Manipulation of Disodium Rhodizonate: Factors for Fast-Charge and Fast-Discharge Sodium-Ion Batteries with Long-Term Cyclability

Organic sodium-ion batteries (SIBs) are one of the most promising alternatives of current commercial inorganic lithium-ion batteries (LIBs) especially in the foreseeable large-scale flexible and wearable electronics. However, only a few reports are involving organic SIBs so far. To achieve fast-charge and fast-discharge performance and the long-term cycling suitable for practical applications, is still challenging. Here, important factors for high performance SIBs especially with high capacity and long-term cyclability under fast-charge and fast-discharge process are investigated. It is found that controlling the solubility through molecular design and determination of the electrochemical window is essential to eliminate dissolution of the electrode material, resulting in improved cyclability. The results show that poly(vinylidenedifluoride) will decompose during the charge/discharge process, indicating the significance of the binder for achieving high cyclability. Beside of these, it is also shown that decent charge transport and ionic diffusion are beneficial to the fast-charge and fast-discharge batteries. For instance, the flake morphology facilitates the ionic diffusion and thereby can lead to a capacitive effect that is favorable to fast charge and fast discharge.