The research team at Siemens’ global research unit Corporate Technology in Erlangen, Germany, has successfully made the Lithium-ion battery safer than before besides extending their service life using new methods and additional improvements.
A new cell chemistry was developed until it was mature enough for general application as part of the joint research project – ‘Intrinsically Safe Battery’ (EiSiBatt) – which was funded by the German Ministry for Economic Affairs and Energy. The end result was the creation of Lithium ion batteries that were safe even when overcharged and also last for a higher number of charge-discharge cycles (20,000) than the previous top value of around 5,000.
Owing to their high energy densities, Lithium-ion batteries are very attractive energy storage systems. Looking at Siemens alone one can see that it is used in a wide range of applications from small energy storage systems for hearing aids to medium-size storage systems for cranes and machine tools, and large storage systems for power grids.
The anodes of the new battery cell consist of lithium titanate unlike the old ones using graphite and lithium iron phosphate, thus replacing the lithium metal oxide at the cathode. The scientists also developed a model that simulates a behavior of battery systems where hundreds of new cells are interconnected like in the compact large storage systems.
As reported by the company, the scientists understood the behavior of the battery and described it mathematically after numerous measurements and simulations. The model not only encompasses the batteries’ electrical behavior, but also their mechanical and thermal behavior. The simulations assisted scientists in finding out how the new batteries’ output and energy content are affected when the batteries are used to stabilize power networks or regulate frequencies, for example.
The associated battery management system that controls the cells’ charge level was developed by Facilis, a team of engineers at Drive Technologies in Chemnitz. Components available from Siemens were used for the system concept to ensure smooth interaction. For example, a Simotion control system analyzes the cells’ voltage and temperature enabling the software to take on additional tasks, such as when the battery is incorporated into a power grid or a drive network.
A variety of Siemens business areas are expected to gain a competitive edge with the new cell. A demonstrator has been created for engineers to test various possible applications. Specialists from chemicals company Clariant, battery manufacturer Leclanché, and the Centre for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) were involved in the project.
Image courtesy of Siemens