Metal hydroxide – a new stabilizer for the construction of sulfur/carbon composites as high-performance cathode materials for lithium–sulfur batteries

Abstract

Rational design and fabrication of advanced sulfur cathodes is highly desirable for the development of high performance lithium–sulfur (Li–S) batteries. Herein, we report Co(OH)₂ as a new stabilizer for the sulfur cathode by constructing a cobalt hydroxide-covered sulfur/conductive carbon black (CCB) electrode with the help of thermal and hydrothermal treatments. In this composite, (Co(OH)₂@S/CCB), the sublimed sulfur is anchored in the CCB, followed by a uniform coating of Co(OH)₂ nanosheets. As cathode materials of lithium–sulfur batteries, the as-prepared Co(OH)₂@S/CCB electrode exhibits remarkable electrochemical performances with a high capacity of 1026 mA h g⁻¹ at 0.1C (1C = 1675 mA g⁻¹) and 829 mA h g⁻¹ at 1C. Moreover, it maintains high coulombic efficiencies above 97% after 200 cycles at 1C, much higher than those of the S/CCB counterpart electrode (85%). After 200 cycles at 1C, a high capacity retention of 71.2% is obtained, better than that of the S/CCB electrode (20.2%). The enhanced performance is mainly due to the Co(OH)₂ layer which helps to inhibit the shuttle diffusion of polysulfides, resulting in improved capacity retention and cycling life.