An interfacially coupled Mott–Schottky heterojunction encapsulated in graphitized nanofibers for an ionic-liquid hybrid supercapacitor operable from −25 °C to 60 °C

MXene–SnSe Mott–Schottky heterostructures embedded in graphitized carbon nanofibers enable a 3.5 V ionic-liquid hybrid supercapacitor with high energy density and stable cycling from −25 °C to 60 °C.