Instead, it is more correct to speak of potential of electrolyte reduction at negative potentials, and of potential of solvent oxidation at positive potentials. In this opinion we provide a correct thermodynamic representation for the electrochemical stability of the electrolyte, based on redox potentials and Fermi level of the electron in solution, and demonstrate that the use of terms HOMO and LUMO should be avoided when talking about the electrochemical stability of electrolytes. Presence of electrolytes and other molecules can also significantly affect the redox potentials of the solvent leading to offset as high as 4 eV from the HOMO energies. In addition, natural bond orbital (NBO) analysis, intramolecular charge transfer (ICT) mechanism, electronic charge density analysis, highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), and vertical energy transitions are studied with time-independent and time-dependent level density functional theory. The term HOMO stands for highest occupied molecular orbital while the term LUMO stands for lowest unoccupied molecular orbital. The terms HOMO and LUMO are under the subtopic molecular orbital theory in general chemistry. The greater the mobility of the electrons in large conjugated orbital systems, the greater the distribution of the energy throughout the molecule stabilizing it. While redox potentials in some cases show strong correlation with HOMO energies, the offset can be of several eVs. The HOMO-LUMO energies and MEP map were computed to determine the energy gap and probable sites of electrophilic and nucleophilic reactivity in the. The key difference between Homo and Lumo is that the HOMO donates electrons whereas the LUMO receives electrons. HOMO stands for Highest occupied molecular orbital while LUMO stands for Least unoccupied molecular orbital. HOMO-LUMO gap changing the properties of a substance: The excitations become easier as the HOMO-LUMO gap converges which is responsible for the color in transition metal complexes. On the other hand, redox potentials are directly related to the Gibbs free energy difference of the reactants and products. HOMO and LUMO are concepts derived from approximated electronic structure theory while investigating electronic properties of isolated molecules, and their energy levels do not indicate species participating in redox reactions. A widespread misconception in the lithium ion battery literature is the equality of the energy difference of HOMO and LUMO of the solvent with the electrochemical stability window.
0 Comments
Leave a Reply. |