不同电流密度下锌枝晶生长规律原位成像研究

In-situ Imaging of Zinc Dendrite Growth under Different Current Densities

当前以水系锌离子电池(AZIBs)为代表的低成本、高安全性大规模电化学储能技术是水系电池研究的重点,其中锌负极不均匀沉积引起的枝晶问题是这种新型电池走向产品化的主要瓶颈。本文采用机械抛光与振动抛光相结合的样品表面处理方法获得了表面平滑的锌片用作AZIBs负极;自主设计了分别与光学显微镜和原子力显微镜相结合的锌枝晶生长原位观测液体池,将对电极放置在锌工作电极的正上方,最大程度还原了锌负极的真实工作环境,在此基础上对锌枝晶的生长过程进行原位表征,辅助以SEM物相测试,系统总结了不同电流密度下锌枝晶的生长规律。低电流密度下锌枝晶形态大部分倾向于均匀沉积,沉积表面较为平缓,但部分区域会生长稀疏且体积较大形态的锌枝晶,枝晶表面成海绵状;高电流密度下锌枝晶生长为致密尖锐的六方板状结构,本实验中所探究的锌沉积规律对于构建高性能水系锌离子电池具有重要指导意义。

The current low-cost and high safety large-scale electrochemical energy storage technology represented by water-based zinc ion batteries(AZIBs)is the focus of research on water-based batteries.The dendritic problem caused by uneven deposition of zinc negative electrodes is the main bottleneck for the commercialization of this new type of battery.This article adopts a sample surface treatment method combining mechanical polishing and vibration polishing to obtain a smooth surface zinc sheet as the negative electrode of AZIBs;We independently designed a liquid pool for in-situ observation of zinc dendrite growth in combination with optical microscopy and atomic force microscopy,Placing the counter electrode directly above the zinc working electrode maximizes the restoration of the true working environment of the zinc negative electrode.Based on this,in-situ characterization of the growth process of zinc dendrites was carried out,assisted by SEM phase testing.The growth patterns of zinc dendrites under different current densities were systematically summarized.Under low current density,the morphology of zinc dendrites mostly tends to be uniformly deposited,with a relatively flat deposition surface.However,in some areas,sparse and bulky zinc dendrites will grow,and the surface of the dendrites will be sponge like;Under high current density,zinc dendrites grow into dense and sharp hexagonal plate-like structures.The zinc deposition patterns explored in this experiment have important guiding significance for constructing high-performance aqueous zinc ion batteries.