Dynamic Ionic Transport Actuated by Nanospinbar-Dispersed Colloidal Electrolytes Toward Dendrite-Free Electrodeposition

Abstract

Inhibiting uneven dendritic Li electroplating is crucial for the safe and stable cycling of Li metal batteries (LMBs). Homogeneous and fast Li+ transport towards the Li surface is required for uniform and dendrite-free deposition. However, the traditional ionic transport of static liquid electrolytes involving electromigration and molecular diffusion can trigger a greater disparity in the Li concentration over the Li surface, leading to irregular dendrite growth. Here, a convective Li+ transfer for suppressing dendrite growth through magnetic nanospinbar (NSB)-dispersed colloidal electrolytes is presented. An ultrahigh-aspect-ratio NSB consisting of a paramagnetic Fe3O4 nanoparticle array and silica outer coating is synthesized. Manipulating the external electromagnetic force can remotely control the rotation of individual NSBs without dispersion failure, thereby generating mesoscale turbulence inside the cells. Regardless of the electrolyte composition, rotating the NSB can reduce the Li+ diffusion layer thickness from the bulk and evenly redistribute the Li+ flux over the Li surface, thereby suppressing Li dendrite growth. The NSB-dispersed electrolyte with advanced salt/solvent compositions demonstrates stable cycling of LMBs over 600 cycles with 70% capacity retention, thereby outperforming the NSB-free cell.