Electrochemical and Rheological Properties of Poly(vinyl alcohol) and Carbon Nanotube Composite Binders for Lithium Sulfur Battery Applications

This study develops a method for the air-controlled electrospraying of poly (vinyl alcohol) (PVA)/carbon nanotube (CNT) nanocomposite binders for enhanced thermal stability, conductivity and electrochemical performance in in lithium-sulfur (Li-S) batteries and electrochemical supercapacitors. CNTs are comprised of carbon atoms in hexagonal formations with a backbone of alternating carbon-carbon double bonds that form linear high aspect ratio walled tubes. Chemically oxidized CNTs have carboxylic acid, carbonyl, and epoxide functional groups on the side walls and tips of the carbon hexagons along the CNT structure. In this method, CNTs were chemically oxidized in strong acids at high temperature, PVA was hydrolyzed and mixed with the oxidized carbon nanotubes, and the resulting PVA/CNT mixture was air-controlled electrosprayed to form nanocomposite PVA/CNT binder films through hydrogen bonding and physical crosslinking. The PVA/CNT binder films are characterized using Fourier transform-infrared spectroscopy, thermogravimetric analysis, rheometry, Raman spectroscopy, scanning electron microscopy (SEM), and with electrochemical techniques such as cyclic voltammetry and impedance spectroscopy to show evidence of chemical functionalization, thermal and mechanical stability, enhanced conductivity, low charge transfer resistance, and lithium-sulfur (Li-S) and electrochemical charge-discharge performance, respectively. Performance showed promising cycling, high capacitance, and conductivity. Ultimately, our analysis allows for the scalable application of the thermally stable and conductive binder in high-performance batteries and supercapacitors.