Constructing a Janus Catholyte/Cathode Structure: A New Strategy for Stable Zn-Organic Batteries.

ABSTRACT

Organic materials are promising candidates for the electrodes of aqueous zinc-ion batteries due to their nonmetallic nature, environmental friendliness, and cost-effectiveness. However, they often suffer from significant dissolution during the charge-discharge process, which poses a major hurdle to their practical applications. Inspired by membrane-less organelles in cells, a simple and versatile strategy is proposed-constructing a Janus catholyte/cathode structured electrode based on liquid-liquid phase separation, in which redox-active organic molecules are confined in the liquid state within the activated carbon, thereby eliminating the volume effect and preventing their diffusion into the electrolyte. The customization of phase separation systems by leveraging the hydrophobicity/hydrophilicity differences of various anions is successfully demonstrated. This approach allows for precise regulation of ion cluster/coordination structures, enabling the confinement of active substances while ensuring efficient ion transport. Consequently, the as-constructed Zn||Janus catholyte/cathode cells exhibit superior reversible rate capacity (186 mA h g-1 at 5.0 A g-1) and remarkable cycling performance (retention of 72.5% after 12 000 cycles). The strategy in building Janus catholyte/cathode structured electrodes breaks free from the limitations imposed by traditional solid-state electrodes, offering tremendous opportunities for exploring diverse advanced battery systems.