An insoluble p-type organic polymer cathode with a 9,9′-bicarbazole core for highly stable Li/Na/K-based dual-ion full batteries

Abstract

A p-type organic polymer cathode called poly[bicarbazole-alt-dihydrophenazine] (P(BCz4PZ)) is designed for dual-ion batteries (DIBs). P(BCz4PZ) can stably store PF₆⁻ anions above 3 V versus Li/Na/K-metal anodes, bringing in a theoretical specific capacity (C_T) of ∼155 mA h g⁻¹. Meanwhile, P(BCz4PZ) can show high initial columbic efficiency values of 91%/87%/96% in Li/Na/K-based half cells. Consequently, the Li/Na/K-based dual-ion full batteries can be fabricated by using P(BCz4PZ) as the universal cathode without any pretreatments, as well as the low-cost graphite (C)/hard carbon (HC)/graphite (C) as the related anodes respectively. The three full batteries can deliver the peak discharge capacities of 115/122/122 mA h g⁻¹_cathode and the high average discharge voltages of 3.29/3.3/2.8 V, corresponding to the high energy densities of 193/185/140 W h kg⁻¹ based on total mass (cathode + anode + electrolyte), respectively. Except for Li element, the electrodes in our three dual-ion full battery systems are composed of the cost-effective and readily accessible elements of C, H, N, P, F, Na and K.