Multiple Working Mechanisms Enabled by an Iodized Organic Salt Cathode for High Energy Density Potassium–Organic Batteries

Organic redox-active materials (REDOX-OAMs) with high structural adjustability have significant applied prospects for potassium–organic batteries, but they are limited by low reversible capacity and moderate reaction potential. Herein, inspired by the grafting technique in botany, a multifunctional REDOX-OAM (EV-I2) is designed, consisting of bipyridine (EV2+) with double active sites and iodide anions (2I–) with high working potential. In this EV-I2 architecture, a dual-ion K+/FSI– costorage mode could be realized through the multiple REDOX reaction mechanism. DFT calculations and in/ex situ characterization techniques also illustrate this multiple-working mechanism. Consequently, the energy density of the K-EVI2 battery is nearly three times (718.4 Wh kg–1) higher than that of the K-EV battery (268.5 Wh kg–1), along with reversible capacity of 308.0 mAh g–1 and high working potential of nearly 3.5 V. This work achieved a breakthrough in energy density of potassium–organic batteries and paved a way for exploring multifunctional REDOX-OAM with multiple reaction mechanisms.