Theoretical Investigation of Janus ReSSe Monolayers Doped with Cu<i>_n</i> Metal Clusters (<i>n</i> = 1–3) for Detecting Gases from Thermal Runaway Decomposition in Lithium-Ion Batteries

Effective detection and timely resolution of internal faults in lithium-ion batteries (LIBs) are necessary prerequisites for the safe use of batteries. In this study, the adsorption properties of four lithium-ion battery thermal runaway characteristic gases (CO, CH₄, C₂H₂, and C₂H₄) on the surface of ReSSe monolayers modified with Cu<i>_n</i> (<i>n</i> = 1-3) clusters were systematically investigated based on first-principles calculations. The calculation results showed that the introduction of Cu₁, Cu₂, and Cu₃ reduced the bandgap of the ReSSe monolayer to 0.077, 0.399, and 0.170 eV, respectively, and significantly enhanced the gas sensing performance of ReSSe. By calculating and analyzing parameters such as deformation charge density (DCD), energy band structure, density of states, molecular orbitals, sensitivity, and recovery time during gas adsorption, it was revealed that the Cu₂-ReSSe system exhibited excellent adsorption capacity and sensing performance for C₂H₄. The adsorption energy and sensitivity reached -1.03 eV and 12.58, respectively. The recovery time of C₂H₄ on the Cu₂-ReSSe surface was 10.93 s under the temperature condition of 398 K, which indicates that this material can realize the repeated detection of C₂H₄ at suitable temperatures, and it is an up-and-coming candidate for a C₂H₄ gas sensor. This study provides theoretical support for the application of Cu metal-cluster-anchored ReSSe-based materials in the field of lithium-ion battery fault detection.