Macromolecular-level polymer brush layer enabling geometric customization of lithium deposits

Dendrite formation is the major hurdle limiting the deployment of energy-dense Li-metal batteries, including the solid-state prototypes. Through grafting polyether amine (PEA) brushes onto reduced graphene oxide (RGO) sheets, here, we present precise control over the metallic deposits according to the preset two-dimensional (2D) geometry. The experiment and simulation results reveal that the lithiophilic ether groups of PEA not only induce uniform nuclei distribution but also tailor the ion migration pathway along the optimized polymer chain, enabling conformal deposits propagation via a bionic “seedling technology.” The regulated Li deposition behaviors are further demonstrated in an energy-dense battery (2.1 mAh, Li(Ni_0.85Co_0.1Al_0.05)O₂|PEA grafted RGO) and all-solid-state prototype (LiFePO₄|PEA grafted RGO with composite electrolyte). Their encouraging cycle performance, coupled with the wide range of applicability, affords great potential to customize the geometry of Li deposits according to the preset orientations. Uncontrolled Li dendrite growth significantly limits the cycle life of metallic batteries. In this work, Zhang et al. realize control over the metallic deposits by constructing a polymer-brush layer on a preset substrate. The all-solid-state cell incorporating the customized Li anode exhibits superior interfacial properties and cycling stability.