Hyderabad-based CSIR research institute has develped a rechargeable magnesium metal battery, which can replace the currently used, highly toxic lead acid battery used widely for UPS and inverter instruments, bringing relief to many environmentalists.
The Fluoro-Organics division of Council of Scientific and Industrial Research-owned Indian Institute of Chemical Technology in Hyderabad said the new magnesium battery with natural graphite cathode is safe. Ionic liquid used in an electrolyte is also safe, non-flammable and non-corrosive compared to sulphuric acid used in lead acid battery, the research team said in a statement to the media.
The rechargeable Magnesium battery has been developed by Dr J. Vatsala Rani and her team in Fluoro-Organics division of CSIR-IICT has cost advantage and the mechanism is not available till date, CSIR-IICT said.
The new battery uses eco-friendly materials — magnesium (anode), modified natural graphite (cathode) and ionic liquid electrolyte — which are safe and easily available. The Mg-ions from the anode diffuse into the graphite layers of the cathode during discharge and revert to the anode when they are charged. The ionic liquid used as electrolyte was prepared in-house and was found to be stable and non-corrosive at room temperature, the institute said.
“The capacity of the cell is 5mAh at a voltage of approximately 2.0V vs Mg. Studies are in progress to improve the capacity of the battery. The cycle life of the battery is established for 800 to 900 cycles. As of now, the shelf life of the battery is estimated to be 2-3 years. The electrode materials are reusable and also biodegradable,” it said.
“Indian industries and Government agencies should come forward in replacing the highly toxic lead acid battery with rechargeable magnesium battery,” Dr Vatsala Rani said, pitching for a replacement of the current lead batteries.
But she is not alone in developing magnesium-based batteries as the experiment has been taken up in many labs around the world. The advantage with magnesium is that unlike lithium ions, which can carry only one electrical charge each, doubly charged magnesium ions shuttle two at a time — instantly multiplying the electrical energy that can be released for the same volume, said one report.
Moreover, magnesium comes with its own challenge. Lithium zips through electrolytes and electrodes, but magnesium moves with its two charges as if through treacle. Peter Chupas, a researcher at Argonne National Laboratory with the JCESR, says his team has found that magnesium exerts a strong pull on oxygen atoms in any surrounding solvent, attracting clusters of solvent molecules that make it bulkier.
Kristin Persson at Lawrence Berkeley is using a supercomputer to simulate the innards, trying to find a combination of electrodes and electrolytes that will allow magnesium to pass through more easily. “Right now, we are crunching through around 2,000 different electrolytes,” she said recently.
Pellion Technologies in Cambridge, with several secret patents under its sleeve, is developing more-open electrode structures to help the magnesium ions to flow. Global electronics firms such as Toyota, LG, Samsung and Hitachi are also working on magnesium cells but the progress in their research is still kept secret.
Why Fluoro-organic chemicals?
Eversince a blanket ban was imposed on the use of Freon, halons and several CFC generating substances that deplete the ozone layer in the mid-1990s, the technology for substitutes like HFCs became the focus and the global players like Dupont and ICI have some closely kept secret technologies.
The IICT has focused on developing fluorine based chemicals and products and succeeded in the past to develop HFC-134a and FM-200 (a substitute for halons) which are under commercial production by SRF limited that produces about 4,000 tons of HFC-134a per annum worth Rs. 120 crore.