Realizing high-performance of quinone-based cathode via multiple active centers for aqueous zinc ion batteries

Abstract

Aqueous zinc ion batteries (AZIBs) have received widespread consideration owing to non-toxicity, proper capacity, and abundant reserves. Among numerous cathode materials, organics with adjustable structures are prospective campaigners. Naphtha [2, 3-h] naphtha [2', 3': 7, 8] quinoxalino [2, 3-a] naphtha [2', 3': 7, 8] quinoxalino [2, 3-c] phenazine-5, 10, 15, 20, 25, 30-hexaone (AQPH) with large conjugated structure is synthesized through convenient condensation reaction. As an organic cathode of AZIBs, multiple active sites endow AQPH with a decent capacity (297.7 mAh g−1 under 0.05 A g−1) and a brilliant cycling life (over 10,000 cycles under 10 A g−1). Simultaneously, large conjugated structure supplies AQPH with a rapid electron transfer rate, inducing a high Zn2+ diffusion coefficient (3.3 × 10−10∼2.6 × 10−8 cm2 s−1) and an outstanding rate ability (96.7 mAh g−1 under 20 A g−1). Furthermore, theoretical calculations and ex-situ characterizations prove that CO and CN are the active sites of Zn2+ storage. This work demonstrates that expanded conjugated structure and increased active centers of organic molecules are beneficial for accomplishing sustainable high-performance AZIBs.