Development of free-standing h-BN/rGO/S composite cathodes for Li-S batteries: h-BN content and temperature effect

Abstract

This study aims to improve the properties of Li-S batteries and overcome their disadvantages by utilizing hexagonal boron nitride (h-BN) nanocomposites with unique features that provide advantages in their applications. For this purpose, composite films were produced using h-BN with superior mechanical and chemical properties along with reduced graphene oxide (rGO) possessing high electrical conductivity. Free-standing and flexible h-BN/rGO/S composite paper electrodes containing different weight ratios of functionalized h-BN were prepared. The obtained binder-free composite papers were employed as cathodes in Li-S batteries and applied at different temperatures. In this study, the structural, morphological, and thermal analyses of the composite cathodes were conducted using X-ray diffraction (XRD), field emission gun scanning electron microscopy (FEG-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The optical measurements were carried out by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and ultraviolet–visible spectroscopy (UV–Vis). After assembling CR2032 button cells, electrochemical performance tests were applied to assess the charge–discharge capacities. A high discharge capacity of 427 mAh g⁻¹ was achieved after 1000 cycles. As a result, h-BN/rGO-based composites have been developed as environmentally friendly and metal-free materials, further enhancing the electrochemical performance and electron transport of lithium batteries.