Metal–organic cathode compounds with low solubility and more viable eco-efficient production still suffer from relatively low voltage and limited discharge capacity because their redox reactions solely rely on active organic functional groups or metal clusters. Here, a metal–organic compound Cu₂(p-O₂NC₆H₄CO₂)₄(EtO)₂ was demonstrated to have high capacity of 243 mA h g^–1 and high-voltage plateaus of 3.66, 3.15, 2.25, and 2.08 V vs Li⁺/Li through first-principles calculations. Electronic structure analysis reveals Cu²⁺ ↔ Cu^x+ (1 < x < 2) and O^y– (1 < y < 2) ↔ O^2– in a metal–ligand moiety and N⁵⁺ ↔ N^x+ (4 < x < 5) and O^2– ↔ O^z– (1 < z < 2) in −NO₂ groups, achieving high voltage and capacity by operating cooperative cationic–anionic redox reactions based on multiple active sites and hierarchical chemical bonds. Furthermore, the Cu₂(p-O₂NC₆H₄CO₂)₄(EtO)₂ is also predicted to have good electrochemical reversibility because the cationic conversion reaction is inhibited by a higher-voltage anionic reaction and hierarchical chemical bonds of [MO₅]ⁿ⁻. The present study provides a strategy to design metal–organic cathode compounds with high performance.

中文翻译：

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金属有机化合物中多个活性位和多级化学键对提高阴极性能的协同作用

具有较低溶解度和更可行的生态效率生产的金属有机阴极化合物仍遭受相对较低的电压和有限的放电容量，因为它们的氧化还原反应仅依赖于活性有机官能团或金属簇。在这里，金属有机化合物Cu ₂（p -O ₂ NC ₆ H ₄ CO ₂）₄（EtO）₂被证明具有243 mA hg ^–1的高容量和3.66、3.15、2.25的高压平稳性，通过第一性原理计算得出2.08 V vs Li ⁺ / Li。电子结构分析显示Cu 2 ⁺ ↔Cu ^{x +}（1 < x <2）和O ^{y –}（1 < y <2）↔O ^2–在金属-配体部分中以及N ⁵⁺ ↔N ^{x +}（4 < x <5）和O ^2– ↔O ^{z –} -NO ₂基团中的（1 < z <2），通过基于多个活性位和分级化学键的阳离子-阴离子协同氧化还原反应来实现高电压和高容量。此外，Cu ₂（p -O ₂ NC ₆ H ₄ CO ₂）₄（EtO）₂也被预测为具有良好的电化学可逆性，因为阳离子转化反应是由更高电压阴离子反应和[MO的分层化学键抑制₅ ] ^{ñ -} 。本研究提供了设计高性能金属有机阴极化合物的策略。