0205SAE Batteries FuelCells Webinar comsol

8/19/2019 0205SAE Batteries FuelCells Webinar comsol

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Modeling Batteries and Fuel Cellsusing COMSOL Multiphysics®

Edmund Dickinson

Application EngineerCOMSOL

© Copyright 2015 COMSOL. COMSOL, COMSOL Multiphysics, Capture the Concept, COMSOL Desktop, COMSOL Server,

and LiveLink are either registered trademarks or trademarks of COMSOL AB. All other trademarks are the property of

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Agenda

• Why Simulate Batteries and Fuel Cells?

– Simulating with COMSOL Multiphysics®

• The Multiphysics Approach

• Batteries and Fuel Cells Modeling

• Live Demo

– Lithium-Ion Battery

– Q&A Session

– How To

– Try COMSOL Multiphysics

– Contact Us

This simulation of a lithium-ion battery pack


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Why Simulate Batteries and Fuel Cells?

• Conception and understanding

– Enables innovation

• Design and optimization – Achieve the highest possible

performance

• Testing and verification

– Virtual testing is much faster

than testing physical prototypes

Simulation of a high-temperature PEM fuel cell


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Simulating with COMSOL Multiphysics®

• Electrical, mechanical, fluid,and chemical simulations

• Multiphysics – Include andcouple all relevant physicaleffects

• Single physics in one integrated

environment

• Cross-disciplinary productdevelopment


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All Industries Benefit from Multiphysics Simulation


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Model Builder

Provides instant

access to any of the

model settings

• CAD/Geometry

• Materials

• Physics

• Mesh

• Solve

• Results

A Complete Simulation Environment

Graphics Window

Ultrafast graphic presentation,

stunning visualization

COMSOL Desktop®

Straightforward to

use, the Desktop

gives insight and full

control over the

modeling process


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Product Suite – COMSOL 5.0


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Application Design Tools

Simulation Application

Any COMSOL model can be turned into an

app with its own interface using the tools

provided in the Application Builder

Application Builder

Provides all the tools

needed to build andrun simulation apps

• Form Editor

• Method Editor


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Run Applications

Simulation Apps

They can be run in a COMSOL® Client for

Windows® and major web browsers

COMSOL Server™

The engine for

running COMSOL

apps and the hub for

controlling their

deployment,

distribution, and use

Microsoft and Windows are either registered trademarks or trademarks

of Microsoft Corporation in the United States and/or other countries.


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The Batteries & Fuel Cells Module

• Specialized tool

– Models and simulates all major types of battery and fuel cell

applications

• Ease-of-use

– Pre-built descriptions of charge and mass transfer in electrolyte

– Straightforward description of porous materials

– Support for mass transport and reaction in solids, liquids, and

gas mixtures

• Multiphysics

– Include fluid flow and heat transfer together with

electrochemical reactions


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Batteries

• Lithium-ion

• Nickel-metal hydride and nickel-cadmium

• Lead-acid

• Flow batteries and novel technologies.

• Generate charge-discharge curves under different

loading cycles

• Predict thermal behaviour and optimize cooling

strategy

• Study parasitic loss and capacity fade mechanisms

• Multiphysics:

– charge transfer

– mass transfer (e.g. of Li+)

– intercalation reactions at porous electrodes

– heat transfer

Simulation of an air-cooled cylindrical battery

showing temperature and air flow velocity.


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Fuel Cells

• Proton exchange membrane (PEMFC),

high and low temperature

• Solid oxide (SOFC)

• Direct methanol and carbonate

• Generate polarization curves

• Identify rate-limiting processes

• Optimize design to maximize efficiency

or thermal properties

• Multiphysics:

– charge transfer in membrane

– mass transfer in gas diffusion layers (GDLs)

– fluid flow in gas channels and GDLs

Mass transport of hydrogen and oxygen in a PEM fuel cell.


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Poll Question

Are you primarily interested in simulating:

• Fuel Cells• Lithium-Ion Batteries

• Other Batteries

•

Other Electrochemical Cells• None of the above


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Multiple Processes = Multiphysics

• Charge balances in the electrodes

and electrolyte

– Currents, voltages, and current

distribution

• Material balances

– Concentrations and mass fluxes

• Momentum balances

– Influence of fluid flow

• Energy balance

– Influence of heating and temperature


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The Electrochemical Cell

• An electrochemical cell consists of an electrolyte in contact with two or

more electrodes.

• In a discharging battery or fuel cell, power is extracted from a favorable

chemical reaction. – when recharging a battery, power is input to drive a chemical reaction.

• Only total current and voltage are measurable, but current density may not

be spatially uniform.

electrochemical cell A

VIcell

V cell


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Electrolyte – Conduction of Ions

• A metal conducts current by transport of electrons.

• In electrochemistry, we are interested in materials (“electrolyte”)

that conduct current by transport of ions.

• For example, if we dissolve table salt (NaCl) in water:

Na+

Na+

Na+

Cl-

Cl-

Cl-

direction of formal current density, J

anode cathode


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Sources of Loss

• Resistive: “ohmic drop” – loss due to the resistivity of the electrolyte to

the passage of current.

• Kinetic: loss due to the finite rate of electrochemical reaction at the

electrode-electrolyte interface.

• Mass transfer: “loss” (limited current) due to the finite rate of transport

of reactants to the electrode-electrolyte interface.

• So-called primary, secondary and tertiary currentdistributionsconsider

each successive mechanism of loss.

• Nonideality (nonlinearity) in the current-voltage relationship.


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The PEMFC and the Li-Ion Battery


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The Electrochemistry Interfaces

Core interfaces

Application-specific

interfaces


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• Solve for currents in electrode and electrolyte domains.

• The current obeys Ohm’s law: specify the conductivity.

• Specify reaction currents at electrode-electrolyte interfaces.

• Starting assumption: current densities do not depend on concentration of

reactants (negligible depletion).

Secondary Current Distribution


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Other Charge Transfer Interfaces

Primary Current Distribution

• Assumes that all electrolysis

reactions are at equilibrium.

• No electrode kinetics: only ohmic

drop influences current-potential

relationship.

Tertiary Current Distribution

Nernst-Planck

• Solves chemical species transport for

all charge-carrying ions (Nernst-

Planck equations).

• Needed when current densities are

significant enough to cause ion

depletion.

• Useful for complex chemistries.


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Batteries and Fuel Cells

• Battery Interfaces for somebattery types:

– predefined coupling ofSecondary Current Distribution

with concentrated speciestransport of the chargecarriers (e.g. Li+)

• For fuel cells, couple

Secondary Current

Distribution to Fluid Flowand Chemical SpeciesTransport interfaces


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Studies

• Stationary: steady-state (DC)

current-voltage relation in a cell

• Time-Dependent: dynamic current-

voltage relation in a cell

• AC Impedance: for electrochemical

impedance spectroscopy


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Li-ion Battery Discharge Curve

• Simple 1D example including:

– Electric current through the

electrodes

– Ionic current in the solvent both in

the separator and permeating the

porous electrodes

– Mass transport of Li+ in the

electrolyte, including concentration

effects on electrical conductivity andcharge/discharge current distribution

– Intercalation and solid diffusion of Li

in the spherical particles that form

the electrodes

Cell voltage during a transient load cycle.


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Li-ion Battery Concentration Profile

• Visualize the dischargeand recharge process:

– change in free Li+concentration in theelectrolyte

–

change in intercalated Liconcentration at thesurface of the particles ineach electrode

Free electrolyte and inserted Li concentration during recharge after

one 2000 s 1C discharge cycle.


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Li-ion Battery: Comparative Study

• A parametric sweep isused to solve for thedischarge behavior

under different appliedcurrents.

• Compare:

–

different temperatures – different loading

concentrations

– different electrolytes

Discharge curves relating cell voltage to state of charge for different

discharge rates (for varying drawn current).


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Li-Ion Battery Drive Cycle

• Battery model is loaded with a

realistic drive cycle for a hybrid

vehicle.

• Output such as voltage and

state-of-charge can be traced.

– Evaluate battery performance.

• Temperature is computed with

a coupled heat transfer analysis.

– Determine factors of safety.

Temperature and state-of-charge of a Li-ion battery

during a realistic drive cycle for a hybrid vehicle.


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Capacity Fade of a Li-ion Battery

• Extended battery model to

include:

– parasitic side reactions occurring in the

cathode cause capacity fade

– growth and increased resistance of the solid-

electrolyte interphase (SEI) layer with repeated

cycling

• Events interface used to define a

voltage-controlled charge-discharge

cycle

– even when the exact times of switching from

charge to discharge are not known without

solving the model, the system electronics can

be solved together with the battery chemistry

Evolution of cell voltage vs cycle time for successive

discharges of a Li-ion battery subject to side reactions and

increased SEI resistance.


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Spirally Wound Battery

• 2D analysis of a spirally

wound “jelly-roll” battery

• Real dimensions of

electrodes, separators and

current collectors are

included

•

Solve for current distributionand mass transport Elevation plot of inserted Li concentration in

different layers of a spirally wound battery.


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High Temperature PEM Fuel Cell

• Assess efficiency and loss in a

polymer electrolyte membrane

(PEM) fuel cell

• Included in the model:

– Electronic current in the porous GDL

– Electrolyte current by proton transfer in

the membrane

– Electrochemical reaction in the catalyst

distributed between the GDL and the

PEM

– Reaction rates depend on reactant

concentration as well as overpotential

– Mass transport and fluid flow of the gas

mixtures on the anode and cathode

side

Concentrations of hydrogen in anode (bottom, rainbow coloring)

and oxygen in cathode (top, thermal coloring) at Vcell = 0.4 V.


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PEMFC Polarization Curve

• Ohmic and kinetically

controlled regimes

revealed through a

polarization curve

• Use parametric analysis

to relate experimental

data to prevailing

physical effects in

complex systems

Polarization curve of cell average current density (A/m2) vs applied

cell voltage (V).


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Fuel Cell with Serpentine Flow Field

• Multiphysics coupling offluid flow and transportof gas species in a fuel

cell cathode

• Porous flow resolved inthe GDL

– consumption of oxygencauses a change incomposition of the flow

Plot of O2 consumption along the serpentine flow channels

above the cathode GDL of a fuel cell.


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Vanadium Redox Flow Battery

• Tertiary current

distribution analysis of a

redox flow battery.

• Predict potential and

concentration profiles to

optimize the geometryof the design.

Concentrations of reactants (blue-red colors) and products

(green-red colors) in the anode and cathode of a vanadium

sulfate redox flow battery.


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Heat Transfer

• Sources – Joule heating

– Irreversible reaction losses

– Reversible reaction losses

• Heat transport – Convection

– Conduction

• Electrochemical unit cells – High conductivity (electronic conductors)

– Short distances (micrometers)

Heat transfer in cooling pipes of a battery stack.


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Liquid-Cooled Li-ion Battery Pack

• Fluid flow analysis and heat

transfer in cooling pipes of a Li-

ion stack

• Heat source taken from a 1D

(thin layer) model of the battery

chemistry

• Could extend to include change

of chemistry due to

temperature change (two-waycoupled) Temperature in different parts of a liquid-cooled lithium-

ion battery pack.


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Battery Impedance Model

• Li-ion battery interface

solved in the frequency

domain to predict

impedance response.

• Least-squares optimization

used to automatically find

simulation parameters that

best fit experimental data.Impedance calculations compared to experimental data.


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• From model to app:

– Application Builder for

COMSOL Multiphysics

allows development of an

app. – The application allows a

user to load experimental

data and either manually or

automatically fit the

impedance parameters.

– No specialist COMSOLMultiphysics knowledge

required for the application

user.

Battery Impedance Application


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Demo: 2D Lithium-Ion Battery

• 2D analysis of a Li+ ion battery

• Use Lithium-Ion Battery interface

to follow intercalation and current

density distribution

– design optimization

• Compute a discharge curve

Concentration of intercalated Li in the anode and cathode of adischarging battery.


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2D Li-ion Battery - Schematic

discharge cathode (LixMnO4)

discharge anode (LixC6)

Li+

electrolyte: 2 M LiPF6 in 1:2 EC : DMC

current collector: i=-200 A/m2

current collector: Ground / 0 V


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Q&A Session


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Product Suite – COMSOL 5.0


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0205SAE Batteries FuelCells Webinar comsol