The properties of electrolyte systems based on standard nonaqueous solvent composed of a mixture of dialkyl and alkylene carbonates and new commercially available lithium salts potentially capable of being an alternative to thermally unstable and chemically active lithium hexafluorophosphate LiPF₆ in the mass production of lithium-ion rechargeable batteries are surveyed. The advantages and drawbacks of electrolytes containing lithium salts alternative to LiPF₆ are discussed. The real prospects of substitution for LiPF₆ in electrolyte solutions aimed at improving the functional characteristics of lithium-ion batteries are assessed. Special attention is drawn to the efficient use of new lithium salts in the cells with electrodes based on materials predominantly used in the current mass production of lithium-ion batteries: grafitic carbon (negative electrode), LiCoO₂, LiMn₂O₄, LiFePO₄, and also solid solutions isostructural to lithium cobaltate with the general composition LiMO₂ (M = Co, Mn, Ni, Al) (positive electrode).

The introduction of 3d transition metals into the van der Waals gaps of titanium dichalcogenides with layered structures gives rise to an interesting family of intercalation compounds, the physical properties of which differ substantially from those of the host compound due to “host–guest” and “guest–guest” interactions, resulting in ordering of the intercalated metal. Fe_xTiSe₂ is one of the most intriguing of such intercalation compounds due to its special electronic and magnetic properties. In this paper, the influence of the iron concentration on the crystal structure, electronic structure and chemical bond in the Fe_xTiSe₂ intercalation compounds is studied across a wide composition range (0 ≤ x ≤ 0.50) within the homogeneous region of the system. Photoelectron, resonance photoelectron and X-ray absorption spectroscopy methods were combined with thermodynamic electromotive force (EMF) measurements for the Li|Li⁺|Fe_xTiSe₂ cell in order to monitor the Fermi energy concentration dependence. The electronic structure changed substantially as the Fe content increased. A proposed model of the Fe_xTiSe₂ electronic structure transformation implies that iron atoms form Ti–Fe–Ti bonds at x < 0.40, but that Fe–Fe bonds prevail at x ≥ 0.40 when nanoscale iron chains appear in the van der Waals gap.