Dft-guided design of a synergistic interface in N-Ni₃S₄@NG for enhanced potassium-ion battery performance

The development of potassium-ion batteries (PIBs) is hampered by the lack of anode materials capable of withstanding the severe structural stresses and slow kinetics induced by the large K⁺ ion. This work presents a rationally designed anode developed through a synergistic density functional theory (DFT) and experimental approach. DFT screening identified nitrogen as the optimal dopant for a Ni₃S₄/graphene heterostructure, predicting a metallized electronic structure with a high density of states (DOS) at the Fermi level (E_F), a strong K⁺ adsorption energy of −2.58 eV, and a low diffusion barrier of 0.22 eV. Guided by these insights, the dual nitrogen-doped N-Ni₃S₄@NG heterostructure was synthesized. The material exhibited exceptional electrochemical performance, including a high reversible capacity of 480mAh g⁻¹ at 0.1 A g⁻¹, remarkable rate capability (180mAh g⁻¹ at 1 A g⁻¹), and unprecedented stability with 79.4 % capacity retention after 800 cycles. Crucially, electrochemical impedance spectroscopy confirmed vastly improved charge transfer kinetics, with a significantly reduced resistance of 10 Ω for the doped composite versus 24 Ω for its pristine counterpart. The direct correlation between computational predictions and experimental results validates a DFT-guided paradigm for engineering high-performance energy storage materials through precise electronic and interfacial control.