Phase transformation induced benzene rings activation in a metal–organic framework to boost sodium storage performance

Abstract

• A phase transformation process in a MOF (Cobpdc) is confirmed. • The new phase (Cobpdc-400) delivers a reversible capacity of 413 mA h g −1 . • Cobpdc-400 stores more Na + owing to activated sp 2 carbon of benzene rings. • This mechanism provides new insights on Na + storage behavior of MOFs. Metal-organic frameworks (MOFs) with permanent porosity and various crystal structures are promising materials for sodium-ion batteries (SIBs). The developing of new materials and the understanding of their sodium storage mechanisms and behaviours is critical to realize the practical application of MOFs in battery industry. In this communication, we report a unique sodium storage behaviour that more sodium ions can be inserted into the benzene rings of ligands and bond with sp 2 carbon leading to superior sodium storage performance, which is realized via a benzene rings activation mechanism induced by thermally driven phase transformation. This work provides a new avenue for designing MOFs and other common types of carbonaceous materials to achieve superior sodium storage performance.