<p>Severe structural collapse along with fast capacity fading is one of the key challenges to meet the needs for commercial O3-type layered cathodes. Here, Cu/Cr are utilized as robust dopants for O3-NaNi_0.2Fe_0.4-xMn_0.3Cu_0.1Cr_xO₂ (NFMCC) to achieve the purpose of reconstructing the crystal lattice and regulating the interlayer structure. It is found that the synergistic effect between Cu and Cr facilitates suppressing the oxygen vacancies and transition metals (TMs) migration in the TMs layer, bringing forth the release of the internal stress, and eventually preventing the rupture in the NFMCC polycrystals upon repeated cycling. The Na⁺/vacancy arrangement and phase transitions are also greatly suppressed, which is further verified by single voltage plateaus upon Na⁺ extraction/insertion. The sufficient sodium in the O3-type cathodes easily induces the good structural stability at deep desodiation states and adequate reversible capacity during Na⁺ desodiation. Consequently, Cu-substituted NFMCC exhibits a high specific capacity of 120 mAh g⁻¹ and remarkable cycling performance with a capacity retention of 87.71% after 100 cycles. This work provides a fundamental insight for paving the way to extend the lifespan of cathodes for SIBs.</p>