Potassium storage mechanism of In2S3/C nanofibers as the anode for potassium ion batteries

The excellent electrochemical performance of indium sulfide (In 2 S 3 ) in lithium ion batteries (LIBs) and sodium ion batteries (SIBs) prompted us to explore its energy storage mechanism in potassium ion batteries (PIBs). In this work, In 2 S 3 /C nanofibers are successfully synthesized by simple electrospinning and subsequent vulcanization . In K half cells, compared to commercial In 2 S 3 electrodes, In 2 S 3 /C nanofibers as anode materials for PIBs show outstanding electrochemical performance, which can deliver reversible capacities of 397.6 (25), 366.2 (50), 335.2 (100), 307.8 (200), 260.4 (500) and 212.2 mAh g −1 (1000 mA g −1 ), respectively. In K full cells, In 2 S 3 /C nanofibers can also show good potassium storage performance and can light up 15 light emitting diodes (LEDs). The superb electrochemical performance of In 2 S 3 /C nanofibers is due to the in-situ composite with self-nitrogen-doped carbon matrix and the nanoization of In 2 S 3 particles, which buffers the volume effect and improves the conductivity of the material during the potassium storage process. In addition, the mechanism of potassium storage of In 2 S 3 /C nanofibers was systematically studied by cyclic voltammetry (CV), ex-situ XRD, TEM and XPS methods. The mechanism of In 2 S 3 for K-ion storage can be described as the conversion reaction: In 2 S 3  + 6K +  + 6e − ⇌ In + 3K 2 S.