Conversion Reaction in the Binder-Free Anode for Fast-Charging Li-Ion Batteries Based on WO<sub>3</sub> Nanorods
Raman Bekarevich, Yuriy Pihosh, Yoshinori Tanaka, Kei Nishikawa, Yoshitaka Matsushita, Takanobu Hiroto, Hirohito Ohata, Takahisa Ohno, Tsutomu Minegishi, Masakazu Sugiyama, Takehiko Kitamori, Kazutaka Mitsuishi, Kazunori Takada
Abstract
The development of lithium-ion batteries (LIBs) with high-energy densities faces challenges to meet the ever-growing market demands. Tungsten oxide (WO3) with high theoretical capacity and low cost is a potential replacement for conventional graphite anodes, whose low reversible capacity limits the energy densities of existing LIBs. However, large volumetric changes during the cycling result in the degradation of WO3-based electrodes. Hence, we integrated an anode based on vertically aligned WO3 nanorods with a current collector. The controlled geometry of binder-free anodes minimized volumetric expansion effects and conferred high mechanical stability proven by stable cycling performance up to a rate of 3 C without disintegration. Ex situ X-ray diffraction and electron microscopy analyses supported by theoretical calculations revealed the appearance of the intermediate active phases during conversion reaction.