A company called 24M (24 Molar), has been spun out of the advanced battery company A123 Systems. It will develop a novel type of battery based on research conducted by Yet-Ming Chiang, a professor of materials science at MIT and founder of A123 Systems. He says the battery design has the potential to cut those battery costs by 85 percent.
The battery pack alone in many electric cars can cost well over $10,000. Cutting this figure could make electric vehicles competitive with gasoline-fueled cars.
The new company has raised $10 million in venture-capital funding, and about $6 million from the Advanced Research Projects Agency-Energy (ARPA-E), which will fund collaboration between the company and MIT and Rutgers University.
24M uses a “semisolid” energy storage material (rather than the solid electrode material used in most batteries today), and that it combines the best attributes of conventional batteries, fuel cells, and flow batteries while avoiding some of the disadvantages of these technologies.
The problem with a fuel cell is that it can’t be recharged by applying electrical current–you need to refill the fuel tank. That’s fine if the fuel is widely available, but right now hydrogen can be hard to come by. Flow batteries require vast amounts of electrolyte because their energy density is low. “It’s like managing a large swimming pool full of corrosive liquid,” Chiang says. As a result, flow batteries are not practical for cars. As with fuel cells, the new battery can store large amounts of energy without also needing large amounts of supporting materials to extract.
They have developed a proof-of-concept device–which was needed to get the Arpa-e grant. They have a goal of five years to get the first systems out in the field.
The zinc-bromine flow battery design promises energy storage for less than $500 per kilowatt-hour. That’s about a third the cost of storage using lithium-ion batteries and even somewhat less than the cost of using sodium-sulfur batteries. MIT received $5 million of Recovery Act money to further develop a semi-solid (perhaps a gel) electrolyte flow battery which has the potential of being about an eighth the cost of today’s electric vehicle batteries.
A flow battery is a form of rechargeable battery in which electrolyte containing one or more dissolved electroactive species flows through an electrochemical cell that converts chemical energy directly to electricity. Additional electrolyte is stored externally, generally in tanks, and is usually pumped through the cell (or cells) of the reactor, although gravity feed systems are also known. Flow batteries can be rapidly “recharged” by replacing the electrolyte liquid (in a similar way to refilling fuel tanks for internal combustion engines) while simultaneously recovering the spent material for re-energization.
Various classes of flow batteries exist including the redox (reduction-oxidation) flow battery, in which all electroactive components are dissolved in the electrolyte. If one or more electroactive component is deposited as a solid layer the system is known as a hybrid flow battery. The main difference between these two types of flow battery is that the energy of the redox flow battery can be determined fully independently of the battery power, because the energy is related to the electrolyte volume (tank size) and the power to the reactor size. The hybrid flow battery, similar to a conventional battery, is limited in energy to the amount of solid material that can be accommodated within the reactor. In practical terms this means that the discharge time of a redox flow battery at full power can be varied, as required, from several minutes to many days, whereas a hybrid flow battery may be typically varied from several minutes to a few hours.
Another type of flow battery is the redox fuel cell. This has a conventional flow battery reactor, which only operates to produce electricity (i.e. it is not electrically recharged). Recharge occurs by reduction of the negative electrolyte using a fuel (e.g. hydrogen) and oxidation of the positive electrolyte using an oxidant (typically oxygen or air).
Examples of redox flow batteries are the vanadium redox flow battery, polysulfide bromide battery (Regenesys), and uranium redox flow battery. Hybrid flow batteries include the zinc-bromine, cerium-zinc and all-lead flow batteries