p. 1 1 capacitive storage science chairs:bruce dunn and yury gogotsi panelists: michel armand...
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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
p. 2
Capacitive Storage Science
Supercapacitors bridge between batteries and conventional capacitors
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
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Capacitive Storage Science: technology challenges
Capacitor Systems and Devices- Increased energy density
- Longer life cells- Self-balancing- Cost
Electrolytes for Capacitor Storage
Design electrolytes for EC operation: high ionic conductivity; wide electrochemical window, chemical and thermal stability; non toxic,
biodegradable and/or renewable
EDLC and Pseudocapacitive Charge Storage Materials New strategies are needed to improve power and energy density of
charge storage materials
30 MJ CAPACITOR STORAGE SYSTEM30 MJ CAPACITOR STORAGE SYSTEM
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Capacitive Storage Science: current status
Capacitor Systems and DevicesHigh specific capacitance (100 F/g) and fast response time (~ 1 sec), but energy storage (2-10 wh/kg) not sufficient for many appsLong shelf (10 yr) and cycle (>1M) life
Electrolytes for Capacitor StorageTraditional Electrolytes:
- 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
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Capacitive Storage Science: current status
0
200
400
600
800
1000
1200
1400
AC
CNT
MPC CAGC60 NRC
PANI/AC
PEDT/AC
PIThi
PFDT
PPy/AC
MPFPT
DAAQ
PAn/CNT
P3MTPEDT
PAn
RuO2/PAPPA
RuO2(sol-gel)
RuO2(ED)
RuO2(sol-gel)RuO2/ACRuO2/AC
RuO2(ESD)RuO2/CB
RuO2/CNTRuO2/ACRuO2/CXG
RuO2/MPCRuO2/ACNiO SnO2 / Fe3O4
MnOx
NiO/RuO2
MnO2
NiO
MnO2
Ir0.3Mn0.7O2
MnO2
Spe
cific
Cap
acita
nce
/ F
g-1
Carbons Polymers Metal Oxides RuO20
200
400
600
800
1000
1200
1400
0
200
400
600
800
1000
1200
1400
AC
CNT
MPC CAGC60 NRC
PANI/AC
PEDT/AC
PIThi
PFDT
PPy/AC
MPFPT
DAAQ
PAn/CNT
P3MTPEDT
PAn
RuO2/PAPPA
RuO2(sol-gel)
RuO2(ED)
RuO2(sol-gel)RuO2/ACRuO2/AC
RuO2(ESD)RuO2/CB
RuO2/CNTRuO2/ACRuO2/CXG
RuO2/MPCRuO2/ACNiO SnO2 / Fe3O4
MnOx
NiO/RuO2
MnO2
NiO
MnO2
Ir0.3Mn0.7O2
MnO2
Spe
cific
Cap
acita
nce
/ F
g-1
Carbons Polymers Metal Oxides RuO2
EDLC Charge Storage Materials: Majority of present day EDLC devices are based on activated carbon
Multifunctional Materials for Pseudocapacitors:Pseudocapacitive materials generally exhibit higher specific capacitance and energy density relative to high-surface-area carbon
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Capacitive Storage Science: basic-science challenges, opportunities, and needs
EDLC Charge Storage Materials- Materials utilizing only double layer storage
require understanding of pore structure and ion size influences on charge storage
- Identify new strategies in which EDLC materials 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 for pseudocapacitive materials are not well understood.
- 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
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Capacitive Storage Science: basic-science challenges, opportunities, and needs
Electrolytes for Capacitor Storage- Create new electrolyte formulations enabling
high voltage devices and revolutionary electrode combinations for capacitive storage;
- New salts, new solvents, immobilizing matrices designed for capacitor storage
Theory and Modeling- Structure and dynamics of solvent
and ions in non-polar nanopores.
- Electronic characteristics of carbon
and MOx electrodes.
- Validation against simple model experiments.
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Capacitive Storage Science: basic-science challenges, opportunities, and needs
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 Capture using Capacitors:
40% of energy is recovered
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Capacitive Storage Science: Materials for Electrical Double Layer Capacitors
Ralph Brodd Patrice Simon
Ranjan Dash John Ferraris*
* Subpanel leader
Subpanel members
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Potential scientific impact
Potential impact on EES
Summary of research directionScientific challenges
Capacitive Storage Science: PRD: Charge Storage Materials by Design
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
Enhance EDLC materials performance by creating designed architectures, surface functionality, tailored porosity, and thin conformal films, matched synergistically with appropriate electrolyte systems.
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Capacitive Storage Science: Materials for Electrical Double Layer Capacitors technology challenges
New strategies are required to improve both power and energy density of EDLC materials
Materials Synthesis
Designed Architectures
Modeling Input/Output
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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
Capacitive Storage Science: PRD Charge Storage Materials by Design
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Materials utilizing mixed charge storage
Highly reversible redox-active functionalities on high surface area electrodes
Thin dielectric or conducting coatings on ordered high surface area materials
Surfaces decorated with nanowires having active functionality
Requires new synthesis methodology
Capacitive Storage Science: PRD Charge Storage Materials by Design
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Capacitive Storage Science: 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
Materials utilizing synthetic ordered architectures
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Capacitive Storage Science: PRD: Charge Storage Materials by Design
Materials Synthesis
Designed Architectures
Development of new EDLC materials and architectures will dramatically boost:
Power and Energy!
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Capacitive Storage Science: Sub-panel on Materials for Pseudocapacitors and Hybrid Devices
Samson Jenekhe, sub-Panel lead
Prashant Kumta
Jeffrey Long
Katsuhiko Naoi
John Newman
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Capacitive Storage Science: PRD: Multifunctional Materials for Pseudocapacitors and Hybrid Devices
New Research Directions
•Investigation of new materialsbeyond metal oxides•Multifunctional architecture.•Rational design of materials and structures.•Understand fundamental charge-storage mechanisms.
Motivation: Pseudocapacitors enable energy densities significantly higher than for double-layer capacitors.
Challenge: Simultaneously maximize both energy density and power density, and enhance lifetime.
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Capacitive Storage Science: Multifunctional Materials for Pseudocapacitors and Hybrid Devices
= New opportunities for fundamental understanding and scientific advances.
New Materials + Architectures
Vanadium Nitride, VN nanocrystals
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Capacitive Storage Science: Electrolyte subpanel members
Keryn Lian*
Bruno Scrosati
Michel Armand
Wesley Henderson
* Subpanel lead
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Capacitive Storage Science: technology challenges
Aqueous and non-aqueous electrolytes with the following properties:
■ immobilized matrix■ produced from sustainable sources■ high ionic conductivity■ chemical and thermal stability■ large electrochemical stability window (>5V)■ non-toxic, biodegradable and/or recyclable■ exceptional performance with long device lifetime
Bulk
Interfacial Device Performance
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Capacitive Storage Science: PRD Topic: Molecular Understanding of Electrolyte Interactions in Capacitor ScienceFundamental lack of understanding: solvent-salt structure and physical
properties.
Bulk Properties Diverse materials (salt, solvent, immobilizing matrices, …) Various conditions (temperature, concentration, …) Experimental measurements (phase diagrams, spectroscopy, …) Modelling and simulations
Interfacial Effects 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.
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Potential scientific impact Potential impact on EES
Summary of research directionScientific challenges
Capacitive Storage Science: PRD Topic: Molecular Understanding of Electrolyte Interactions in Capacitor Science
Understanding the mechanism of charging and degradation
New electrolyte formulations enabling revolutionary novel electrochemical capacitor devices
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
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Capacitive Storage Science: Theory & Modeling sub-panel members
Martin Bazant (MIT), sub-panel lead
Katsumi Kaneko (Chiba University, Japan)
Lawrence Pratt (Los Alamos)
Henry White (University of Utah)
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Capacitive Storage Science: current status of modeling
Equivalent circuit models (transmission-line models) Pros: Simple formulae, fit to experimental impedance spectra Cons: No nonlinear dynamics, microstructure, chemistry…
Continuum models (Poisson-Nernst-Planck equations). Pros: analytical insight, nonlinear, microstucture 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
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Mathematical theory (beyond equivalent circuits) 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 Develop accurate models for MD and MC simulations 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
Capacitive Storage Science: priority research directions for modeling
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Potential scientific impact Potential impact on EES
Summary of research directionScientific challenges
Capacitive Storage Science: Theory and Modeling
Continuum, atomistic, & quantum models
Fundamental understanding and modeling tools for supercapacitors across all length and time scales.
•Discovery of new physical phenomena- nanopore behavior, nonlinear dynamics…
•New models at system, microstructure, molecular, and electronic levels
•New multi-scale simulation methods
• Models for rational design of EES systems
• Prediction of new materials
• Increased power and energy density
• Time scale: decades to centuries
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Capacitive Storage Science: Sub-panel members: Capacitive Devices and Systems
Andrew Burke
John R. Miller
Pat Moseley
Joel Schindall
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Potential scientific impact Potential impact on EES
Summary of research directionScientific challenges
Capacitive Storage Science: Capacitive devices and systems
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
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Increased energy density
Longer life at high voltages and temperatures
Self-balancing series strings of cells without electronics
Safe failure modes under extreme conditions
Technologies to enable reduced device cost
Capacitive Storage Science: PRDs: Basic science of Capacitive Devices and Systems