Lithium-ion Batteries Made Cheaper, Safer

The era of less expensive Lithium-ion batteries for electric cars and consumer devices may be on the horizon if Finnish research proves true. Scientists at Aalto University in Finland have created safer methods for battery production they claim reduces worker exposure to harmful chemicals and saves 5 percent in overall manufacturing costs. The study was published in Journal of Power Sources this week.

Lithium-ion batteries have a reputation for being durable and reliable in powering hybrid and electric vehicles as well as many portable electronics. Consumer Reports recommends lithium batteries in high-drain devices such as cameras and alkaline batteries in low-drain devices such as remote controls.

"The increase in electric car use in particular will strongly increase the global demand and production of batteries," says Tanja Kallio, professor at Aalto University.

Manufacturing lithium-ion batteries historically has been a dangerous process because of methylpyrrolidone (NMP). The solvent is typically used in the manufacturing of electrodes, with water. The process also adds cost to the manufacturing process of lithium-ion - about 40 percent higher in cost than nickel-cadmium. The U.S. and other governments strictly regulate the amount of batteries shipped domestically and internationally because of the potentially hazardous chemicals.

Currently, manufacturers use carboxyl methyl cellulose (CMC) binder to reduce the need for hazardous solvents in industrial manufacturing to fabricate carbon electrodes. The process is prone to bacterial growth, making the process inefficient. Aalto University researchers say an alternative is a water-soluble acrylic S020. The new binding agent needed thorough testing because it not only had to be water-soluble but also ideal for chemical, electrochemical and mechanical use, researchers said.

Additionally, using the acrylic S020 made it possible for high capacity retention - more than 500 cycles - and operation at sub-zero temperatures; good news for hybrid drivers living in extreme cold zones. The manufacturing process can also accommodate pilot-scale gravure printing and slot-die coating methods to allow for lithium-ion batteries of different shapes and sizes.

This is no the University's first crack at reducing the cost and risk of making lithium-ion batteries. Earlier this year, researchers covered the electrodes of lithium iron phosphate batteries with extremely thin protective layers. The doping process increased the potential energy of lithium iron phosphate used as a positive electrode.

Should the findings from Aalto University prove to be effective, production of lithium-ion batteries may ramp up even beyond current estimates. The price of lithium-ion batteries is expected to drop more than 70 percent by 2020, according to a McKinsey study. One third of that price reduction represents the manufacturing process. Rising oil prices, an growing interest in electric vehicles, and technology borrowed from electronic manufacturers like Apple, are also contributing to these cost reductions.