Design principles and direct applications of cobalt-based metal-organic frameworks for electrochemical energy storage

Recently, pristine cobalt-based metal-organic frameworks (Co-based MOFs) have received widespread research interest for electrochemical energy storage owing to their tunable pore sizes, structural versatility, huge surface areas, and unique electrochemical properties involved Co central nodes. In this review, the synthetic engineering strategies, such as choosing judicious bridging ligands with multiple redox-active sites, suitable solvents, sophisticated tuning of particle sizes and pore types, and introduction of conductive matrices to Co-based MOFs are comprehensively summarized, in order to construct significantly improved electrochemical performance in energy storage devices. Subsequently, a broad overview of their diversity and complexity of charge storage mechanisms during charge/discharge cycling processes are presented. Moreover, the recent significant advancements of Co-based MOFs with the focus on their direct applications in electrochemical energy storage fields, namely, lithium-ion batteries, supercapacitors, hybrid electrochemical capacitors as well as lithium-sulfur batteries are elaborated in detail. The further existing challenges and perspectives of pristine Co-based MOFs for their applications in electrochemical energy storage devices are highlighted. This review is expected to shed light on the exploitation and rational design of Co-based MOFs, and even new MOF families for advanced energy storage devices in future.