Carbon-based core-shell nanostructured materials for electrochemical energy storage

Materials with a core-shell structure have received considerable attention owing to their interesting properties for their application in supercapacitors, Li-ion batteries, hydrogen storage and other electrochemical energy storage systems. Due to their porosities mimicking natural systems, large surface area for reactions and high dispersion of active sites, carbon-based core-shell (CBCS) materials can provide fast interfacial transport at different length scales of pores, and reduce the diffusion effect or shorten diffusion paths, which can be efficiently harnessed in energy storage. This review systematically outlines the significant advances in the synthesis strategies and different structures of CBCS nanocomposites, including C/C core-shell nanostructures, C core or C shell combined with metal/metal oxides (including hollow core-shell nanostructures), and carbon material (CM) supported core-shell nanostructures. The corresponding properties and recent applications in electrochemical energy storage of the three classes of CBCS nanostructured composites were analyzed in detail. We focus on how to promote the design of novel structures with advanced properties and performance in energy storage. Finally, we propose a perspective and challenges for the development of these controllable CBCS structured materials.