Rational application mapping of diverse aqueous battery systems

Abstract

Aqueous batteries, known for their inherent safety and low cost, are considered promising candidates for large-scale and high-safety-demand energy storage. However, the rapid advancement and fierce market competition of lithium iron phosphate technologies have led to enhanced performance and lower costs, substantially shrinking the commercial space for aqueous systems. In this Review, we highlight the pressing need for a systematic mapping of aqueous battery technologies to reinvigorate their development and clarify their technological positioning. We begin by analyzing their shared characteristics from the standpoint of water-based electrolytes. We then systematically compare commercialized systems (lead–acid, flow, and alkaline Zn batteries) and non-commercialized chemistries (aqueous Li-/Na-/Zn-/H-ion batteries), highlighting their advantages, limitations, and technological bottlenecks. Furthermore, we propose eight actual application scenarios and match them with appropriate aqueous battery types based on industrial requirements. Our analysis also reveals previously underappreciated internal competition among aqueous systems, particularly among lead–acid, Zn-ion, and Na-ion systems, and the necessity for clearer functional differentiation. This work reshapes the understanding of aqueous battery application landscapes and aims to catalyze their accelerated deployment in safe, low-cost, and scalable energy storage applications.