Selenium (Se) doped CoS2-xSex/NC laminated nanosheets assembled accordion architecture for robust and durable sodium/potassium ion batteries

• Selenium (Se) doped CoS 2-x Se x /NC laminated nanosheets assembled accordion architecture was successfully prepared. • Hierarchical accordion architecture with thin CoS 2-x Se x nanosheets facilitate Na + /K + transport. • CoS 2-x Se x /NC delivers outstanding rate capacity and cycle stability for SIBs and PIBs. • Laminated nanosheets architecture and Se doping improve electronic conductivity and structure stability. In this manuscript, selenide (Se)-doped cobalt sulfide (CoS 2-x Se x /NC) with accordion architecture has been triumphantly synthesized by the synergistic high-temperature sulfidation/selenization processes of the layered close-packed structure precursor. The successful Se doping into CoS 2 crystal structure can effectively extend to the interlayer spacing of CoS 2 and greatly improve the electrochemical conductivity of the electrode material. Besides, the Se doping also provide enough reactive active sites for the Na + transport and laminated nanosheets structure of CoS 2-x Se x /NC greatly hinder the heavy volume expansion of electrode material during the repeated charging/discharging processes. When used as the Na + battery (SIBs) anode materials, the CoS 2-x Se x /NC electrode can maintain the high specific capacity of 421.7 mAh g −1 at 1.0 A g −1 after 1000 cycles. Besides, it can also hold the wonderful capacity 390 mAh g −1 at 5.0 A g −1 after 1500 cycles. This heteroatom doping strategy could pave a bright avenue for the design and preparation of novel metallic sulfides with nonmetal elements doping with excellent electrochemical and battery performance for SIBs/PIBs.