Rechargeable solid-state sodium-ion batteries (SSSBs) hold great promise for safer and more energy-dense energy storage. However, the poor electrochemical stability between current sulfide-based solid electrolytes and high-voltage oxide cathodes has limited their long-term cycling performance and practicality. Here, we report the discovery of Na_3-xY_1-xZr_xCl₆ (NYZC) as an ion conductor that is both electrochemically stable (up to 3.8 V vs. Na/Na⁺) and chemically compatible with oxide cathodes. Its high ionic conductivity of 6.6 x 10^-5 S cm^-1 at ambient temperature, several orders of magnitude higher than oxide coatings, is attributed to abundant Na vacancies and cooperative MCl₆ rotation, resulting in an extremely low interfacial impedance. A SSSB comprising a NaCrO₂+NYZC composite cathode, Na₃PS₄ electrolyte, and Na-Sn anode exhibits an exceptional first-cycle Coulombic efficiency of 97.1% at room temperature and can cycle over 1000 cycles with 89.3% capacity retention at 40°C. These findings highlight the immense potential of halide ion conductors for SSSB applications.

可充电固态钠离子电池（SSSB）有望带来更安全，更密集的能量存储。然而，当前基于硫化物的固体电解质和高压氧化物阴极之间的差的电化学稳定性限制了它们的长期循环性能和实用性。在这里，我们报告了Na _{3- x} Y _{1- x} Zr _x Cl ₆ （NYZC）作为离子导体的发现，该离子导体在电化学上是稳定的（相对于Na / Na ⁺高达3.8 V ），并且与氧化物阴极化学相容。高离子电导率6.6 x 10 ^-5 S cm ^-1 在环境温度下，由于大量的Na空位和MCl _6的协同旋转，导致比氧化物涂层高几个数量级，从而导致极低的界面阻抗。包含NaCrO ₂ + NYZC复合阴极，Na ₃ PS ₄电解质和Na-Sn阳极的SSSB在室温下具有97.1％的出色的第一循环库仑效率，并且可以在1000次循环中循环，并在40°时保持89.3％的容量C。这些发现凸显了卤代离子导体在SSSB应用中的巨大潜力。