High Power Cell for Mild and Strong Hybrid Applications Including Chevrolet Malibu 2017-01-1200
Electric vehicles have a strong potential to reduce a continued dependence on fossil fuels and help the environment by reducing pollution. Despite the desirable advantage, the introduction of electrified vehicles into the market place continues to be a challenge due to cost, safety, and life of the batteries. General Motors continues to bring vehicles to market with varying level of hybrid functionality. Since the introduction of Li-ion batteries by Sony Corporation in 1991 for the consumer market, significant progress has been made over the past 25 years. Due to market pull for consumer electronic products, power and energy densities have significantly increased, while costs have dropped. As a result, Li-ion batteries have become the technology of choice for automotive applications considering space and mass is very critical for the vehicles. Although there is not one definition for mild and strong hybrid, for the purpose of GM applications, mild hybrid systems have a nominal voltage range of 85-115V as nominal voltage range, and strong hybrid systems have a nominal voltage range of 300-325 V. This paper outlines how the vehicle propulsion system requirements are tied to cell selection on the basis of performance, safety, and packaging. A general cell format criteria and performance comparison of various options leading to selection of this particular high power cell is discussed. A prismatic metal can cell containing NMC as cathode material, combined with mixture of surface modified carbon with amorphous carbon, and electrolyte with additives in it was chosen to deliver optimal capacity, power, and a safe cell to meet battery pack requirements.