Intercalative Motifs‐Induced Space Confinement and Bonding Covalency Enhancement Enable Ultrafast and Large Sodium Storage

Alloying-type metal sulfides with high theoretical capacities are promising anodes for sodium-ion batteries, but suffer from sluggish sodiation kinetics and huge volume expansion. Introducing intercalative motifs into alloying-type metal sulfides is an efficient strategy to solve the above issues. Herein, robust intercalative In-S motifs are grafted to high-capacity layered Bi2S3 to form a cation-disordered (BiIn)(2)S-3, synergistically realizing high-rate and large-capacity sodium storage. The In-S motif with strong bonding serves as a space-confinement unit to buffer the volume expansion, maintaining superior structural stability. Moreover, the grafted high-metallicity Indium increases the bonding covalency of Bi-S, realizing controllable reconstruction of Bi-S bond during cycling to effectively prevent the migration and aggregation of atomic Bi. The novel (BiIn)(2)S-3 anode delivers a high capacity of 537 mAh g(-1) at 0.4 C and a superior high-rate stability of 247 mAh g(-1) at 40 C over 10000 cycles. Further in situ and ex situ characterizations reveal the in-depth reaction mechanism and the breakage and formation of reversible Bi-S bonds. The proposed space confinement and bonding covalency enhancement strategy via grafting intercalative motifs can be conducive to developing novel high-rate and large-capacity anodes.