<p>An important area of research in the field of aqueous lithium-ion batteries (ALIBs) is the development of effective electrolytes capable of providing high cycling stability of aqueous systems. One of the key factors determining the cycling performance of ALIBs is the formation of a stable electrode–electrolyte interface, which can be achieved by adding an organic solvent to the aqueous electrolyte. In this study, ternary electrolytes of the composition Li₂SO₄–water–tetraglyme with different H₂O/TG ratios at a salt concentration of 2&#xa0;mol&#xa0;dm⁻³ were investigated. Electrochemical studies revealed that the presence of TG in the electrolyte substantially enhances the cycling performance of the LiMn₂O₄ electrode, achieving capacity retention of up to 60% after 430 cycles at charge/discharge rates of 3/1.5 C and exhibiting excellent rate capability. Impedance spectra obtained at different cycles confirm the crucial role of a stable SEI with low charge transfer resistance, formed in the presence of TG, in ensuring the high stability of the specific characteristics of LiMn₂O₄ during cycling. The values of the lithium diffusion coefficient in LiMn₂O₄ with different electrolytes, calculated by the Randles–Sevcik equation, are very close and range from 6.01 × 10⁻¹⁰ to 1.40 × 10⁻⁹ cm²&#xa0;s⁻¹.</p> Graphical abstract <p></p>