Perspective on Aqueous Batteries: Historical Milestones and Modern Revival

Aqueous batteries have played a pivotal yet fluctuating role in the evolution of electrochemical energy storage. From their foundational success in lead-acid and nickel-based chemistries to their eclipse by lithium-ion batteries, aqueous systems were long regarded as technologically inferior due to limited energy density and poor cycling stability. However, the urgent demand for safe, low-cost, and sustainable storage has sparked a renaissance, fueled by breakthroughs in electrolyte engineering and advanced electrode materials for both anodes and cathodes. This review revisits the historical trajectory of commercialized aqueous batteries, extracting lessons from past successes and failures while highlighting the technological advances that now enable extended voltage windows, improved cycling stability, and scalable manufacturing. We argue that the future of aqueous batteries lies not in directly competing with lithium-ion in high-energy applications, but in complementing them across grid-scale storage, uninterruptible power supplies, and decentralized energy systems where safety, cost, and recyclability are paramount. By connecting history with current progress, we reflect on how these insights reshape expectations for the next generation of aqueous batteries and their role in a more diversified and sustainable energy storage landscape.