Electron Percolating Shielded Interlayer Enabling Ultrastable All‐Solid‐State Lithium Metal Batteries

Abstract The electron percolation of grain boundaries in Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) induces internal lithium deposition and penetration, causing short circuits of all‐solid‐state batteries, which has become a significant obstacle hindering the practical application of LLZTO. In this work, an electron‐percolating shielded interface constructing strategy is proposed between LLZTO and lithium metal (Li) to simultaneously suppress the Li dendrite growth at both the interface and within the LLZTO electrolyte. A Poly[bis(4‐phenyl)(2,4,6‐triMethylphenyl)aMine] (PTAA)/SnO 2 (PS) bilayer is therefore designed between LLZTO and Li metal (LLZTO‐PS|Li), where the hole‐rich PTAA and electron‐rich SnO 2 generate a reverse electric field that effectively blocks the electron leakage, thereby reducing the electronic conductivity of LLZTO and preventing its internal dendrite formation. Furthermore, the smooth and compact PTAA/SnO 2 coating significantly enhances interfacial contact and equalizes the interfacial potential to promote a uniform Li plating. As a result, the Li|LLZTO‐PS|Li symmetric battery achieves stable cycling for over 5000 h at 0.1 mA cm −2 and 2500 h at 0.5 mA cm −2 . The Li|LLZTO‐PS|LiFePO 4 full battery demonstrates 86.2% capacity after 2000 cycles at 1 C. This study presents a novel interfacial engineering strategy for enhancing the performance and durability of garnet‐based all‐solid‐state lithium‐metal batteries.