Subodh Mhaisalkar Nanyang Technological University
Krishna Shenai University of Toledo
Gehan Amaratunga University of Cambridge
Arokia Nathan University College London
F1: New Energy Systems I
Monday AM, November 28, 2011
Back Bay C (Sheraton)
11:00 AM - **F1.1
Solid State Paper Battery.
Rodrigo Martins 1 2 , Elvira Fortunato 1 2 , José Inácio Martins 3 , Isabel Maria Ferreira 1 2 Show Abstract
1 Materials science Department, FCTUNL, Caparica Portugal, 2 CEMOP, Uninova, Caparica Portugal, 3 Eng. Quimica, FEUP, Porto Portugal
R. Martins, E. Fortunato, B. Brás, J.I. Martins, I. FerreiraThe possibility of producing flexible, recyclable, non-toxic, and light weight electronic devices made with and on paper is highly appealing. Furthermore, the low-cost production of these devices renders them economically feasible and, since cellulose is one of the most abundant biopolymers on Earth, they are also ecologically disposable. Powering, in an integrated manner paper electronic devices is a challenging goal. This demand could be fulfilled by producing thin film batteries into the same paper device substrate. By doing so, self-sustained and energetic autonomy is achieved while keeping it mobile, light and flexible. Although cellulose based batteries have been reported, the need of liquid electrolytes, impregnation of salt solutions or CNTs paper functionalization, limits its integration into the substrate of the paper transistors. In this work we produce dry paper batteries where papers is simultaneously used as electrolyte and membrane. Moreover, the paper battery is rechargeable by expositing it to water vapor.Likely in most batteries, in this dry battery the voltage is dependent on the chosen pair of metal electrodes, while the current density depends on the thickness of the paper electrolyte, its porosity, bulk contents, density and composition of fibers. Thereafter, by actuating in any of these characteristics, the output of the device can be optimized to a specific purpose. All solid state batteries with Al/paper/LiAlF4/WO3/V2O5/GZO (zinc oxide doped with gallium oxide) structure show a voltage of 1.4 V. Moreover, paper reached in P2O5, SiO2, Al2O3 and CaO components contain higher concentration of ions (Na+, Cl-, SO4 (-2), PO4 (-3) , and Ca2+) leading to higher current density.
11:30 AM - F1.2
A Thin-Film Battery Architecture Generated by Rapid Layer-by-Layer Assembly.
Forrest Gittleson 1 , Gustave Macheras 1 , Andre Taylor 1 Show Abstract
1 Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, United States
Lithium polymer technology represents the current energy density leader in commercially available lithium batteries. Despite the literal and figurative flexibility of this technology and its wide potential for application in cell phones, laptops, and other portable devices, the processes for design, assembly, and packaging of lithium-ion polymer cells are limited. We demonstrate a versatile technique for thin-film assembly that is used to produce layer-by-layer (LbL) films of active lithium battery materials. The spin-spray layer-by-layer (SSLbL) method allows rapid assembly of polymer-composite films with nano-level control and superior uniformity when compared to films produced by the common dip-coating method of LbL assembly. Thin films of several different polyelectrolyte systems with incorporated carbon nanotubes (CNT) were analyzed for charge/discharge capacity, cycling stability, ion conductivity, and electrical conductivity. We found that when the amount of active material (CNT) is controlled in these electrode films, the selection of the polymer matrix, as well as the LbL deposition parameters, has a significant effect on cycle stability and capacity. Tuning the ion conductivity of the polymer matrix by varying layer thickness and polymer blend content is an essential tool in optimizing electrode performance. Polymer electrolyte films were also assembled by the SSLbL method, demonstrating the effect of salt content, polymer choice, and polymer concentration on ion conductivity. These findings showcase a novel method of developing improved solid polymer electrolytes, which have been shown to exhibit a better safety profile than more common polymer-gel electrolytes. Patterning of functional battery materials using the SSLbL technique is also demonstrated and has particular relevance in the design of micro-scale or flexible batteries.
11:45 AM - F1.3
Highly Flexible Printed Batteries: Properties, Processing and Performance.
Abhinav Gaikwad 1 , Daniel Steingart 1 Show Abstract
1 CUNY Energy Institute, The City College of New York, New York, New York, United States
Direct write printing technologies can be used to print battery electrodes of desired capacity and form factor. Printed batteries have advantages such as low cost, substrate as packaging, and high material yield. Moreover the battery can be tailored specifically to niche device requirements in ways traditional battery cannot. However, even printed batteries, as they are now are not sufficient for fully flexible electronics. Existing battery electrodes, printed or otherwise, are formulated with stiff, non-compliant components and brittle composites, making these electrodes fundamentally at odds with the mechanical perturbations expected during the use cycle of a flexible device . Thus, a functional, flexible printed battery requires a wholesale reconsideration of the traditional components and optimization methods.To examine this coupling, we have studied the electrochemical and mechanical performance of a printed silver micro-battery in a microfluidic device. We observed that discharge of the battery decreased when the electrode was under a shear stress and different phases of silver oxide had different mechanical strength. We also demonstrated a technique to make highly flexible battery electrodes by embedded the electroactive material inside a mesh support. The mesh absorbed the stress during bending.In present work we extend these methods to secondary battery systems while also linking ink rheology and printing parameters to the final battery. From the rheological property of the ink and the desired electrode dimensions the necessary printing parameters are shown to be predictable through basic continuum fluid dynamics modeling. Beyond the mechanics of deposition, we examine the mechanical-electrochemical behavior of our composite through a combinatorial study of binder, solvent, and active materials. In this we relate the drop in discharge capacity of the battery during flexing with electrode cracking and also present techniques such as EIS to predict the drop in discharge capacity with bending radius.
12:00 PM - F1.4
Reverse Electrowetting – A New Approach to High-Power Harvesting of Mechanical Energy.
Tom Krupenkin 1 , J. Ashley Taylor 1 , Supone Manakasettharn 1 Show Abstract
1 , University of Wisconsin - Madison, Madison, Wisconsin, United States
Over the last decade electrical batteries have emerged as a critical bottleneck in portable electronics development. High-power mechanical energy harvesting can potentially provide a valuable alternative to the use of batteries, but until now, its adoption has been hampered by the lack of an efficient mechanical-to-electrical energy conversion technology. In this talk a novel mechanical-to-electrical energy conversion method is discussed. This method is uniquely suited for high-power energy harvesting from a wide variety of previously inaccessible environmental mechanical energy sources, including human locomotion. The method is based on reverse electrowetting (REWOD) – a novel microfluidic phenomenon. Electrical energy generation is achieved through the interaction of arrays of moving microscopic liquid droplets with novel nanometer-thick multilayer dielectric films. Advantages of this process include the production of very high power densities, up to 1 KW per sq. m; the ability to directly utilize a very broad range of mechanical forces and displacements; and the ability to directly output a broad range of currents and voltages, from several volts to tens of volts. We hope that the REWOD-based energy harvesting can provide a novel technology platform for a broad range of new electronic products and enable reduction of cost, pollution, and other problems associated with the wide-spread battery use.
12:15 PM - F1.5
Stretchable Electrochemical Capacitors: Power for Stretchable Electronics.
Pritesh Hiralal 1 2 , Darryl Cotton 2 , Yinglin Liu 2 , Piers Andrew 2 , Gehan Amaratunga 1 Show Abstract
1 Engineering, University of Cambridge, Cambridge United Kingdom, 2 Nokia Research Center, Nokia, Cambridge United Kingdom
Stretchable electronics allows a number of uses and tolerances which are not possible with rigid or even flexible electronics (flexible electronics or printed circuit boards). Whereas application of flexible electronics is limited to flat substrates, stretchable electronics can cover moving parts, such as joints in robotic elements, and also curved substrates or unusual materials such as silk, paper, leather etc. However, under stretch conditions, materials face large strains and changes in shape. Components need to be fabricated which can tolerate and function under these conditions. Substrate and interconnects should be made stretchable rather than flexible or rigid. Extensive efforts to advance stretchable electronics, including the integration of active components like diodes, transistors and integrated circuits, as well as sensors and actuators have been made. Here we demonstrate a power source, electrochemical capacitors, constructed onto copper substrates patterned on an elastomer, which withstand stretch ratios up to 100% before failure and deliver capacitances of 150mF/cm2. The fabrication process allows for mass production with roll-to-roll techniques based on printing and laminating. With stretchable interconnects, the electrochemical capacitors allow the construction of self-powered stretchable electronic devices.
12:30 PM - **F1.6
Low Voltage and Flexible Electronics Based on Graphene.
Manish Chhowalla 1 Show Abstract
1 , Rutgers University, Highland Park, New Jersey, United States
Graphene and its derivatives possess unique properties that make them attractive for both nano- and macro-electronics. Gaphene holds tremendous promise for large area electronics where the research is motivated by enabling low cost and flexible devices. Flexible displays, radio-frequency identification tags and large-surface sensor networks are examples of some macro-electronic devices that would benefit from the use of high mobility graphene as the channel material. Although the use of lightweight substrates and flexible active materials are useful towards making large area electronics technology portable, it is also necessary to develop devices that provide minimal power dissipation that can be powered by small batteries or by near-field radio-frequency coupling. In this presentation, I will present results of our work demonstrating how graph