Doug Chrisey and Minoru Tomozawa Rensselaer Polytechnic Institute, Troy, NY Ram Katiyar, Reji Thomas, and Ashok Kumar University of Puerto Rico, Rio Piedras, Puerto Rico 1 518 928-9921, [email protected] • The five main forms of energy are: – Heat – Chemical – Electromagnetic – Nuclear – Mechanical • It is widely recognized that a serious limitation of green power sources (wind, solar) is their time profile is independent of demand • Energy storage is a key hurdle! Valve Regulated Lead Acid Battery System 10 10 EEStor, TX 9 10 Zenn Motors 8 10 7 10 6 10 5 10 4 10 3 Capacitors 10 Ultracapacitors Gasoline 2 10 Fuel 1 Batteries 10 Specific Power (W/Kg) Power Specific Cells 1 0.01 0.1 1 10 1 10 2 10 3 10 4 10 5 Specific Energy (W-hr/Kg) • Capacitance: C = εo εr A/d 2 2 • Energy: U = ½ CV = εo εr ½ Eb • The maximum energy stored requires a material system with very high dielectric constant and even more importantly a very high breakdown voltage – Increased surface area/volume improves the energy storage capacity • For capacitive energy storage, we need materials that will both withstand high electric fields (≥1 MV/cm) and maintain a very high dielectric constant Multi- Layer Ceramic Capacitor (MLCC) Terminations Inner Electrodes Ceramic Material • High electrical power (and energy density) • Long cycle life • Full system voltage • Integral to the structure – Allow application-specific geometries • Can be engineered for “graceful failure” – Fusing techniques • Solid state (NO CHEMISTRY) • Safe & environmentally friendly (low by-products) Pulsed Laser Deposition Technique : • Transfer of Pellet Stoichiometry • Reproducible • Deposition in Reactive Gases (Oxygen) • Rapid Production of Smooth Films Typical Deposition Conditions: • Temperature: RT - 950 °C • Pressure: 10-7 - 1 Torr • Deposition Rate: 0.1 - 10 Å/sec Vacuum Chamber UV Transparent Window 248 nm Excimer 1-2 J/ Laser cm2 Target Heated Substrate • Note density of PLD deposited thin film Pellet (target) Thin Film 0.2 µm MgO • Scalability Processing • Cost Commercial Composite Paste • Volumetrics • Gravimetrics Materials • Printing technologies for electronics • Glass viscosity decreases gradually with temperature – No solid-liquid transition, low temperature processing – Displace air from composite* • Most commercial glasses have dielectric constant of 4-10 • Addition of special components (BaO, TiO2, Nb2O3, and La2O3) increases the dielectric constant to 20-30 • Some glass compositions, can be turned into crystals by a controlled heat treatment, BaO-TiO2,-SiO2, and Ba2O3 system glass precipitates into BaTiO3 micro-crystals having a dielectric constant of 250-650 • The hermetic seal between glass and ceramic improves electric breakdown – Eliminate columnar grain boundary breakdown Ag Electrode Dielectric Al2O3 Substrate 20 µm PMN/Glass Ag PMN/Glass Ag Al2O3 • New materials – Dielectrics – Glass • Core-shell coating – Increase breakdown voltage – Increase insulation resistance – Lower thermal processing • Novel approach to improved capacitive energy/power density storage materials – Interesting composite material to study – Requires processing beyond screen printings current capability • Paradigm shift technology for energy storage • Market potential – Commercial and military applications – Entirely new systems .