Insights into the Function of Electrode and Electrolyte Materials in a Hybrid Lithium–Sodium Ion Cell

Hybrid Li-Na ion batteries (HLSIBs) become attractive since 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 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 TEM and XPS analyses. The competitive solvation/desolvation of Li+ and Na+ by ethylene carbonate (EC) molecules is modeled as binuclear hetero-complexes, Li+Na+(EC)n (1≤n≤8), in the framework of DFT computations. The hybrid ion cell operates by ...