Preparation of CoO/SnO2@NC/S composite as high-stability cathode material for lithium-sulfur batteries

Abstract

To improve the sulfur loading capacity of lithium-sulfur batteries (Li-S batteries) cathode and avoid the inevitable “shuttle effect”, hollow N doped carbon coated CoO/SnO2 (CoO/SnO2@NC) composite has been designed and prepared by a hydrothermal-calcination method. The specific surface area of CoO/SnO2@NC composite is 85.464 m2·g−1, and the pore volume is 0.1189 cm3·g−1. The hollow core-shell structure as a carrier has a sulfur loading amount of 66.10%. The initial specific capacity of the assembled Li-S batteries is 395.7 mAh·g−1 at 0.2 C, which maintains 302.7 mAh·g−1 after 400 cycles. When the rate increases to 2.5 C, the specific capacity still has 221.2 mAh·g−1. The excellent lithium storage performance is attributed to the core-shell structure with high specific surface area and porosity. This structure effectively increases the sulfur loading, enhances the chemical adsorption of lithium polysulfides, and reduces direct contact between CoO/SnO2 and the electrolyte.