A high-efficiency N/P co-doped graphene/CNT@porous carbon hybrid matrix as a cathode host for high performance lithium–sulfur batteries

Abstract

Heteroatom-doped carbon hybrids containing sp²-hybridized and sp³-hybridized nanocarbons have attracted immense interest as sulfur hosts due to their unique 3D conductive networks and synergistic effect of physical absorption and chemical interaction on suppressing the dissolution of polysulfides. However, the reported carbon hybrids always require a tedious fabrication process, including multistep chemical vapor deposition and a thermally stable catalyst. Therefore, it is highly desirable to exploit a simple, renewable, and scalable strategy to fabricate 3D heteroatom-doped carbon hybrids. Herein, a N, P-co-doped 3D carbon hybrid was successfully fabricated via a one-pot pyrolysis process. Due to the rapid Li⁺/e⁻ transport among the 3D interconnected porous frameworks and effectively suppressed polysulfide dissolution by physical confinement and chemical interaction, the assembled Li–S batteries exhibit excellent electrochemical performance. The as-obtained cell delivers an ultrahigh initial discharge capacity of 1446 mA h g⁻¹ at 0.1C as well as an excellent rate capability of 921 mA h g⁻¹ at 1C. Additionally, a reversible and stable discharge capacity of 795 mA h g⁻¹ is maintained after 400 cycles at 1C, corresponding to an extremely low capacity decay of 0.034% per cycle. Such a design strategy is eco-friendly and generally applicable to combine the sp² nanocarbon with sp³ amorphous carbon, which is crucial to construct 3D interconnected hierarchical porous carbons for advanced energy storage for applications in various fields, such as lithium batteries, catalysis and hydrogen storage.