Solid‐State Lithium Metal Batteries with Extended Cycling Enabled by Dynamic Adaptive Solid‐State Interfaces

Abstract Improving the long‐term cycling stability of solid‐state lithium (Li)‐metal batteries (SSBs) is a severe challenge because of the notorious solid–solid interfacial contact loss originating from the repeated expansion and contraction of the Li anodes. Here, it is reported that high‐performance SSBs are enabled by constructing brick‐and‐mortar electrolytes that can dynamically adapt to the interface changes during cycling. An electrolyte film with a high mechanical strain (250%) is fabricated by filling viscoelastic (600% strain) and piezoelectric block‐copolymer electrolytes (mortar) into a mixed conductor Li 0.33 La 0.56 TiO 3‐x nanofiber film (brick). During Li‐plating, the electrolytes can homogenize the interfacial electric field and generate piezoelectricity to promote uniform Li‐deposition, while the mortar can adhere to the Li‐anode without interfacial disintegration in the reversed Li‐stripping. As a result, the electrolytes show excellent compatibility with the electrodes, leading to a long electrochemical cyclability at room temperature. The symmetrical Li//Li cells run stably for 1880 h without forming dendrites, and the LiFePO 4 /Li full batteries deliver high coulombic efficiency (>99.5%) and capacity retention (>85%) over 550 cycles. More practically, the pouch cells exhibit excellent flexibility and safety for potential practical applications.