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

All‐solid‐state lithium metal batteries are regarded as next‐generation devices for energy storage due to their safety and high energy density. The issues of lithium 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=15GPa, hardness = 0.13GPa) 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 symmetrical battery shows an ultra‐stable cycling (>2000 hours at 0.1 mA cm−2 at 60 °C, >500hours at 0.1mA cm−2 at 30 °C). Moreover, the LiFePO4/Li and LiNi0.8Co0.1Mn0.1O2/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.