The fast development of flexible and wearable electronics increases the demand for flexible secondary batteries, and the emerging high-performance K-ion batteries (KIBs) have shown immense promise for the flexible electronics due to the abundant and cost-effective potassium resources. However, the implementation of flexible cathodes for KIBs is hampered by the critical issues of low capacity, rapid capacity decay with cycles, and limited initial Coulombic efficiency. To address these pressing issues, a freestanding K-rich iron hexacyanoferrate/carbon cloth (KFeHCF/CC) electrode is designed and fabricated by cathodic deposition. This innovative binder-free and self-supporting KFeHCF/CC electrode not only provides continuous conductive channels for electrons, but also accelerates the diffusion of potassium ions through the active electrode–electrolyte interface. Moreover, the nanosized potassium iron hexacyanoferrate particles limit particle fracture and pulverization to preserve the structure and stability during cycling. As a result, the K-rich KFeHCF/CC electrode shows a reversible discharging capacity of 110.1 mAh g⁻¹ at 50 mA g⁻¹ after 100 cycles in conjunction with capacity retention of 92.3% after 1000 cycles at 500 mA g⁻¹. To demonstrate the commercial feasibility, a flexible tubular KIB is assembled with the K-rich KFeHCF/CC electrode, and excellent flexibility, capacity, and stability are observed.

中文翻译：

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用于柔性和可穿戴钾离子电池的富钾六氰基铁酸铁/碳布电极

柔性和可穿戴电子产品的快速发展增加了对柔性二次电池的需求，而新兴的高性能钾离子电池（KIB）由于丰富且具有成本效益的钾资源而在柔性电子产品中显示出巨大的前景。然而，KIB 柔性阴极的实施受到容量低、循环容量快速衰减以及初始库仑效率有限等关键问题的阻碍。为了解决这些紧迫问题，通过阴极沉积设计和制造了独立式富钾六氰基铁酸铁/碳布（KFeHCF/CC）电极。这种创新的无粘合剂、自支撑 KFeHCF/CC 电极不仅为电子提供连续的导电通道，而且还加速钾离子通过活性电极-电解质界面的扩散。此外，纳米级六氰基铁酸钾铁颗粒限制颗粒破裂和粉碎，以在循环过程中保持结构和稳定性。结果，富K的KFeHCF/CC电极在100次循环后在50mA g ^{-1下表现出110.1mAh g -1}的可逆放电容量，并且在500 mA g ^-1下1000次循环后容量保持率为92.3% 。为了证明商业可行性，将柔性管状 KIB 与富钾 KFeHCF/CC 电极组装在一起，并观察到优异的柔性、容量和稳定性。