A High-Voltage Organic Framework for High-Performance Na- and K-Ion Batteries

Abstract

The organic metal-ion battery field remains challenged by the lack of high-voltage alkali-cation reservoir cathode materials. Whereas a few recent breakthroughs provided valuable solutions for Li-ion storage, Na-ion and K-ion organic reservoirs with high voltage and ambient stability remain elusive. Herein, we show that the versatile benzene-1,2,4,5-tetrayltetrakis methylsulfonyl-amide (PTtSA) tetra-anionic framework displays universal performance for alkali cation storage. The new synthesized Na4-PTtSA and K4-PTtSA phases reversibly exchange two Na+ or K+ equivalents per formula unit at redox potentials of 2.5 V vs Na+/Na and 2.6 V vs K+/K, respectively. A singular comparative analysis of Li-, Na-, and K-ion phases discloses the impact of the alkali cation on the physicochemical properties, with direct impact on the electrochemistry of the materials. This work not only offers guidance and principles to tune the redox properties of organic redox materials via spectator cations but also highlights the versatility of organic materials for alkali cation storage.