Differently Modified ZnO Monolayers as Key Gas Sensors for Lithium-Ion Thermal Runaway: A DFT Study

Area of Science:

• Materials Science
• Computational Chemistry
• Chemical Engineering

Background:

• Lithium-ion batteries (LIBs) pose fire risks due to thermal runaway, releasing toxic gases like acetylene (C₂H₂), ethylene (C₂H₄), methane (CH₄), and hydrogen (H₂).
• Rapid and reliable detection of these gases is crucial for safety and early warning systems.

Purpose of the Study:

• To investigate the adsorption behavior of toxic gases on modified zinc oxide (ZnO) using first-principles calculations.
• To evaluate the potential of transition metal-doped ZnO as a gas-sensing material for detecting gases released during LIB thermal runaway.

Main Methods:

• First-principles calculations were employed to study surface doping (TM-ZnO) and defect doping with Zn vacancies (TM_D-ZnO) using transition metals (Ir, Os, W, Pt).
• Adsorption properties of C₂H₂, C₂H₄, CH₄, and H₂ on the doped ZnO structures were calculated.
• Sensing properties, including bandgap changes and recovery times, were evaluated.

Main Results:

• Defect-doped structures (TM_D-ZnO) exhibited greater geometric stability.
• Chemical adsorption of C₂H₂ and C₂H₄ was observed, with the TM-ZnO system showing stronger adsorption performance.
• The W-ZnO/H₂ system demonstrated strong chemical adsorption with an adsorption energy (E_ad) of -0.82 eV.
• Specific doped ZnO systems showed significant bandgap changes and rapid recovery times, indicating potential for reusable gas sensing.

Conclusions:

• Metal-modified ZnO, particularly W-ZnO/H₂, Ir_D-ZnO/CH₄, and Ir_D-ZnO/H₂, shows potential as a reusable gas-sensing element for detecting harmful gases like methane and hydrogen.
• This research highlights metal-doped ZnO as a promising material for developing effective harmful gas monitoring systems.