The Role of Hydrogen Bonding in Aqueous Batteries: Correlating Molecular-Scale Interactions with Battery Performance

The pursuit of reliable and sustainable energy storage solutions has spurred significant research activity in the development of aqueous batteries (ABs). However, the energy density and cycling stability of ABs have remained stubbornly limited, leading to a plethora of host material designs and electrolyte modulation strategies. As an intermolecular interaction force, the hydrogen bond (HB) presents a promising avenue for optimizing the performance of electrode materials and electrolytes. However, HB chemistry in ABs remains poorly understood to date. Therefore, this Review aims to provide an updated summary of the current understanding of HB chemistry (mechanism, type, strength), the effect of HB on electrolytes (conductivity, freezing point, decomposition potential, viscosity, and dissolubility), and host materials' performance (stacking, insulation, ionic conductivity). In addition, we construct a vivid illustration of the structure-activity relationship between molecular-scale HB interactions and macroscale battery performance. A series of representative case studies in which HBs are used to optimize electrochemical performance are discussed. Finally, advanced methodologies for characterization of HBs are described in detail. This Review provides new insights into the relationship between HB chemistry and battery performance. It also provides guideline for building high-energy and high-rate ABs taking advantage of HB chemistry.