Exploring highly reactive anode materials is crucial for further development of potassium ion batteries (PIBs). Conversion-type materials have the merit of high energy density as anode for PIBs, while suffering from inferior stability and poor rate capability. Herein, we propose to utilize iron carbodiimide (FeNCN) as the anode for PIBs to achieve stable and high-rate potassium storage performance for the first time. The smaller electronegativity and strong covalent bonding structure of FeNCN facilitate improving the charge transfer kinetics of battery systems. Consequently, the FeNCN anode deliver a high reversible capacity (515 mAh/g at 50 mA g⁻¹) and remarkable long-life span over 350 cycles with capacity retention of 90 % (133 days, current density 100 mA g⁻¹). Moreover, the mechanism for potassium ion storage of FeNCN was revealed by in-situ XRD, ex-situ XPS, and FT-IR. The feasibility of FeNCN as an anode for PIBs paves the way for transition metal (Cr, Mn, Fe, and Co) carbodiimides to be investigated as potential energy storage materials.

探索高活性负极材料对于钾离子电池 (PIB) 的进一步发展至关重要。转换型材料作为 PIBs 的负极具有能量密度高的优点，但稳定性较差，倍率性能较差。在此，我们建议利用碳化二亚胺铁（FeNCN）作为 PIBs 的阳极，首次实现稳定和高速率的钾存储性能。FeNCN较小的电负性和强共价键结构有助于改善电池系统的电荷转移动力学。因此，FeNCN 负极具有高可逆容量（50 mA g ^-1时为 515 mAh/g ）和超过 350 次循环的显着长寿命，容量保持率为 90%（133 天，电流密度 100 mA g ^-1）。此外，通过原位 XRD、非原位 XPS 和 FT-IR 揭示了 FeNCN 的钾离子储存机制。FeNCN 作为 PIBs 阳极的可行性为过渡金属（Cr、Mn、Fe 和 Co）碳二亚胺作为潜在的储能材料的研究铺平了道路。