Exfoliation and restacking route to Keggin-Al13-treated layered ruthenium oxide for enhanced lithium ion storage performance

Owing to their unique molecular structure and chemical reactivity, Keggin-Al13 ([AlO4Al12(OH)24(H2O)12]7+) ions demonstrate versatility in various chemical reactions. Herein, ruthenium oxide nanosheets are introduced as a promising host material for the intercalation of Keggin-Al13 ions with the aim to enhance electrochemical energy storage. Ruthenium oxide, known for its high energy density as an anode material in lithium-ion batteries, faces limitations in terms of cycling stability caused by volume expansion during lithiation. To address these limitations, an approach involving the intercalation of Keggin-Al13 ions into ruthenium oxide nanosheets is developed. The resulting Al13-treated RuO2 (AR-150), heated at 150 °C, maintained the increased interlayer spacing, compared to that of the pristine layered ruthenium oxide. The AR-150 consisting of restacked nanosheets exhibits a considerably increased pseudocapacitance contribution (83.8% at 0.8 mV s−1). In addition, the expanded lamellar structure of AR-150 effectively mitigates volume expansion during repeated lithiation, demonstrating impressive cycling stability. It maintains a reversible capacity of 379.0 mA h g−1 with a capacity retention of 75.0% after 120 cycles at 100 mA g−1. This strategy based on the intercalation chemistry utilizes the unique properties of ruthenium oxide nanosheets to advance their applications in electrochemical energy storage.