A Flow Cell Battery Installed In Prototype Super Car

Liechtenstein based nanoFLOWCELL AG has built a prototype vehicle equipped with flow cell battery power train.  The car, called the QUANT e-Sportslimousine, is on display at the Geneva Motor Show.  The firm claims the flow cell battery system supports an electric car driving range of between 400 to 600 km (249 to 373 miles) in the QUANT e-Sportlimousine prototype.

As a road worthy design the first automobile with a nanoFLOWCELL power train aroused great international media interest. This highly anticipated, revolutionary power train technology and energy-storage system could give new momentum to the electric vehicle industry.

Flow batteries or flow cells combine aspects of an electrochemical battery cell with those of a type of fuel cell. The difference is in the electrolyte.  Electrolyte fluids in flow cells are usually metallic salts in aqueous solution that can be pumped from tanks through the battery.  This forms a kind of battery cell with a cross-flow of electrolyte liquid.  The advantage of this system is that the larger the storage tanks for the electrolyte fluid are, the greater the energy capacity.  Keep in mind the concentration of an electrolytic solution contributes to the quantity of energy that it contains.

At the heart of the system, a membrane separates the two electrolytic solutions, but allows the electrical charge to pass through and thereby produce power for the drive train.

To charge or discharge nanoFLOWCELL’s flow battery the two different electrolytic solutions are pumped through the appropriate battery cell in which an electrode (anode or cathode) is located. A membrane separates the two electrolyte chambers of different chemistry. At a nominal voltage of 600 V and 50 A nominal current, the system in the lab is achieving continuous output of 30 kW.

According to nanoFLOWCELL, its flow battery has a specific energy of about 5 times that of a Li-ion battery (600 Wh/kg compared to ~120 Wh/kg). The company attributes the performance of the company’s flow battery to the characteristics of its newly-developed and unspecified electrolytic fluids made up of metallic salts at very high concentration.

Offering a bit more information, the company says that a large increase in the number of charge carriers in the electrolyte fluid within the battery significantly increased its performance compared to conventional redox flow-cells (about 5 times the specific energy and several orders of magnitude more specific power).

The company also claims its flow cells can go through 10,000 charging cycles with no noticeable memory effect and suffer almost no self-discharging. That would be over 27 years of service life at a daily charge frequency.

The QUANT e-Sportlimousine prototype carries two 200-liter (53 gallons US) tanks on board, for a total energy capacity of 120 kWh. The prototype’s energy consumption is about 20 kWh/100 km, when driving in the lower load range.  Increasing the tank volume of the to 800 liters would be possible, the company says.

The catch is once the electrolytic fluids are discharged, the contents of both tanks must to be replaced. The prototype features a double tank system with dual filler necks, one for each electrolyte, to keep times for the electrolyte liquid replacement to a minimum.

The prototype uses four electric motor units (120 kW continuous, 170 kW peak per unit) for all-wheel drive with torque vectoring and two supercapacitor banks for energy storage. Peak torque per wheel is 2,900 N·m (2,139 lb-ft). The company says acceleration from 0 to 100 km/h is 2.8 seconds.

That where the international media attention motivates.  These are supercar numbers.

A central VCU (vehicle control unit) is responsible for controlling the driving and charging currents throughout the entire power train.  Supercapacitors provide the peak power to the four drive motors, and also serve as a general energy buffer for the vehicle’s electrical system and storage for regenerative braking energy.

There is more development coming.  Last month nanoFLOWCELL AG announced a partnership with Bosch Engineering GmbH to further develop vehicle electronics for the QUANT e-Sportlimousine.  The company is planning on producing four drivable prototypes in 2014.

nanoFLOWCELL AG, formerly JUNO Technology Products AG, reforming in late 2013, is a research and development center based in Vaduz, Liechtenstein.  Their focus is on the advanced development of drive technology and the classification of flow-cell technology.  The firm as Juno showed the earlier NLV Quant prototype at the Geneva Motor Show in 2009.

As noted, the performance is in the supercar range where costs can be as extreme as the performance.  It also serves as a platform for development that may well trickle into the mass market.  With range in the 300 mile zone and possibly decades of service life the trickle would be welcome, very welcome indeed.