(537e) Charge Storage Mechanism of Iron Oxide Electrode Material for Aqueous Electrochemical Energy Storage

The demand for high performance rechargeable batteries is increasing in recent years with the rapid development in electronic devices.

Over the past centuries, iron has been playing an imperative role in shaping human civilization and economic growth, where United States alone generates over 40 million of tons of iron ore per year. There are several advantages making iron an obviously attractive raw material for a rechargeable battery, including low cost, ease of oxidation and multiple oxidation states, a natural and abundant element on earth, and little effects on our environment and human health in its oxide form. Unfortunately, despite the great progress that has been achieved, the performance of iron oxide electrode materials is still unsatisfactory and further improvement is needed.

Our research focus on lepidocrocite (γ-FeOOH) layered materials, which was synthesized via facile one-step wet chemistry. The crystal structure of γ-FeOOH materials was confirmed by X-ray diffraction (XRD) measurement and their electrochemical performance toward aqueous electrochemical storage were tested by Cyclic Voltammetry (CV) in three-electrode half-cell system. The crystal structure change during CV tests was investigated by in situ XRD measurement. Our results showed that the electrochemical performance of γ-FeOOH was dependent on the concentration of sodium sulfate and pH of the electrolyte. Our research showed clear evidence of the energy storage mechanism of iron oxide in alkaline solution, which provides insight on the exploration of new type of charge storage mechanism using iron-based electrode materials.