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 Ti₃C₂T_x 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.