Designing Organic Cathodes for Aqueous Zinc Batteries: Materials Chemistry of Carrier Selectivity, Mechanistic Validation, and Practical Benchmarking

Abstract

Organic cathodes for aqueous zinc batteries are attractive because both their donor environments and structural organization can be tuned at the molecular and framework levels. The central materials challenge, however, is not simply to achieve redox activity, but to design hosts that support a chemically defensible and durable carrier pathway under aqueous operating conditions. Although electrochemical performance has improved substantially, carrier assignment often remains uncertain, and Zn 2+ -dominant storage is still frequently inferred from indirect evidence. This review establishes a carrier-selective framework for understanding and designing organic cathodes in aqueous zinc batteries. Carrier identity depends on how donor environment, H + accessibility, confinement, partial Zn 2+ desolvation, electrolyte structure, and operating conditions act together, rather than on host properties alone. On this basis, we define evidence standards for distinguishing Zn 2+ -dominant, H + -dominant, mixed, and unresolved storage, and relate these assignments to benchmarking under practically relevant conditions. We further connect mechanistic interpretation to measurable electrochemical outcomes, particularly capacity retention and rate response, under controlled testing protocols. By treating Zn 2+ -selective storage as a materials-chemistry problem rather than an assumed electrochemical outcome, this review provides a structured basis for interpreting reported performance and guiding the development of organic cathodes with more selective and durable storage pathways.