Ultrafast Metal Electrodeposition Revealed by In Situ Optical Imaging and Theoretical Modeling towards Fast‐Charging Zn Battery Chemistry

Abstract

Metallic Zn is a preferred anode material for rechargeable aqueous batteries towards a smart grid and renewable energy storage. Understanding how the metal nucleates and grows at the aqueous Zn anode is a critical and challenging step to achieve full reversibility of Zn battery chemistry, especially under fast-charging conditions. Here, by combining in situ optical imaging and theoretical modeling, we uncover the critical parameters governing the electrodeposition stability of the metallic Zn electrode, that is, the competition among crystallographic thermodynamics, kinetics, and Zn 2 + -ion diffusion. Moreover, steady-state Zn metal plating/ stripping with Coulombic efficiency above 99 % is achieved at 10-100 mA cm À 2 in a reasonably high concentration (3 M) ZnSO 4 electrolyte. Significantly, a long-term cycling-stable Zn metal electrode is realized with a depth of discharge of 66.7 % under 50 mA cm À 2 in both Zn j j Zn symmetrical cells and MnO 2 j j Zn full cells.

Highly Reversible Zn Metal Anodes Enabled by Freestanding, Lightweight, and Zincophilic MXene/Nanoporous Oxide Heterostructure Engineered Separator for Flexible Zn-MnO2 Batteries

“…Such a structure results from uneven Zn nucleation and deposition because of the inhomogeneous electric field distribution. 26,42,55 The uneven Zn deposition further leads to the growth of Zn dendrites by the selfamplification mechanism. 56−58 At a deposition capacity of 1.0 mAh cm −2 , Zn dendrites grow into irregular and big particles.…”

“…At a plating capacity of 0.5 mAh cm –2 , a loose structure with inhomogeneous Zn jumbled clusters is formed using the pristine separator. Such a structure results from uneven Zn nucleation and deposition because of the inhomogeneous electric field distribution. ,, The uneven Zn deposition further leads to the growth of Zn dendrites by the self-amplification mechanism. − At a deposition capacity of 1.0 mAh cm –2 , Zn dendrites grow into irregular and big particles. With further deposition to 2.0 mAh cm –2 , the Zn dendrites maintain a terrible structure with sharp tips displayed.…”

Semi‐Immobilized Ionic Liquid Regulator with Fast Kinetics toward Highly Stable Zinc Anode under −35 to 60 °C

“…[16][17][18] To improve the performance of the aqueous ZIBs to meet the commercial demands, many efforts have been made to simultaneously address Zn anode issues of metal corrosion, dendrite growth, and other side reactions. [19][20][21] Thus far, many strategies have been developed to improve the electrochemical stability and reversibility of Zn anodes, such as current collector construction, structure modification of Zn anode, introducing protective layer, and electrolyte system optimization. [22][23][24][25][26] Among them, the interface engineering is considered to be a comprehensive effective method due to the direct effect on the Zn 2+ desolvation and Zn deposition.…”

An Ultrahigh Rate and Stable Zinc Anode by Facet‐Matching‐Induced Dendrite Regulation

“…This is because the surface inhomogeneity of Zn is hard to be completely eliminated by these strategies, and the irregular Zn plating/stripping still occurs at high current densities. [ 15 ] Because of the even more severe “self‐amplifying” effect of dendrites, rapid battery failure is almost inevitable. Consequently, the Zn plating/stripping current density of the above‐developed materials rarely exceeds 20.0 mA cm −2 , which is insufficient for practical use of Zn‐ion batteries.…”