Porous-dual-shell structure and heterojunction Co3O4@NiCo2O4 accelerating polysulfides conversion for all-solid-state lithium sulfur batteries

Abstract

All-solid-state lithium sulfur batteries (ASSLSBs) hold significant promise in the application of high energy density batteries, yet they suffer from poor ionic conductivity, low Li⁺ transference number and unsatisfactory lithium polysulfides (LiPSs) conversion. In this paper, porous-dual-shell structure and heterojunction Co₃O₄@NiCo₂O₄ is prepared and composited with polyethylene oxide (PEO)-based solid polymer electrolytes (SPEs) to address these problems. The superimposed electric field for Co₃O₄@NiCo₂O₄ composed of the heterointerfaces -build-in electric field and the surface oxygen-rich vacancies-build-in electric field facilitates the dissociation of Li salts, thus improving the ionic conductivity. It exhibits high ionic conductivity of 1.04 × 10⁻³ S/cm and Li⁺ transference number of 0.48 at 60 °C. Besides, the incorporation of Co₃O₄@NiCo₂O₄ heterojunction enables fast LiPSs conversion and improves the electrochemical kinetics. The Li//Li cell can work stably for 1100 h at 0.1 mA/cm². The Li//S cell provides an initial capacity of 1170 mA h/g, a reversible capacity of 620.1mA h/g after 100 cycles and 308.3 mA h/g after 450 cycles at 0.2 C.