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Dissolved oxygen (DO) in the electrolyte of aqueous zinc ion batteries (AZIBs) can cause irreversible side reactions in zinc metal anode. Therefore, the accurate detection of the DO concentration in the aqueous electrolyte is crucial for the performance promotion and mechanistic studies of AZIBs. Herein, organic electrochemical transistor (OECT) based DO sensors are developed by utilizing a carbon fiber (CF) derived CF/platinum/Nafion/polydimethylsiloxane composite as the gate electrode and amine-doped poly(3,4-ethylenedioxythiophene): polystyrene sulfonate as the channel semiconductor. Operating at a gate-source voltage of −0.1 V and a drain-source voltage of −0.025 V, the OECT-DO sensor demonstrates a high sensitivity (141 mV decade−1), a low detection limit (0.0011 mg L−1), a wide linear range (0.027–8.7 mg L−1), and good stability, which are attributed to the transconductance capability of OECT. The exceptional performance of the OECT-DO sensor enables the accurate monitoring of DO content in aqueous zinc sulfate electrolyte, which provides an opportunity to gain an insight of the impact of DO concentration on the zinc metal electrode. This study not only provides a cost-effective and efficient solution for detecting DO concentration in aqueous electrolytes, but also explores the potential applications of OECT sensors in the energy storage devices. • OECT sensor for detecting dissolved oxygen (DO) in aqueous electrolyte was fabricated for the first time. • The transconductance capability of OECT-DO effectively improved its DO sensing performances. • OECT-DO showed high sensitivity, low detection limit, wide linear range, and good stability. • The influence of DO in aqueous electrolyte on zinc-ion battery was studied with OECT-DO. [ABSTRACT FROM AUTHOR]

Prepared via a solution-based fabrication strategy, the PDI-EDA/CB composites rendered the zinc ion batteries with them as the cathodes obvious performance improvement in rate capability and cycling stability. [Display omitted] Organic electroactive compounds can be applied as alternative cathodes in rechargeable zinc ion batteries (ZIBs) instead of using inorganic cathode materials with low stability or high toxicity. However, many reported organic ZIB cathodes have some limitations, which are their tedious synthesis processes and low yields. In this work, perylene diimide-ethylenediamine/carbon black (PDI-EDA/CB) composites are prepared with a high yield of over 88% under mild conditions via a solution-based processing method. As the organic cathodes in aqueous ZIBs, the PDI-EDA/CB composites have a high specific capacity of 118.0 mA h g−1 at 0.05 A g−1; this capacity can be maintained as 95.0 mA h g−1 even at a high current density of 5.00 A g−1. Also, PDI-EDA/CB has good cycling stability by reserving 70.5% of its initial capacity after 1500 charge-discharge cycles at 1.00 A g−1, outperforming many recently reported ZIB cathodes. As disclosed by the structural and electrochemical characterization of PDI-EDA/CB, its excellent electrochemical performance is due to the zinc ion storage mechanism of PDI-EDA and the solution-based fabrication method. [ABSTRACT FROM AUTHOR]