A new fire-retardant—dimethyl(2-methoxyethoxy)methylphosphonate (DMMEMP) has been synthesized and evaluated as a high safe electrolyte solvent for lithium-ion batteries. This report summarizes the physical and electrochemical properties of the new compound. It is found that, this nonflammable phosphonate has a moderate viscosity, a high dielectric constant and a good thermal stability. It can provide a wide electrochemical stability window of 0–5.5V (vs. Li+/Li), a high conductivity of 2.0mScm−1 at 20°C with 1M LiTFSI. The electrochemical performance investigated with the Li/LiFePO4 half-cells shows a good capacity of 148.1mAhg−1 and a coulombic efficiency close to 100% at the 10th cycle.