Anchoring succinonitrile by solvent-Li+ associations for high-performance solid-state lithium battery

In this work, a new type of highly Li+ conductive, scalable, deformable succinonitrile-based composite solid-state electrolyte (denoted as SN-CSSE) is proposed as a promising solid electrolyte for room-temperature solid-state lithium battery (SSLB). The electrospinning poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) framework and UV-irradiation method are applied to improve the mechanical properties of SN. To overcome the side reactions on lithium (Li) anode, the concentrated lithium salt is exploited to anchor SN molecules within solvent-Li+ associations, which avoids direct contact between SN and Li metal and realize uniform Li deposition. Owing to the unique structural integration, the SN-CSSE exhibits high ionic conductivity of 1.1 × 10−3 S·cm−1 at 30 °C, wide electrochemical window (0 ~ 5.1 V vs. Li+/Li), favorable mechanical strength (4.76 MPa), and excellent interfacial compatibility with Li (stable at a current density of 0.2 mA·cm−2 for over 500 h). The LiFePO4/Li cells provide an outstanding rate capability (5C) and cycling performance (a retention of 95% after 800 cycles at 1C). Moreover, the solid-state pouch cell displays a favorable capacity of 15.6 mAh and maintains good cycling stability without significant capacity degradation after 150 cycles. Even under different abuse conditions, the cell still operated well, portending high application potential in safety-required battery systems.