Polyanion compounds are considered as promising electrodes for potassium-ion batteries (PIBs) due to their structural diversity and chemical versatility. However, the cycling performance of previously reported electrodes at high current densities still suffers from their relatively sluggish electron and ion transport kinetics. Here, by combining K2Ti2(PO4)3 (KTP) framework with KTiOPO4 (KTOP) composition, we construct a series of KTP/KTOP/C heterojunctions (denoted as KTP/KTOP/C-n) via selectively phosphorylatiny from metal-organic framework (MOF) precuror, and demonstrate the successful synergistic cooperation of both electron and ion transport kinetics by carefully controlling the structure and composition. Comparative analysis and density functional theoretical calculations confirm the reaction kinetics and pseudocapacitive behaviors can be dramatically promoted by synergistically structural, electronic and ionic modulations. Consequently, the optimized KTP/KTOP/C-2 delivers an impressive specific capacity of 140 mAh/g after 150 cycles at 100 mA g−1 and superior cycling stability with 79 mAh/g for 2000 cycles at a high current of 1000 mA g−1. Furthermore, it displays outstanding rate performance, achieving 87 mAh/g at 2000 mA g−1.

中文翻译：

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MOF 的选择性磷酸化构建高性能钾离子电池的 KTP/KTOP/C 异质结


聚阴离子化合物因其结构多样性和化学多功能性而被认为是很有前途的钾离子电池 （PIB） 电极。然而，先前报道的电极在高电流密度下的循环性能仍然受到其相对缓慢的电子和离子传输动力学的影响。在这里，通过将 K2Ti2（PO4）3 （KTP） 框架与 KTiOPO4 （KTOP） 组成相结合，我们通过来自金属有机框架 （MOF） 的选择性磷酸化构建了一系列 KTP/KTOP/C 异质结 （表示为 KTP/KTOP/C-n），并通过仔细控制结构和组成证明了电子和离子传输动力学的成功协同合作。比较分析和密度泛函理论计算证实，反应动力学和伪电容行为可以通过协同结构、电子和离子调制来显着促进。因此，优化的 KTP/KTOP/C-2 在 100 mA g-1 下循环 150 次后可提供令人印象深刻的 140 mAh/g 比容量，并在 1000 mA g-1 的大电流下提供 79 mAh/g 的 2000 次循环稳定性。此外，它还具有出色的倍率性能，在 2000 mA g−1 时达到 87 mAh/g。