Pristine metal-organic frameworks for next-generation batteries

Li-ion batteries (LIBs) are meeting the emerging bottleneck originated from the low elemental abundance and high cost of lithium. Therefore, other energy-storage batteries beyond LIBs, including sodium-ion, potassium-ion, multivalent metal-ion, and lithium-sulfur batteries, have aroused great research interest and gradually become effective alternatives. But, the large ion radius of sodium/potassium ions and the dissolution effect of the formed polysulfides during cycling result in the higher demands imposed on the electrodes of sodium/potassium-ion and lithium-sulfur batteries. Originated from the uniform porosity and high surface area, infinite possibility of functionalization of ligands, pores and metal ions, chemical tunability and other special properties, the metal organic frameworks (MOFs) can furnish more possibilities and are directly explored as the electrodes to address these concerns besides MOFs derivatives. This review summarizes the synthesis and design strategies of pristine MOFs for direct electrode applications in sodium-ion, potassium-ion, multivalent metal-ion and lithium-sulfur batteries. Their applications as the solid-state electrolyte and the protective film or artificial solid electrolyte film for metal anode batteries are also discussed. Besides the illumination and comparison of various design principles for MOFs and related materials, the electrochemical energy-storage mechanism of specific MOF-involved materials has also been discussed in details. In addition, prospects for developing pristine MOF-based materials and their direct applications as electrodes for next-generation batteries are also presented.