Three Birds with One Stone: Tetramethylurea as Electrolyte Additive for Highly Reversible Zn-Metal Anode

摘要

Aqueous Zn-metal batteries are the most promising system for large-scaleenergy storage due to their high capacity, high safety, and low cost. The Znmetalanode, however, suffers from continuous parasitic reactions, randomdendrite growth, and sluggish kinetics in aqueous electrolytes. Herein, a highdonor number solvent, tetramethylurea (TMU), is introduced as electrolyteadditive to enable highly reversible Zn-metal anode, where the TMU can 1)preferentially adsorb on the Zn surface to inhibit Zn corrosion and suppressparasitic reaction, 2) solvate with Zn~(2+) and exclude the H_2O from Zn~(2+) solvationsheath to weaken water activity significantly, and 3) contribute to form aninorganic-organic bilayer solid electrolyte interphase to enable homogeneousand rapid Zn~(2+) transport kinetic for dendrite-free Zn deposition. Benefitingfrom these three merits, the resulting aqueous electrolyte demonstrates ahighly reversible Zn plating/stripping cycling in a Zn||Ti asymmetric cell forover 1200 cycles and in a Zn||Zn symmetric cell for over 4000 h. As a proofof-concept, the aqueous Zn-metal full cells assembled with various state-of the-art cathodes also deliver excellent cycling performance even with a 10 μmthin Zn anode, favoring the practical application.