WO2001004920A1

WO2001004920A1 - An energy storage device

Info

Publication number: WO2001004920A1
Application number: PCT/AU2000/000836
Authority: WO
Inventors: Peter John Mahon
Original assignee: Energy Storage Systems Ltd
Current assignee: Energy Storage Systems Ltd
Priority date: 1999-07-12
Filing date: 2000-07-12
Publication date: 2001-01-18
Anticipated expiration: 2002-01-12
Also published as: US20050083021A1; CA2379011A1; JP2003504819A; EP1204980A1; EP1204980A4

Abstract

An energy storage device (1) includes a cylindrical shrink wrap housing (2) having two opposed metal terminals (3, 4). An electrochemical device in the form of a dry cell alkaline battery (5) is disposed within housing (2) for providing an electrical potential between the terminals. An electric double layer supercapacitor (6) is wrapped around and mounted to housing (2) and connected to terminals (3, 4) in parallel with battery (5).

Description

TITLE: AN ENERGY STORAGE DEVICE

The present invention relates to an energy storage device.

The invention has been developed primarily for providing an energy store for

portable electrical devices such as mobile telephones and laptop computers and will be

described hereinafter with reference to that application. However, the invention is not

limited to that particular field of use and is also applicable to other electrical loads

including those that are remote from mains supplies or those that have high peak

currents and low average currents.

BACKGROUND OF THE INVENTION

Dry cell and alkaline batteries, both in primary and secondary form, are used in

a wide variety of applications. Primary batteries are once only or disposable batteries,

while secondary batteries are rechargeable. Batteries of these kinds are used in mobile

and cellular telephones, portable computers, cordless electric power tools, household

appliances, cameras, and other mobile devices to name but a few. These form of

batteries are preferred as they provide a relatively high energy density and are

relatively inexpensive. The latter is of particular importance for primary cells which

are, in effect, consumables.

Batteries are either primary and secondary sources and can be either wet or dry

cell. Some of the commonly available types are alkaline, Lithium ion, Lithium

polymer, Nickel Metal Hydride, Nickel Cadmium or Carbon Zinc. Of the primary

batteries, the most common batteries are in the form of cylindrical cells, each of which

provides a potential of about 1.5 Volts. A number of such cells are generally

connected in series to provide the necessary voltage for the device concerned. These cells are specified by size categorisations, which are designated, for example, as N,

AAAA, AAA, AA, C and D. Other prismatic forms are also available.

These batteries suffer from several limitations including poor accommodation

of wide variations in load currents and a low efficiency at high load currents.

Accordingly, in circumstances where a constant load current is drawn, such as in a

torch, a battery is an ideal source of energy. However, where varying load currents,

and particularly high load currents for high power applications are encountered, the

battery life becomes compromised. For example, when a power tool, such as an

electric drill, is operating at a constant low current to provide a given torque, the

battery is efficiently providing the necessary energy requirements. However, should

the operator require a higher torque for a short period, a pulse or surge of power will

be required. Although this demand for transitory power is common in many electrical

appliances and devices, it is not efficiently provided by a battery. There are a number

of strategies that are adopted to overcome this inherent compromise. For the example

of the electric drill, it is known to make use of adjustable gearing to provide a wider

range of available torque.

Similar problems to that foreshadowed above for the drill arise for other

devices whether they are toys, electronic games, mobile or cellular phones, portable or

laptop computers or the like. In an attempt to address this limitation it has been

known to provide a battery having a slightly lower internal resistance. However, this

form of battery design compromises the energy density of the resultant battery.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

According to a first aspect of the invention there is provided an energy storage

device including:

a housing having two terminals;

an electrochemical device disposed within the housing for providing an

electrical potential between the terminals; and

a first capacitor mounted to the housing and being electrically connected to the

terminals in parallel with the electrochemical device.

Preferably, the capacitor extends about the housing. More preferably, the

housing is cylindrical and extends between two opposed axially spaced apart ends,

whereby the ends define respective terminals and the capacitor extends about the

housing intermediate the ends.

Preferably also, the capacitor is an electric double layer supercapacitor

including:

a capacitor housing;

a first and a second opposed sheet electrodes disposed within the housing and

being respectively electrically connected to the terminals;

a separator located between the electrodes; and

an electrolyte intermediate the electrodes for allowing charge to be stored at

the electrodes.

In a preferred form, the capacitor is flexible and wrapped about the housing.

However, in other embodiments, the capacitor is flexible and configured as a tube that is disposed within the housing. Preferably, in either case, the capacitor is wrapped

around the electrochemical device.

Preferably, the electrochemical device is generally cylindrical and extends

between two opposed axially spaced apart ends and the first capacitor extends axially

away from one of the ends. More preferably, the energy storage device includes a

second capacitor which has an aperture for receiving the electrochemical device.

In a preferred form, the aperture receives both the electrochemical device and

the first capacitor. More preferably, the second capacitor is tubular and extends about

the first capacitor and the electrochemical device.

Preferably, the electrochemical device is a battery and the capacitor is an

electric double layer supercapacitor. More preferably, the battery is a Li-Ion battery

that has a solid electrolyte. Even more preferably, the electrolyte includes a polymer.

Preferably also, the electrochemical device and the capacitor each include a

pair of electrodes that are electrically connected to the respective terminals. More

preferably, the electrodes are fixedly connected to the respective terminals. However,

in some embodiments, at least one of the electrodes of the supercapacitor are

selectively electrically isolated from the terminals. In the case of the latter, it is

preferred that the energy storage device includes a switch that is electrically disposed

between one of the terminals and one of the electrodes of the capacitor for effecting

the selective electrical isolation.

The electrochemical device and the capacitor each include a power density and

an energy density. Preferably, the energy density of the electrochemical device is greater than the energy density of the capacitor and the power density of the

electrochemical device is less than the power density of the capacitor.

According to a second aspect of the invention there is provided an energy

storage device including:

a housing having two terminals; and

a first capacitor forming part of the housing and connected to the terminals.

Preferably, the housing has a form factor corresponding or being related to

battery size designations N, AAAA, AAA, AA, C or D.

More preferably, an electrochemical device is disposed within the housing for

providing electrical energy to the terminals. More preferably, the electrochemical

device extends about the housing.

Preferably also, the housing is cylindrical and extends between two opposed

axially spaced apart ends, whereby the ends define respective terminals and the

capacitor extends about the housing intermediate the ends.

Preferably, the capacitor is an electric double layer supercapacitor including:

a capacitor housing;

a first and a second opposed sheet electrodes disposed within the housing and

being respectively electrically connected to the terminals;

a separator located between the electrodes; and

an electrolyte intermediate the electrodes for allowing charge to be stored at

the electrodes.

In a preferred form, the capacitor is flexible and wrapped about the housing.

around the electrochemical device.

Preferably also, the electrochemical device is generally cylindrical and extends

away from one of the ends. More preferably, the energy storage device is of hollow

construction with an aperture for receiving the electrochemical device. Even more

preferably, the aperture receives both the electrochemical device and a second

capacitor.

In a preferred form, the first capacitor is tubular and extends about the second

capacitor and the electrochemical device.

According to another aspect of the invention there is provided an energy

storage device including:

a housing having an interior and an exterior where the interior defines a cavity;

two terminals disposed on or adjacent to the exterior of the housing for

electrically engaging with respective terminals of a load that requires a predetermined

load current;

an electrochemical device disposed within the cavity and being electrically

connected to the terminals for providing a first current to the load; and

a capacitor disposed within the cavity and being electrically connected to the

terminals in parallel with the electrochemical device for providing a second current to

the load, whereby the first current and the second currents collectively sum to the

predetermined load current. Preferably, the electrochemical device includes an anode and a cathode that are

respectively fixedly electrically connected to the terminals by way of an anode tab and

a cathode tab, and the capacitor includes a positive electrode and a negative electrode

that are respectively fixedly electrically connected to the terminals by way of a

positive electrode tab and a negative electrode tab. More preferably, the terminals

extend from the interior to the exterior and the anode tab, the cathode tab, the positive

electrode tab, and the negative electrode tab are disposed entirely within the cavity.

In a preferred form, the capacitor is an electric double layer supercapacitor

including:

a capacitor housing;

a first and a second opposed sheet electrodes disposed within the housing and

being respectively electrically connected to the terminals;

a separator located between the electrodes; and

an electrolyte intermediate the electrodes for allowing charge to be stored at

the electrodes.

Preferably, the housing is flexible. More preferably, the energy storage device

is flexible. In other embodiments, however, the housing and the electrochemical

device are rigid and the capacitor is flexible and packed about the electrochemical

device.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way of

example only, with reference to the accompanying drawings in which: Figure 1 is a schematic perspective view of an energy storage device according

to the invention;

Figure 2 is a cross section taken along line 2-2 of Figure 1;

Figure 3 is a schematic plan view of the supercapacitor used in the device of

Figure 1, where the supercapacitor is shown in the unwound configuration;

Figure 4 illustrates the supercapacitor of Figure 3 in a wound configuration prior

to mounting to the housing;

Figure 5 is a chart illustrating the discharge profile for a prior art battery and an

energy storage device according to the present invention;

Figure 6 is a schematic sectional view of another device according to the

invention;

Figure 7 is a schematic plan view of an alternative supercapacitor;

Figure 8 is a plan view of another energy storage device according to the

invention that is for use with a GSM telephone and which includes the supercapacitor

of Figure 7; and

Figure 9 is a schematic cross sectional view taken along line 9-9 of Figure 8.

Referring to the drawings, and in particular to Figure 1 and Figure 2, there is

illustrated an energy storage device 1. The device includes a cylindrical shrink wrap

housing 2 having two opposed metal terminals 3 and 4. An electrochemical device in

the form of a dry cell alkaline battery 5 is disposed within housing 2 for providing an

electrical potential between the terminals. An electric double layer supercapacitor 6 is

wrapped around and mounted to housing 2 and connected to terminals 3 and 4 in

parallel with battery 5. DETAILED DESCRIPTION OF THE INVENTION

As shown in Figure 3, supercapacitor 6 is formed from two like opposed

rectangular aluminium sheet electrodes 10 which are maintained in a spaced apart

overlying configuration by an intermediate separator 11. Each electrode includes a

coating of activated carbon for providing a high surface area. Moreover, each

electrode includes a protruding tab, which are separately numbered 15 and 16. The

tabs includes respective central apertures 17 and are configured such that they

protrude from opposite edges of the respective sheets.

The elements shown in Figure 3 are placed in a package with only tabs 15 and

16 protruding. An electrolyte is placed in the package before it is sealed. This

arrangement is then wound to provide the tubular supercapacitor 6, as best shown in

Figure 4. The supercapacitor is hollow and extends axially between a first end 19 and

a second opposed end 20. Each of the ends includes an aperture 21.

The internal diameter of the supercapacitor is such as to complementarily

receive battery 5, which is inserted through one of apertures 21. Moreover, ends 19

and 21 are axially spaced apart to be co-terminus with the adjacent ends of the battery.

That is, supercapacitor 6 provides a sheath into which battery 5 is received. Once so

received, tabs 17 and 18 are folded across respective adjacent apertures 21 and

welded, soldered or otherwise electrically connected to the battery terminals such that

battery 5 and supercapacitor 6 are connected in parallel. In this embodiment use is

made of ultrasonic welding. It will be appreciated that the positive terminal of battery

5 includes a detent which is received by and which extends through aperture 17. Thereafter shrink wrap 2 is applied and device 1 is ready for use. It will be

appreciated that device 1 , when wound, has a total wall thickness of about 0.2 mm.

That is, device 1 only increases the diameter of the battery about which it is disposed

by about 0.4 mm.

Supercapacitor 6 provides a capacitance of about 0.5 Farads and an esr of 10

milliohms. Accordingly, device 1 offers performance characteristics which are far

superior to that of battery 5 alone. That is, in situations where pulse loading of device

1 occurs, a predominance of the energy provided will be from supercapacitor 5. This

reduces the pulse load on battery 5 and, as such, allows the battery life to be extended.

Moreover, between pulses battery 5 is able to recharge supercapacitor 6. That is, as

the internal resistances of batteries are generally higher than the esr or equivalent

series resistance of a capacitor or supercapacitor the use of such a capacitor or

supercapacitor in parallel with the battery reduces the effective resistance of the

resultant energy storage device.

Another preferred embodiment of the invention is illustrated in Figures 7, 8 and

9. More particularly, with reference to Figure 8, there is shown an energy storage

device 41 including a hard plastics housing 42. Device 41 has two rectangular metal

terminals 43 and 44 which are adjacent one another and a bottom edge 45 of the

housing. Device 41 is selectively engaged by way of formations 46 and 47 with a

GSM telephone (not shown). Moreover, terminal 43 and 44 are located to abut

corresponding terminals on the telephone to allow energy transfer to the telephone.

Device 41 includes an electrochemical device in the form of a Li-Ion battery 48

disposed within housing 42 for providing an electrical potential between the terminals. Battery 48 includes two electrode tabs 49 which electrically connect the respective

positive and negative electrodes of the battery (not shown) to terminals 43 and 44.

A capacitor, in the form of a supercapacitor 50, is mounted internally to

housing 42 and is electrically connected to terminals 43 and 44 in parallel with battery

48. That is, supercapacitor 50 includes two electrode tabs 51 that electrically connect

the respective electrodes of the supercapacitor to terminals 43 and 44.

In the embodiment shown, tabs 51 are sandwiched between respective tabs 49

and terminal 43 and 44. In some embodiments the actual physical connection between

the tabs and the terminals is effected by welding or soldering. In this specific

embodiment, however, the connection is effected by ultrasonic welding.

As best shown in Figure 7, Supercapacitor 50 includes two electrodes 52 from

which respectively extend tabs 51. The electrodes are generally rectangular and

include respective carbon coatings that are opposed with each other. The electrodes

are maintained in a fixed spaced apart configuration by a porous separator 53 that is

non-conductive. The electrodes and the separator are contained within a sealed

plastics laminar package 54 which contains an electrolyte for allowing ionic

conduction between the electrodes. Tabs 51 extend from package 54 for connection

with terminals 43 and 44, as discussed above.

In this embodiment, supercapacitor 50 is flexible to facilitate its incorporation

into housing 42. This also allows supercapacitor 50 to be retro fitted into some

existing housings. An example of the construction of such a flexible supercapacitor is

disclosed in a copending PCT patent application numbered PCT/AU99/00780, the

disclosure of which is included herein by way of cross reference. In some embodiments the housing is specifically configured to accommodate a

rigid supercapacitor.

Battery 48 includes a solid polymer electrolyte (not shown) which, while

providing good energy density, places a severe limitation on the peak current that can

be provided by the battery if damage is to be avoided. The combination of battery 48

and supercapacitor 50, however, is selected so that, for the currents loads experienced,

they do not suffer this same disadvantage. That is, the low esr of supercapacitor 50

ensures that peak current demand will be substantially supplied by the supercapacitor.

That is, supercapacitor 50 is providing an averaging effect on the battery current. In

this case the peak battery current will be closer to the average battery current than

would be the case in the absence of the supercapacitor.

Based upon the above teaching, it becomes clear that the capacitance of

supercapacitor 50 has to be sufficient to provide the energy required by the load in a

typical cycle. This will also assist in limiting the peak current of the battery to much

less than the peak current demanded by the load.

This embodiment of the invention is particularly advantageous as it makes use

of a simple parallel connection and involves no intervening and expensive control

circuitry. In some embodiments, however, use is made of a switch (not shown) for

selectively electrically isolating at least one of the tabs 51 from the respective terminal

of device 41. This switch can be manually operated, although in other embodiments it

is electrically operated by way of an IC.

As with many digital devices, the load that a GSM telephones presents to an

energy supply device has a pulsed characteristic. This places a severe compromise on such a supply that utilises a battery as its only source. That is, the battery has to be

designed to achieve a reasonable power density which, in turn, compromises energy

density. The present invention, however, limits that compromise.

To better illustrate this, reference is made to Figure 5. The first curve, labelled

22, shows the discharge characteristic of three serially connected prior art dry cell

primary batteries under a pulse load such as that provided by a GSM mobile

telephone. The voltage provided by the batteries is dependent not only upon the

remaining energy stored but also on the size and duration of the pulsed load. In

addition, the internal resistance of a battery generally increases with decreasing energy

stored. Thus there is a threefold effect. Firstly as a result of high power pulses the

battery looses energy or capacity due to I R energy losses. Secondly, as the energy

stored in the battery becomes depleted, the I R energy losses increase. Thirdly, the

voltage provided at the battery terminals decreases due to the IR drop as a result of the

increased internal resistance of the battery, the increasing IR drop with increasing

resistance, and the decreasing energy stored.

In the chart of Figure 5, the minimum operating voltage for the particular

application is 3 Volts. In so far as the prior art device is concerned this minimum is

reached quickly due to the three fold effect mentioned above.

An embodiment of the invention utilising series connected batteries of the same

capacity, in parallel combination with respective series connected supercapacitors 6,

provides the characteristic illustrated with curve 23. That is, the operational life of

this embodiment is greater than that of the prior art as the I R losses, the voltage drop

at the terminals of the device and the increase in battery internal resistance are less. This is a direct result of supercapacitor 6 working in parallel with battery 5 to supply

most of the energy required by the individual pulses at the time of the pulse. This, in

turn, occurs due to the lower esr and large capacitance of supercapacitor 6 and the

quantum of the energy drawn with each pulse. Due to the lower esr of supercapacitor

6 the voltage drop across the energy storage device during the pulse is small and

certainly less than that suffered by the prior art device illustrated in curve 22.

As the internal resistance of the battery is not now of such concern, the battery is

configured for maximum energy density rather than maximum power density. The

supercapacitor accommodates the power requirements of the load which allows the

battery to be designed for maximum energy density. This combination also provides

an extended life for the preferred embodiments in comparison to corresponding prior

art devices.

In another embodiment, illustrated in Figure 6 where corresponding features are

denoted by corresponding reference numerals, a device 30 includes an electrolytic

capacitor 31. This additional capacitor extends axially away from one end of battery 5

and is sheathed within supercapacitor 6. Capacitor 31 is connected in parallel with

both battery 5 and supercapacitor 6. While capacitor 31 has a much smaller

capacitance and similar or smaller esr to supercapacitor 6, it allows device 30 to

accommodate extremely high frequency pulses without compromising the life of the

battery.

Preferably, the external dimensions of device 30 correspond with the external

dimensions of a prior art battery. For example, in one embodiment, device 30 has external dimensions of a AA battery, although the battery 5 utilised within the device

is an AAA cell.

In other embodiments, supercapacitor 6 is disposed wholly within the existing

housing of the battery. In other embodiments, battery 5 and capacitor 31 are utilised

without supercapacitor 6.

Although the supercapacitor and battery are shown as a single unit, they are, in

some cases, separately obtained and combined by the user. Particularly in the Figure 1

embodiment, the supercapacitor can be retro fitted to an existing battery, whether or

not that is a primary or a secondary cell.

The embodiments of the invention are particularly advantageously applied to

pulsed load applications. Preferably, the esr and capacitance of the capacitor or

supercapacitor used in parallel with the battery are selected based upon the

characteristics of the load. Accordingly, while general purpose devices are also

constructed, the invention allows economical tailoring of energy storage devices to

load specific applications.

The use of a supercapacitor that is flexible has a number of advantages. For

example, in some embodiments, the supercapacitor is combined in an existing housing

with an existing rigid electrochemical cell. That is, the flexible nature of the

supercapacitor allows it to be folded and/or wrapped about the electrochemical cell

and to fill any available space in the housing rather than having to have a purpose

specific space made available for it. Accordingly, cost and capital savings can be

realised. In other embodiments, however, specific packaging is produced. Another example of the benefits of the flexible packaging is obtained in those

embodiments which also utilise flexible battery packaging, such as has been achieved

with Li-Ion batteries that have solid polymer electrolytes. That is, the flexible

packaging for the two different energy storage components can be selected to be

similar, and in some cases, the same. Moreover, the common problem of electrolyte

contamination is minimised as only one pair of terminals emerges from the package

rather than two separate pairs as would be the case with separate packages. That is,

the point of ingress of contaminants is greatest about the point of bonding between the

terminals and the packaging.

The preferred embodiments of the invention that have been described above

offer respective unitary energy storage devices that combines at least two different

device types. These combinations provide:

• Improved energy supply characteristics, particularly to pulsed loads;

• Improved run-times for the electrical device, which is of considerable significance

to portable devices such as mobile telephones and laptop computers;

• Peak current limiting for the battery - which extends battery lifetime and prevents

damage to the battery;

• A single package for two separate types of storage devices, which adds

considerable convenience to users of portable devices; and

• A combination of storage devices that will compatibly interact during both charge

and discharge cycles. Although the invention has been described with reference to specific examples it

will be appreciated by those skilled in the art that it may be embodied in many other

forms.

Claims

CLAIMS:-

1. An energy storage device including:

a housing having two terminals;

an electrochemical device disposed within the housing for providing an electrical

potential between the terminals; and

terminals in parallel with the electrochemical device.

2. An energy storage device according to claim 1 wherein the capacitor extends

about the housing.

3. An energy storage device according to claim 2 wherein the housing is cylindrical

and extends between two opposed axially spaced apart ends, whereby the ends define

respective terminals and the capacitor extends about the housing intermediate the ends.

4. An energy storage device according to claim 1 wherein the capacitor is an electric

double layer supercapacitor including:

a capacitor housing;

a first and a second opposed sheet electrodes disposed within the housing and

being respectively electrically connected to the terminals;

a separator located between the electrodes; and

an electrolyte intermediate the electrodes for allowing charge to be stored at the

electrodes.

5. An energy storage device according to claim 1 wherein the capacitor is flexible

and wrapped about the housing.

6. An energy storage device according to claim 1 wherein the capacitor is flexible

and configured as a tube that is disposed within the housing.

7. An energy storage device according to claim 1 wherein the capacitor is wrapped

around the electrochemical device.

8. An energy storage device according to claim 1 wherein the electrochemical

device is generally cylindrical and extends between two opposed axially spaced apart

ends and the first capacitor extends axially away from one of the ends.

9. An energy storage device according to claim 8 including a second capacitor

which has an aperture for receiving the electrochemical device.

10. An energy storage device according to claim 9 wherein the aperture receives both

the electrochemical device and the first capacitor.

11. An energy storage device according to claim 9 wherein the second capacitor is

tubular and extends about the first capacitor and the electrochemical device.

12. An energy storage device according to claim 1 wherein the electrochemical

device is a battery and the capacitor is an electric double layer supercapacitor.

13. An energy storage device according to claim 12 wherein the battery is a Li-Ion

battery.

14. An energy storage device according to claim 13 wherein the Li-Ion battery

includes a solid electrolyte.

15. An energy storage device according to claim 14 wherein the electrolyte includes

a polymer.

16. An energy storage device according to claim 1 wherein the electrochemical

device and the capacitor each include a pair of electrodes that are electrically connected

to the respective terminals.

17. An energy storage device according to claim 16 wherein the electrodes are

fixedly connected to the respective terminals.

18. An energy storage device according to claim 16 wherein at least one of the

electrodes of the supercapacitor are selectively electrically isolated from the terminals.

19. An energy storage device according to claim 18 including a switch that is

electrically disposed between one of the terminals and one of the electrodes of the

capacitor for effecting the selective electrical isolation.

20. An energy storage device according to claim 1 wherein the electrochemical

device and the capacitor each include a power density and an energy density, wherein the

energy density of the electrochemical device is greater than the energy density of the

capacitor and the power density of the electrochemical device is less than the power

density of the capacitor.

21. An energy storage device including:

a housing having two terminals; and

a first capacitor forming part of the housing and connected to the terminals.

22. An energy storage device according to claim 21 wherein the housing has a form

factor corresponding or being related to battery size designations N, AAAA, AAA, AA,

C or D.

23. An energy storage device according to claim 21 wherein an electrochemical

device is disposed within the housing for providing electrical energy to the terminals.

24. An energy storage device according to claim 21 wherein the device extends about the housing.

25. An energy storage device according to claim 21 wherein the housing is

cylindrical and extends between two opposed axially spaced apart ends, whereby the

ends define respective terminals and the capacitor extends about the housing

intermediate the ends.

26. An energy storage device according to claim 21 wherein the capacitor is an

electric double layer supercapacitor including:

a capacitor housing;

a first and a second opposed sheet electrodes disposed within the housing and

being respectively electrically connected to the terminals;

a separator located between the electrodes; and

an electrolyte intermediate for allowing charge transfer between the electrodes.

27. An energy storage device according to claim 21 wherein the capacitor is flexible

and wrapped about the housing.

28. An energy storage device according to claim 21 wherein the capacitor is flexible

and configured as a tube that is disposed within the housing.

29. An energy storage device according to claim 21 wherein the capacitor is wrapped

around the electrochemical device.

30. An energy storage device according to claim 21 wherein the electrochemical

ends and the first capacitor extends axially away from one of the ends.

31. An energy storage device according to claim 21 wherein the energy storage

device is of hollow construction with an aperture for receiving the electrochemical

device.

32. An energy storage device according to claim 31 wherein the aperture receives

both the electrochemical device and a second capacitor.

33. An energy storage device according to claim 32 wherein the first capacitor is

tubular and extends about the second capacitor and the electrochemical device.

34. An energy storage device including:

two terminals disposed on or adjacent to the exterior of the housing for

load current;

an electrochemical device disposed within the cavity and being electrically

connected to the terminals for providing a first current to the load; and

a capacitor disposed within the cavity and being electrically connected to the

predetermined load current.

35. An energy storage device according to claim 34 wherein the electrochemical

device includes an anode and a cathode that are respectively fixedly electrically

connected to the terminals by way of an anode tab and a cathode tab, and the capacitor

includes a positive electrode and a negative electrode that are respectively fixedly electrically connected to the terminals by way of a positive electrode tab and a negative

electrode tab.

36. An energy storage device according to claim 35 wherein the terminals extend from

the interior to the exterior and the anode tab, the cathode tab, the positive electrode tab,

and the negative electrode tab are disposed entirely within the cavity.

37. An energy storage device according to claim 34 wherein the capacitor is an

electric double layer supercapacitor including:

a capacitor housing;

a first and a second opposed sheet electrodes disposed within the housing and

being respectively electrically connected to the terminals;

a separator located between the electrodes; and

38. An energy storage device according to claim 36 wherein the housing is flexible.

39. An energy storage device according to claim 38 wherein the energy storage

device is flexible.

40. An energy storage device according to claim 36 wherein the housing and the

electrochemical device are rigid and the capacitor is flexible and packed about the

electrochemical device.