Breaking Bond-Strain Lockstep in Multielectron Anodes

The pervasive bond-strain negative feedback loop in multi-electron conversion-alloy anodes, where strong covalent bonds constrain lattice transformation during sodiation, induces strain accumulation and bond rupture. This results in sluggish kinetics and severe capacity decay, crippling the viability as high-capacity anode. Here, this negative feedback loop through interstitial atomic wedging is broken. Ni is implanted into Sn₄P₃ interlayers via mechanochemical synthesis, which serve as atomic-scale rivet that topologically pin migrating species while simultaneously weakening Sn─P bonds. This dual-channel regulation is achieved via geometrical pinning coupled with electronic reconfiguration, which jointly establish metallic percolation networks and rapid ion-diffusion pathways. It is further revealed that dynamic Ni─P covalent buffers suppress Sn/P aggregation during (de)sodiation, enabling structural integrity. Consequently, Ni_0.41Sn₄P₃ delivers a high specific capacity of 958.9 mAh g^-1 at 0.1 A g^-1, with an initial Coulombic efficiency of 93.6% and enables full cells to achieve an energy density of 293.3 Wh kg^-1. This work demonstrates that interstitial bond-strain rebalancing coupled with orbital-hybridized band engineering can resolve the classic trade-off between reaction stability and kinetics in multi-electron reactions. The strategy offers a generalizable materials design principle toward high-energy-density storage systems.