Abstract
Aqueous zinc-polymer batteries (AZPBs) comprising abundant Zn metal anode and redox-active polymer (RAP) cathodes can be a promising solution for accomplishing viable, safe and sustainable energy storage systems. Though a limited number of RAPs have been successfully applied as organic cathodes in AZPBs, their macromolecular engineering towards improving electrochemical performance is rarely considered. In this study, we systematically compare performance of AZPB comprising Zn metal anode and either poly(catechol) homopolymer (named P(4VC)) or poly(catechol) copolymer (named P(4VC86-stat-SS14)) as polymer cathodes. Sulfonate anionic pendants in copolymer not only rendered lower activation energy and higher rate constant, but also conferred lower charge-transfer resistance, as well as facilitated Zn2+ mobility and less diffusion-controlled current responses compared to its homopolymer analogue. Consequently, the Zn||P(4VC86-stat-SS14) full-cell exhibits enhanced gravimetric (180 versus 120 mAh g−1 at 30 mg cm−2) and areal capacity (5.4 versus 3.6 mAh cm−2 at 30 mg cm−2) values, as well as superior rate capability both at room temperature (149 versus 105 mAh g−1 at 150 C) and at −35 °C (101 versus 35 mAh g−1 at 30 C) compared to Zn||P(4VC)100. This overall improved performance for Zn||P(4VC86-stat-SS14) is highly encouraging from the perspective applying macromolecular engineering strategies and paves the way for the design of advanced high-performance metal-organic batteries.
Highlights
Developing safe, cost-effective, viable, and high-performance rechargeable batteries is vital for realizing the sustainable energy-based low-carbon footprint society [1,2]
(5.4 versus 3.6 mAh cm−2 at 30 mg cm−2 ) values, as well as superior rate capability both at room temperature (149 versus 105 mAh g−1 at 150 C) and at −35 ◦ C (101 versus 35 mAh g−1 at 30 C)
It is demonstrated that the enhanced rate performance for the copolymer over the homopolymer was linked to a combination of lower activation energy, higher redox reaction rate and improved Zn2+ ion mobility. By exploiting these electrochemical enhancement features, we demonstrate the construction of practical organic electrodes employed in a Zn||P(4VC86 -stat-SS14 ) battery with high areal capacity (5.4 mAh cm−2 ; one of the highest reported value till date for redoxactive polymer (RAP) in Aqueous zinc-polymer batteries (AZPBs)) with high rate capability (1.5 mAh cm−2 at 10 C) and good cycling stability (74% capacity retention over 400 cycles at 1 C)
Summary
Developing safe, cost-effective, viable, and high-performance rechargeable batteries is vital for realizing the sustainable energy-based low-carbon footprint society [1,2]. Almost all of the commercial batteries, including the most efficient lithium-ion technologies contain toxic, scarce and/or environmentally unfriendly elements, which will hinder the desired target of achieving sustainable energy systems [3,4]. This triggers an ever-growing interest in finding alternative sustainable energy storage solutions. In this regard, aqueous batteries comprising organic electrode materials should provide ample opportunities owing to their inherent advantages in terms of abundance, harmlessness, safety, synthetic versatility, functional tunability, and low cost [5,6]. The organic cathodes can be considered as a sustainable alternative to conventional inorganic electrode materials owing to their natural abundance, less geopolitical constraints on resource availability, ease of synthesis, and can be sometimes bio-based and biodegradable
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