Large π-Conjugated Porous Frameworks as Cathodes for Sodium-Ion Batteries.

Organic sodium-ion batteries (OSIBs) are promising alternatives of inorganic lithium-ion batteries. The cathodes of OSIBs still suffer from low capacity, poor rate performance, and low cyclability. For the first time, we demonstrate the large π-conjugated porous frameworks (CPFs) as cathodes for OSIBs, motivated by the speculation that the CPFs are capable of enhancing charge transport, facilitating ionic diffusion, inhibiting dissolution, as well as improving stability. The batteries based on the obtained CPFs indeed delivered much better electrochemical performance than the small molecular construction units without any complex post-treatments. The moderate BET surface area of CPFs and the detailed analyses suggested that the micropores and the lamellar structure should be responsible for the fast ionic diffusion. We believe that this work will provoke growing interest of CPFs for OSIBs with functional molecular design toward high performance and pave a venue to achieve OSIBs in large-scale applications.