A Crystalline Polymer Cathode for Sodium-Organic Batteries

Abstract

Sodium-organic batteries (SOBs) are widely recognized as a rising star in large-scale energy storage technology because of their abundant resources, high energy density, and environmental friendliness. However, the poor cyclability and rate performance due to high solubility and poor conductivity with organic electrode materials limit their practical applications. Here, we constructed a new crystalline polymer, poly(tetraaminobenzoquione) (PTABQ), featuring a layered structure with a conjugated backbone and intermolecular hydrogen bonds. Benefiting from the crystalline structure with one-dimensional O-channels and highly conjugated backbone, PTABQ shows high electronic conductivity (10−7 S cm−1) and fast ion diffusion ability (∼10−8 cm2 s−1). PTABQ displays a discharge capacity of 380 mAh g−1 with an average voltage of 2.0 V and nearly 90% capacity retention after ultra-long 2800 cycles at 3 A g−1 (∼8 C), which is superior to the reported organic cathode materials. It also exhibits an impressive rate performance of 290 mAh g−1 at 8 A g−1 (∼20 C). Our work highlights the importance of constructing the crystal structure for effective utilization of active sites and fast ion diffusion, which sheds light on the development of an efficient and sustainable energy storage system.