Despite the promises in high‐energy‐density batteries, Li‐metal anodes (LMAs) have suffered from extensive electrolyte decomposition and unlimited volume expansion owing to thick, porous layer buildup during cycling. It mainly originates from a ceaseless reiteration of the formation and collapse of solid‐electrolyte interphase (SEI). This study reveals the structural and chemical evolutions of the reacted Li layer after different cycles and investigates its detrimental effects on the cycling stability under practical conditions. Instead of the immediately deactivated top surface of the reacted Li layer, the chemical nature underneath the reacted Li layer can be an important indicator of the electrolyte compositional changes. It is found that cycling of LMAs with a lean electrolyte (≈3 g Ah−1) causes fast depletion of salt anions, leading to the dynamic evolution of the reacted Li layer structure and composition. Increasing the salt‐solvent complex while reducing the non‐solvating diluent retards the rate of depletion in a localized high‐concentration electrolyte, thereby demonstrating prolonged cycling of Li||NMC622 cells without compromising the Li Coulombic efficiencies and high‐voltage stability.

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.

Dynamic Ionic Transport In article number 2204052, Hochun Lee, Yong Min Lee, Hongkyung Lee, and co‐workers demonstrate Li dendrite suppression with 1‐μm long, magnetic nanospinbar (NSB) dispersed electrolytes. Spatially distributed NSBs within various electrolytes can generate mesoscale turbulence actuated by an external rotating magnetic field. NSB‐assisted dynamic Li+ transfer enables fast and uniform seeding of Li nuclei, inhibiting dendritic Li electroplating, thereby leading to stable cycling of Li‐metal batteries. Dynamic ionic transfer via NSB colloids opens new possibilities for out of mass‐transfer‐limit in various electrochemical systems.

Tailoring the Li+ microenvironment is crucial for achieving fast ionic transfer and a mechanically reinforced solid–electrolyte interphase (SEI), which administers the stable cycling of Li‐metal batteries (LMBs). Apart from traditional salt/solvent compositional tuning, this study presents the simultaneous modulation of Li+ transport and SEI chemistry using a citric acid (CA)‐modified silica‐based colloidal electrolyte (C‐SCE). CA‐tethered silica (CA‐SiO2) can render more active sites for attracting complex anions, leading to further dissociation of Li+ from the anions, resulting in a high Li+ transference number (≈0.75). Intermolecular hydrogen bonds between solvent molecules and CA‐SiO2 and their migration also act as nano‐carrier for delivering additives and anions toward the Li surface, reinforcing the SEI via the co‐implantation of SiO2 and fluorinated components. Notably, C‐SCE demonstrated Li dendrite suppression and improved cycling stability of LMBs compared with the CA‐free SiO2 colloidal electrolyte, hinting that the surface properties of the nanoparticles have a huge impact on the dendrite‐inhibiting role of nano colloidal electrolytes.

No abstract