Al3+-doped Fe3Se4 anchored on MXene: A novel composite anode for high-capacity and stable potassium-ion batteries

Abstract

Potassium-ion batteries (PIBs) have emerged as a promising alternative to lithium-ion batteries due to the abundant availability of potassium resources and cost-effectiveness, yet their practical application remains hindered by anode material challenges such as substantial volume expansion, sluggish kinetics, and poor cycling stability. This study addresses these limitations through a synergistic design combining Al³⁺ doping with MXene substrate engineering, resulting in a novel Al-Fe₃Se₄/MXene composite anode. The hierarchical urchin-like Al-Fe₃Se₄ nanostructure was synthesized via a solvothermal method and subsequently anchored on a two-dimensional V₂C MXene matrix. Comprehensive characterization (XRD, XPS, SEM/TEM) confirmed successful Al³⁺-doping-induced crystal structure modulation and effective MXene integration. Electrochemical evaluations demonstrated superior performance with a high reversible capacity of 386.9 mAh g⁻¹ at 0.1 A g⁻¹ and 73.1 % capacity retention after 200 cycles, the electrochemical performance is significantly superior to that of Fe₃Se₄ materials comparable. Mechanism analysis revealed that Al³⁺ doping enhances structural stability while the MXene conductive network facilitates charge transfer kinetics. This work innovatively employs a dual modification strategy that synergistically combines cation doping and conductive substrate engineering, providing valuable insights for developing high-performance PIB anodes. The proposed method offers a novel approach to the design of electrode materials, which holds significant practical implications for the development of next-generation energy storage systems.