Horizontally Aligned Zn Crystals Deposition with 1T VSe2 Functional Layer for Dendrite-Free Zn Metal Anodes

Abstract

To fulfill the high requirement for high-energy-density storage, Zn ions batteries (ZIBs) has been garnering great scientific attention and considered the promising candidate due to the moderate redox potential, high safety and reasonable cost. However, the problem of the inferior reversibility and limited-service period owing to the issues of side reactions and Zn dendrites hinder its application. In our study, the hexagonal 1T VSe2, owns metallic appearance, was used as the zincophilic film to replace the conventional metal and graphene-based matrix for hexagonal closest packed (HCP) typed Zn metal electrodeposition in ZIBs. Our experimental results discovers that 1T VSe2/Zn anode is beneficial to regulating Zn crystal morphology from randomly oriented to horizontally (002)-oriented plate-like. Combining with computational modelling, the early stage of Zn nucleation and morphological evolution is investigated from atomistic to meso scale. VSe2 substrate exhibits higher adsorption energy (-0.54 eV) with Zn, contrasting with graphene (-0.38 eV) and pure Zn (-0.48 eV) based on the density functional theory (DFT) calculations. And classical molecular dynamic (MD) simulations reveal the plate-like Zn electrodeposits undergo a reorientation transition with a higher fraction of the (002) facet due to the rapid adatom diffusion coefficient, which effectively prohibits the dendrite formation. The symmetric cell with modified electrodes shows an ultra-stable cyclic life with 50 mV overpotential up to 2500 cycles in the condition of 1 mA cm-2 and 1 mAh cm-2.