Effective stress dissipation by multi-dimensional architecture engineering for ultrafast and ultralong sodium storage

Stress accumulation is a key factor leading to sodium storage performance deterioration for NiSe₂-based anodes. Therefore, inhibiting the concentrated local stress during the sodiataion/desodiation process is crucial for acquiring stable NiSe₂-based materials for sodium-ion batteries (SIBs). Herein, a stress dissipation strategy driven by architecture engineering is proposed, which can achieve ultrafast and ultralong sodium storage properties. Different from the conventional sphere-like or rod-like architecture, the three-dimensional (3D) flower-like NiSe₂@C composite is delicately designed and assembled with one-dimensional nanorods and carbon framework. More importantly, the fundamental mechanism of improved structure stability is unveiled by simulations and experimental results simultaneously. It demonstrates that this designed multidimensional flower-like architecture with dispersed nanorods can balance the structural mismatch, avoid concentrated local strain, and relax the internal stress, mainly induced by the unavoidable volume variation during the repeated conversion processes. Moreover, it can provide more Na⁺-storage sites and multi-directional migration pathways, leading to a fast Na⁺-migration channel with boosted reaction kinetic. As expected, it delivers superior rate performance (441 mA h g⁻¹ at 5.0 A g⁻¹) and long cycling stability (563 mA h g⁻¹ at 1.0 A g⁻¹ over 1000 cycles) for SIBs. This work provides useful insights for designing high-performance conversion-based anode materials for SIBs.