Interfacial Self-assembly of Organics/MXene Hybrid Cathodes Toward High-Rate-Performance Sodium Ion Batteries

Conjugated quinones are promising cathode materials for sodium-ion batteries. However, the contemporary primary conjugated quinones cathodes still hold to limited capacity, poor rate performance and low cyclability, due to the poor electronic and ionic conductivity. Herein, a series of high-performance conjugated-quinones@MXene hybrid cathodes is constructed by an in situ polymerization-assembly strategy based on the hydrogen bond and S-Ti interaction. The PAQS@Ti3C2Tx MXene hybrid, as a typical example, exhibits sandwiched structure with intimate PAQS@MXene contact, resulting in efficient interfacial mass transfer. The assembled MXene is able to build interconnected conductive channels in the hybrid cathodes for continuous and fast electrons/ions transport, which is verified by both the experimental results and density functional theory (DFT) calculations. As a result, the optimal PAQS@MXene hybrid electrode delivers excellent electrochemical performances with high capacity (∼242 mA h g-1 at 100 mA g-1), superior fast-charge/discharge ability (∼148 and 121 mA h g-1 at 5 and 10 A g-1, respectively), and ultralong cycle life (capacity as high as 57 mA h g-1 after 9000 cycles at 5 A g-1), which are more superior to that of the pure PAQS electrodes. Besides, the analogous PPTS@Ti3C2Tx MXene hybrid cathode also shows better performances compared to the pure materials.