p. 1 Capacitive Storage Science Chairs: Bruce Dunn and Yury Gogotsi Panelists: Michel Armand (France) Martin Bazant Ralph Brodd Andrew Burke Ranjan Dash John Ferraris Wesley Henderson Sam Jenekhe Katsumi Kaneko (Japan) Prashant Kumta Keryn Lian (Canada) Jeff Long John Miller Katsuhiko Naoi (Japan) Joel Schindall Bruno Scrosati (Italy) Patrice Simon (France) Henry White
Capacitive Storage Science. Chairs:Bruce Dunn and Yury Gogotsi Panelists: Michel Armand (France)Martin Bazant Ralph Brodd Andrew Burke Ranjan Dash John Ferraris Wesley Henderson Sam Jenekhe Katsumi Kaneko (Japan) Prashant Kumta - PowerPoint PPT Presentation
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Materials under extreme conditions: panel membersPanelists: Ralph Brodd Andrew Burke Ranjan Dash John Ferraris Wesley Henderson Sam Jenekhe p. * Supercapacitors are able to attain greater energy densities while still maintaining the high power density of conventional capacitors. Supercapacitors provide versatile solutions to a variety of emerging energy applications including harvesting and regenerating energy in transportation, industrial machinery, and storage of wind, light and vibrational energy. This is enabled by their sub-second response time. *Halper, M.S., & Ellenbogen, J.C., MITRE Nanosystems Group, March 2006 p. * EDLC and Pseudocapacitive Charge Storage Materials New strategies are needed to improve power and energy density of charge storage materials p. * Capacitor Systems and Devices High specific capacitance (100 F/g) and fast response time (~ 1 sec), but energy storage (2-10 wh/kg) not sufficient for many apps Long shelf (10 yr) and cycle (>1M) life Electrolytes for Capacitor Storage - aqueous (KOH, H2SO4) - corrosive, low voltage - organic (AN or PC and [Et4N][BF4] or [Et3MeN][BF4]) - low capacitance, toxicity and safety concerns Ionic Liquid Electrolytes - safer, but viscosity too high, conductivity too low for capacitor applications; improvements in properties from mixing with organic solvents Theory and Modeling Variety of approaches available – continuum, atomistic, ab initio; all have advantages and limitations p. * EDLC Charge Storage Materials: p. * EDLC Charge Storage Materials require understanding of pore structure and ion size influences on charge storage exploit both multiple charge storage mechanisms; combine double layer charging and pseudocapacitance to enhance energy and power densities Multifunctional Materials for Pseudocapacitors - The underlying charge-storage mechanisms - Opportunities for new directions in pseudocapacitor materials; single phase and multi-phase; nanostructure design of novel 3-D electrode architectures with tailored ion and electronic transport p. * Electrolytes for Capacitor Storage high voltage devices and revolutionary electrode combinations for capacitive storage; designed for capacitor storage - Electronic characteristics of carbon p. * Capacitor Systems and Devices Higher volumetric and gravimetric energy density with less than one second response time: Increased voltage, increased specific capacitance Improved device safety: Non-toxic, non-flammable electrolyte Regenerative Energy p. * Ralph Brodd Patrice Simon Ranjan Dash John Ferraris* Potential scientific impact Identify new strategies in which EDLC materials simultaneously exploit multiple charge storage mechanisms. Establish nanodimensional spatial control of the interface utilizing tethered functionalized molecular wires. Understand ion transport across interfaces EDLC systems will be rationally designed to revolutionize their utilization throughout the energy sector Develop new EDLC materials and architectures to dramatically boost energy and power densities Anticipate impact in decades p. * technology challenges New strategies are required to improve both power and energy density of EDLC materials Materials Synthesis Designed Architectures Modeling Input/Output Systematic guidelines are currently lacking for development of improved charge storage materials Materials utilizing only double layer charge storage Requires fundamental understanding of pore structure and “effective” ion size Requires new synthesis methodology Materials utilizing mixed charge storage Highly reversible redox-active functionalities on high surface area electrodes
Requires new synthesis methodology PRD Charge Storage Materials by Design Electrode materials with controlled pore size and surface area deposited in ordered geometries with intimate contact to current collectors Requires new synthesis methodology p. * Materials Synthesis Designed Architectures Development of new EDLC materials and architectures will dramatically boost: Power and Energy! Samson Jenekhe, sub-Panel lead New Research Directions Multifunctional architecture. Understand fundamental charge-storage mechanisms. Challenge: Simultaneously maximize both energy density and power density, and enhance lifetime. p. * = New opportunities for fundamental understanding and scientific advances. immobilized matrix non-toxic, biodegradable and/or recyclable Bulk Interfacial Fundamental lack of understanding: solvent-salt structure and physical properties. Bulk Properties Various conditions (temperature, concentration, …) Modelling and simulations Same approaches to explore interfacial and confined pore interactions differ from the bulk Performance Create a fundamental understanding of link between device performance and bulk/interfacial molecular interactions. p. * Potential scientific impact Knowledge will cross-over to battery systems The ideal electrolyte is an immobilized material produced from sustainable sources, which has high ionic conductivity; wide electrochemical, chemical and thermal stability; and is non toxic, biodegradable and/or renewable Explore new salts, new solvents, immobilizing matrices designed for capacitor storage Examine bulk properties (solvent-salt interactions), interfacial effects and behavior in confined spaces using measurements and modelling Understand effect of additives and impurities Enable high power technologies for load levelling, improve energy efficiency. Enable novel energy recovery applications, HEVs and PHEVs p. * Lawrence Pratt (Los Alamos) p. * Pros: Simple formulae, fit to experimental impedance spectra Cons: No nonlinear dynamics, microstructure, chemistry… Continuum models (Poisson-Nernst-Planck equations). Cons: point-like ions, mean-field approximation, no chemistry Atomistic models (Monte Carlo, molecular dynamics). Pros: molecular details, correlations, atomic mechanisms. Cons: <10,000 atoms, < 10ns, limited chemical reactions. Quantum models (ab initio quantum chemistry and DFT) Pros: Mechanisms and chemical reactions from first principles. Cons: <100 atoms, <ps, periodic boundary conditions VERY FEW MODELS HAVE BEEN APPLIED TO SUPERCAPACITORS p. * Derivation of nonlinear transmission line models for large voltages Modified Poisson-Nernst-Planck equations (steric effects, correlations…) Continuum models coupling charging to mechanics, energy dissipation,… Physics & chemistry of electrolytes Entrance of ions into nanopores -- desolvation energy and kinetics. Ion transport, wetting, surface activation, and chemical modification. Physics & chemistry of electrode materials Electron and ion transport in capacitor electrodes. Theory of capacitance of metal oxides and conducting polymers. Validation against simple model experiments Ordered arrays of monodisperse pores, single carbon nanotubes. Spectroscopic and x-ray analysis of ions and solvent in confined spaces p. * New multi-scale simulation methods Prediction of new materials p. * Andrew Burke New approaches for higher specific capacitance :electrode materials with improved morophology, uniform micropores, higher cell voltages, non-toxic, high conductivity, electrolytes, and low resistance separator materials Develop and use efficient, low cost and safe capacitive products to efficiently harvest and recover waste energy in applications that include electrical grid storage, renewable solar and wind energy, transportation, industrial stop-go machinery, mining, and microstorage of light, vibration, and motion energy Improved understanding of fundamental capacitive energy storage and optimization of a device as a system Improved material synthesis and processing Efficient, fast, distributed capacitive energy storage for a wide range of applications p. * Increased energy density Safe failure modes under extreme conditions Technologies to enable reduced device cost 30 MJ CAPACITOR STORAGE SYSTEM 30 MJ CAPACITOR STORAGE SYSTEM 0 200 400 600 800 1000 1200 1400 AC CNT MPC CAG C 60 NRC PANI/AC PEDT/AC PIThi PFDT PPy /AC MPFPT DAAQ PAn /CNT P3MT PEDT PAn RuO 2 /PAPPA RuO 2 (sol