Modified separators for rechargeable high-capacity selenium-aluminium batteries

It is an urgent demand to explore high capacity positive electrode materials for rechargeable aluminium batteries. Elemental selenium has attracted great attention due to the competitive volumetric capacity (3253 m Ah cm⁻³) and improved electrical conductivity (~1 × 10⁻³ S m⁻¹) in comparison with the widely-developed sulfur positive electrode. In a conventional battery configuration with ordinary separators, the selenium aluminium battery exhibits a high discharge voltage of ~1.52 V vs Al/Al³⁺, with unexpected dramatic capacity decay within 20 cycles. For addressing such critical issues, here a novel prototype of separator modified with CMK-3 porous carbon coating was developed, aiming to substantially promoting the rechargeable capacity and cycling stability of the selenium aluminium batteries (SABs). As anticipation, the as-assembled SABs presented an enhanced specific capacity up to 1009 mA h g⁻¹ at the current density of 1000 mA g⁻¹. The results of the mechanism suggest that SABs with the presence of CMK-3 modified separators have well suppressed the unexpected shuttle effects induced by soluble selenium chloroaluminate compounds. Apparently, the simple strategy in this work offers a high-efficiency approach for massively boost the rechargeable abilities of the SABs, with extended applications in other types of aluminium batteries with related energy storage mechanism.