Hierarchical Columnar RuO₂Nanoplates and Their Improved Cycle Life Performance at High Capacity

Abstract

RuO 2 has been studied for a long time as a model electrode for lithium ion battery, however, little is known about their cycle life at high capacity. Using a simple low-pressure chemical vapor deposition process, hierarchical columnar RuO 2 nanoplates were directly deposited on stainless steel current collectors. Powder X-ray diffraction revealed the existence of the rutile form of RuO 2 ( P 42/ mnm, a = 4.499 Å, c = 3.111 Å), with a (110) preferred orientation for the as-deposited materials. The electrodes showed significant cycle life improvement versus Li/Li + at high capacity (932 mAh g –1 ). This capacity is higher than expected for the conversion reaction (806 mAh g –1 ) of RuO 2 . Galvanostatic discharge–charge experiments were performed in the range of 4.0 to 0.1 V versus Li/Li + at a constant current density of ∼806 mA g –1 . These self-supported electrodes have shown 94% reversibility for the first 30 cycles and 81% after 60 cycles, which indicate good kinetics and excellent capacity retention. This significant improvement in the electrochemical properties is attributed to the growth process and the chemical and mechanical robustness of the electrode.