Cellulose-Assisted Vertically Heterostructured PEO-Based Solid Electrolytes Mitigating Li-Succinonitrile Corrosion for Lithium Metal Batteries

In the field of solid-state lithium metal batteries (SSLMBs), constructing vertically heterostructured poly(ethylene oxide) (PEO)-based solid electrolytes is an effective method to realize their tight contact with cathodes and Li anodes at the same time. Succinonitrile (SN) has been widely used in PEO-based solid electrolytes to improve the interface contact with cathodes, enhance the ionic conductivities, and obtain a high electrochemical stability window of PEO, but its application is still hindered by its intrinsic instability to Li anodes, which results in corrosion and side interactions with lithium metal. Herein, the cellulose membrane (CM) is introduced creatively into the vertically heterostructured PEO-based solid electrolytes to match the PEO-SN solid electrolytes at the cathode side. With the advantage of the interaction between −OH groups of CM and −C≡N groups in SN, the movement of free SN molecules from cathodes to Li anodes is limited effectively, resulting in a stable and durable SEI layer. In specific, the Li||LiFePO4 battery with the CM-assisted vertically heterostructured PEO-based solid electrolyte by in situ preparation delivers a discharge capacity of around 130 mAh g–1 after 300 cycles and capacity retention of 95% after 500 cycles at 0.5 C. Our work provides a solution to construct PEO-based solid electrolytes feasible to match cathodes and Li anodes effectively by intimate contact with electrodes.