Flexible and Free-Standing Organic/Carbon Nanotubes Hybrid Films as Cathode for Rechargeable Lithium-Ion Batteries

Organic carbonyl compounds are promising electrode materials for high-performance lithium-ion batteries (LIBs), but generally suffer from poor cycling stability, low utilization, inferior rate performance, and relatively low reduction potential. In order to solve these problems, we report a dissolution-recrystallization method to prepare flexible, binder-free, and free-standing hybrid films of sodium 1,4-dioxonaphthalene-2-sulfonate and multiwalled carbon nanotubes (NQS/MWNTs) as high-performance cathode for rechargeable LIBs. The hybrid films demonstrate high utilization of NQS, stable cycling, and high-rate capability. The superior electrochemical performance is attributed to decreased size and high polarity of NQS, three-dimensional intertwined conductive network formed by MWNTs. Moreover, NQS/MWNTs show high initial reduction potential at 2.97 V, which is well explained via density functional theory (DFT) calculations. Meanwhile, the reversible redox mechanism of NQS/MWNTs during discharge/charge process is revealed by in situ infrared spectroscopy (IR) test and the stability of fully discharged product is further confirmed by DFT calculations. This study illustrates a facile method to build high-performance flexible rechargeable batteries with sustainable organic materials.