A deep insight into the adsorption mechanisms of lithium-ion battery thermal runaway gases onto Cu-decorated hBN for gas sensing applications using DFT

Abstract

Lithium-ion batteries, due to their environmental friendliness and high energy capacity, are extensively used in the field of transportation and energy storage. However, the problem of thermal runaway in lithium-ion batteries has become a serious threat to humans. Therefore, considering these issues, we have investigated the adsorption mechanism of thermal runaway gases (C₂H₄, CO, CO₂, H₂, and CH₄) onto pristine hBN and Cu-doped hBN using Density Functional Theory (DFT). The adsorption of C₂H₄, CO, CO₂, H₂, and CH₄ gas molecules on pristine hBN occurs via physisorption, resulting in poor recovery time, charge transfer, selectivity and sensitivity. However, substitutional doping of Cu atoms at the B vacancies causes thermal runaway gases to be adsorbed chemically. DOS calculations showed that the adsorption of C₂H₄, CO, CO₂, H₂, and CH₄ gas molecules reduces the band gap of Cu doped hBN, indicating the chemoresistive behaviour of Cu-doped hBN. Furthermore, various other calculations, such as charge density differences, showed that C₂H₄, CH₄, CO, CO₂ and H₂ gases act as electron donors and Cu-doped hBN acts as an electron acceptor, whereas RDG calculations confirmed that weak vdW and strong attractive non-covalent interactions exist in the case of pristine hBN and Cu-doped hBN, respectively. Finally, our DFT results confirmed that Cu-doped hBN exhibits enhanced sensitivity and recovery time towards thermal runaway gases, thereby making Cu-doped hBN a potential candidate for use as a sensing material in gas sensors to detect thermal runaway gases.