MURI Overview

1. MURI Overview Principal Investigators Rampi Ramprasad, Steve Boggs, Greg Sotzing (U. Connecticut) Curt Breneman (RPI) Mike Chung (Pennsylvania State U.) Sanat Kumar (Columbia U.) Bob Weiss (U. Akron)

2. Energy Storage Technologies High energy density capacitors 1 msec 1 sec • Capacitors are the only option for rapid discharge (e.g., pulsed power) applications 1000 sec Adapted from: Abruna, Kiya & Henderson, Physics Today, December 2008 issue

3. An Example: Pulsed Power • Rapid release of electrical energy from an energy storage capacitor allows power to be amplified many fold at modest average power consumption Food preservation Surface Processing Metal Forming, Joining Health Care Energy Delivery Systems Civilian Use Inertial Fusion Magnetic Fusion Nuclear Weapons Effects Simulations Department of Energy High Resolution Radar Kinetic Energy Weapons Weapons Simulation Radiation Weapons Beam Weapons Adapted from: Pulsed power technology and applications – North America, EPRI Report (1999) Defense Industry

4. Energy Density Trends • Metalized self-clearing capacitors have lead to the recent increases in energy density • While an order of magnitude improvements in energy density per decade has occurred in the past, a saturation is seen in recent years (at ~ 3-5 J/cc) Anderson, LINAC Proceedings (2006) Sarjeant et al, IEEE Proceedings (2001) Energy density (J/cc) MacDonald et al, IEEE Proceedings (2009)

5. Material Requirements • Large dielectric constant & low loss • High breakdown strength (extrinsic) • Large band gap & minimal defect states • Processability • Good mechanical, thermal & thermodynamic stability

6. The Current “Standard” • Biaxially-oriented polypropylene (BOPP) • Breakdown field of 700 V/mm (~ 1 cm2 for 10 mm films) • Highly crystalline • Low dielectric constant of ~ 2.2 • Polyvinyledeneflouride (PVDF) • Shares many of the above properties and has high dielectric constant (~ 12) • But exhibits ferroelectric loss (due to coercivity)

7. Current Approaches • Ferroelectric relaxors • Losses due to coercivity low rep rate applications • Multilayer films • Reduced correlated defect densities • Filled polymers • High filler volume fractions required • Modification of base polymer • Functional group & back bone

8. Overall Goals & Vision Also: How do physical disorder (e.g., different conformations, morphology, nanoscopic-macroscopic defects) and chemical disorder (e.g., chemical impurities, chemical defects) affect these properties? We seek polymers with • High dielectric constant (electronic, ionic, dipolar) • Moderate band gap • Large extrinsic breakdown • High stability (thermodynamic and thermal) • Goodprocessability • Good resistance to high field ageing Vision: If we can identify (or develop an intuition) for the fundamental (chemical) factors that control the dielectric constant, band gap, breakdown field and ageing, we can use this understanding to design synthesizable, stable polymeric capacitor dielectrics To achieve this, we need robust methodologies to determine the above properties for polymers spanning a large chemical space

9. Three Directions/Sub-projects Screening for new materials Exploration of the polymer chemical space High-throughput DFT calculations QSPR – Polymer Informatics Parallel synthesis work Ramprasad, Breneman, Sotzing Morphology & functionalization Morphology predictions Optimization of PP-OH polymers The role of OH functional groups Processing & characterization Kumar, Chung, Weiss (& Boggs, Ramprasad) Breakdown & aging Intrinsic breakdown Role of extrinsic factors (defects, disorder) Aging Multi-scale & statistical treatment Boggs, Ramprasad (& Kumar, Weiss)