With the rapid development of flexible electronics, low-cost, flexible, high-energy-density power sources are urgently needed. Theoretically, the emerging rechargeable potassium-ion batteries (KIBs) could be a promising candidate due to the abundance and low cost of potassium resources. However, owing to the absence of high-performance cathode materials and effective methods to fabricate robust and soft electrodes, producing flexible KIBs remains a daunting challenge. Herein, cyanotype is successfully employed as a photographic printing technique for the fabrication of a low-cost, scalable, and flexible cathode. The combined advantages of optimized crystallinity and morphology of the cathode materials as well as the ultralight and robust nature of the flexible electrode endow the KIB with superior performance including high energy density (up to 232 Wh kg⁻¹) and excellent flexibility. This low-cost and scalable photographic printing technique as well as the promising electrochemical results will promote the development of flexible electronics.

随着柔性电子器件的快速发展，迫切需要低成本，柔性，高能量密度的电源。从理论上讲，由于钾资源的丰富和低成本，新兴的可再充电钾离子电池（KIB）可能是有前途的候选者。然而，由于缺乏高性能的阴极材料和有效的方法来制造坚固而柔软的电极，生产柔性KIB仍然是一项艰巨的挑战。在此，氰基型被成功地用作照相印刷技术，以制造低成本，可缩放和柔性的阴极。^-1）和出色的柔韧性。这种低成本和可扩展的照相打印技术以及有希望的电化学结果将促进柔性电子学的发展。