Electric cars and Lithium-ion battery technology

Battery and its management system is one of the key technologies of electric vehicles. In the past few years, most enterprises in the development of electric vehicles has been embarrassed, mainly because the use of lead-acid, nickel cadmium, nickel metal hydride battery (Ni-MH) and so on. Now, after research and experiments, the use of a higher energy density lithium-ion battery to replace lead and nickel-metal hydride batteries, used in the automotive sector is becoming a core technology, which is light weight, energy storage and large power, no pollution, and no secondary pollution, long life, self-discharge coefficient, a wide range of temperature adaptation, is the electric bicycles, electric motorcycles, electric cars, large trucks, such as better electric car batteries. The disadvantage is more expensive, less secure. But now there is technology developed lithium manganese oxide, lithium iron phosphate, lithium vanadium phosphate and other new materials, greatly improving the safety of lithium-ion battery, and reduces costs.

With the dramatic cost reduction and performance greatly improved, many automobile manufacturers have been put into use lithium-ion batteries. The following table is the main manufacturers of lithium-ion battery development and production summary. As of October 2006 until more than 20 countries have the world's major depot for lithium-ion battery research and development. Such as Fuji Heavy Industries and NEC to develop low-cost monomer (Cell) manganese lithium-ion battery (ie, lithium manganese batteries), with high security, low cost features of the life of the vehicle environment, up to 12 years, 10 million kilometers , and pure electric vehicles the vehicle life quite. Toshiba may be the rapid development of rechargeable lithium-ion batteries, in addition to small, high-capacity characteristics, the use of nano-particles can homogenization fixation techniques, allow lithium-ion battery anode adsorbed evenly, and can in one minute charged to within 80% of its capacity, and then after 6 minutes fully charged. Johnson Controls battery plant major U.S. demand for electric cars lithium-ion batteries in properties in September 2005 in Milwaukee, Wisconsin, set up R & D locations, in January 2006 another 50% funded jointly established with the French battery company Saft Johnson Controls-Saft Advanced Power Solution (JCS). JCS in August 2006 to undertake the U.S. Department of Energy (DOE) led by the 2-year USABC (United States Advanced Battery Consortium) lithium-ion battery electric vehicle research and development plan contract, other automakers are also contracted with to provide high-power lithium-ion batteries.

In the lithium-ion batteries of the research level, there are a number of indicators over the USABC long-term targets for 2010 proposed by the goals set have been able to develop a dosage of 50 to 80 kilograms, suitable for electric bicycles, electric motorcycles , petrol hybrid vehicles, hybrid electric vehicles, traveling at 80 kilometers from the small, light to work for household use lithium-ion battery electric cars, and good enough safe driving performance. Since 1997, the Suzhou industrial experience as a national star Constant lithium-ion battery industrialization demonstration project base, its battery pack has been developed by the United States and the European Union UL ExtraEnergy independent testing and certification organization, and built the first power in Suzhou Lithium-ion battery production lines and a smooth trial production, mass production now.

Currently, lithium-ion batteries used in electric vehicle project, a battery life of the mechanism (high-power battery aging characteristics, aging battery diagnosis, the electrochemical model of the aging batteries, the battery life prediction method development), battery performance at low temperature (low temperature performance characteristics, low temperature electrolyte model, low temperature performance analog), tolerance, thermal deviation, over the load deviation, diagnosis and reduce battery costs (materials selection and development, low-cost manufacturing) and so on. Long-term exploration and research focused on two aspects of systems and materials.

On the one hand, most of the companies announced electric vehicle battery laboratory test data, such as acceleration, charge time, continuing mileage, etc., must in the actual operation of the complex external environment, to further verify its reliability, and production batch quality control. On the other hand, in the production of lithium-ion batteries, lithium ion battery separator material not required for a substantive breakthrough, all rely on imports more expensive, accounting for 30% of the cost of power than the battery. If this material to achieve large-scale production technology, can significantly reduce costs.

In addition, some experts believe that the early 90s from the 20th century, the success of national research electric cars, although the battery specific energy than it is now a new battery to be small, but a variety of electric vehicle testing for the performance indicators, on the general users, but also to meet the. Then fail to realize the main reason for the industrialization of electric vehicles is that battery life is too short. Pure battery electric vehicle components used in general to account for the cost of one half of new car, if you need people in the car within a few years that replacement batteries, it means that the use of high cost. Now, the second-generation electric vehicle battery energy density has been greatly improved battery materials and battery production structure has also made great progress, but its life has not been a major breakthrough. Even if the acceleration can fully meet or exceed the highest level in today's fuel vehicles, battery charging and an electric vehicle fuel mileage to more than a box of the current increase in oil mileage, battery life constraints as a result of the high usage costs will also become commercialization of a major bottleneck.

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