Joseph P. Fellner

Polymer–ceramic composite protonic conductors

Abstract This paper reviews emerging polymer–ceramic composite protonic conductors in the context of their usefulness as membrane material for fuel cells. These composite protonic conductors appear to exhibit a superior propensity to retain water, enhanced conductivity, superior thermal and mechanical robustness, and reduced permeability of molecular species.

Lithium-ion testing for spacecraft applications

The Air Force Research Laboratory is developing lithium-ion batteries for low earth orbit (LEO) and geosynchronous earth orbit (GEO) spacecraft applications. As a part of this lithium-ion battery development effort, a testing program is underway to determine the viability of lithium-ion batteries for LEO/GEO applications. For LEO, lithium-ion battery cycle lifetimes of >60,000 cycles at 25% depth-of-discharge (DOD) are projected. For GEO, lifetimes of >14 years at 80% depth-of-discharge are projected.

Testing of Lithium-Ion 18650 Cells and Characterizing/Predicting Cell Performance

The performance of lithium-ion cells, as determined from in-house testing, is primarily a function of cell design/materials, charge/discharge rate, ambient temperature, and the number of charge/discharge cycles. Testing of lithium-ion 18650 cells was performed in order to characterize their behavior and to eventually predict the performance of lithium-ion cells of various sizes. AC impedance spectroscopy was used to determine the interfacial resistance of the lithium-ion cells as a function of temperature, state-of-charge, and cycle number. From these results, a nonisothermal mathematical model was developed and preliminary results are presented.

Rechargeable Lithium-Ion Based Batteries and Thermal Management for Airborne High Energy Electric Lasers

Abstract : Advances in the past decade of the energy and power densities of lithium-ion based batteries for hybrid electric vehicles and various consumer applications have been substantial. Rechargeable high rate lithium-ion batteries are now exceeding 6 kW/kg for short discharge times 160 Whr/kg at > 1.0 kW/kg). Some preliminary test data on a rechargeable lithium-ion polymer battery is presented. The use of high rate rechargeable lithium-ion batteries as a function of onboard power, electric laser power level, laser duty cycle, and total mission time is presented. A number of thermal management system configurations were examined to determine system level weight impacts. Lightweight configurations would need a regenerative thermal energy storage subsystem.

Thermodynamic equations for a model lithium-ion cell

Fundamentals of classical thermodynamics of electrochemical systems have been employed to formulate mathematical equations for a model lithium-ion and lithium electrode concentration cell. Equations have been formulated to determine the energetic lithium interaction coefficients in the solid lithium-ion electrode phases and the salt mean activity coefficient in the electrolytic solution used in the model cell from the measured experimental data. In addition, a mathematical equation to predict the open-circuit voltage of the model cell for the case of differing electrolyte compositions in its porous electrodes has been developed.

Development of a Distributed Integrated Modeling Environment to Study the Impact of Subsystem Performance on an Air Vehicle Design

The Distributed Analysis Modeling Environment (DAME) is a system developed for the AFRL Propulsion Directorate Power Division to serve as an integrated modeling environment. The focus of the system is to facilitate communication between researchers in different areas of expertise and to allow them to share models with a minimal amount of confusion and effort. As air vehicle design moves into the future, the trend toward increased integration of systems and subsystems with greater interdependence between these systems requires increased collaboration earlier and earlier in the design process. The earlier this integration can be taken into account and designed for, the better the end product will be. By combining modeling efforts earlier in the process through integrated system models or “systems of systems,” better decisions can be made of where the current technology is lacking and where increased research effort needs to be focused. The DAME is a tool that will allow the creation of integrated air vehicle models to enable researchers to take advantage of the current information and knowledge as it becomes available, rather than relying on potentially outdated models. In this paper, we detail the architecture of the DAME illustrating how it was implemented in a multi-user Windows Server environment utilizing Phoenix Integration’s ModelCenter and Analysis Server software. In addition, we present an integrated air vehicle model developed for the DAME environment. The model consists of a number of subsystem blocks, including engine, power and thermal management systems; linked to an air frame model developed in a program called FLight OPtimzation System (FLOPS). With the demonstration we illustrated connectivity between the different models through the DAME environment, both locally and across the network. I. Introduction S we move into the future, increased computational power and communication capabilities allow greater interaction and collaboration between researchers during all stages of development. One area where these capabilities are extremely valuable is during the initial design stages where new concepts and technologies are evaluated and tested for effectiveness and viability. In this domain, researchers in one area of expertise do not necessarily know what others are doing, other than basic requirements handed down from above. Furthermore, it is not always clear what is the best technology to move forward with. There is usually no concrete method to illustrate what technology is going to improve the end product and this was the case in our work with the air vehicle platform. Our objective was to provide a tool to assist in the evaluation process. We wanted to enable researchers from different backgrounds and research areas to share development and modeling work in order to evaluate how their particular technology would fit into the larger picture of the air vehicle platform. This allows more informed design decisions based on how a particular technology will impact the capabilities of the end product. To meet this