Element screening of metal sites in Fe-based Prussian blue framework materials for ammonium ion battery applications: a first-principles study

Abstract

Prussian blue framework materials are expected to be the next generation of electrode materials for commercial batteries because their three-dimensional framework structures facilitate the rapid transport and storage of ions and a variety of redox processes. This work compared the calculations of the model before and after the dispersion correction, and the model considering the effect of van der Waals force was more stable. In addition, the distances between H, C and N atoms were within the range of van der Waals force. Thus it was confirmed that NH₄⁺ was adsorbed on the A_x site in the Prussian blue framework material (A_xM_a[M_b(CN)₆]) by van der Waals interaction, and the charge transfer was mainly achieved by the interaction between the H atom in NH₄⁺ and the N atom in the Prussian blue framework. On this basis, the properties of NH₄⁺ batteries were theoretically screened for the Fe-based Prussian blue analogues (PBAs) with different M_a elements (M_a = Co, Cu, Fe, Mg, Mn, Ni, V or Zn). Considering the regulating effect of different metal elements on the electronic structures of PBAs, MgFe and ZnFe PBAs as the electrode materials of NH₄⁺ batteries are expected to show excellent electrochemical energy storage performance in organic electrolytes.