Functional nanosheet fillers with fast Li+ conduction for advanced all-solid-state lithium battery

Abstract

Polymer electrolyte-based solid-state lithium metal batteries can accommodate high energy density and address safety issues, while polymer electrolytes suffer from low lithium ion migration and weak mechanical strength. Hence, as an exceptionally facile and practical strategy, it is of great significance to search for functional fillers to lift the performance of current polymer electrolytes and explore their role in ion transport. Nanosheet materials with a positive charge field, such as V_O,NCECN (CeO₂ and g-C₃N₄ composites containing oxygen and nitrogen defects), are outstanding candidates. Combining the calculated and experimental results, we reveal the unique nanosheets structure could achieve the maximum area of contact with PEO, so that the surface of the filler is exposed to more coordination sites to promote the transport of Li⁺, and improve the ion conductivity (1.08×10⁻⁵ S cm⁻¹ at 25°C). As a result, a lithium battery consisting of composite solid electrolyte (CSE) still has a capacity of 135 mAh g⁻¹ after 200 cycles at a current density of 0.3 C when matched with a commercial NCM811 electrode. These findings highlight that functional fillers improve the electrochemical properties of polymers and provide a feasible design solution for high-performance solid electrolytes.