Confining SnS2@N, S codoped carbon in core-shell beads of necklace-like fibers towards ultrastable anode for flexible potassium-ion battery

Tin sulfide (SnS2) with high theoretical capacity and layered structure is a promising anode candidate for potassium-ion batteries (PIBs). However, the sluggish kinetics, huge volume expansion and polysulfide intermediates dissolution restrict its development. To address these issues, a necklace-like hybrid fiber with core–shell beads is designed to achieve the high-performance anode for PIBs. The cores of the beads are assembly by SnS2 nanocrystals dotted in N, S codoped carbon (NSC) matrix. Then they are encapsulated by NSC based shell and form the core–shell structured beads internal the hybrid fiber (CSN fiber). The carbon matrix of SnS2@NSC CSN fiber gives fast ion/electron pathways and facilitates to decrease particle aggregation. Meanwhile, N, S codpants favor to trap the polysulfides intermediates and alleviate the sulfur loss during cycling. Moreover, the voids internal the beads further provide the high accommodation to volume change. Taken all above advantages, the SnS2@NSC CSN fiber achieves the excellent high rate capability and ultrastable cycling property, which obtains a low capacity decay rate of 0.013% after 2000 cycles at 2 A g−1. Moreover, its good mechanical characteristics ensure the fabrication of the flexible PIB full cell, which achieves the high pliability, superior power/energy density and high reliability in diverse working conditions. Therefore, this work not only gives a new clue to design the high-performance electrode for potassium storage, but also propels the applications of PIBs for diverse electronics.