A cellulose-based lithium-ion battery separator with regulated ionic transport and high thermal stability for extreme environments

Separators play a critical role in lithium-ion batteries. However, the restrictions of thermal stability and inferior electrical performance in commercial polyolefin separators significantly limit their applications under harsh conditions. Here, we report a cellulose-assisted self-assembly strategy to construct a cellulose-based separator massively and continuously. With an ultrahigh ionic conductivity in electrolytes of 3.7 mS·cm⁻¹ and the ability to regulate ion transport, the obtained separator is a promising alternative for high-performance lithium-ion batteries. In addition, integrated with high thermal stability, the cellulose-based separator endows batteries with high safety at high temperatures, greatly expanding the application scenarios of energy storage devices in extreme environments.