Most electrolytes currently used in Li-ion batteries contain halogens, which are toxic. In the search for halogen-free electrolytes, we studied the electronic structure of the current electrolytes using first-principles theory. The results showed that all current electrolytes are based on superhalogens, i.e., the vertical electron detachment energies of the moieties that make up the negative ions are larger than those of any halogen atom. Realizing that several superhalogens exist that do not contain a single halogen atom, we studied their potential as effective electrolytes by calculating not only the energy needed to remove a Li(+) ion but also their affinity towards H2O. Several halogen-free electrolytes are identified among which Li(CB11H12) is shown to have the greatest potential.

The concept of net electrophilicity (electroaccepting power relative to electrodonating power) is introduced. It provides expected trends in most cases. A net electrophilicity scale is presented. Various reactivity descriptors for 32 molecules are calculated at the B3LYP/6-311+G(d) level of theory. Profiles of net electrophilicity along the reaction paths of thermoneutral, exothermic, endothermic, and cycloaddition reactions are analyzed. Net electrophilicity often attains its minimum value for a stable state or a favorable reaction.

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A new electronic structure principle, viz., the principle of electrophilicity equalization isproposed. An analytical justification as well as a numerical support for the same is provided.