LAUSR

Organic materials are promising electroactive components of energy storage devices such as lithium-ion batteries and electrochemical capacitors. Among them, low-molecular-weight organics have attracted attention as higher-energy-density, environmentally friendly, and inexpensive electrode materials, but their poor cycle performance is the main drawback. Using in situ XRD measurement in aqueous electrolyte system, here we investigated the capacity fading mechanism of an organic electrode based on low-molecular-weight quinones. Although the capacity fading of such organic electrodes is generally attributed to their elution into the electrolyte, our structural analysis reveals that the capacity fading is also associated with the expansion of an electrochemically inactive region, which persists in the electrode but does not take part in the reversible redox reactions. Moreover, the detailed analysis of the XRD patterns suggests that the capacity fading of the electrode is accompanied by the crystal growth of ...