Neuron‐Like Silicone Nanofilaments@Montmorillonite Nanofillers of PEO‐Based Solid‐State Electrolytes for Lithium Metal Batteries with Wide Operation Temperature

Poly(ethylene oxide) (PEO)‐based composite solid electrolytes (CSEs) are promising to accelerate commercialization of solid‐state lithium metal batteries (SSLMBs). Nonetheless, this is hindered by the CSEs' limited ion conductivity at room temperature. Here, we propose design, synthesis, and application of the bioinspired neuron‐like nanofillers for PEO‐based CSEs. The neuron‐like superhydrophobic nanofillers are synthesized by controllably grafting silicone nanofilaments onto montmorillonite nanosheets. Compared to various reported fillers, the nanofillers can greatly improve ionic conductivity (4.9 × 10−4 S cm−1, 30 °C), Li+ transference number (0.63), oxidation stability (5.3 V) and mechanical properties of the PEO‐based CSEs because of the following facts. The distinctive neuron‐like structure and the resulting synaptic‐like connections establish numerous long‐distance continuous channels over various directions in the PEO‐based CSEs for fast and uniform Li+ transport. Consequently, the assembled SSLMBs with the CSEs and LiFePO4 or NCM811 cathodes display superior cycling stability over a wide temperature range of 50 °C to 0 °C. Surprisingly, the pouch batteries with the large‐scale prepared CSEs kept working after being repeatedly bent, folded, cut or even punched in air. We believe that design of neuron‐like nanofillers is a viable approach to produce CSEs with high room temperature ionic conductivity for SSLMBs.