Interfacial impedance model and ion diffusion mechanism of MXene/NiCo-LDHs interstratification hybrid assembly electrode

In previous studies, our research team found that the two-dimensional interstratification assembly electrode has the advantage of high energy density. However, the impedance mechanism model and interface ion diffusion law under different interstratification assembly methods are not clear. Here, we used two-dimensional MXene and NiCo-LDHs as raw materials, and prepared 1:3, 1:1 and 3:1 interstratification assembled MXene/NiCo-LDHs composite electrodes by the substrate surface direct spray method, respectively. The impedance analysis was carried out by electrochemical impedance spectroscopy (EIS), respectively, and the diffusion coefficients of OH- ions in three models were measured and calculated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT). Studies have shown that for 2D interstratification assembled electrodes, when the pseudocapacitive layer is closer to the electrolyte (when MXene:NiCo-LDHs = 1:3), the interface impedance is the smallest (Rct = 56.5 Ω), the ion diffusion efficiency is the fastest (DOH- (M1L3) = 7.5706 × 10-15 cm2 s-1), and the electrochemical performance is the best, which provides important guidance for the design of two-dimensional interstratification assembled electrodes.