Amorphous Nitride‐chloride Solid‐State Electrolytes for High Performance All‐Solid‐State Lithium Batteries

High-performance solid-state electrolytes (SSEs) are crucial for advancing all-solid-state batteries (ASSBs). Amorphous SSEs, in particular, offer promising advantages due to their grain-boundary-free nature, which facilitates intimate solid-to-solid contact and uniform lithium-ion flux, thereby improving composite electrode performance. Here, we report a class of SSEs based on a nitrogen-chlorine dual-anion framework, formulated as Li_{3 x +0.1}ZrN_xCl_4.1, for high-voltage ASSBs. Unlike widely studied crystalline Li₂ZrCl₆ with a triclinic structure, increased N^3- substitution drives a structural transition to an amorphous phase (Li_1.3ZrN_0.4Cl_4.1), which achieves a significant enhancement in Li⁺ conductivity from 0.46 to 3.01 mS cm^-1, alongside improved oxidative stability up to 4.8 V. This dual-anion SSEs exhibits excellent compatibility with high-energy LiNi_0.83Co_0.06Mn_0.11O₂ (NCM83) cathodes. The corresponding full cells deliver a high reversible capacity of 200.1 mAh g^-1 at 4.5 V with outstanding capacity retention of 95.1% after 150 cycles at 0.2 C, along with remarkable long-term cycling stability exceeding 3000 cycles at 3 C. Furthermore, the electrochemical stability of Li_1.3ZrN_0.4Cl_4.1 in conjunction with NCM83 is still preserved under elevated temperatures (50 °C) and higher cut-off voltages (up to 4.8 V). These results highlight the promise of dual-anion amorphous electrolytes, paving the way for the design of next-generation SSEs beyond traditional single-anion systems.