Free-standing Na2C6O6/MXene composite paper for high-performance organic sodium-ion batteries

Sodium-ion batteries (SIBs) are regarded as the ideal low-cost choice for next-generation large-scale energy storage system. Carbonyl-based organic salt-disodium rhodizonate (Na2C6O6) with high theoretical specific capacity (501 mAh·g−1) is considered as a promising cathode material for SIBs. However, the dissolution of active material in electrolyte and low electronic conductivity lead to rapidly capacity decay and poor rate performance. Herein, a simple method is designed to construct free-standing and flexible Ti3C2Tx Na2C6O6/MXene paper via vacuum-assisted filtration and antisolvent approach. The MXene can form an electronic conductive network, adsorb the active materials, and offer additional active sites for Na storage. The binder-free Na2C6O6/MXene paper delivers excellent electrochemical property with a high rate performance of 231 mAh·g−1 at 1,000 mA·g−1 and a high capacity of 215 mAh·g−1 after 100 cycles. This work provides an attractive strategy for designing high-performance organic electrode materials of SIBs.