A Comparative Study of Prussian Blue Analogues as Cathode Materials for Monovalent Lithium/Sodium/Potassium Ion Batteries by First-Principles Calculations

Prussian blue analogues (PBAs) demonstrate exceptional promise due to their 3D diffusion channels and multiple redox-active sites. However, as cathode materials for monovalent ion batteries, there are some issues that remain unclear. We conduct a comparative study of the PBAs MFe(CN) 6 (M = Fe, Co, and Mn) for lithium/sodium/potassium ion batteries (LIBs/SIBs/PIBs) by first-principles calculations. We identify the structure evolution and electrochemical characteristics of A x MFe(CN) 6 for LIBs/SIBs/PIBs during the charging process. Based on the electrochemical performance and diffusion barrier of cations, MFe(CN) 6 is more suitable as a cathode material for SIBs compared with LIBs and PIBs. What’s more, the electronic state and the spin-only magnetic moment reveal that the redox sequences of corresponding transition metals are consistent in LIBs, SIBs, and PIBs. In particular, the CoFe(CN) 6 system shows a change in the ground state spin configuration from high-spin to low-spin in the charging process. This work establishes an important theoretical foundation for the design of advanced cathode materials.