If batteries are the question, calcium could be the answer
Everybody needs energy. Our smartphones, computers and cars draw it from their batteries, which have different traits according to various materials they are made from. Currently, lithium-ion batteries represent a huge part of the market, but have technological limitations: it is not super abundant on Earth so its costly. And lithium batteries have low-density energy, which means they can store only a limited amount of energy, in the order of 200 Wh/kg (watt-hour per kilo). There might be another option. CARBAT (calcium Rechargeable BAttery Technology) is a European FET (Future and Emerging Technologies) project which involves four European research institutions. It aims to produce a proof of concept prototype for a new rechargeable high-energy density battery (over 650 Wh/kg) and assemble a full cell made of calcium – that’s right, the stuff that’s good for your bones and found in cows’ milk. “In battery fabrication it’s crucial to avoid critical materials that are not abundant and difficult to obtain, like lithium. On the contrary, calcium is the fifth most abundant element on Earth’s crust,” says Rosa Palacìn Peiró, a research professor at the Institute of Materials Science (ICMAB), Barcelona, where the CARBAT project is coordinated. “We are looking for a new kind of battery to be safe, cheap, sustainable, with high energy density and a long lifetime, to use it in all sorts of small or large-scale purposes,” says Palacìn. And it’s these large-scale applications that the project team is keeping in mind, from portable electronics up to electric vehicles and the grid. According to Palacìn, the best technology depends on the application you are targeting. “For smartphones, for example, the most important features are energy density, weight, and size: not the lifetime, since you probably expect to replace your phone after a few years. When you move to cars the situation is different: you care they last, even if they become more expensive. For the grid, the situation is even more complicated: batteries have to be cheap and to last a lot, their weight or size is not so important.” Why calcium? Calcium is a promising candidate for many reasons. “To understand the potential of calcium we have to take a step back. Inside a battery, two separate elements exchange electrons creating an electric current. In a rechargeable battery, this electrons’ flux is reversible. We are looking for a chemical compound that can give a certain flux of electrons, meaning a voltage, in the order of 4 V,” Palacìn explains. Scientists started to use lithium to produce batteries because its properties fit these purposes. But in the periodic table of elements, calcium and lithium occupy the same region, which means they share many chemical properties. But it doesn’t end here: in a calcium-based battery, it’s possible to store a higher amount of energy than a lithium one, because of calcium’s atomic structure: its atoms have two valence electrons, instead of just one for lithium. Along with its cheapness and abundance, these reasons make calcium one of the best candidates among all the chemical elements for making new batteries. Interdisciplinarity and sustainability The CARBAT project combines both experimental and computational methods. The plan is to study interesting calcium compounds to produce batteries and test them in laboratories. Firstly, theoretical physicists calculate which materials could be useful, adopting sophisticated quantum chemical numerical simulations: they investigate materials properties like crystalline structure and diffusion. Some materials will work, others won’t: it is hard to be sure at the very beginning. Read the full article on: http://www.fetfx.eu/story/batteries-question-calcium-answer/
Keywords
calcium, sustainable approach, battery technology, energy