Methylthiourea as Electrolyte Additive Strategy for Zn-Metal Anode Stability and Reversibility of Zn-Ion Batteries

Zinc-ion batteries (ZIBs) are considered as a good choice in energy storage technologies due to their high safety and low environmental impact. However, various disadvantages related to Zn dendrite formation, hydrogen generation, and corrosion generated during the charge/discharge process greatly limit the commercialization of ZIBs. Among various electrode components, electrolytes are attracting attention from many researchers because they can solve problems occurring at the anode-cathode interface from a fundamental point of view. Here, we present the use of methylthiourea (MTU) as an electrolyte additive to inhibit the growth of zinc dendrites and obtain smooth Zn deposits. In the presence of MTU, Zn dendrite formation is successfully controlled, the electrochemical performance of the Zn|Zn symmetric cell is significantly improved over 1000 h at a current density of 1 mA cm⁻², and stripping of the deposited zinc is uniformly allowed. In addition, the Zn-ion full cell using the V₂O₅/C cathode exhibits consistent capacity retention up to 450 cycles. This study demonstrates that the use of methylthiourea as an electrolyte additive to enhance the electrochemical stability and reversibility of ZIBs can be cost-effective.