Advanced Energy Materials and Research

Biography

Biography: Haojie FEI

Abstract

Statement of the Problem: Lithium-sulfur batteries are considered as a promising candidate for next-generation energy-storage devices due to their high theoretical energy density of 2600 W h kg-1 (sulfur cathode coupled with lithium metal anode). The sulfur cathode has a high theoretical specific capacity of 1673 mA h g-1. It is low cost and environmentally friendly. However, there are several challenges in sulfur cathodes before using in practical application such as low conductivity of sulfur and their intermediates, large volumetric expansion during lithiation and “shuttle effect” of soluble polysulfides.
Methodology & Theoretical Orientation: In this study, we have prepared sulfur microspheres with hollow structures by adding MWCNT. These hollow structures are able to provide space for the expansion of sulfur during the lithiation. Then, the sulfur microspheres were wrapped by MnO2 nanoflakes, which can strongly absorb the polysulfides to prevent from the “shuttle effect”. Moreover, carbonized polyaniline (PANI) separated reduced graphene oxide (RGO) was used as the conducting additives coupled with carbon black, which helps to build a light and conductive matrix. The characterization of electrode materials was performed by XRD, SEM, TEM and Raman spectroscopy. The electrochemical performance of assembled lithium sulfur batteries was measured by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) techniques. The effect of hollow structure in the sulfur microspheres on the electrochemical performance especially on cycling life was evaluated.
Findings: The hollow structure in the sulfur microspheres were obtained by adding MWCNT during the formation of sulfur. MnO2 shells were easily created by one-step oxidation. The hollow structure provides space for the expansion of sulfur during the charge/discharge, resulting in a better cycling stability.