In recent years, potassium-ion batteries (KIBs) have emerged as a promising alternative candidate to replace lithium-ion batteries for large-scale energy storage devices owing to the natural abundance of potassium and similar mechanism as lithium-ion batteries. In particular, transition metal oxide cathode materials have attracted growing attention due to their high theoretical capacities and low cost compared with other cathode materials. Nevertheless, due to the larger ionic radius of K-ions, transition metal oxide cathode materials suffer from irreversible structural evolution and interlayer-gliding of transition metal layers in potassiation/depotassiation, which results in sluggish kinetics and structural instability. This limited capacity and unsatisfactory cycling properties inhibit the practical application of potassium-ion batteries. It still remains a challenge to develop the suitable cathode materials for potassium-ion batteries. In this work, the interlayer-gliding and irreversible P3–O3 structure transition were suppressed via the replacement of cobalt and iron, and the doping mechanism was investigated by in situ x-ray diffraction. The incorporation of Co ions and Fe ions enlarges the d-space between the transition metal layers, reduces the resistance of K⁺ migration, and provides the buffer spaces to suppress the interlayer-gliding and P3–O3 phase transformation in electrochemical potassium-ion storage, leading to an enhanced rate capability (58 mA h g⁻¹ at 1 A g⁻¹) and superior cycling stability (71% after 300 cycles at 200 mA g⁻¹). This strategy provides a better understanding for the effect of Co–Fe substitution in suppressing interlayer-gliding and improving electrochemical properties for the development of a novel cathode material for potassium-ion batteries.

中文翻译：

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抑制层状 P3 型 K0.5Mn0.7Co0.2Fe0.1O2 阴极材料在电化学钾离子存储中的层间滑移

近年来，由于钾的天然丰度和与锂离子电池相似的机制，钾离子电池（KIB）已成为替代锂离子电池用于大型储能设备的有前途的替代品。尤其是过渡金属氧化物正极材料由于与其他正极材料相比具有较高的理论容量和较低的成本而受到越来越多的关注。然而，由于钾离子的离子半径较大，过渡金属氧化物正极材料在钾化/脱钾过程中存在不可逆的结构演化和过渡金属层的层间滑动，导致动力学缓慢和结构不稳定。这种有限的容量和不令人满意的循环性能阻碍了钾离子电池的实际应用。开发合适的钾离子电池正极材料仍然是一个挑战。在这项工作中，通过取代钴和铁来抑制层间滑动和不可逆的 P3-O3 结构转变，并研究了掺杂机制原位X 射线衍射。Co离子和Fe离子的掺入扩大了过渡金属层之间的d-空间，降低了K ⁺迁移的阻力，并为抑制电化学钾离子存储中的层间滑移和P3-O3相变提供了缓冲空间，从而导致增强的速率能力（58毫安汞柱^-1 1 A G ^-1）和优异的循环稳定性（在200mA克300次循环后71％^-1）。该策略为开发新型钾离子电池正极材料提供了对 Co-Fe 替代抑制层间滑动和改善电化学性能的影响的更好理解。