Molecular modeling of organic redox‐active battery materials

Abstract

Organic redox‐active battery materials are an emerging alternative to their inorganic counterparts currently used in the commercialized battery technologies. The main advantages of organic batteries are the potential for low‐cost manufacturing, tunability of electrochemical properties through molecular engineering, and their environmental sustainability. The search for organic electroactive materials that could be used for energy storage in mobile and stationary applications is an active area of research. Computer simulations are used extensively to improve the understanding of the fundamental processes in the existing materials and to accelerate the discovery of new materials with improved performance. We will focus on two main types of redox‐active organic battery materials, that is, solid‐state organic electrode materials and organic electrolytes for redox flow batteries. Because organic materials are made of molecular building blocks, the molecular modeling methodology is usually the most appropriate to investigate their properties at the electronic and atomistic scales. After introducing the fundamentals of computational organic electrochemistry, we will survey its most recent applications in organic battery research and outline some of the remaining challenges for the development and applications of atomic‐scale modeling techniques in the organic battery context. This article is categorized under: Structure and Mechanism > Computational Materials Science Software > Molecular Modeling Electronic Structure Theory > Density Functional Theory

From absolute potentials to a generalized computational standard hydrogen electrode for aqueous and non-aqueous solvents

“…The prediction of redox potentials using quantum-chemical calculations is central for understanding mechanisms and developing materials for electro-synthesis, 1,2 energy storage [3][4][5][6][7][8] and energy conversion. [9][10][11][12][13][14][15][16] Experimentally, these reactions are typically performed in water but non-aqueous solvents and ionic liquids are also far from uncommon.…”

A Computational Protocol Combining DFT and Cheminformatics for Prediction of pH-Dependent Redox Potentials

“…Its pH dependence is especially important in aqueous RFBs, where the pH affects the molecules’ solubility and electrochemical behavior and can even be exploited to increase the voltage [ 15 ]. The main theoretical concepts and the most commonly used computational methods for modeling organic redox materials have recently been summarized by the present authors in a review article [ 16 ]. Here, we will not repeat those general concepts and focus instead on how different methods and details of the procedure affect the agreement with experimental data.…”

A Computational Protocol Combining DFT and Cheminformatics for Prediction of pH-Dependent Redox Potentials

“…14 The main theoretical concepts and the most commonly used computational methods for modeling organic redox materials have recently been summarized by the present authors in a review article. 15 Here, we will not repeat those general concepts and focus instead on how different methods and details of the procedure affect the agreement with experimental data. We will use notation consistent with ref.…”

“…We will use notation consistent with ref. 15 throughout this article. The experimental redox potentials at pH 0, 7, and 13 reported by Wedege et al 16 for a set of molecules of the quinone family have been chosen as a consistent data set for validating our computational protocol.…”

“…Such multiple anions can be challenging for the convergence of electronic structure methods since the additional electrons may not be sufficiently stabilized. 15 Moreover, the accuracy of implicit solvation models is known to deteriorate when increasing the charge of the solute. 18 For these reasons it is preferable to compute the redox potential at pH=0 and then transform it to higher pH values 19,20 using expressions based on the Nernst equation such as eq.…”