Conjugated C≡C Linked Organic Polymers With Thiadiazole-Induced Electron-Ion Decoupling Toward Long-Life Lithium...

The pronounced reactivity of Li⁺, coupled with the uncontrollable side reactions with the electrolyte, presents considerable safety hazards in lithium-metal batteries (LMBs). Herein, a unique conjugated organic polymer (Alkynyl-COP-TD) featuring carbon-carbon triple bonds (C≡C) as π-bridges and thiadiazole-induced electron-ion decoupling effect is designed to stabilize the lithium-metal anode interface. By tuning its bandgap, the molecularly optimized electronic structure of Alkynyl-COP-TD not only accelerates electron transport within the polymer but also establishes "electronic shielding layer" that further prevents electron escape into the electrolyte, while simultaneously enhancing the mechanical stability of the interface. Furthermore, the incorporation of thiadiazole units in Alkynyl-COP-TD further facilitates the interactions between lithophilic sites (C≡C, aromatic ring) and Li⁺, accelerating Li⁺ diffusion-deposition kinetics and charge transfer, as determined by a variety of advanced in-situ/ex-situ characterizations. Consequently, compared with thiadiazole-free Alkynyl-COP, Alkynyl-COP-TD-based symmetric cell exhibits an extraordinarily extended cycle life, surpassing 2500 h at 5 mA cm^-2. In addition, the full cell assembled with the Alkynyl-COP-TD-based electrode remains stable after 1600 cycles with an average capacity degradation rate of only 0.015% per cycle and demonstrates improved rate performance. This work brings an intriguing insight of the molecular design of multifunctional artificial interfacial layers for LMBs.