Technology at glance

Dipl Ing Simona Vrabiescu - Marketing EuropeDipl Ing Gaëlle Tipaka - Application EngineerUltracapacitors Seminar – Istanbul 09/02/2012

Ultracapacitors Seminar

Technology at a glance

• Ultracapacitor definition

• Basic formula

• Topology (Power and Current)

• Ageing

• Building stacks

• Batteries

• Ultracaps vs. Batteries• Ultracaps vs. Batteries

• Why using Ultracapacitor

Maxwell Technologies Ultracapacitors

• Maxwell ultracapacitors provide the longest life, low maintenance energy storage for short duration power requirements resulting in the lowest total cost of ownership

Designed to meet the life of the application maintenance-free

Module technology to meet environmental conditions

Production capability to meet high volume needs

Green materials Green materials

What is a supercapacitor?

THEY STORE MASSIVE AMOUNTS THEY STORE MASSIVE AMOUNTS OF ENERGYOF ENERGY

THEY STORE MASSIVE AMOUNTS THEY STORE MASSIVE AMOUNTS OF ENERGYOF ENERGY

AND THEN RELEASE IT:AND THEN RELEASE IT:

FASTFAST

They store Energy

…lot’s of it

Ultracapacitor technology: The film capacitor

The plate capacitor

Capacitor:

•2 electrodes separated by a dielectric (plastic film, paper, aluminium oxyde)

•Charge are accumulated on the surface of the electrode. So the higher surface the higher capacitance

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Dielectric

Electrode AElectric conductivity

Electrode BElectric conductivity

_ +++++++++

________

d

SC =

ε

How to increase capacitance ?

Ultracapacitor technology

Separator

Grind

Activation

Electrodefabrication

CoatingRollingKneadingPasting

Separator

Electrode

+

_

++

+

_

_

_

_

_

_

+

+

+

+

ElectrodeElectrolyte

+_

+

++

+

__

_

_

+

+

+

+

+

+

+

+

_

_

_

_

_

_

_

_

_

_

+

+_Surface areaThickness

Capacitance ~

Thickness of Helmholz layer ~ 1nm

Carbon powder surface area up to 3,000m2/g

Capacitors up to 3,000F

Construction of Maxwell Ultracapacitor

• The most important element of the ultracapacitor is the electrode assembly – the jelly roll structure.

Aluminum foil tab endCarbon electrode filmPaper separator

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Paper separatorOpposite electrode

Electrochemical Capacitors (EC) - Symmetric

EC – Physical energy storageAdsorption of ionSolvated ionsConductivity, σ(SOC)E = f(electrode surface area)Non-Faradaic, no mass transfer

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Non-Faradaic, no mass transfer

++Re Ri Re

C(U) C(U)

Size Scaled

Ultracapacitor Technology

Size Scaled

• Carbon electrode 100 mm 10 km Mt. Everest

• Carbon particle 5 mm 500 m Petronas Towers

• Micro-pores 2 nm 20 cm Bucket

• Ions 0.7 nm 7 cm Grapefruit

Ultracapacitors Key Features

Excellent power density

High durability and long lifetime

– 1 Million cycles

– 10 years lifetime

Standard form factors

Highly efficient energy transfer

Cost effective in terms of Wh-

cycles

Stable performance over large

-40 -20 0 20 40 60 80T [ºC]

94

96

98

100

102

Capacitance [%

]

Stable performance over large

temperature range

Safety certifications

– UL certified

– EU norms

– Automotive standards

T [ºC]

-40 -20 0 20 40 60 80

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

Real [Ω

]

T [ºC]

100 Hz100 Hz

0.1 Hz0.1 Hz

0

Basic formula

Basic Formulas

Definition of Capacitance:

C = Q/V (1)

Charge = current * time: Q = I*t C*V = I*t (1a)

Solving for voltage: V = I*t/C (2)

Dynamic Voltage: dV/dt = I/C (3)

Stored Energy E = ½ C*V2 (4)

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Stored Energy E = ½ C*V2 (4)

At initial voltage Vo, Eo = ½ C*Vo2

At final voltage Vf, Ef = ½ C*Vf2

Delivered energy = Eo – Ef ∆E = ½ C*(Vo2 – Vf

2) (5)

Conclusion on Ultracapacitors

• An UCAP is a CURRENT SOURCE: means the voltage across the terminal changes while the current remains constant during charge / discharge

• => Variation of energy = CHANGE of voltage => Voltage Window

• No Transformation of Matter (no chemical reaction) during charge / discharge, but displacement of ions

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discharge, but displacement of ions

• Temperature

• Usage cycles occurrences

Topology

TopologyConstant currentConstant current

Constant current: recurent shape

I

dT

19

T

• T Period

• D Duty Cycle in the range 0<d<=1

• Q Quantity of charge => I x dT [As, C]

• <I> Mean value => IxdT/T = Ixd or Q/T [A]

• I2t Normalized energy => IxIxdT [A2s]

• IrmsEffective current => square root(I2t/T) [Arms]

Constant current: complex shape

I1

t1t2

I2

20

T

• T Period

• Q Quantity of charge => I1x t1 + I2 x t2 [As, C]

• <I> Mean value => Q/T [A]

• I2t Normalized energy => I1xI1x t1 + I2xI2 x t2 [A2s]

• Irms Effective current => square root(I2t/T) [Arms]

Ultracapacitor Available Charge & Energy

Apply energy storage fundamentals:

Q, charge in Coulombs

U, potential in Volts

I, current in Amperes

T, time in seconds

ITCUQ ==

U(t)Umx Q E

Fuel Gauge

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U(t)

i(t)Io

Umx/2Q/2

Q/2

Q=0

E/4

E=0

0 T

Ageing

Factors affecting life

Temperature

Ambiant

Fire

Radiant

Open

High RMS

current

Heating up due to losses by

Joule effect

ESR

RPCAP

BOOSTCAP Devices

23

Venting

Internal Stress

External Stress

Mechanical

damage / Deformation

Radiant

Crunch

Punch through

Over voltage

Gaz production

by dissociation

Determination of thermal stress

Get the RMS current value or the I2t value

Estimate the temperature rise using the value of the thermal resistance given on the Datasheet

And applying the equation: Temp rise [°C] = Rth x Irms x Irms x ESR

Add that value to the highest ambient temperature to determine the cell body temperature

Compare the cell temperature with life time expectation and max admissible temperature

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Compare the cell temperature with life time expectation and max admissible temperature

Increase the capacitance (next bigger cell) or add on more branch in parallel if the rise is too important

Cell ageing

• DC life The cell is kept continuously at a given voltage and exposed to a temperature. This is the

typical field of UPS application or very low cycling systems.

The life is affected by Voltage and temperature

At low temperature the ion mobility is low and some stay trapped in the pores or separator. There is a fast decay due to the « inactivation » of the pores but a fast decay due to the temperature => again both phenomena adds up and capacitance decay

At higher temperature the ion mobility increases and trapped ions moves again so the performances recovers but the decay due to the aging increases

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At higher temperature the ion mobility increases and trapped ions moves again so the performances recovers but the decay due to the aging increases

Gaz production due to the impurities decay in time affected by voltage and temperature. At high voltage the temperature determine the aging. If voltage is reduced then gaz production may decay as well so the life is not strictly affected by voltage

• Cycle Life Higher current affects decay by gaz production (temperature)

Lower average voltage lower the decay due to voltage

Building stacks

Serialising cells/modules: why a balancing?

• Single cell = Low Voltage

Several cells must be connected in serie U

Multiple branches could be paralleled E, P

But a cell is affected with variation and changes of

•Capacitance ESR Leakage

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•Capacitance ESR Leakage

By Manufacturing process

With Temperature

With Cell Voltage

By Sollicitation (cycled or steady)

Building Stacks: Risks

Cap1

ESR1

B1

Rp1

A1

Cap2

ESR2

B2

Rp2

A2

Capn

ESRn

Bn

Rpn

An

Ucell1 Ucell2 Ucelln

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U Stack

Cell Voltage => ageing accelerates, gassing

Opening

Temperature => ageing accelerates, gassing

Sollicitation (cycled or steady)

Goals of the ideal balancing

• Limit the voltage dispersion along a stack

• Reduce the « exposure » time to voltage higher than admissible by the system design

• Dont degrade the system efficiency

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• Be simple and Reliable

Balancing

• Cell strings should theoretically maintain voltage balance Current through all cells in a series string is always the same.

Cells in a string should come from the same capacitance bin, and age similarly.

Therefore, ideally the voltage on each cell should always be the same.

– (dV/dt)=I/C= same for all cells

• In reality, small differences in capacitance, ESR, and leakage current can cause voltage imbalance

• Impact of imbalance Cells overvoltage when string is fully charged

Cells reverse voltage when string is discharged

Passive Balancing

Passive systems are those which bypass a portion of current across each cell

Passive – this method will constantly bleed energy away from the system. Install bleed resistor(s) in parallel with each cell. Choose resistors so that the bleed current is 10-20x the cell’s leakage current at the rated voltage.

Example of calculation:

Balancing Resistance (Rbal1) = Cells voltage / (10 to 100 * I leakage).

Rbal1 Rbal2 Rbaln

Advantages– Good performance, particularly in standby systems

Disadvantages– Continuous power drain– Slower response to overvoltage situations

Rbal

Rpkbal =

Cap1

ESR1

B1

Rp1

A1

Cap2

ESR2

B2

Rp2

A2

Capn

ESRn

Bn

Rpn

An

Ucell'1 Ucell'2 Ucell'n

U Stack

Active Balancing

Active systems are the one controlling the individual cell voltage

• Active dissipating – this method is used to prevent a cell from being over-voltaged. When the cell is charged to a pre-determined level, the circuit will turn on and start bleeding energy away from the cell. Install a circuit board and set a threshold voltage.

Voltage DetectorDissipative components

Reverse Voltage

ProtectionOne circuit

Advantages– Can lower overvoltage cells more quickly– Low parasitic loss when not activated

Disadvantages– System must reach high voltages for balancing to occur

Protection

ESD Protection

LED “Balancer ON”

per cellTwo circuits

per board

Conclusion on balancing

• For a given stack voltage the number of cell is a function of the parameter dispersion

• The use of balancing circuitry will affect the steady state but may not be efficient during transition state

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state but may not be efficient during transition state

• A simple dissipative solution should be preferred in respect of cost, reliability and simplicity

Batteries

Storage of electrical Energy

35

Common Chemistries/Technologies

36

•G. Delille, B. François, “A Review of Some Technical and Economic Features of Energy Storage Technologies for Distribution System Integration”, in Proc. International

Conference on Electrical Machines and Power Systems (ELMA’08), Sofia, Bulgaria, vol. 1, pp. 67-72, Oct. 2008.

Secondary Batteries I

37

Secondary Batteries II

38

Example: discharge curves

39

Source: FIAMM FGH

Pb Battery: Cold performances

40

Source: Saft

Major contributors to performance change

41

Conclusion on Batteries

• A battery is a VOLTAGE SOURCE: means the voltage accross the terminal remains about constant during charge / discharge

• => Variation of energy = Stable voltage

• Transformation of Matter (chemical reaction) during charge / discharge

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• Temperature Usage cycles occurencies charge phase

Ultracaps vs. Batteries

Ultracapacitor vs. Battery

Battery/Ultracapacitor Technical Discussion

• Ratio of ultracapacitor to battery depends upon the “drive cycle” --usage pattern of the system Optimize ultracapacitor size – beyond such size, adding more does not add to

performance

• Passive configuration No technical hurdles

Does the addition of ultracapacitors provide sufficient performance improvement (fuel consumption, battery life, battery savings)

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(fuel consumption, battery life, battery savings)

• Active configuration Requires DC-DC converter to allow the battery and ultracapacitor to operate at

different voltages

Microprocessor to control power flow from each type of energy storage

• Batteries and ultracapacitors are complementary technologies Optimize size and cost

Take advantage of ultracapacitor power and cycling capabilities and battery energy capability

Comparison: Ultracaps vs. Batteries

Ragone Power and Energy Source: Ralph Brodd, “The Future of Batteries,” ACG meeting, Chicago, IL, 17 May 20081,000

10,000

100,000

Ni-Cd Ni-MH

Sp

ecif

ic P

ow

er,

W/k

g a

t C

ell

Level Super

capacitors

Li-ionHigh

Energy

Li-IonHigh Power

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1

10

100

0 20 40 60 80 100 120 140 160 180 200

Specific Energy, Wh/kg at Cell Level

Lead acid

LiM-Polymer

Sp

ecif

ic P

ow

er,

W/k

g a

t C

ell

Level

Energy

Ragone Power and Energy

Sp

ecif

ic P

ow

er,

W/k

g a

t C

ell

Level

1’000

10’000

100’000

Lead acidwith UC

Ultracapacitors

Li-ionHigh Energy

with UC

Li-IonHigh Power

with UC

Future combinations of Ultra capacitors & Batteries

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Specific Energy, Wh/kg at Cell Level

Sp

ecif

ic P

ow

er,

W/k

g a

t C

ell

Level

1

10

100

0 20 40 60 80 100 120 140 160 180 200

with UC

Cycling Capabilities: Ultracaps vs. Batteries

Lead acid

Nickel Cadmium

3’000 load cycles (20% DOD)

10,000 load cycles (40% DOD)

Lithium Ion

Ultracapacitors

20,000 load cycles (40% DOD)

1’000’000 load cycles

More than

Po

ten

tia

l

Batteries

How to combine?

Po

ten

tia

l

Charge / Discharge

• No absolute limits between batteries & capacitors • Intercalation = mechanical expansion = aging

Coupling requires active or passive devices to maximize the energy use from / to

Ultracapacitors

Standard configuration

Primary SourceICE, Fuel Cell, other

DC-DC converter

Buck/Boost

Auxiliaries

η1

η BCAP

Other loads andusers

Braking chopper Braking Resistor

Denotes unidirectional energy flow

Denotes bidirectional energy flow

η nnnn Denotes efficiency level for the function

BOOSTCAP®

storage unit

Hoist Drive Motor

DC-Link Bus

η2

Gantry Drive Motor

Trolley Drive Motor

η3

η4

Forklifts

Advantages

Battery replacement (Fuel cell + Ultracaps)

Deliver and receive power peaks

Optimizing the primary energy source size

Full energy recuperation

Fuel savings

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Longer operating hours

Increasing Battery life

Conclusions

• Ultracapacitor can contribute to reduce the stress on the battery

• Ultracap can extend the durability of the battery

• The "hybridization" Typology can be optimized for each application(s)

• Direct coupling will benefit to the battery if there is a internalresistance ratio >1.0

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resistance ratio >1.0

• Low power and low cycled application (ie portable devices) can benefitfrom Ultracapacitor pulse enhancement

• In various field application the battery stress release is demonstrated

Why using supercapacitors?

Our world

x

We need to be efficient - reduce CO2- produce Clean Energy- deliver it efficiently

Supercaps liability

Maxwell has today more than 5 millions supercaps cells installed in windmill for

safety reason.

They work (among other functions)

as UPS (uninterrupted Power

Supply) for the pitch system. The liability of the supercaps must be excellent to avoid catastrophic

failure...failure...

Application Model

Power in excess Application

Losses = Heat

Energy CaptureLimited

Primary Energy Primary Energy Primary Energy Primary Energy sourcesourcesourcesource

(Internal Combustion Engine, Fuel Cells,

Batteries, etc)

Slow Time ConstantContinuous

Power Usage

Peak Power demand

Application

Continuous low power

Peak power delivery

Application Model

Power in excess Application

Losses = Heat

Peak power delivery

Energy CaptureHigh efficiencyDynamicDynamicDynamicDynamic

Energy StorageEnergy StorageEnergy StorageEnergy Storage(BOOSTCAP®)

Fast Time Constant

Primary Energy Primary Energy Primary Energy Primary Energy sourcesourcesourcesource

(ICE, FC, Batteries, etc)

Slow Time Constant

Continuous Power Usage

Peak Power demand

Application

Continuous low power

Charging as needed

Our product range…

Standard Cells & Modules (multi-cells)

Heavy Transportation Module

HTM125

K2 Line 650F to 3000F

PC Line 10F

HC Line 1F to 150F 56V UPS Modules

BC Line 310F to 350F

16 V Modules (Large & Small Cells)75V Module 48 V Module Series

Large Cell Overview

• Maxwell’s industry leading large

capacity ultracapacitors continue to innovate and lead

the industry in energy and

power density, reliability and lifetime

Large Cell Overview

• KEY FEATURES

De-facto standard capacities and

form factor

Multiple terminal configurations for

customer usability

High reliability welded connections

• TARGET MARKETS

Heavy Transportation – bus, train,

construction, mining, cranes

Backup Power

Wind

Automotive – stop-start, micro

hybrids

Grid storage

Medium Cell Overview

• Maxwell’s technology

leadership in high capacity cells is duplicated in medium

capacity cells to bring high

density, high reliability, and the longest lifetime

Medium Cell Overview

• KEY FEATURES

High reliability cell construction

Terminal design for high current,

high power applications

• TARGET MARKETS

Wind turbines

UPS <2kW

Valves and actuators

Small Cell Overview

• PC and HC Series

ultracapacitors feature Maxwell Technologies’ patented

electrode with superior reliability

and lifetime

Small Cell Overview

• KEY FEATURES

HC Series

Industry standard form factor

PC10 Line

Thin form factor

High reliability package

• TARGET MARKETS

Smart Meters, Automated Meter

Reading

Server, solid-state disk drives

Valves, actuators

Engine Start Module Overview

• Maxwell Technologies Engine

Start Module is an easy to install solution to enhance

starting reliability in mission

critical trucking environments.

Overview Engine Start Module

• KEY FEATURES

Lowers Total Life cycle cost for

engine start

Green initiatives for private fleets

Easy integration into existing

starting systems with multiple

batteries

Life of the truck starting power

• TARGET MARKETS

Large trucks, 9-15L diesel engines

Diesel motor generator sets

Marine

Standard battery size

16V Module Overview

• Maxwell Technologies’ 16V

energy storage modules incorporate industry leading

large cells with rugged

enclosures to provide superior reliability and lifetime for both

cycling and backup power

applications.

16V Module Overview

• KEY FEATURES

Rugged housing

Water resistant

Passive or active balancing

models

16V rating matches systems

designed around batteries

•TARGET MARKETS / APPLICATIONS

Engine starting

Wind turbine pitch control

UPS

48V Module Overview

• Maxwell Technologies’ 48V

energy storage modules incorporate industry leading

large cells with rugged

enclosures to provide superior reliability and lifetime for both

cycling and backup power

applications.

48V Module Overview

• KEY FEATURES

Passive balancing for high power

cycling

Rugged aluminum case

Light weight

Water and dust resistant

• TARGET MARKETS/ APPLICATIONS

Hybrid bus

Construction and mining

equipment

UPS

125V Module Overview

• Highly ruggedized module

which meets all requirements for heavy transportation

applications with digital

monitoring

125V Module Overview

• KEY FEATURES

Ruggedized construction to meet

heavy transportation requirements

E-mark certification for to meet

EMI/EMC requirements

CAN digital communications and

monitoring

Dust, vibration and water resistant

• TARGET MARKETS

Hybrid bus, trolley bus

Construction and mining

Cranes, RTGs

56V UPS Module Overview

• A long life energy storage

module for datacenter, hospital and industrial transition power

backup with the Lowest Total

Cost of Ownership

56V Module Overview

• KEY FEATURES

Form factor for easy installation

into standard equipment racks

Maintenance free

Green, environmentally clean

technology, especially compared

to lead-acid batteries

Long lifetime (8-14 years)

• TARGET MARKETS

Datacenter UPS with Fuel Cell or

Motor-generator

Hospital UPS with Fuel Cell or

Motor-generator

Large industrial manufacturing for

flat panel displays, integrated

circuits

Fast recharge

Low Duty Cycle Modules

• A long life energy storage

module for wind turbine pitch control and DC-DC link voltage

support with the high reliability

and Lowest Total Cost of Ownership

Low Duty Cycle Modules

• KEY FEATURES

16V, 64V and 75V operating

voltage

Maintenance free

Green, environmentally clean

technology, especially compared

to lead-acid batteries

Long lifetime (up to 15 years)

• TARGET MARKETS

1-10MW wind turbines

Low voltage or high voltage

pitch motors

Renewable energy farms DC link

up to 480V

Mechanical design built to survive

nacelle vibrations

Questions & Remarks

Thank you