EAGER: Layered Nanotube Composite Electrodes for Energy Storage

Yale University, New Haven CT

Investigators

Abstract

0938842 Lutkenhaus This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This research will investigate electrochemical processes occurring within proof of concept nanostructured electrodes created using an integrated approach consisting of layer-by-layer (LbL) assembly technique and nanotemplating. The proof-of-concept electrodes will contain annular layers of lithium battery intercalation cathode material, ion conducting polymer, and electron conducting polymer within a nanotube geometry. LbL assembly is the sequential adsorption of oppositely charged species to a substrate (in this case, a nanoporous template). The combined processing techniques impart a hierarchical structure where materials properties and three-dimensional geometry at multiple length scales can be finely controlled. Such a design is expected to produce shorter reaction-diffusion path-lengths, increased surface area, and increased electrode utilization relative to planar LbL film electrodes. The resulting nanostructured cathode will represent a breakthrough in specific energy, power density, and stability relative to conventional, planar electrodes. Thus, the research will contribute not only to scientific understanding of electrochemical processes in nanostructured electrodes, but to the continued development of effective energy storage media. Intellectual Merit: Smaller, lighter, energy dense power sources are desired for small-scale applications such as portable electronics and miroelectromechanical systems. A great challenge is to create a power source smaller than the device to be powered; this is especially important as the application approaches the micro- to nanoscale. A long term goal of the PI?s lab is to create micro- to nanoscale power sources from the directed assembly of hard and soft materials. As a preliminary effort, this EAGER project targets the creation of a proof-of-concept cathode, where nanotube arrays act as small-scale cathode ?forests?. Initial challenges include the directed adsorption of materials in the confined dimensions of a template pore, and the understanding of electrochemical reaction-diffusion processes at the nanotube surfaces. Success of this project paves the way for the creation of a nanotube battery, where each component (anode, electrolyte, and cathode) is sequentially deposited using LbL assembly and nanotemplating. The broader impact of the research is the creation of a new class of hierarchically manufactured materials, where control over multiple length scales is demonstrated. The so-called ?layered nanotubes? will contain annular layers of intimately interfaced materials, each performing a designated function (lithium intercalation, ion conduction, electron conduction, mechanical reinforcement). This concept can be extended beyond electrochemistry to reaction/separation processes, where one layer could catalyze a reaction and the next layer could separate the products, or to drug delivery where each annular layer could deliver a specific drug or bind to a specific receptor site. The ?big picture? goal of the PI is to create and use multi-layered multifunctional nanostructures that can perform a sequential set of tasks at the micro- to nanoscale. By applying this system to lithium-ion batteries, the research aims to address the expanding and varied needs of effective energy media for ever-smaller applications. The results of this work will be broadly disseminated through journal articles and conference proceedings. A simplified version of the system described above will be integrated into classroom and outreach activities for teaching students about electrochemistry fundamentals and principles.