A “Dual‐Defense, Self‐Adaptive” Shield for Lithium Metal Anodes: Marrying Rigidity and Flexibility via Hierarchical Dynamic Bonds

Lithium metal is an ideal anode characterized by its ultra‐high theoretical specific capacity and low redox potential. However, in liquid electrolytes, its surface is vulnerable to forming an unstable solid electrolyte interphase (SEI) that repeatedly fractures during cycling, leading to uncontrolled lithium dendrite propagation and battery failure. To solve this, we developed an artificial self‐adaptive polymer protective layer (DACP) that stabilizes the anode through synergistic supramolecular hydrogen bonds and Diels‐Alder (D‐A) dynamic covalent bonds. The strategic incorporation of dual dynamic bonds enables a hierarchical response: weak hydrogen bonds break quickly to dissipate stress and suppress microcracks (rapid self‐adaptive response), while strong D‐A bonds reversibley restructure network to maintain integrity under large deformations (dynamic response to ensure long‐term stability). This self‐adaptive/dynamic multiple response mechanism effectively reduces electrode volume fluctuations during cycling and inhibits dendrite propagation and dead Li accumulation. DACP‐modified anodes show excellent cycling stability in Li||Li symmetric cells (>6500 h at 10 mA cm −2 ) and enhanced performance in high‐loading Li ||NMC811 full cells (Li foil thickness: 50 µm; mass loading: 9.7 mg cm −2 ) compared to Bare‐Li. This strategy offers a practical path toward durable, safe Li metal anodes for next‐generation batteries.