Altering polythiophene derivative substrates to explore the mechanism of heterogeneous lithium nucleation for dendrite-free lithium metal anodes

Lithium metal batteries (LMBs) possess outstanding theoretical energy density and have attracted widespread attention as the next generation of energy storage devices for various crucial applications. However, the commercialization of LMBs has to simultaneously overcome numerous challenges, such as inferior Coulombic efficiency and cycling performance, high self-discharge, and complicated interfacial reactions. It has traditionally been an enormous challenge about the uniform deposition of lithium on the surface of current collector to relieve the formation of lithium dendrites. In this study, a novel efficient strategy of plating uniform lithiophilic polythiophene derivatives substrates on Cu foils was developed and the nucleation mechanism of Li ions on polythiophene derivatives substrates was further explored. We first explored the interaction between polythiophene derivatives substrates and Li ions by first-principles calculations, and found shorter side chains of polythiophene derivatives can enhance the adsorption energy and promote the diffusion rate of Li ions. Polythiophene derivatives substrates have a large number of dispersive lipophilic sites and Li ions diffusion channels in the main chain, which can effectively regulate the nucleation and growth stages of Li ions deposition. We further found polythiophene derivatives with different side chains can induce the electrodeposition of Li ions with different morphology, while the polythiophene derivatives with the shortest side chains can contribute to the most excellent cycle efficiency, resulting in a uniform lithium deposition with less lithium dendritic growth experimentally. © 2020 Science Press