Hollow N-doped carbon-encapsulated Cu2Se/CoSe2 heterostructure with functionalized separator for fast and stable rechargeable aluminum batteries

A dual-protection strategy suppresses polyselenide shuttling and volume expansion for stable Al batteries. • Cu 2 Se/CoSe 2 heterointerfaces accelerate redox kinetics and optimize electronic structure for Al storage. • Hollow carbon nanotubes buffer mechanical strain and confine active species during cycling. • Achieving 274.2 mAh g −1 over 1000 cycles and high-rate performance up to 3.2 A g −1 . Transition metal selenides (TMSs) hold great promise as high-capacity cathode materials for rechargeable aluminum batteries (RABs) owing to their cost-effectiveness and favorable redox activity. However, their practical implementation is severely plagued by the structural collapse induced by volume expansion and the rapid capacity decay caused by polyselenide dissolution in acidic ionic liquid electrolytes. Herein, a dual-protection strategy is proposed by rationally constructing a hollow nitrogen-doped carbon nanotube-encapsulated Cu 2 Se/CoSe 2 heterostructure (NC@Cu 2 Se/CoSe 2 ), coupled with an acetylene black-modified separator (AB/GF/A). In this integrated architecture, the hollow conductive carbon skeleton physically confines the active species and buffers mechanical strain, while the bimetallic selenide heterojunction accelerates reaction kinetics. Synergistically, the functionalized separator further suppresses the shuttle effect by intercepting dissolved species. Benefiting from these multidimensional merits, the assembled RABs manifest superior electrochemical performance, delivering a high reversible capacity of 274.2 mAh g −1 after 1000 cycles at 1.0 A g −1 , and 250 mAh g −1 at a high rate of 3.2 A g −1 . This work offers a comprehensive perspective on integrating heterostructure engineering with separator modification to unlock the potential of advanced RABs. Download: Download high-res image (197KB) Download: Download full-size image A hollow N-doped carbon-encapsulated Cu 2 Se/CoSe 2 heterostructure is developed as a high-capacity cathode for rechargeable aluminum batteries. The integrated design, featuring an internal bimetallic selenide heterojunction and an acetylene black-modified separator, effectively buffers volume expansion and suppresses the shuttle effect of dissolved species, enabling exceptional cycling stability and rate capability.