General Motors Corp. believes it has the inside track to the future of the auto industry with its plan to bring electric-powered cars to the market, using thousands of lithium ion battery cells - and it cannot get there without plastics.
Resins are the binder material for the active ingredient in those batteries, they are in the separator film, they provide the housings and they are the conduit for cables throughout the car.
``There is much more plastic content and processing technology in these cars than there is in the internal combustion engine,'' said Ann Marie Sastry, director of the energy systems engineering program at the University of Michigan. She spoke during an interview at the auto industry's Management Briefing Seminars, held Aug. 6-10 in Traverse City.
Detroit-based GM and its technology partners, including battery maker A123Systems Inc. - named as a co-developer of battery systems for GM's electric-drive E-Flex program during the Traverse City event - are getting the headlines. But plastics firms are busy behind the scenes tweaking materials to make GM's dream a reality.
``This is an important specialty segment,'' said Mike Sanders, business manager of energy storage systems at DuPont Co. ``We're looking at issues like how do you improve it, how do we deal with safety issues, how can we make it more stable?''
GM is not alone in its lithium ion interest. Toyota Motor Corp. plans to use them in its next generation of hybrid vehicles, replacing the nickel-metal-hydride batteries now used. Lithium cells carry more power per cell, allowing carmakers to use smaller battery packs.
Lithium ion batteries are not new. They already are in high production worldwide with about 6 billion cells expected to be made this year, powering laptops, cell phones, power tools and an array of other consumer electronic products. Plastics already are in use in those batteries.
Each cell, about the size of an AA battery, is a spiral made up of active ingredients in the anode and cathode, which are separated by a film. Lithium flows through the film, releasing energy. The chemicals that make up the active ingredients in the anode and cathode are housed inside extrudable resins - typically polyvinylidene difluoride or polytetrafluoroethylene - essentially as a high level of filler material in the resin.
The rolled cells are placed inside battery packs. A typical laptop computer contains three to four cells.
The biggest problem the auto industry faces is in ensuring the cells are stable enough for the harsh conditions they would face on the road.
Lithium ion batteries are susceptible to overheating, leading to some high-profile incidents in which telephones, laptop computers and even heart defibrillators have burst into flames when they got too hot. A puncture from a nail or other such objects also can set off a massive failure.
A123Systems, based in Watertown, Mass., says it has overcome the heat and stability problem by using nanophosphate as an active ingredient its batteries, in place of cobalt oxide. But Sanders noted that other battery makers are improving their batteries' capabilities through improved materials.
``The technology is proven, but on a vehicle there are issues that need to be worked on, which will be the focus of the next years,'' said Frank Weber, global vehicle line executive and chief engineer for GM's E-Flex platform.
GM is hedging its bets by signing development agreements with a number of suppliers.
While A123Systems is signed up for the E-Flex program, GM signed on Johnson Controls Inc.'s joint venture, Johnson Controls-Saft Advanced Power Solutions, to work on the lithium ion batteries for its prototype Saturn Vue Green Line plug-in hybrid. JCI-Saft uses the cobalt oxide chemistry in its batteries.
``I don't think there's going to be any one solution,'' Sanders said. ``There are going to be multiple solutions.''
And once the battery issues get settled, automakers and their suppliers still must revamp the way they currently make electrical cables.
The typical electrical wire in today's car is coated with PVC, and only carries the current from a 12-volt battery. PVC simply is not durable enough to stand up to the currents being run through a thousand or more lithium ion batteries per car, according to Sanders.
``Commodity resins aren't going to come into play here,'' he said.
But none of those issues - temperature stability, production or materials - are likely to stop the industry's battery movement. Unlike some other technologies, such as fuel-cell systems, lithium ion batteries already have been proved on the market. It is just a matter of fine-tuning them for automotive use, Sanders said.
