodes. As a result, the electrode exhibits a high rechargeable volumetric capacity of about 200 mA h cm−3, which is more than the capacity of most 3D-nanostructured cathodes reported in the literature. Additionally, thanks to the combination of the small thickness of the active material and its high contact area with the current collector and electrolyte, the cathode can deliver significantly high capacity during high rate charging and discharging, demonstrating its potential for use in high volumetric capacity and fast charging Li-ion batteries.