Interphase Building of Organic–Inorganic Hybrid Polymer Solid Electrolyte with Uniform Intermolecular Li⁺ Path for Stable Lithium Metal Batteries

Abstract

Abstract Lithium (Li) metal has been generally noticed as the most prospective anode for next‐generation batteries attributed to its outstanding theoretical capacity and low electrochemical potential. Nevertheless, the unstable solid‐electrolyte interphase (SEI) and uncontrollable dendrite growth cause poor reversibility and fetter the practical application of Li metal anodes. Herein, a new organic–inorganic hybrid polymer artificial SEI (POSS‐LiBMAB) layer with uniform lithium‐ion paths at a molecular level is designed to stabilize Li metal anodes. The SEI layer is constructed by the thiol–ene “click chemistry” reaction between inorganic polyhedral oligomeric silsesquioxane containing eight‐mercaptopropyl (POSS‐SH) with lithium bis (allylmalonato) borate (LiBMAB) on Li foil. What is more, the POSS‐LiBMAB film can be cross‐linked and self‐reinforced via intermolecular SC bonds. Benefiting from its flexible polymeric covalent structure and noble inorganic Si 8 O 16 ‐type cubes, the organic–inorganic hybrid polymer layer is flexible and effectively tolerates the volume change of Li metal anodes during plating/stripping cycles. In addition, this layer shows loose and uniformly distributed electrostatic interaction between Li + and charge delocalized sp 3 boron–oxygen anions, which aids to form a uniform intermolecular Li + path regulating the homogeneous distribution of Li + flux on Li anodes. Finally, the designed POSS–LiBMAB layer has high ionic conductivity and lithium‐ion transference number, which can effectively promote Li + diffusion and guide Li deposition beneath the SEI layer. Therefore, with the protection of the POSS‐LiBMAB layer, the Li metal anode exhibits stable cycling at 5 mA cm −2 for more than 1000 h, and the LFP//Li full cells also present outstanding cycling stability.

Topics & Concepts