Finding a stable organic electrolyte to improve the cycling life of lithium-oxygen (Li-O2) batteries is of primary importance. Tetra(ethylene) glycol dimethyl ether (TEGDME) based electrolytes are the most commonly used in Li-O2 batteries, however, they are still unstable in the presence of superoxides or singlet oxygen, and finally result in the performance reduction during long-term operation. Here a stable electrolyte designed to solve this issue is reported. By mixing dissociative LiFSA salt with methyl pivalate (MP) solvent at super-high concentration, an unusual three-dimensional network of FSA- anions and solvent molecules strongly complexed with Li+ ions is obtained. This unusual structure of the superconcentrated solution is different from the dilute and moderately concentrated solutions. Due to its special structural characteristics, the Li-O2 battery with the superconcentrated LiFSA/MP electrolyte exhibited excellent cycling stability, which was about 4 times higher than the battery with the conventional TEGDME based electrolyte.