Molecular deciphering of hydrophobic, Zinc-philic and robust Amino-functionalized Polysilane for Dendrite-free Zn Anode

Abstract

As one of most prospective anode materials of aqueous batteries, Zn metal faces severe electrolyte corrosion and fatal dendrite growth. To address these issues, the electrolyte/Zn interface needs to be carefully engineered. Here, a dense and robust layer of polysilane functionalized by -NH2 is coated on Zn in a new way. In this layer, -NH2 provides adequate alkalinity and important interaction with Zn2+, enhancing the hydrolysis and regulating the Zn2+ flux. Propyl groups increase the flexibility to buffer inevitable strain/stress and the hydrophobicity to reduce the permeation of water. Si-O-Zn enables the durable interface between Zn and this layer. These results lead to superior mechanical property, suppressed side reactions and uniform plating/stripping. Hence, it shows excellent electrochemical performance, ∼300 hours at 20 mA cm-2 for 10 mAh cm-2 (Depth of Discharge ∼57%) in symmetrical cells, and average Coulombic efficiency of 99.8% during 800 cycles for 3 mAh cm-2 in asymmetrical cells. Even at a high loading of MnO2, a small N/P ratio and a limited electrolyte, the full cells coupled still display a capacity of ∼2.93 mAh cm-2 after 100 cycles at 0.5 C.