# Engineering Polyampholytes for Energy Storage Devices: Conductivity, Selectivity, and Durability

## TL;DR

This review explores how polyampholytes can be engineered to improve performance in various energy storage devices like batteries and fuel cells.

## Contribution

The paper provides design rules and strategies for engineering polyampholytes to optimize conductivity, selectivity, and durability in energy storage systems.

## Key findings

- Polyampholytes enhance ion transport and interfacial stability in Li and Zn batteries by suppressing dendrites and stabilizing interphases.
- Antifreeze hydrogels and poly(ionic liquid) networks maintain conductivity and elasticity in supercapacitors under strain and at low temperatures.
- Zwitterionic interlayers in solar cells improve charge extraction and work function alignment, while ordered networks in fuel cells enable selective ion transport.

## Abstract

Polyampholytes combine cationic and anionic groups in one macromolecular platform and are emerging as versatile components for energy storage and conversion. This review synthesizes how their charge balance, hydration, and architecture can be engineered to address ionic transport, interfacial stability, and safety across batteries, supercapacitors, solar cells, and fuel cells. We classify annealed, quenched, and zwitterionic systems, outline molecular design strategies that tune charge ratio, distribution, and crosslinking, and compare device roles as gel or solid electrolytes, eutectogels, ionogels, binders, separator coatings, and interlayers. Comparative tables summarize ionic conductivity, cation transference number, electrochemical window, mechanical robustness, and temperature tolerance. Across Li and Zn batteries, polyampholytes promote ion dissociation, homogenize interfacial fields, suppress dendrites, and stabilize interphases. In supercapacitors, antifreeze hydrogels and poly(ionic liquid) networks maintain conductivity and elasticity under strain and at subzero temperature. In solar cells, zwitterionic interlayers improve work function alignment and charge extraction, while ordered networks in fuel cell membranes enable selective ion transport with reduced crossover. Design rules emerge that couple charge neutrality with controlled hydration and dynamic crosslinking to balance conductivity and mechanics. Key gaps include brittleness, ion pairing with multivalent salts, and scale-up. Opportunities include soft segment copolymerization, ionic liquid and DES plasticization, side-chain engineering, and operando studies to guide translation.