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Deep sodium extraction/insertion of sodium cathodes usually causes undesired Jahn–Teller distortion and phase transition, both of which will reduce structural stability and lead to poor long‐cycle reliability. Here we report a zero‐strain P2‐ Na_2/3Li_1/6Co_1/6Mn_2/3O₂cathode, in which the lithium/cobalt substitution contributes to reinforcing the host structure by reducing the Mn³⁺/Mn⁴⁺redox, mitigating the Jahn–Teller distortion, and minimizing the lattice change. 94.5 % of Na⁺in the unit structure can be reversibly cycled with a charge cut‐off voltage of 4.5 V (vs. Na⁺/Na). Impressively, a solid‐solution reaction without phase transitions is realized upon deep sodium (de)intercalation, which poses a minimal volume deviation of 0.53 %. It attains a high discharge capacity of 178 mAh g⁻¹, a high energy density of 534 Wh kg⁻¹, and excellent capacity retention of 95.8 % at 1 C after 250 cycles.

Deep sodium extraction/insertion of sodium cathodes usually causes undesired Jahn–Teller distortion and phase transition, both of which will reduce structural stability and lead to poor long‐cycle reliability. Here we report a zero‐strain P2‐ Na_2/3Li_1/6Co_1/6Mn_2/3O₂cathode, in which the lithium/cobalt substitution contributes to reinforcing the host structure by reducing the Mn³⁺/Mn⁴⁺redox, mitigating the Jahn–Teller distortion, and minimizing the lattice change. 94.5 % of Na⁺in the unit structure can be reversibly cycled with a charge cut‐off voltage of 4.5 V (vs. Na⁺/Na). Impressively, a solid‐solution reaction without phase transitions is realized upon deep sodium (de)intercalation, which poses a minimal volume deviation of 0.53 %. It attains a high discharge capacity of 178 mAh g⁻¹, a high energy density of 534 Wh kg⁻¹, and excellent capacity retention of 95.8 % at 1 C after 250 cycles.

Layered transition metal oxides are appealing cathodes for sodium‐ion batteries due to their overall advantages in energy density and cost. But their stabilities are usually compromised by the complicated phase transition and the oxygen redox, particularly when operating at high voltages, leading to poor structural stability and substantial capacity loss. Here an integrated strategy combing the high‐entropy design with the superlattice‐stabilization to extend the cycle life and enhance the rate capability of layered cathodes is reported. It is shown that the as‐prepared high‐entropy Na_2/3Li_1/6Fe_1/6Co_1/6Ni_1/6Mn_1/3O₂cathode enables a superlattice structure with Li/transition metal ordering and delivers excellent electrochemical performance that is not affected by the presence of phase transition and oxygen redox. It achieves a high reversible capacity (171.2 mAh g⁻¹at 0.1 C), a high energy density (531 Wh kg⁻¹), extended cycling stability (89.3% capacity retention at 1 C for 90 cycles and 63.7% capacity retention at 5 C after 300 cycles), and excellent fast‐charging capability (78 mAh g⁻¹at 10 C). This strategy would inspire more rational designs that can be leveraged to improve the reliability of layered cathodes for secondary‐ion batteries.

Aqueous zinc ion batteries are receiving unprecedented attention owing to their markedly high safety and sustainability, yet their lifespan particularly at high rates is largely limited by the poor reversibility of zinc metal anodes, due to the random ion diffusion and sluggish ion replenishment at the reaction interface. Here, a tunnel‐rich and corona‐poled ferroelectric polymer‐inorganic‐composite thin film coating for Zn metal anodes to tackle above problems, is proposed. It is demonstrated that the poled ferroelectric coating can better deconcentrate and self‐accelerate ion migration at coating/Zn interface during the electroplating process than untreated ferroelectric coating and bare Zn, thus enabling a compact and horizontally‐aligned Zn morphology even at ultrahigh rates. Notably, a maximal cumulative plating capacity of over 6500 mAh cm⁻²(at 10 mA cm⁻²) is achieved for the surface‐modified Zn metal anode, showing extraordinary reversibility of Zn plating/stripping. This work provides new insights in stabilizing Zn metal electrodeposition at the scale of interfacial ion diffusion.