Hierarchical nanostructure of RuO2 hollow spheres with enhanced lithium ion storage and cyclic performance

RuO2 hollow spheres as a macroporous model structure for substituting a graphite anode in a lithium ion battery were successfully fabricated by utilizing the electrostatic attraction between exfoliated RuO2 nanosheets and cationic polymers onto the polystyrene (PS) templates. According to the results of scanning electron microscopy, thin RuO2 nanosheets were homogeneously covered onto the polystyrene beads before calcination. Transmission electron microscopy images clearly indicated complete removal of the PS templates after calcination at 500 degrees C for 2 h, leading to RuO2 hollow spheres with a macroporous structure. Electrochemical charge/discharge experiments demonstrated a much larger lithium storage capacity for the RuO2 hollow spheres described here (600 mAh/g) than that of bare rutile RuO2 (340 mAh/g), highlighting the effectiveness of this synthetic technology. (C) 2017 Elsevier B.V. All rights reserved.