context: The small thickness of an active material and its high contact area with the current collector and electrolyte can be simultaneously realized using 3D-structured conductive substrates. The higher surface area of a 3D-current collector can allow distributing the active material over a thinner coating (or, similarly, increasing the loading of the active material while keeping its thickness low), simultaneously maintaining open porosity for the electrolyte. Such core–shell, structurally integral electrode design can be achieved with a variety of micro- and nanostructured 3D substrates, such as micropillars, nanoporous metals, inverse metal opals or interconnected metal nanowires, which have a big advantage over macroscopic 3D foams in effective utilization of the electrode volume. Compared to nanostructured electrodes based on nanoparticles embedded in binding and conductive additives, the electrodes based on monolithic 3D structures are typically less tortious (translating to lower polarization resistance) and can be often fabricated with high spatial precision (e.g. by lithography or area-selective electrodeposition), making them particularly attractive for all-solid-state microbatteries.