# Asymmetric Electrolytes Govern Tetrahydroxozincate Dynamics for Stable Alkaline Zinc Batteries

## TL;DR

Researchers improved alkaline zinc batteries by using specially designed molecules to stabilize the electrolyte and extend battery life.

## Contribution

A new molecular design using cobalt porphyrins enhances zincate decomposition and zinc ion transport in alkaline batteries.

## Key findings

- Co-3N-O modified electrolyte enables stable cycling for over 80,000 seconds at 5 mA cm−2.
- Zn||Ni batteries with the engineered electrolyte achieve 110 stable cycles at 1 mA cm−2.
- The molecular asymmetry of Co-3N-O improves Zn(OH)4^2− dissociation and Zn^2+ transport.

## Abstract

Green electrochemical energy storage is essential for carbon neutrality, and alkaline zinc batteries offer a compelling solution due to their inherent safety, low cost, and high energy density. However, their performance is limited by parasitic reactions, including corrosion, gas evolution, and slow Zn/ZnO conversion kinetics stemming from inefficient dissociation of the tetrahydroxozincate [Zn(OH)4
2−] intermediate. We address this by designing a series of cobalt porphyrins (Co‐4N, Co‐3N‐O, Co‐3N‐S) that modulate the metal center's charge density for accelerating Zn(OH)4
2
− decomposition, and control Zn2
+ transport through the carboxyl‐functionalized peripheries. The Co‐3N‐O‐modified electrolyte achieves exceptional stability, maintaining stable cycle for over 80,000 s at 5 mA cm−
2, which is more than four times longer than the <20,000 s achieved by the conventional KOH + ZnO electrolyte. In Zn||Ni batteries, this molecularly engineered electrolyte enables 110 stable cycles at 1 mA cm−2, significantly outperforming the unmodified system, which sustained only 20 cycles. These findings elucidate a structure‐kinetics relationship for zincate regulation and demonstrate how customized molecular asymmetry can overcome persistent challenges in aqueous battery chemistry, offering a pathway to high‐performance, durable energy storage systems.

This research tackles the limitations of alkaline zinc batteries by designing a series of metalloporphyrin molecules (Co‐4N, Co‐3N‐O, Co‐3N‐S) as electrolyte additives. The asymmetric structures, particularly Co‐3N‐O, accelerate the Zn(OH)4
2
− decomposition via a modulated metal center and control Zn2
+ transport through carboxyl groups. This approach enables the stable cycles of 80,000 s at 5 mA cm−2. It demonstrates a molecular solution to challenges in aqueous battery chemistry.