Improving the kinetics and surface stability of sodium manganese oxide cathode materials for sodium rechargeable batteries with Al2O3/MWCNT hybrid networks

Abstract

We report the design and fabrication of a novel functional material in which protective Al₂O₃ nanoparticles are merged with highly conductive multi-walled carbon nanotubes (MWCNTs). In this paper, we discuss in detail the effects of the Al₂O₃/MWCNT hybrid networks on the electrochemical performance of sodium manganese oxide (Na_0.44MnO₂), which is used as an electrode material in sodium rechargeable batteries. The Al₂O₃/MWCNT hybrid networks, which are uniformly dispersed on the surface of Na_0.44MnO₂, change its surface bonding nature, resulting in an improvement in the cycling performance and rate capability of Na_0.44MnO₂. We ascribe these enhancements in performance to the inhibition of the formation of damaging NaF-based solid-electrolyte interface (SEI) layers during cycling, which enables facile transfer of Na ions through the Na_0.44MnO₂ electrode/electrolyte interface. Our findings regarding the control of the chemistry and bonding structure of the Na_0.44MnO₂ particle surfaces induced by the introduction of the Al₂O₃/MWCNT functional hybrid networks provide insight into the possibilities for achieving sodium rechargeable batteries with high power density and stability.