WO3 Nanostructures Modified with Carbon and Sulfur Used as Anode for Li-Ion Batteries

Abstract

Nowadays, energy problems have become one of the biggest challenges in our society and they have drawn worldwide attention. Rechargeable lithium-ion batteries (LiBs) are a good option thanks to their potential applications as power sources for electric vehicles and mobile devices due to their high energy density and good cycle stability. Much effort has recently been devoted to find alternative anode materials and replace graphite in LiBs, like transition metal oxides that are currently being investigated (1).Specifically, tungsten oxide (WO3) has attracted much interest as an anode due to its excellent properties: high electronic conductivity (10–10−6 s cm−1), high intrinsic density (>7 g cm−3), small radius, and correct crystalline phase for rapid ion insertion and superior electrochemical performance (2).In this research, the effects of the morphology and composition of WO3 nanostructures on the charge/discharge behavior for Li-ion batteries are methodically examined.On the one hand, a simple method is used to synthesize crystalline WO3 nanostructures, with a well-defined morphology by means of an electrochemical procedure known as electrochemical adodization. Then, an annealing treatment at 600◦C in air environment for 4 h was carried out. In the second electrode synthesized, a carbon layer was uniformly deposited on WO3 nanostructures to obtain a WO3/C electrode. Finally, WO3/WS2 electrodes were prepared by means of in situ sulfurization of WO3 one-step solid-state synthesis using tungsten trioxide (WO3) and thiourea as precursor material.The different electrodes synthesized have been morphologically characterized by using X-ray photoelectron spectroscopy, X-ray diffraction analysis, transmission electron microscopy, Raman spectra, and field-emission scanning electron microscopy.The performance of the nanostructures applied as anodes for energy storage in Li-ion batteries and their specific capacity was evaluated by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and Charge-Discharge curves. Among all the synthesized samples, WO3/C nanostructures reveal the best performance as they exhibit the greatest discharge capacity and cycle performance (820 mA h g−1). Acknowledgments Authors would like to express their gratitude to AEI (PID2019-105844RB-I00/ AEI/10.13039/501100011033) for the financial support. M. Cifre-Herrando thank Ministerio de Universidades for the concession of the pre-doctoral grant (FPU19/02466). G. Roselló-Márquez also thanks the UPV for the concession of a post-doctoral grant (PAID-10-21) and for the grant to promote postdoctoral research at the UPV (PAID.-PD-22). Finally, project co-funded by FEDER operational programme 2014-2020 of Comunitat Valenciana (IDIFEDER/18/044) is acknowledged. References Li P, Li X, Zhao Z, Wang M, Fox T, Zhang Q, et al. Correlations among structure, composition and electrochemical performances of WO3 anode materials for lithium ion batteries. Electrochim Acta. 2016;192:148–57. 2. Lian C, Xiao X, Chen Z, Liu Y, Zhao E, Wang D, et al. Preparation of hexagonal ultrathin WO3 nano-ribbons and their electrochemical performance as an anode material in lithium ion batteries. Nano Res. 2016;9(2):435–41.