Self-assembly of Co-doped MnO2 nanorod networks with abundant oxygen vacancy-modified separators for high-performance Li–S batteries

Abstract

Lithium–sulfur batteries (LSBs) are broadly considered to be the most promising next-generation energy storage because of their ultrahigh theoretical energy density and cost-effectiveness. However, the “shuttle effect” and sluggish conversion kinetics of polysulfides severely hinder their practical application. To address these challenges, a unique Co-doped MnO₂ nanorod network layer with oxygen vacancies (Co-MnO_x) was devised by self-assembly on a commercial separator through the chemical growth method for high-performance LSBs. The Co-MnO_x modified separators (Co-MnO_x@PP) not only effectively alleviate the “shuttle effects” but also accelerate the redox conversion of polysulfides. More importantly, the Co-MnO_x@PP demonstrated superior thermostability and flame-retardant properties owing to the chemical growth method. The LSBs with Co-MnO_x@PP separators exhibited a high reversible capacity of 902.0 mA h g⁻¹ and 562.2 mA h g⁻¹ at 0.5 C for 20 °C and 60 °C after 200 cycles, respectively. Even at 3 C, after 500 cycles, a superb cycling performance of 715.2 mA h g⁻¹ with an ultra-low decay of 0.069% for each cycle was achieved. Therefore, this proposed strategy of a Co-doped MnO₂ nanorod network layer with oxygen vacancies will provide a new route for rationally devising durable and efficient LSBs.