A universal approach for predicting electrolyte decomposition in carbon materials: On the basis of thermodynamics

Abstract

A new methodology based on thermodynamic theorem is introduced and tested here to describe electrochemical side reactions of nonaqueous-based electrolytes in energy storage devices. The reactions are most likely to be triggered by carbon materials that contains active sites including metal atoms and crystalline defects. As an example, decomposition reactions of a widely-used solvent for nonaqueous electrolytes, propylene carbonate (PC), are discussed in detail. Mechanisms and equilibrated electrode potentials of PC decomposition are predicted by generalized computational hydrogen electrode approach, which agrees well with experimental results. Li, Na, K, Mg, Ca, Ti, Cr, Fe, Ni, Mo atoms tethered by single and double vacancy defects are found hazardous in energy storage devices including alkali metal ion batteries and electrochemical capacitors, for they can make PC decompose within the electrode potential window of these devices. Differences in key electronic and thermodynamic properties of studied metal elements are proposed as reactivity descriptors. Dominating contributions to reactivity of metal atoms are unveiled by data engineering. The methodology raised in this work provides broad impact for theoretically predicting side reactions in energy storage devices, and proves the accuracy of generalized computational approach in nonaqueous-based energy storage systems.