Tailoring Nitrogen Species in Disk-Like Carbon Anode Towards Superior Potassium Ion Storage

Carbon materials, as promising anode candidates for K⁺ storage due to their low cost, abundant sources, and high physicochemical stability, however, encounter limited specific capacity and unfavorable cycling stability that seriously hinder their practical applications. Herein, a feasible strategy to tailor and stabilize the nitrogen species in unique P/N co-doped disk-like carbon through the Sn incorporation (P/N_Sn -CD) is presented, which can largely enhance the specific capacity and cycling capability for K⁺ storage. Specifically, it delivers a high specific capacity of 439.3 mAh g^-1 at 0.1 A g^-1 and ultra-stable cycling capability with a capacity retention of 93.5% at 5000 mA g^-1 over 5000 cycles for K⁺ storage. The underlying mechanism for the superior K⁺ storage performance is investigated by systematical experimental data combined with theoretical simulation results, which can be derived from the increased edge-nitrogen species, improved content and stability of P/N heteroatoms, and enhanced ionic/electronic kinetics. After coupling P/N_Sn -CD anode with activated carbon cathode, the KIHCs can deliver a high energy density of 171.7 Wh kg^-1 at 106.8 W kg^-1 , a superior power density (14027.0 W kg^-1 with 31.2 Wh kg^-1 retained), and ultra-stable lifespan (89.7% retention after 30 K cycles with cycled at 2 A g^-1 ).