Multifunctional Fluorine-Nitrogen Modified Carbon Quantum Dots for Enhanced Solid Polymer Electrolytes Toward Solid-State Lithium Batteries

Abstract

Solid polymer electrolytes (SPEs) are pivotal for developing all-solid-state lithium batteries due to their enhanced safety, but their practical application is hindered by low ionic conductivity. Herein, fluorine-nitrogen modified carbon quantum dots (FNCDs) are designed and prepared as a multifunctional filler to overcome this limitation. The FNCDs provide abundant sites for Li + transport and immobilize anions (TFSI -), promoting Li salt dissociation. Moreover, the fluorinated surface ensures excellent compatibility with the fluorinated polymer matrix (PVDF-HFP), facilitating favorable interfacial Li + hopping channels. Consequently, the FNCDs-incorporated SPE (FNCDs-SPE) film achieves a high ionic conductivity of 9.59×10 -4 S cm -1 and a Li + transference number of 0.77. It also exhibits enhanced mechanical strength (3.53 MPa) and elasticity (249.2% elongation). When paired with LiFePO4, LiCoO2, or NCM811 cathodes, the corresponding solid-state cells demonstrate exceptional cycling stability. This work highlights the great potential of zero-dimensional fluorinated carbon materials in developing high-performance SPEs.