Diagnosing the Electrostatic Shielding Mechanism for Dendrite Suppression in Aqueous Zinc Batteries

Abstract

Aqueous zinc electrolytes offer the potential for cheaper rechargeable batteries due to their safe compatibility with the high capacity metal anode, yet they are stymied by irregular zinc deposition and consequent dendrite growth. Suppressing dendrite formation by tailoring the electrolyte is a proven approach from lithium batteries, yet the underlying mechanistic understanding that guides such tailoring does not necessarily directly translate from one system to the other. Here, we show that the electrostatic shielding mechanism, a fundamental concept in electrolyte engineering for stable metal anodes, has different consequences for the plating morphology in aqueous zinc batteries. We use operando electrochemical transmission electron microscopy to directly observe the zinc nucleation and growth under different electrolyte compositions, and reveal that electrostatic shielding additive suppresses dendrites by inhibiting secondary zinc nucleation along the (100) edges of existing primary deposits, and encouraging preferential deposition on the (002) faces, leading to a dense and block‐like zinc morphology. The strong influence of the crystallography of Zn on the electrostatic shielding mechanism was further confirmed with Zn||Ti cells and density functional theory modelling. This work demonstrates the importance of considering the unique aspects of the aqueous zinc battery system when using concepts from other battery chemistries.This article is protected by copyright. All rights reserved

Rescuing zinc anode–electrolyte interface: mechanisms, theoretical simulations and in situ characterizations

“… 219 Very recently, an electrostatic shielding effect mechanism has been further confirmed via in situ liquid-cell TEM, which is close to the practical AZIBs batteries. 220 In this case, as shown in Fig. 6d , LiCl will induce preferential secondary nucleation on the previously deposited Zn flakes along the (002) plane, resulting in the formation of stacked zinc flakes.…”

Electric Double Layer Oriented Eutectic Additive Design toward Stable Zn Anodes with a High Depth of Discharge

“…Therefore, the Zn 2+ flow density and the electric field strength felt by Zn 2+ are reduced by GPC. [20] Meanwhile, Zn x P y O z -rich SEI derived from GPC can be favorably constructed in the chargerich site, regulating the interfacial diffusion and deposition of Zn at the interface [21] and terminating dendrite growth. [22] The Fourier Transform Infrared Spectrometer (FTIR) was first employed to study the influence on water's hydrogen bond network caused by various hydrogen bond forming sites of GPC.…”

A hydrophobic phenolic polymer layer with high-flux Zn2+-specific regular channels for stabilizing aqueous zinc anodes

“…9 During plating, desolvation and deposition occur preferentially at the tips such as sharp edges, corners, or defects, where the charge density is higher than in smooth areas. 10 Moreover, the occurrence of the “tip effect” intensifies an uneven electric field distribution on the electrode surface and influences the flux distribution of Zn 2+ , consequently strengthening non-uniform deposition, accelerating dendrite growth, and eventually resulting in penetration of the separator as well as short circuits. 11,12 Additionally, the localized high electric field promotes the HER and corrosion of the Zn anode with the presence of coordinated water and a significant amount of free water in the system.…”