Small changes, big gains: standardizing non-electrode coin cell components in aqueous zinc battery research

Abstract

Aqueous Zinc Metal Batteries (AZMBs) hold the potential for safe and cost-effective solutions for next-generation energy storage. While coin cells are the most used model in lab studies, current literature often overlooks the influence of the non-electrode components, namely the current collector, spacer, spring, and casing materials. The lack of standardization of AZMB coin cells assembly stifles reproducibility, applications, and comparisons across studies. Here, we present a systematic study that reveals the profound impact of these non-electrode components on AZMB performance. We found the optimal coin cell comprises a titanium or copper current collector, stainless steel (SS) components (spacer, spring, and casing) protected by a copper foil, and an electrolyte volume of 40 μL. This optimized AZMB coin cell attains a 99.78% coulombic efficiency (CE), in stark contrast with the 99.3% achieved by a Zn∥Cu asymmetric coin cell (control). In addition, these optimizations improve the cyclability by more than 20 times over the control (1950 vs. 80 cycles). Despite the straightforward and cost-effective nature of these modifications, their undeniable repercussion on AZMB performance substantiates the importance of moving towards standardized non-electrode coin cell components and assembly protocols in this field. Our study, and proposed standards, enable accurate evaluation and comparisons of the impact of additives, current variations, and other performance-enhancing strategies in AZMB research.