A well-dispersed OV-NiCo2O4 nanosphere modified separator for Li-S batteries

The commercialization of lithium-sulfur batteries is facing great challenges, such as the "shuttle effect" and the poor conductivity of sulfur and Li2S2/Li2S, so it is extremely important to design new separator-modified materials with fast charge transfer capability and effective immobilization of polysulfides (LiPSs) to facilitate their conversion to address these challenges. In this paper, we propose a simple way to synthesize NiCo2O4 nanospheres containing oxygen vacancies (O-V-NiCo2O4 NSs) and thus modify the separator. The synthesized O-V-NiCo2O4 NSs accelerated the conversion of LiPSs through strong chemical interactions. In addition, the introduction of oxygen vacancies provided more active sites for LiPSs, which improved the electron conduction rate and accelerated the ion transport. Based on the above advantages, the battery with an O-V-NiCo2O4 modified separator showed excellent electrochemical performance (the initial capacity of the battery was 801 mA h g(-1) at 0.5 C, the specific capacity of discharge was maintained at 695 mA h g(-1) after 500 cycles, and the capacity retention rate was as high as 87%).