Severe structural evolution and high content of [Fe(CN)₆]^4– defects drastically deteriorate K-ion storage performances of Prussian blue-based cathodes. Herein, a potassium manganese iron copper hexacyanoferrate (KFe_2/3Mn_1/6Cu_1/6HCF), with suppressed anionic vacancies, eliminated band gap, and low K-ion diffusion barrier, is regarded as a cathode for potassium-ion batteries. The entropy stabilization effect and robust Cu–N bond induced by the inert Cu-ion with large electronegativity boost KFe_2/3Mn_1/6Cu_1/6HCF to exhibit great phase state stability, thus inhibiting the structural transition of monoclinic ↔ cubic. Hence, KFe_2/3Mn_1/6Cu_1/6HCF undergoes a zero-stress solid-solution reaction mechanism, where Fe and Mn serve as dual active sites for charge compensation. Consequently, KFe_2/3Mn_1/6Cu_1/6HCF displays a high reversible capacity of 127.5 mAh·g^–1 with an energy density of 469.2 Wh·kg^–1 at 10 mA·g^–1 and superior cyclic stability with a high retention of 90.7% over 100 cycles. A high-energy-density K-ion full battery is assembled, contributing an ultralong lifetime over 1000 cycles with a low-capacity fading rate of 0.038% per cycle.

中文翻译：

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钾离子电池中抑制相析的普鲁士蓝模拟阴极的熵和电子结构调制


严重的结构演变和高含量的 [Fe（CN）₆]^4– 缺陷急剧恶化了普鲁士蓝基阴极的 K 离子存储性能。在此，钾锰铁铜六氰基铁酸盐 （KFe_2/3Mn_1/6Cu_1/6HCF） 具有抑制阴离子空位、消除带隙和低 K 离子扩散势垒，被认为是钾离子电池的阴极。具有大电负性的惰性 Cu 离子诱导的熵稳定效应和强大的 Cu-N 键使 KFe_2/3Mn_1/6Cu_1/6HCF 表现出很好的相态稳定性，从而抑制了单斜↔立方的结构转变。因此，KFe_2/3Mn_1/6Cu_1/6HCF 发生零应力固溶反应机制，其中 Fe 和 Mn 作为电荷补偿的双活性位点。因此，KFe_2/3Mn_1/6Cu_1/6HCF 在 10 mA·g^–1 时表现出 127.5 mAh·g^–1 的高可逆容量，能量密度为 469.2 Wh·kg^–1，具有优异的循环稳定性，在 100 次循环中保留率高达 90.7%。组装高能量密度 K-ion 满电池，可在 1000 次循环中实现超长使用寿命，每次循环 0.038% 的低容量衰减率。