Multiscale Engineered Bionic Solid‐State Electrolytes Breaking the Stiffness‐Damping Trade‐Off

All-solid-state lithium metal batteries (LMBs) are regarded as next-generation devices for energy storage due to their safety and high energy density. The issues of Li dendrites and poor mechanical compatibility with electrodes present the need for developing solid-state electrolytes with high stiffness and damping, but it is a contradictory relationship. Here, inspired by the superstructure of tooth enamel, we develop a composite solid-state electrolyte composed of amorphous ceramic nanotube arrays intertwined with solid polymer electrolytes. This bionic electrolyte exhibits both high stiffness (Young's modulus=15 GPa, hardness=0.13 GPa) and damping (tanδ=0.08), breaking the trade-off. Thus, this composite electrolyte can not only inhibit Li dendrites growth but also ensure intimate contact with electrodes. Meanwhile, it also exhibits considerable Li⁺ transference number (0.62) and room temperature ionic conductivity (1.34×10^-4 S cm^-1), which is attributed to oxygen vacancies of the amorphous ceramic effectively decoupling the Li-TFSI ion pair. Consequently, the assembled Li symmetric battery shows an ultra-stable cycling (>2000 hours at 0.1 mA cm^-2 at 60 °C, >500 hours at 0.1 mA cm^-2 at 30 °C). Moreover, the LiFePO₄/Li and LiNi_0.8Co_0.1Mn_0.1O₂/Li all-solid-state full cells both show excellent cycling performance. We demonstrate that this bionic strategy is a promising approach for the development of high-performance solid-state electrolytes.