Zinc-ion batteries (ZIBs) are promising alternatives to lithium-ion batteries due to their safety, cost-effectiveness, and environmental sustainability. However, their widespread adoption is hindered by zinc dendrite formation, which leads to reduced cycle life and potential safety risks. This study investigates zinc-doped polypyrrole (Zn-doped PPy) as a functional protective coating for zinc anodes using density functional theory (DFT) simulations to understand its structural, electronic, and interfacial properties. We first analyze the intrinsic electronic properties of polypyrrole (PPy), demonstrating that its charge distribution and polymer backbone structure play a key role in conductivity and stability. Through computational modeling, we determine that Zn preferentially binds to nitrogen sites in PPy via coordinate covalent bonding, providing a stable environment for Zn incorporation. Electronic band structure analysis confirms that Zn doping enhances the electrical conductivity of PPy significantly, improving charge transport within the electrode. Beyond conductivity improvements, Zn doping promotes uniform Zn deposition by creating favorable nucleation sites, reducing the likelihood of dendrite formation. Adsorption energy calculations reveal that Zn-doped PPy exhibits a stronger interaction with Zn compared to undoped PPy, reinforcing its role in facilitating uniform metal plating. This enhancement is crucial for preventing irregular Zn growth and extending the cycle life of ZIBs. Additionally, adhesion studies indicate that Zn-doped PPy forms stronger interfacial bonds with the Zn anode, ensuring long-term stability of the protective coating. This improved adhesion prevents mechanical detachment during cycling, making Zn-doped PPy a viable, durable surface modification strategy for ZIBs. Overall, our first-principles study highlights Zn-doped PPy as an effective protective layer for Zn anodes, offering enhanced conductivity and improved Zn nucleation. In particular, it is noted that the superior adhesion of PPy on the Zn anode surface implies the mitigation of dendrite formation. Zn-doped PPy represents a scalable and practical solution for advancing next-generation zinc-ion battery technology.
