High‐Entropy Deep Eutectic Solvent Achieves Ultra‐Low Polarization Zinc Anode Chemistry

Abstract

Deep eutectic solvents (DESs), a new class of green solvents, have emerged as promising candidates for electrolytes due to their exceptional electrochemical stability. However, the DES always exhibits unacceptable polarization of cells due to its high viscosity and low ionic conductivity, which limit its practical application in batteries. In this work, the cell polarization of DES is effectively reduced to a level comparable to that of pure aqueous electrolytes by increasing the entropy of DES via the disorder-making strategy of solvation structure. Theoretically, constructing the high-entropy deep eutectic solvent (HEDES) promotes the formation of more aggregates with high disorder, which accelerates mass transfer kinetics. As a result, the proposed HEDES (configuration entropy 17 times higher than traditional electrolyte) can achieve durable zinc plating/stripping behavior for more than 2000 h with low polarization and still maintain good stability even in extreme environments. The cylindrical zinc-ion capacitor under gram-level loading can achieve a high discharge current up to 3 A, providing ideas for the design of electrolytes for zinc-based energy storage devices.