In Situ Self‐Healing of Lithium Dendrites via Hydrogen‑Bond Network Construction in PEG‑UPy@ LLZO Electrolyte

ABSTRACT Solid‐state electrolytes (SSEs) are regarded as promising candidates for high‐energy‐density lithium metal batteries (LMBs), but their practical application is severely hindered by lithium dendrite growth. Currently, numerous self‐healing electrolytes are reported to suppress lithium dendrite growth. However, the self‐healing functions reported so far are limited to repairing mechanical damage in the electrolyte membrane caused by lithium dendrite penetration; they cannot repair the lithium dendrites themselves. To address this, we utilize the hydrogen‑bond network formed by UPy‑UPy self‑assembly to design and prepare the composite electrolyte PEG‑UPy@LLZO. This electrolyte not only possesses the ability to self‑heal mechanical damage but also, for the first time, achieves active in‑situ self‑repair of lithium dendrites through the synergistic effect between the polymer and the ceramic filler. Experiments show that after a short‑circuit failure induced by lithium dendrites, the battery's charge‑‐discharge function can be restored simply by letting it rest, without any external intervention. The Li symmetric cell exhibits stable cycling for over 1000 h at 0.2 mA cm ⁻² and 60°C. Furthermore, the LiFePO ₄ (LFP) full cell maintains 75.36% capacity retention after 1000 cycles at 1C. This material‐based active healing strategy provides a viable pathway to overcome the dendrite challenge in LMBs.