Built-in electric field-driven stress dissipation in multifaceted Bi₂S₃/Bi₂Te₃ heterostructures for sodium-ion batteries

Sodium-ion batteries (SIBs) hold great promise for large-scale grid energy storage, but their development is hindered by electrode pulverization induced by excessive volume changes and strain accumulation during long-term cycling. Herein, we present a capable strategy to address these challenges by integrating built-in electric fields (BIEFs) across multiple interfaces and cross-linked internal structure to enhance ultrafast Na⁺ kinetics and alleviate internal strain. Using Bi₂S₃/Bi₂Te₃ heterostructures as a model system, we demonstrate that the synergistic effects of micro-scale BIEFs and macro-scale cross-linked architectures efficiently disperse internal stresses in multiple directions. Multi-physics simulation and experimental results reveal the ability of this design to stabilize conversion-type anodes, achieving a remarkable rate capability of 575 mAh g⁻¹ at a current density of 5.0 A g⁻¹ with an impressive long-term cycling stability exceeding 3000 cycles. This work highlights a versatile approach to strain management, paving the way for the design of durable and high-performance conversion-type anodes for sodium-ion batteries.