K-ion hybrid capacitors (KIHCs) have been attracted extensive attention. However, the large radius of K-ion impedes the exploration of electrode materials for KIHCs. Herein, we demonstrate a one-step calcination of mango seed shuck to prepare the natural N/O co-doped hard carbon (NOHC) as the excellent anode for KIHCs. The NOHC shows a capacity retention of 93.5% of initial reversible capacity (186.3 mA h g⁻¹) after 500 cycles at 0.1 A g⁻¹ with a superior rate performance (103 mA h g⁻¹ at 2 A g⁻¹). Further, the K-ion intercalation mechanism and the stable solid electrolyte interphase layer are revealed by ex-situ X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) techniques, clarifying the excellent electrochemical performance of the NOHC anode for KIHCs. Consequently, the fabricated KIHCs by NOHC anode and activated carbon cathode deliver acceptable energy and power densities (68 W h kg⁻¹ and 2000 W kg⁻¹) as well as long cycling stability with a retention of 80% over 1000 cycles at 1 A g⁻¹. This study offers the practical preparation of natural NOHC by a low-cost mass production route, which would advance the biomass application and energy materials preparation for practical KIHCs and beyond.

K离子混合电容器（KIHC）已引起广泛关注。但是，K离子的大半径阻碍了KIHCs电极材料的探索。在这里，我们演示了芒果种子去壳的一步煅烧，以制备天然N / O共掺杂硬碳（NOHC）作为KIHC的极好阳极。所述NOHC节目的初始可逆容量为93.5％的容量保持率（186.3毫安ħ 克^-1）500次循环后在0.1 A 克^-1具有优异的倍率性能（103毫安ħ克^-1以2A克^-1）。此外，通过非原位X射线光电子能谱（XPS）和透射电子显微镜（TEM）技术揭示了K离子嵌入机理和稳定的固体电解质中间相层，从而阐明了NOHC阳极用于KIHC的优异的电化学性能。因此，由NOHC阳极和活性炭阴极制造的KIHC可以提供可接受的能量和功率密度（68 W h kg ^-1和2000 W kg ^-1）以及长循环稳定性，在1 A下1000次循环中保持80％ g ^-1。这项研究通过低成本的大规模生产途径提供了天然NOHC的实际制备方法，这将促进实际KIHC的生物质应用和能源材料制备及其他应用。