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.　©　2023　The　Authors.　InfoMat　published　by　UESTC　and　John　Wiley　&　Sons　Australia,　Ltd.