Effective inhibition of zinc dendrites during electrodeposition using thiourea derivatives as additives

The electrodeposition of zinc with thiourea derivatives as additives was investigated. The dynamic deposition and dissolution processes of zinc deposits were monitored in situ with synchrotron radiation X-ray imaging to reveal the inhibition role of additives on zinc dendrites. The real-time images show a large amount of zinc dendrites grow directly on the substrate surface in blank electrolyte. The microstructure of zinc deposits is sensitive to the molecular structure of additives. After adding thiourea derivatives, both the nucleation overpotential and the degree of polarization increase in the order of additive-free<thiourea (TU)<allylthiourea (ATU)<methylthiourea (MTU). TU can suppress partly the formation of zinc dendrites but the zinc deposits present a very loose structure. Both ATU and MTU can effectively inhibit the growth of zinc dendrites and get smooth deposits. Moreover, the anodic stripping of deposited zinc in the presence of MTU can proceed with a homogenous dissolution. These results will potentially benefit for the zinc-based rechargeable batteries.