Properties and structural arrangements of the electrode material CuDEPP during energy storage

Abstract

Devices for electrical energy storage need to provide high energy yields and output power, guaranteeing at the same time safety, low costs, and long operation times. The porphyrin CuDEPP [5,15‐bis(ethynyl)‐10,20‐diphenylporphinato] copper(II) is a promising electrode material for various battery systems both as anode and cathode. While its functionality has been demonstrated experimentally, there is no atomistic information as to why CuDEPP expresses these interesting properties or how the incorporation of ions affects its structure so far. To answer these questions, CuDEPP is investigated using density functional theory (DFT). Starting with the smallest possible unit (i.e., a single molecule), the spatial dimensionality of the structure is successively increased by studying: 1) di‐ and trimers, 2) molecular stacking in a 1D chain, 3) extending these chains to planar CuDEPP sheets, and finally 4) a three‐dimensionally extended polymer structure. Having thoroughly investigated the isolated properties of the CuDEPP material itself, afterward the insertion (or intercalation) of different ions (including Li, Mg, and Na) is studied, to understand the energetics, diffusion barriers, and structural changes (e.g., volume expansion) within the CuDEPP host material.