[en] A novel compound, tri-(4-methoxythphenyl) phosphate, was synthesized and investigated as a safety electrolyte additive for lithium-ion batteries. It was found that this additive could lower the flammability of the electrolyte, and thereby enhance the thermal stability of the Li-ion battery. Moreover, this molecule can also be polymerized at 4.35 V (vs. Li/Li⁺) to form a conducting polymer, which can protect the batteries from voltage runaway at overcharge by internal bypassing the overcharging current in the batteries. Thus, it is possible to use this electrolyte additive to provide both overcharge protection and flame retardancy for lithium-ion batteries without much influence on the battery performance

[en] The ionic conductivities of EC-based multi-component electrolytes in various solvent compositions were measured over a wide temperature range of +40 to -40 deg. C, and the factors affecting the low temperature conductivities of the electrolytes were discussed. It is revealed from the experimental results that the co-solvents with high dielectric constant and low viscosity can improve the ionic conductivity at room temperature, whereas, only the co-solvents which possess low melting points can effectively expand the operating temperature range of the electrolyte. The Li-ion batteries using the optimized electrolyte of 1M LiPF₆/EC-DMC-EMC (8.3:25:66.7) show the capacity retentions about 90.3% of their nominal capacities when discharged to 2.0V at -40 deg. C at 0.1C, demonstrating excellent low temperature performances