1D Insertion Chains Induced Small‐Polaron Collapse in MoS2 2D Layers Toward Fast‐Charging Sodium‐Ion Batteries

Abstract Molybdenum disulfide (MoS 2 ) with high theoretical capacity is viewed as a promising anode for sodium‐ion batteries but suffers from inferior rate capability owing to the polaron‐induced slow charge transfer. Herein, a polaron collapse strategy induced by electron‐rich insertions is proposed to effectively solve the above issue. Specifically, 1D [MoS] chains are inserted into MoS 2 to break the symmetry states of 2D layers and induce small‐polaron collapse to gain fast charge transfer so that the as‐obtained thermodynamically stable Mo 2 S 3 shows metallic behavior with 10 7 times larger electrical conductivity than that of MoS 2 . Theoretical calculations demonstrate that Mo 2 S 3 owns highly delocalized anions, which substantially reduce the interactions of Na−S to efficiently accelerate Na + diffusion, endowing Mo 2 S 3 lower energy barrier (0.38 vs 0.65 eV of MoS 2 ). The novel Mo 2 S 3 anode exhibits a high capacity of 510 mAh g −1 at 0.5 C and a superior high‐rate stability of 217 mAh g −1 at 40 C over 15 000 cycles. Further in situ and ex situ characterizations reveal the in‐depth reversible redox chemistry in Mo 2 S 3 . The proposed polaron collapse strategy for intrinsically facilitating charge transfer can be conducive to electrode design for fast‐charging batteries.