Architecture-Tunable Bottlebrush Polymers as Artificial Solid Electrolyte Interphases for Lithium Metal Batteries

Lithium (Li) metal offers the highest theoretical capacity and lowest electrochemical potential among anode materials, yet its practical use is hindered by unstable interfacial chemistry, leading to dendrite formation and rapid capacity loss. To address this, we introduce a new class of fully grafted bottlebrush polymers (BBPs), featuring a robust polynorbornene backbone and lithiophilic polyethylene glycol (PEG) side chains, as architecture-tunable artificial solid electrolyte interphases (SEIs). By systematically varying backbone and side-chain lengths, we elucidate how molecular entanglement governs the mechanical resilience and ion coordination capacity of polymer interphases. The optimized BBP forms a lithiophilic, entangled network that resists electrolyte swelling, suppresses impedance buildup, and promotes uniform Li deposition. Comprehensive electro-chemo-mechanical and theoretical analyses corroborate the essential role of architecture-driven entanglement in establishing stable SEIs. This work establishes a new molecular design strategy for artificial SEIs, leveraging polymer entanglement to achieve durable, high-efficiency Li metal anodes.