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Stored electricity

Company develops a battery for electric vehicles and solar and wind systems

EDUARDO CESARElectrocell battery, indicated for buses and trucksEDUARDO CESAR

Knowledge and experience are two important factors for technological development and both were very much present in the conception and construction of a new type of battery. Manufactured for the first time in Brazil, it can store power in electric vehicles. The innovation was developed by Electrocell, in São Paulo, which was set up 12 years ago, with engineers from the industrial batteries and surface treatment areas. It specializes in the development and construction of fuel cells, which produce power from hydrogen, by means of a chemical reaction between this gas and the oxygen in the atmosphere. These generators emit no pollutants, work quietly with no vibration, and can be either stationary in a residence, business or event, or can generate power inside a vehicle. The company has already sold about 75 of these cells, mostly to companies and research institutions, with the idea of demonstrating this still experimental technology that is evolving everywhere in the world.

Electrocell batteries are made up of bipolar graphite plates for use in vehicles and also for storing power in renewable energy systems, such as those based on solar and wind power. “They are suitable for entirely electric vehicles, mainly buses and trucks in market niches, such as mail services, power companies, delivery companies and golf carts, for example,” says engineer Gerhard Ett, a researcher and Electrocell partner. “Our battery was designed to supply power systems cheaply. It stores power after being recharged in a socket, in the case of vehicles, or with the power generated in solar panels during the day, or even by wind-powered generators.”

“Our bipolar batteries can cost 15% to 25% of the price of lithium ion batteries, the most widely used in cutting-edge equipment, from vehicles to cell phones,” says engineer Gilberto Janólio, another of Electrocell’s partner-researchers. “Lithium batteries are unbeatable in terms of the power density they can store, but the cost and duration of our battery makes them worthwhile,” says Ett. Inspiration for the batteries came from industrial lead-acid batteries, used, for example, by telephone exchanges for a few hours when their power supply system fails. Batteries such as these are also fitted in the small electric vehicles used in football stadiums for removing injured players from the field or on golf courses and at events. “Our batteries have far less lead than traditional batteries and last much longer,” says Ett. The research conducted at the company resulted in thin layers of lead oxide being applied to the graphite plates. “This is an evolution of  lead batteries; it’s material that’s 100% recyclable and reusable, and meets European environmental standards,” says Janólio.

To develop the battery, researchers from the São Paulo company used bipolar graphite plates used in fuel cells, which conduct and distribute the hydrogen inside the equipment. They also make the link between the polymer membrane assembly for the exchange of protons and the electrodes, known as the membrane electrode assembly (MEA).

In the battery, the graphite plates have a thin layer of  lead and some additives and, as in the cells, they form a single set. “The use of the cell concept in the battery is unprecedented,” says Ett. “Today, each plate costs – 20, whereas the one we make goes for R$2,” says the researcher. The new battery concept lasts for 1,000 charging cycles. Each cycle means the battery discharges fully and then recharges; this can be done 1,000 times, while traditional automotive lead batteries only get to 100 cycles. “The energy expended by our battery is 60 watt-hours (Wh) per kilo, versus the 85 Wh of the lithium battery,”  says Janólio. The cost of the Electrocell battery to future customers is US$ 200 per kilowatt-hour (kWh), while lithium batteries cost US$600 to US$1200, according to figures from the international market collected by the company.

The new battery has already had its patent accepted by the Patent Cooperation Treaty (PCT), which allows this document to be deposited in hundreds of countries. “We already had the patent of the plates for the fuel cells and now we have deposited it widely, worldwide,” says Ett. “We want to go into the international market and we’re negotiating the license of the patent with several companies in Brazil and abroad. This is a lengthy process and we need to be careful,”  he says. Funding for the research into the new battery came from the cash flow of Electrocell itself, which is an incubated company that was established at the Center for Innovation, Entrepreneurship and Technology (Cietec) and is now operating in the Pre-Technology Park on the Cidade Universitária campus. “But we had the support of FAPESP in developing the graphite plates for the cells, which contributed to the creation of the battery,”  says Ett. The project was carried out between 2004 and 2008 and is part of the Innovative Research in Small Companies (PIPE) program.

The company’s focus is still fuel cells, but it will continue to develop specific batteries. One that is in the project stage is intended for hybrid alcohol-powered vehicles; it would be used in the same automobile alongside a dual fuel  engine and electric batteries, which still provide only a few kilometers (km) of autonomy. Fuel cells are also an option for inclusion in vehicles that can be plugged into a socket for refueling and obtaining more autonomy with hydrogen. Likewise, a small petrol or alcohol engine can supply the vehicle with enough power to run well over 100 km. “The autonomy provided by alcohol, gasoline and diesel is very high as compared to purely electric vehicles with only one battery offer.”  Hydrogen cells are in an intermediate position, but rank first when it comes to low emission of pollutants. The only waste from the cells is water vapor.

One obstacle to the greater use of cells is their high cost, although prices have fallen. There are forecasts for 2013 indicating that prices will drop by as much as 90% relative to 2003 figures, according to Nucellsys, of the German Daimler Group, the parent company of Mercedes-Benz, which develops and produces cells. Prices may fall as the study of materials progresses and with economies of scale. “Renewable energy will be slightly more expensive and will not have, at least in the short and medium term, the same cost as conventional energy. Therefore, scale gains are fundamental. Government purchases are important for this in the transition period, as well as showing private enterprise that a sustainable economy is possible,” says Janólio. Electrocell itself sets its price based on quantity. “Fifty 5-kilowatt (kW) cells cost US$6,000 a kW. Larger, 50-kW cells, also in 50 units, sell for US$ 5,000 a kW,”  says Ett. Individual cells, of course, cost much more. The biggest ones that the company has made so far were public entities or those which also had government financing, such as Eletrobras and, the biggest of all, the one for the Coppe bus, with 77 kW (see article). Another 50 kW unit, for use as a generator, was produced for AES Eletropaulo, with government incentives (see Pesquisa FAPESP nº 92).

The Project
Development of injected graphite compounds applied in electrochemical processes (nº 04/09113-3); Type Innovative Research in Small Companies (Pipe); Coordinator Volkmar Ett – Electrocell; Investment R$ 408,655.56 and US$ 30,883.15 (FAPESP)