Alloying-type bismuth with high volumetric capacity has emerged as a promising anode for sodium-ion batteries but suffers from large volume expansion and continuous pulverization. Herein, a coordination constraint strategy is proposed, that is, chemically confining atomic Bi in an intercalation host framework via reconstruction-favorable linear coordination bonds, enabling a novel quasi-topological intercalation mechanism. Specifically, micron-sized Bi 0.67 NbS 2 is synthesized, in which the Bi atom is linearly coordinated with two S atoms in the interlayer of NbS 2 . The robust Nb−S host framework provides fast ion/electron diffusion channels and buffers the volume expansion of Na + insertion, endowing Bi 0.67 NbS 2 with a lower energy barrier (0.141 vs. 0.504 eV of Bi). In situ and ex situ characterizations reveal that Bi atom alloys with Na + via a solid-solution process and is constrained by the reconstructed Bi−S bonds after dealloying, realizing complete recovery of crystalline Bi 0.67 NbS 2 phase to avoid the migration and aggregation of atomic Bi. Accordingly, the Bi 0.67 NbS 2 anode delivers a reversible capacity of 325 mAh g −1 at 1 C and an extraordinary ultrahigh-rate stability of 226 mAh g −1 at 100 C over 25 000 cycles. The proposed quasi-topological intercalation mechanism induced by coordinated mode modulation is expected to be be conducive to the practical electrode design for fast-charging batteries.

Alloying‐type metals with high theoretical capacity are promising anode materials for sodium ion batteries, but suffer from large volume expansion and sluggish reaction kinetics. Dispersing alloying‐type metal into a buffer matrix with interfacial anionic covalent bonding is an effective method to solve the above issues. Here, this bifunctional structural unit is designed by incorporating high‐capacity Sb metal into a rigid CrSe framework for fast‐charging applications. The high‐capacity and high‐rate sodium storage can be synergistically realized in the bifunctional SbCrSe system, where the rigid CrSe framework endows the SbCrSe3 anodes with superior structural stability and improved intercalative redox pseudocapacitance. Moreover, the volume expansion of Sb during discharge can be buffered by the CrSe chain‐like matrix. The novel SbCrSe3 anode delivers a high charge capacity of 472 mAh g−1 at a current density of 0.4 C and retains ≈100% capacity at 60 C over 10 000 cycles. Further in situ and ex situ characterization reveal the multistep reaction mechanism, and the breakage and formation of reversible SbSe bonds during (dis)charge. The proposed bifunctional structural unit that combines alloying type anodes and intercalative anodes is expected to pave a new road for the development of high capacity and high rate anode materials.