The construction of hybrid metal‐ion batteries faces a plethora of challenges. A critical one is to unveil the solvation/desolvation processes at the molecular level in electrolytes that ensure efficient transfer of several types of charge carriers. This study reports first results on simulations of mixed‐ion electrolytes. All combinations of homo‐ and hetero‐binuclear complexes of Li+, Na+ and Mg2+, solvated with varying number of ethylene carbonate (EC) molecules are modeled in non‐polar and polar environment by means of first principles calculations and compared to the mononuclear analogues in terms of stability, spatial organization, charge distribution and solvation/desolvation behavior. The used PF6− counterion is shown to have minor impact on the geometry of the complexes. The desolvation energy penalty of binuclear complexes can be lowered by the fluoride ions, emerging upon the PF6− decay. These model investigations could be extended to rationalize the solvation structure and ionic mobility in dual‐ion electrolytes.

Hybrid Li–Na ion batteries (HLSIBs) have become attractive because they combine the high energy density of lithium-ion batteries with the safety and low cost of sodium-ion batteries. However, the performance of HLSIBs is still far from the desired. The present study aims to probe the function of electrodes and the electrolyte in model half and full hybrid Li–Na cells by combining experimental and computational methods. As a positive electrode, sodium-deficient nickel manganese oxide, Na2/3Ni1/2Mn1/2O2, with a three-layered structure is used, while spinel Li4Ti5O12 serves as a negative electrode. Two types of conventional LiPF6- and NaPF6-based electrolyte solutions are used. The structure and surface changes in the oxide electrodes after cell cycling are monitored by ex situ transmission electron microscopy and X-ray photoelectron spectroscopy analyses. The competitive solvation/desolvation of Li+ and Na+ by ethylene carbonate (EC) molecules is modeled as binuclear heterocomplexes, Li+Na+(EC) n (1 ≤ n ≤ 8), in the framework of density functional theory computations. The hybrid-ion cell operates by a dual intercalation of Li+ and Na+ in the oxide electrodes, which provokes after few cycles a generation of a mixed Li–Na electrolyte. In the mixed electrolyte, each Li+ and Na+ ion is solvated as much as possible without any competition between them. At the electrode–electrolyte interface, the competition between Li+ and Na+ ions leads to the formation of polynuclear cationic associates which are strongly coupled with electrolyte molecules. The desolvation of the latter is further complicated by the presence of surface-deposited F– ions, resulting in the accumulation of Li+ and Na+ ions at the surface of both the oxide electrodes. Based on the extracted correlations, an outlook of further steps for optimization of the HLSIBs performance is suggested.

Anthraquinone anchored on graphene holds possibilities to design next generation battery combined electrodes and current collectors.