Extraordinarily stable and wide‐temperature range sodium/potassium‐ion batteries based on 1D SnSe₂‐SePAN composite nanofibers

Abstract Developing electrodes with long lifespan and wide‐temperature adaptability is crucial important to achieve high‐performance sodium/potassium‐ion batteries (SIBs/PIBs). Herein, the SnSe 2 ‐SePAN composite was fabricated for extraordinarily stable and wide‐temperature range SIBs/PIBs through a coupling strategy between controllable electrospinning and selenylation, in which SnSe 2 nanoparticles were uniformly encapsulated in the SePAN matrix. The unique structure of SnSe 2 ‐SePAN not only relieves drastic volume variation but also guarantees the structural integrity of the composite, endowing SnSe 2 ‐SePAN with excellent sodium/potassium storage properties. Consequently, SnSe 2 ‐SePAN displays a high sodium storage capacity and excellent feasibility in a wide working temperature range (−15 to 60°C: 300 mAh g −1 /700 cycles/−15°C; 352 mAh g −1 /100 cycles/60°C at 0.5 A g −1 ). At room temperature, it delivers a record‐ultralong cycling life of 192 mAh g −1 that exceeds 66 000 cycles even at 15 A g −1 . It exhibits extremely superb electrochemical performance in PIBs (157 mAh g −1 exceeding 15 000 cycles at 5 A g −1 ). The ex situ XRD and TEM results attest the conversion‐alloy mechanism of SnSe 2 ‐SePAN. Also, computational calculations verify that SePAN takes an important role in intensifying the electrochemical performance of SnSe 2 ‐SePAN electrode. Therefore, this study breaks new ground on solving the polyselenide dissolution issue and improving the wide temperature workable performance of sodium/potassium storage. image