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 SnSe2-SePAN composite was fabricated for extraordinarily stable and wide-temperature range SIBs/PIBs through a coupling strategy between controllable electrospinning and selenylation, in which SnSe2 nanoparticles were uniformly encapsulated in the SePAN matrix. The unique structure of SnSe2-SePAN not only relieves drastic volume variation but also guarantees the structural integrity of the composite, endowing SnSe2-SePAN with excellent sodium/potassium storage properties. Consequently, SnSe2-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 SnSe2-SePAN. Also, computational calculations verify that SePAN takes an important role in intensifying the electrochemical performance of SnSe2-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. (Figure presented.).