Regulating the Electric Double Layer Structures Driven by Current Density for High-Rate Aqueous Zinc Metal Batteries

The notorious dendrite growth, serious Zn corrosion and hydrogen evolution confronted by the Zn anode greatly limit the cycle life of aqueous zinc metal batteries. Here, the structure of electrical double layer (EDL) is designed by a specifically adsorbed anionic surfactant (MOA) featuring a zincophilic phosphate group and hydrophobic long alkyl chain, decreasing the activity of water on the Zn anode, effectively inhibiting the side reactions. More importantly, the reconstructed EDL by MOA exhibits a high current response characteristic, leading to the formation of a denser and thinner EDL under a high current density, which accelerates the diffusion kinetics of Zn²⁺ and benefits the uniform Zn plating/stripping. As a result, the Zn||Zn symmetrical cells achieve an ultra-high cumulative capacity of 60 Ah cm^-2, a long cycle life of 2000 h and a ultra-high current density of 500 mA cm^-2. In addition, The Zn||MnO₂ full cells demonstrate an enhanced cycling performance even under a lean electrolyte (E/C ratio = 15 µl mAh^-1) and high cathode loading (20 mg cm^-2).