January_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | J A N U A R Y 2 0 1 8 1 4 HIGH-CAPACITY ANODES ON A ROLL Scientists at The University of Texas at Austin (UT) developed a new class of anode materials that can dou- ble the charge capacity of lithium-ion battery anodes. The interdigitated eu- tectic alloy (IdEA) anode consists of a foil that is one-quarter the thickness and half the weight of current Li-ion battery anodes and is produced in just two simple steps. While recent efforts to improve Li-ion battery electrodes have focused on building new nanomateri- als atom by atom, the UT researchers discovered that a microme- ter-scale alloy anode could be transformed into a nano- material using traditional metallurgical alloying pro- cesses. To produce IdEA anodes, the team mechani- cally rolls eutectic metal al- loys into nanostructured me- tal foils. “The eutectic mi- crostructure forms naturally because of thermodynam- ics,” explains postdoctoral fellow Karl Kreder. “Then, you can reduce the microstruc- ture by rolling it, which is an extraordinarily cheap step to convert a microstructure into a nanostructure.” Since the 1990s, the primary an- ode for mass-produced rechargeable lithium-ion batteries has been graphite powder coated on a copper foil. The copper adds bulk without improving the battery’s power, and the anode re- quires a laborious manufacturingmeth- od. The manufacture of the IdEA anode omits the complicated slurry coating process, simplifying Li-ion battery pro- duction. utexas.edu . SOURCING ELECTRICITY FROM SALIVA A team of researchers from the University of Limerick, Ireland, discov- ered that putting pressure on a pro- tein found in common biological fluids produces electricity. Known as direct piezoelectricity, the ability to convert mechanical energy into electrical ener- gy is found in materials such as quartz, ENERGY TRENDS Researchers at the University of Limerick are studying new sources of piezoelectric- ity. Courtesy of Sean Curtin, TrueMedia. bone, andwood, but this is the first time it has been observed in crystals of lyso- zyme—a protein found in the whites of bird eggs, as well as in the tears, saliva, and milk of mammals. The extent of the piezoelectricity in lysozyme crystals is significant—on the same order of mag- nitude found in quartz—but unlike con- ventional piezoelectric energy harvest- ers, it is a biological, nontoxic material, easily extracted from natural sources. Possible applications include electroac- tive antimicrobial coatings for medical implants, or time-release mechanisms that administer drugs in the body using lysozyme as a pump that gleans energy from its surroundings. The discovery could also make an impact outside the biomedical field, offering a safer alter- native to typical piezoelectric energy harvesters, which often contain toxic elements such as lead. www.ul.ie . UT researchers in the Cockrell School of Engineering developed a new tin-aluminum anode (right), which exhibits twice the charge storage capacity of a typical copper-graphite anode (left). The DOE’s National Renewable Energy Labo- ratory (NREL), Golden, Colo., entered into a li- cense agreement with MicroLink Devices Inc., Niles, Ill., to commercialize NREL’s patented inverted metamorphic (IMM) multijunction III-V solar cells. IMM cell production reverses the order in which individual sub-cells are typically grown, increasing efficiency and lowering cost compared to traditional multijunction solar cells. nrel.gov, mldevices.com . BRIEFS Hydro-Québec, Canada, and the DOE’s Lawrence Berkeley National Laboratory, Calif., signed a memo- randum of understanding to assess the feasibility of creating a Québec Berkeley joint research center based near San Francisco. The center would develop next-generation battery materials, processes, and methodolo- gies and conduct manufacturing from pilot scale to pre-production levels, ultimately transferring the technol- ogies to battery manufacturers in Québec and California. www.hydroquebec.com , lbl.gov. High-efficiency IMM solar cell wa- fer. Courtesy of MicroLink Devices.