A novel electrolyte system having well structurally controlled aliphatic oligoether dendrons with a carbonate core is developed for lithium ion batteries. The synthetic dendrons have high boiling point, much higher dielectric constant up to 7.4–8.7 and better stability against oxidation than the conventional linear carbonates such as DEC. The ionic conductivities of the electrolyte with 80wt% of dendrons and 20wt% of LiTFSI are 0.11–0.61mScm−1 at 20°C. A 463443-type prismatic battery having the electrolyte solution with 20wt% dendrons was prepared and its battery performance such as capacity and cycleability was investigated. The prismatic battery with dendron-based electrolyte has the same level of capacity to that with the conventional carbonate-based electrolyte, and shows good cycleability, suggesting a high possibility to use as a kind of cosolvents for lithium ion batteries.