Cathode material for batteries the safe bridge to e-mobility

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1 Innovation Spotlight Life Power P2 Andrew Silver Cathode material for batteries the safe bridge to e-mobility Issue: Summer 2012 Lithium iron phosphate is at present the only inherently safe cathode material for automobile batteries on the world market Alternative drive concepts are one of the major challenges of our time for the automotive industry. The fossil fuels are running out. Great hopes for the future now rest with electromobility. But the cathode materials like nickel and cobalt used to date are not only rare, expensive and health hazardous, they also present a considerable fire risk.»the novel cathode battery material lithium iron phosphate from Clariant based on readily available, low-cost iron phosphate has much greater thermal resistance and is therefore much safer,«says Dr. Klaus Brandt, Vice President Battery Materials at Clariant.»The material offers high performance, is rapidly chargeable and also tolerates heat and cold much better.«batteries made from this material offer excellent prospects of helping e-mobility to achieve its breakthrough. One great advantage of electric cars is their high efficiency: about 90 percent of the energy used is converted into movement, whereas in diesel and petrol engines 65 to 70 percent is wasted as useless heat. However, an electric vehicle currently costs about 10,000 euros more than a»normal«car which makes it simply too expensive. Moreover, the existing lithium ion technology provides ranges only of up to 100 to 150 kilometers. Experts therefore see hybrid vehicles dominating the e-mobility market in the next 10 to 15 years. Combining an electric motor with a combustion engine, they offer a convincing compromise between efficiency and eco-friendliness at an acceptable price. The plug-in hybrid needs batteries weighing about 35 kilograms (5 kwh) for its electric motor, thus offering a range of about 40 to 50 kilometers enough for more than 80 percent of all journeys. When the battery charge drops below a certain level, the vehicle automatically and almost imperceptibly switches over to a diesel or petrol engine. Clariant International Ltd Business Unit Catalysis & Energy Lenbachplatz München Germany Life Power P2 Innovation Spotlight Page 1

2 The new Life Power P2: safe, long-life, high-performance Many of these hybrid vehicles will be equipped with a novel battery that uses the innovative Life Power P2 from Clariant. This is a cathode material made of lithium iron phosphate. Life Power P2 is remarkable mainly for its superior material safety. The reason:»unlike the conventional, nickel and cobalt based cathode materials, lithium iron phosphate does not set free oxygen. Therefore lithium iron phosphate does not pose any explosion risk,«explains Professor John Goodenough, who discovered the material. Life Power P2 is found as a natural mineral both in the charged (heterosite) and the discharged state (triphylite) and is thus very stable. Another advantage of Life Power P2 is its long life. The estimated lifetime of a battery made with this material is about 4,000 charging cycles or 10 years. Even after these 4,000 charging and discharging cycles, it still achieves 80 percent of its initial capacity. A battery with Life Power P2 can be charged quickly about six minutes would be enough. With a storage capacity of up to 160 watt hours per kilogram, the material could be used for high energy applications. Moreover, lithium iron phosphate unlike conventional battery materials has a high temperature tolerance ranging from minus 30 C to plus 70 C. No problems are therefore to be expected either in a North Swedish winter or a hot summer s day in Southern Spain. Life Power P2 is also future-proof because lithium and iron are available in sufficient quantities, making them low-cost raw materials which, moreover unlike nickel and cobalt reduce environmental and health risks significantly. The Life Power P2 cathode material for batteries offers many advantages: the material lithium iron phosphate is rich in energy, rapidly chargeable, tolerates heat and cold better than conventional cathode materials, has a long lifetime and above all is safe. On discharging, the anode of the battery sheds electrons and lithium ions. The electrons move through the electric motor and power it. Life Power P2 Innovation Spotlight Page 2

3 New production plant for growing demand The first prototypes of batteries manufactured with Life Power P2 are already being used in electric cars. The material has also proved successful in OEM vehicles: since 2010, a German sports car manufacturer has been offering a starter battery with Life Power P2 as an optional feature. Further applications include batteries for electric scooters or bicycles. To position itself to meet the greatly increasing global demand, at the beginning of 2012 Clariant brought onstream a new production plant in Canada. This facility can produce 2,500 tons of lithium iron phosphate per year a quantity sufficient to equip up to 50,000 electric or 500,000 hybrid vehicles annually with these batteries. It is estimated that about 13 million vehicles with some type of electrified drive system will already be on the road worldwide in 2020, about 3 million of them purely electric. This novel cathode material with a safety profile significantly superior to that of conventional materials is Clariant s decisive contribution to future mobility with electric vehicles worldwide. As soon as the number of electric vehicles is large enough, they can even play an important role in the management of regenerative energies. Visionary concepts such as»vehicle to grid«see electric vehicles serving as energy stores for the public electricity grid. If too much electricity is generated, for example by unexpected wind energy, it can be buffered in the batteries of the electric vehicles. When the grid needs additional energy, the power generators simply source it from the e-mobiles. Initial field trials with this concept have already been conducted in Germany and Japan. New Life Power P2 production plant in Candiac, Canada In visionary concepts like»vehicle to grid«, plug-in hybrids and electric vehicles serve as energy stores for the public electricity grid. Life Power P2 Innovation Spotlight Page 3

4 Chemistry Explained The diversity of e-mobility In addition to automobiles propelled by combustion engines and electric energy, there are also the hybrids which combine both types of propulsion systems in many variants: Animation with sound available at: Micro-hybrids have a fuel-saving automatic start-stop system which switches the engine off at traffic lights and back on to continue driving. Most of them also have a system for recuperation (recovery) of brake energy. In the mild-hybrid variety, an electric drive supports the combustion engine to enhance its performance, for example when starting or accelerating. Purely electric driving is not possible with mild-hybrids. The full hybrid also has a combustion engine supported by an electric motor. Over short distances (about two to three kilometers), however, full hybrids can also drive purely electrically because the combustion engine produces the required electricity. Plug-in hybrids are usually propelled electrically and have a range of 40 to 50 kilometers on battery power alone. When the battery charge is no longer sufficient, a diesel or petrol powered combustion engine drives the car. The battery is charged from the public electricity grid. An electric vehicle with a range extender is driven by an electric motor and also has a small combustion engine to recharge the battery. This range extender increases the range to 300 to 400 kilometers. Unlike plug-in hybrids, in this case the combustion engine does not drive the vehicle directly. Purely electric vehicles, finally, are driven only by electricity and currently have a range of 100 to 150 kilometers. They have a large battery usually integrated in the vehicle floor. The battery is charged at special electric vehicle charging stations. Life Power P2 Innovation Spotlight Page 4

5 Chemistry explained How a rechargeable battery works A rechargeable battery also known as an accumulator or storage battery works according to a simple principle: during charging, electrical energy is converted to chemical energy, and the entire process is reversed when the battery is discharged. The lithium ion accumulator has two electrodes the cathode and the anode, a separator and an electrolyte. As cathode material, besides the conventional metal oxides cobalt, manganese or nickel, the innovative lithium iron phosphate (LiFePO4), Life Power P2, is used. The anode usually consists of graphite or lithium titanate (Li4Ti5O12). Animation with sound available at: The principle is based on the difference in the number of electrons which is lower on one side and higher on the other side and which attempt to achieve a balance. On discharging i.e. when driving a vehicle the anode, the negative pole, sheds an electron and a lithium ion. For current to flow, however, the electron has to take a detour through the electric motor instead of traveling directly to the cathode, the positive pole. This is prevented by the separator which isolates the two electrodes and simultaneously prevents a short circuit. The separator allows only lithium ions to pass which migrate through the electrolyte to the cathode where they are taken up by the lithium iron phosphate. While charging, this process is reversed and the electrons are propelled from the cathode to the anode by an external force the electric motor during which lithium ions are released which flow back through the separator. In the lithium ion battery, therefore, the lithium ions travel back and forward from one electrode to the other. With the Life Power P2 cathode material, this process can be repeated about 4,000 times. If more cycles are necessary, as many as 10,000 cycles can be achieved with the anode material lithium titanate from Clariant, providing a significantly longer lifetime of up to 20 years compared to the traditionally used graphite. Informative Links Life Power P2 Innovation Spotlight Page 5