Potassium-ion batteries (PIBs) have been receiving a great deal of attention owing to abundant and cost-effective potassium resources. However, the key issue is to explore suitable electrode materials for accommodating the large size K-ions reversibly. In this report, K_1.06Mn₈O₁₆/CNT hybrids are systematically studied for the first time as bifunctional PIBs-electrodes, in which Mn-ions play as the redox center. As the cathode, it exhibits excellent electrochemical kinetics and reversibility, as well as highly structure stability. The cathode displays an unprecedented capacity of 309.4 mA h g⁻¹ at 20 mA g⁻¹ with the energy density of 733.3 Wh kg⁻¹ and outstanding rate performance (187.1 mA h g⁻¹ at 500 mA g⁻¹). In addition, the high capacity of 636.6 mA h g⁻¹ at 20 mA g⁻¹, ultra-long cycling lifespan over 500 cycles and remarkable rate capability can also be acquired when the material was tested as the anode. The extraordinary electrochemical properties are ascribed to the well-developed conductive network and robust microstructure stability. Meanwhile, the symmetrical K-ions full cell exhibits high discharge capacity of 241.0 mA h g⁻¹ at 100 mA g⁻¹. This work reveals the K-ions storage mechanism in cryptomelane bifunctional electrodes in depth and the fundamental understanding help us open up a new direction for PIBs.

由于钾资源丰富且具有成本效益，钾离子电池（PIB）受到了广泛的关注。然而，关键问题是探索可逆地容纳大尺寸K离子的合适电​​极材料。在此报告中，首次系统地研究了K _1.06 Mn ₈ O ₁₆ / CNT杂化物作为双功能PIBs电极，其中Mn离子充当氧化还原中心。作为阴极，它具有出色的电化学动力学和可逆性，以及极高的结构稳定性。阴极在20 mA g ^-1下显示出前所未有的容量309.4 mA h g ^-1，能量密度为733.3 Wh kg ^-1和突出的倍率性能（187.1毫安ħ克^-1以500mA克^-1）。另外，当将该材料作为阳极进行测试时，还可以获得在20 mA g ^-1下的636.6 mA h g ^-1的高容量，超过500次循环的超长循环寿命以及显着的倍率能力。非凡的电化学性能归因于发达的导电网络和稳健的微观结构稳定性。同时，对称的K离子全电池在100 mA g ^-1时表现出241.0 mA h g ^-1的高放电容量。这项工作深入揭示了隐甲烷双功能电极中的K离子存储机理，基本的理解有助于我们为PIB开辟新的方向。