Volkswagen wants to make e-mobility attractive for millions of customers. The new battery system, developed for the modular e-drive system, helps to achieve this - with scalable ranges between 330 and more than 550 kilometers.
ELECTRIC FOR ALL is the name of Volkswagen's ambitious vision to make electric mobility affordable for millions of people. From 2020 on, models from the ID. Family, which optimally exploit the potential of e-vehicles in terms of range, space and dynamics will be available. By 2025, sales of the ID. family are to exceed more than one million vehicles per year. The newly developed battery system plays a key role in this context. But how does it work? And what is the strategy behind it?
First things first: The ID. family comes onto the market with high-performance, scalable batteries that can be configured with different capacities for ranges between 330 and more than 550 kilometers. Every customer can therefore choose the range that best suits their own driving habits. For this purpose, Volkswagen has developed a completely new battery system that is less complex than today's solutions, but significantly more powerful, which can be integrated comparatively easy into the ID. models. The result: better customization options. Customers using their e-car in city traffic receive more favorable purchase conditions. Customers who tend to travel longer distances will be getting more range if required.
Battery built like a bar of chocolate
Further advantages of the new battery system include weight optimization (through an aluminum housing), the adaptability of different cell types and integrated cooling. The battery can thus be used to drive one axle or auxiliary axles. The arrangement of the cell modules can be pictured as the individual bars of a chocolate bar. This also results in the shape - which in turn ensures that the battery is easy to install. Volkswagen has also been able to increase the charging performance to up to 125 kW - an unprecedented value in the ID. segment, allowing to accelerat charging and thus shortening charging stops. The battery system is a central element of the modular electric drive system (MEB), the new vehicle architecture from Volkswagen that is consistently designed for electric drives.
The largest German automobile manufacturer uses its broad experience in the development of all-electric and plug-in models. The battery systems are mainly manufactured at the Volkswagen component factory in Braunschweig. The Volkswagen Group Components division, which is responsible for the drive systems and will become an independent division in January 2019, is currently expanding this location in order to produce up to half a million battery systems annually in Braunschweig in the future.
Since 2017, Volkswagen has bundled the development of lithium-ion batteries in a centre of excellence for battery cells in Salzgitter, which is responsible for all battery cells in the Volkswagen Group; in addition, a pilot line for battery cell production is currently being set up at the Salzgitter plant. The Volkswagen Group division also produces components for electric drives: The Kassel plant was specifically restructured for this purpose. Against this backdrop, the company is investing 1.3 billion euros in e-mobility in Braunschweig, Salzgitter and Kassel alone.
Aluminium battery housing with crash frame
The MEB batteries are constructed as follows: The lowest level is a solid collision protection. Above this is the aluminum battery housing with a crash frame, integrated battery cooling and a connection box for the high-voltage and low-voltage vehicle electrical systems (AC, DC and 12V). The newly developed MEB cell modules, which consist of individual battery cells, are inserted into the battery housing. The cell controllers (CMCe) - control units for monitoring the cells (voltage, currents and temperature) and cell balancing (ensuring equal load of the cells in daily operation) - are installed in the longitudinal member of the battery housing. The battery electronics (BMCe) are integrated in the rear part of the battery system as a further control unit. The cell modules are networked with each other via so-called cell module connectors; measuring lines communicate with the battery electronics. The battery housing is closed at the top with a lid at the top, easily removable for possible maintenance.
Since both the "pouch" and "prismatic" designs can be used as cell types, there is a high degree of flexibility in the cooperation with cell suppliers. Volkswagen achieves the highest energy density via a maximum packing density within the cell modules. The energy density and thus also the energy content of the batteries will continue to rise in the coming years. A further breakthrough could also be achieved in the second half of the next decade with the use of solid cells.
A lithium ion battery cell consists of an anode (carbon, copper foil), a separator (porous polyolefin foil, ceramic-coated), a cathode (lithium metal oxide, aluminium foil) and an electrolyte (organic solvents, lithium conducting salt, additives). During charging, the lithium ions migrate from the cathode to the anode and are stored there. The electrical energy - fed in from the power grid - is converted into chemical energy. For this purpose, the electrons flow through the circuit, while the lithium ions flow through the separator. During the discharge process - to operate the electric motor - the lithium ions migrate back to the cathode. The chemical energy is then converted back into electrical energy. In this case, the electrons flow through the circuit and the lithium ions flow through the separator in the opposite direction.
The dynamic development of lithium-ion batteries at Volkswagen lays an important foundation for the success of the newly developed generation of ID. electric vehicles that will be produced from 2019 and will be available from 2020. As the first model of the ID. family, the ID. will be launched – an affordable, four-door, fully networked compact car. In September 2016, Volkswagen presented the first I.D. study at the Paris Salon. 24 months later, the all-electric Volkswagen is approaching production readiness at high speed. With scalable ranges at the level of today's petrol engines and the price level of current diesel, the ID. has the potential to initiate the breakthrough for environmentally friendly electric mobility and thus a new drive era.