Ethylene Carbonate Adsorption and Decomposition on Pristine and Defective ZnO (1010) Surface: A First-Principles Study

TL;DR

This study uses first-principles DFT calculations to analyze how ethylene carbonate interacts with and decomposes on pristine and defective ZnO (1010) surfaces, revealing thermodynamic favorability but kinetic barriers to decomposition.

Contribution

It provides a detailed first-principles analysis of EC adsorption and decomposition pathways on ZnO surfaces, including defective sites, highlighting kinetic barriers that hinder decomposition.

Findings

EC prefers to adsorb via its carbonyl oxygen on Zn sites.

EC shows a strong thermodynamic tendency to decompose on ZnO surfaces.

High activation barriers slow down EC decomposition despite thermodynamic favorability.

Abstract

Fundamental understanding of the reactivity between coating material of Li-ion battery cathode and electrolyte is important in order to obtain suitable coating candidates. Herein, we study ethylene carbonate (EC) adsorption and decomposition reactions on pristine, O vacancy- and Zn vacancy-defected ZnO (10-10) by means of first-principles density functional theory (DFT) calculations. Possible decomposition pathways via H-abstraction and EC ring-opening reaction that leads to the generation of CO2 and C2H4 gases are studied from the thermodynamic and kinetic aspects. Firstly, we find that molecular EC preferably adsorbs on both pristine and defective ZnO (1010) via the bonding between its carbonyl oxygen (OC) and surface Zn. Secondly, subsequent decomposition reactions show large tendency of EC to decompose on both pristine and defective ZnO (10-10). This tendency is indicated by the large thermodynamic driving forces to decompose EC that range from -1.5 eV to -2.5 eV on both pristine and defective ZnO (10-10) (calculated with respect to EC gas phase). The large tendency of EC to decompose, however, is hindered by the high activation barriers of the EC decomposition, shown by the lowest activation barrier of 0.96 eV on Zn vacancy defected ZnO (10-10). Our results thus indicate that EC decomposition on ZnO (10-10) is mainly hindered due to its slow rate of decomposition instead of the thermodynamic factors.