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Abstract: 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 4.35V (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. [Copyright &y& Elsevier]

Abstract: A new fire retardant-dimethyl methyl phosphate (DMMP) was tested as a nonflammable electrolyte solvent for Li-ion batteries. It is found that in the addition of chloro-ethylene carbonate (Cl-EC) as an electrolyte additive, the electrochemical reduction of DMMP molecules can be completely suppressed and the graphite anode can be cycled very well with high initial columbic efficiency (∼84%) and excellent cycling stability in the DMMP electrolyte. The prismatic C/LiCoO2 batteries using 1.0molL−1 LiClO4 +10% Cl-EC+DMMP electrolyte exhibited almost the same charge and discharge performances as those using conventional carbonate electrolytes, suggesting a feasible use of this new electrolyte for constructing nonflammable Li+-ion batteries. [Copyright &y& Elsevier]

Abstract: A polymerizable monomer, diphenylamine (DPAn), is reported to act as a safety electrolyte additive for overcharge protection of 3.6V-class lithium ion batteries. The experimental results demonstrated that the DPAn monomer could be electro-polymerized to form a conductive polymer bridging between the cathode and anode of the battery, and to produce an internal current bypass to prevent the batteries from voltage runaway during overcharge. The charge–discharge tests of practical LiFePO4/C batteries indicated that the DPAn additive could clamp the cell''s voltage at the safe value less than 3.7V even at the high rate overcharge of 3C current, meanwhile, this monomer molecule has no significant impact on the charge–discharge performance of the batteries at normal charge–discharge condition. [Copyright &y& Elsevier]

Abstract: A compound 4-tertbutyl-1,2-dimethoxybenzene (TDB) was synthesized and tested as a redox shuttle for overcharge protection of Li–LiFePO4 batteries. This isomer of tertbutyl-substituted dimethoxybenzene is miscible with the organic polar electrolytes and provides a solution for the poor solubility of ditertbutyl-substituted 1,4-dimethoxybenzenes as a redox shuttle additive. The experimental results demonstrated that the shuttle molecules added in the electrolyte cannot only provide feasible overcharge protection, but also have indiscernible detrimental influences on the charge–discharge behaviors of Li–LiFePO4 cells, showing a great prospect for practical applications in commercial rechargeable lithium batteries. [Copyright &y& Elsevier]

Abstract: A novel room temperature ionic liquid (N-methyl-N-butyl-piperidinium bis(trifluoromethanesulfonyl) imide (PP14-RTIL) ) was synthesized and tested as electrolyte for Li/S cells. The CV results revealed that this new RTIL electrolyte has a wide potential window of 5.2V∼−0.15 (vs. Li/Li+), and is electrochemically stable and workable for lithium and sulfur electrodes. The charge–discharge experiments of Li/S cells using the PP14- RTIL electrolyte demonstrated that the sulfur cathode can achieve a high initial capacity of 1055mAh/g and maintains a reversible capacity of ca. 750 mAh/g after a few of cycles, showing a greatly improved dischargeability and cycleability as compared with the sulfur cathodes cycled in organic liquid or polymer electrolytes. [Copyright &y& Elsevier]

Abstract: The ionic conductivities of EC-based multi-component electrolytes in various solvent compositions were measured over a wide temperature range of +40 to -40°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°C at 0.1C, demonstrating excellent low temperature performances. [Copyright &y& Elsevier]