Presentation at the
59th International Automotive Press Briefing
Boxberg, June 2009

There is a wide consensus in the industry that, in the long term, the future belongs to the electric car – yet over the next 20 years, the internal combustion engine will continue to offer indisputable advantages. Before purely electric cars become a common sight on our city streets, transitional technologies will help pave the way for them. There will be mild, strong, and plug-in hybrids, or electric vehicles with a range extender – a small combustion engine which recharges the battery as required. Whichever type, both hybrid and electric cars require high performance storage of electrical energy. This energy is either supplied via recuperation from braking, from a generator which is driven by a range extender or, simply, from a power socket. Almost all automotive manufacturers and suppliers agree: for energy storage, a battery with lithium-ion technology holds the most promise. This is why Bosch and Samsung SDI have set up the SB LiMotive joint venture with the goal of further developing lithium-ion technology for use in automobiles.

Why lithium-ion technology?
Why lithium-ion batteries? Today, hybrid vehicles still use nickel-metal hydride batteries. However, there is general consensus that the developmental potential of these batteries has been exhausted. In contrast, lithium-ion technology appears much more promising in the medium to long term. This conclusion is based on a series of advantages which this technology offers. For instance, compared to nickel-metal hydride cells, lithium-ion cells have a significantly better power density. Furthermore, due to a high nominal voltage, they also have a higher energy density. Other advantages include their higher cycle durability and longer calendar life as well as the significantly lower self-discharge rate. In other words, if you are away on vacation and don't use your electric car, the battery will barely discharge. Moreover, this technology already has a proven track record in consumer electronics: lithium-ion rechargeable batteries supply power to mobile phones, laptops, as well as Bosch power tools. These properties have made lithium-ion technology the technology of choice for the future of the electric drive. Of course, batteries have to satisfy far higher standards in automobiles than in consumer electronics. Hence, our engineers face tough challenges in the further development of lithium-ion technology.

One example: a journey of 200 kilometers in an electric vehicle weighing 1,000 kilograms requires a battery supplying about 35 kilowatt hours. Today, this kind of battery costs about 500 euros per kilowatt hour – so for 35 kilowatt hours, the battery would cost some 17,000 euros. This is still too high for the industry to offer electrically powered vehicles at an attractive price. Moreover, according to recent surveys, today's drivers would expect an electric car to have a range of at least 200 kilometers, so the performance of the battery would still be too low. Another drawback is that the currently available batteries would not last as long as the car.

In order to bring the lithium-ion battery up to speed for the automobile, we have set the following goals for our development activities at SB LiMotive:
· To considerably improve the power and energy density of the lithium-ion battery
· To significantly reduce battery costs
· To further improve cycle durability and service life
· To adapt the battery to the safety standards of the automotive industry

In order to achieve these goals, our work to further develop the battery takes a three-pronged approach:
· In the chemical components of the individual battery cell and its structure
· In the integration of the cells to form battery modules
· In the battery management system which serves to monitor and regulate the individual cells

Higher power and energy density
Hybrid and electric vehicles place different demands on energy and power density. Electric vehicles require batteries with a high energy density, since a great amount of energy needs to be stored in the battery in order to travel long distances. In contrast, power density is more important for hybrid vehicles because energy needs to be stored and discharged at short intervals. Today, battery cells for hybrid applications deliver about 3,000 watts per kilogram of specific power and some 85 watt hours per kilogram of specific energy. In contrast, those for electric cars deliver 110 watt hours per kilogram. In order to improve both energy and power density, our focus in the first instance is on optimizing the cell chemistry. Our goal is to reach a power density of over 4,000 watts per kilogram by 2012 for hybrid applications and an energy density greater than 150 watt hours per kilogram for electric car applications. This means that within three years, the key performance indicators of lithium-ion batteries will see a 30 to 40 percent improvement.

Charge-cycle requirements also differ between hybrid and electric vehicles. For a hybrid drive, power density is decisive. In other words, it has to be possible to store and release large doses of energy within a short space of time. These shots of energy are required mostly for quick energy recuperation when accelerating and braking. To reduce the strain on the hybrid battery, typically less than twenty percent of the battery capacity is actually used. This frequent charging and discharging means the battery has to be designed to handle more than a million charge cycles in its lifespan. For an electric vehicle, however, roughly 2,500 to 3,000 charge cycles are sufficient. But to achieve an acceptable range, it is necessary to have a difference between maximum and minimum charge of as much as 80 percent, which strains the battery significantly and wears it out faster. In the future, both battery types should have a lifecycle as long as the car itself. This means a lifespan of more than twelve years or a total mileage of 250,000 kilometers.

In simple terms, a lithium-ion battery, like a human being, has a preferred temperature range. In the case of the battery, this is between plus 15 and plus 45 degrees Celsius. In an automobile, however, temperatures can vary between minus 30 and plus 60 degrees Celsius. At low temperatures, the performance of the battery declines. If the temperature increases, however, its lifespan decreases. For this reason, a sophisticated thermal management concept is needed. This can help slow down the aging process and increase the battery cell's lifespan and cycle durability. But thermal management also consumes energy – especially for cooling. To reduce energy requirements, for example, the maximum temperature at which cells can operate could be increased. This is why we aim to expand the working temperature range of the cell by selecting the right materials and optimizing cell structure.

Safety
To meet the high demands of the automotive industry, we are also focusing our efforts on the issue of safety. One way in which we are improving the cell chemistry is by using high-temperature-tolerant electrolytes and flame-resistant materials. For the battery pack, we focus on cell monitoring: the battery management system continuously measures and regulates the individual cells with regards to strength of electric current, voltage, as well as temperature and charge level. This helps protect the battery from overdischarge or overheating. To ensure safe functioning in all operating conditions, a sophisticated thermal management concept guarantees the battery always operates within an optimum, and thus safe, temperature range. Additionally, the crash-safe packaging of the module protects the battery cells in the event of an accident. Consequently, the place where the battery is installed within the vehicle is decisive. Last but not least, we also apply high standards to our production processes in order to satisfy quality requirements with regards to safety as well.

Lower battery costs
Finally, let's look at price, which plays an important role when it comes to making the electric car attractive for consumers. Our meetings with automakers today are nearly exclusively about battery production for mini-series of hybrids and electric vehicles. A big battery with a large energy capacity is needed for applications in electric vehicles. In other words, it takes many cells to achieve an adequate range. We would be able to reduce the number of cells in the future if we could considerably increase the specific power or specific energy of the materials in each cell. This would make the battery lighter and, most importantly, less expensive. Costs can also be reduced by producing on a larger scale. Plus, the battery will become more affordable with a larger procurement volume of raw materials and an increasing standardization of components. As our experience grows over the next few years, we will certainly find new ways to gradually optimize the process costs of battery cell manufacturing. This includes the cheaper production of chemical raw materials as well as the integration of cells in battery modules in large-scale series production. The general consensus is that we will be able to produce a battery pack for about 350 euros per kilowatt hour by 2015, or about two-thirds of the current cost. This would make the battery cost for the electric vehicle I mentioned earlier around 12,000 euros.

Ladies and Gentlemen,
Perhaps you now have a clearer idea of the development work still ahead of us to make the lithium-ion auto battery ready for large-scale series production. Based on our results up until now at SB LiMotive, we are optimistic that we will be able to master the technical challenges that lie ahead of us. We plan to start series production of battery cells for hybrid vehicles in 2011, while series production of cells for electric vehicles is slated for 2012. Start of production of the corresponding battery systems is scheduled to follow soon after each of these dates.

Thank you for your attention.

RF00048 - June 2009