Pseudocapacitive Properties of Nano‐structured Anhydrous Ruthenium Oxide Thin Film Prepared by Electrostatic Spray Deposition and Electrochemical Lithiation/Delithiation

Abstract

Nano‐structured anhydrous ruthenium oxide (RuO2) thin films were prepared using an electrostatic spray deposition (ESD) technique followed by electrochemical lithiation and delithiation. During the electrochemical lithiation process, RuO2 decomposed to nano‐structured metallic ruthenium Ru with the concomitant formation of Li2O. Nano‐structured RuO2 was formed upon subsequent electrochemical extraction of Li from the Ru/Li2O nanocomposite. Electrochemical lithiation/deliathiation at different charge/discharge rates (C‐rate) was used to control the nano‐structure of the anhydrous RuO2. Electrochemical lithiation/delithiation of the RuO2 thin film electrode at different C‐rates was closely related to the specific capacitance and high rate capability of the nano‐structured anhydrous RuO2 thin film. Nano‐structured RuO2 thin films prepared by electrochemical lithiation and delithiation at 2C rate showed the highest specific capacitance of 653 F g–1 at 20 mV s–1, which is more than two times higher than the specific capacitance of 269 F g–1 for the as‐prepared RuO2. In addition, it showed 14% loss in specific capacitance from 653 F g–1 at 20 mV s–1 to 559 F g–1 at 200 mV s–1, indicating significant improvement in the high rate capability compared to the 26% loss of specific capacitance of the as‐prepared RuO2 electrode from 269 F g–1 at 20 mV s–1 to 198 F g–1 at 200 mV s–1 for the same change in scan rate.

Recent Progress in Ruthenium Oxide‐Based Composites for Supercapacitor Applications

“…In order to obtain mesoporous hydrous RuO 2 thin films with organized and accessible porosity, Sassoye and workers used ruthenium‐peroxo‐based sols formed with amphiphilic polystyrene‐polyethylene oxide block copolymers as micelle templates that displayed high gravimetric capacitances . Furthermore, to control the porous morphology of electrostatically‐spray‐deposited anhydrous RuO 2 , electrochemical lithiation and delithiation was executed with improved outcome …”

Designed Nanoarchitectures by Electrostatic Spray Deposition for Energy Storage

“…Hydrous RuO 2 · x H 2 O and anhydrous RuO 2 were successfully prepared by the ESD technique, with specific capacitances of 650 F g −1 and 500 F g −1 , respectively, at a scan rate of 20 mV s −1 . The capacitance of the anhydrous RuO 2 can be further improved by ESD followed by electrochemical lithiation and delithiation . Based on the reversible conversion reaction, the as‐prepared ESD RuO 2 with primary particle sizes of 15–30 nm will be converted to nanostructured RuO 2 ranging from 2 to 5 nm.…”

“…The capacitance of the anhydrous RuO 2 can be further improved by ESD followed by electrochemical lithiation and delithiation. [174] Based on the reversible conversion reaction, the as-prepared ESD RuO 2 with primary particle sizes of 15-30 nm will be converted to nanostructured RuO 2 ranging from 2 to 5 nm. The specific capacitance will be increased to 653 F g −1 at 20 mV s −1 .…”

Engineering nanostructured anodes via electrostatic spray deposition for high performance lithium ion battery application

“…Furthermore, the ESD technique provides the possibility for the preparation of various anodes without the use of extra binder and conductive materials. 58,124,[145][146][147] It has been demonstrated that the ESD technique shows promising application in LIBs.…”