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| United States Patent |
4,366,216 |
| McGinness |
December 28, 1982 |
Electrical energy storage
Abstract
Electrical energy is stored in a device formed of electrodes coupled with an
oxidation-reduction polymer material, such as a polymer of quinone, semiquinone
and hydroquinone units, when a current is supplied to the device to create a
charge gradient thereacross with units at the positive end being oxidized and
units at the negative end being reduced. The charge gradient across the
electrical storage device is increased by arranging a plurality of electrically
conductive barrier laminations made of a material preventing ion passage
therethrough in the oxidation-reduction polymer material to create separated
regions of reduced and oxidized functional groups producing an additive charge
gradient.
| Inventors: |
McGinness; John E. (Houston, TX) |
| Assignee: |
MB-80 Energy Corporation (Houston, TX)
|
| Appl. No.: |
222018 |
| Filed: |
January 2, 1981 |
| Current U.S. Class: |
429/213; 429/152 |
| Intern'l Class: |
H01M 004/60 |
| Field of Search: |
429/212,213,214,215,152,162
|
References Cited [Referenced
By]
U.S. Patent Documents
| 2874204 |
Feb., 1959 |
Morehouse et al. |
429/213. |
| 2880122 |
Mar., 1959 |
Morehouse et al. |
429/212. |
| 3594231 |
Jul., 1971 |
Kraebel |
429/213. |
| 3660164 |
May., 1972 |
Hermann et al. |
429/213. |
| 3993501 |
Nov., 1976 |
Kalaoki-Kis |
429/212. |
| 4246326 |
Jan., 1981 |
Sprengel et al. |
429/212. |
| 4276362 |
Jun., 1981 |
Harvey |
429/213. |
Primary
Examiner: Lefevour; Charles F.
Attorney, Agent or Firm: Epstein;
Robert H.
Claims
What is claimed is:
1. A rechargeable electrical energy storage
device comprising
a pair of spaced electrodes; and
an
oxidation-reduction polymer material coated on said electrodes to store a charge
when an electrical current is supplied thereto.
2. A rechargeable
electrical energy storage device as recited in claim 1 wherein said
oxidation-reduction polymer material has a range of hydration of 1 to 25% by
weight.
3. A rechargeable electrical energy storage device as recited in
claim 1 wherein said oxidation-reduction polymer material has a range of
hydration of 10 to 15% by weight.
4. A rechargeable electrical energy
storage device as recited in claim 1 wherein said oxidation-reduction polymer
material includes quinone, semiquinone and hydroquinone randomly recurring
units.
5. A rechargeable electrical energy storage device as recited in
claim 4 wherein said oxidation-reduction polymer material includes a melanin
polymer.
6. A rechargeable energy storage device as recited in claim 4
wherein said oxidation-reduction polymer material includes a polymer polymerized
from hydroquinone and diethylamine.
7. A rechargeable electrical energy
storage device comprising
a pair of spaced electrodes;
an
oxidation-reduction polymer material coupled with said electrodes; and
a
plurality of barrier laminations made of an electrically conductive material
preventing ion passage therethrough, said barrier laminations being disposed in
spaced relation in said oxidation-reduction polymer material to define layers of
said oxidation-reduction polymer material whereby the charge gradient across
said layers is cumulative.
8. A rechargeable electrical energy storage
device as recited in claim 7 wherein said barrier laminations are made of metal.
9. A rechargeable electrical energy storage device as recited in claim 8
wherein said oxidation-reduction polymer material has a hydration range of from
1 to 25% water by weight.
10. A rechargeable electrical energy storage
device as recited in claim 9 and further comprising a housing hermetically
sealing said electrodes, said oxidation-reduction polymer material and said
barrier laminations to maintain the hydration of said oxidation-reduction
polymer material.
11. A rechargeable electrical energy storage device
comprising
a plurality of layers of oxidation-reduction polymer
material; and
a plurality of barrier laminations separating said layers
of oxidation-reduction polymer material, said barrier laminations being
electrically conductive to pass electrons while preventing passage of ions
thereby providing charge separation when an energy gradient is produced in
response to the supply of electrical energy to said electrical energy storage
device.
12. A rechargeable electrical energy storage device as recited
in claim 11 wherein electrodes are coupled to end layers of said
oxidation-reduction polymer material.
13. A rechargeable electrical
energy storage device as recited in claim 12 wherein said oxidation-reduction
polymer material includes a polymer of quinone, semiquinone and hydroquinone
randomly recurring units.
14. A rechargeable electrical energy storage
device as recited in claim 13 wherein said oxidation-reduction polymer material
has a hydration range of 1 to 25% by weight.
15. A rechargeable
electrical energy storage device as recited in claim 14 and further comprising a
housing hermetically sealing said oxidation-reduction polymer material, said
barrier laminations and said electrodes to maintain said hydration range.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to energy storage and, more particularly,
to devices and methods for storing electrical energy using organic materials.
2. Discussion of the Prior Art
Electrical energy is
conventionally stored in batteries wherein electrons are passed via electrodes
into an electrolyte by means of an ionic modification within the battery.
Conventional batteries utilize a metallic electrode interacting with an ionic
solution, or electrolyte, such that, as the electrode dissolves, electrons are
released for ionic storage in the electrolyte; and, accordingly, such batteries
are referred to herein as ionic batteries since electrical energy is stored and
released thereon on an ionic basis. In discharging ionic batteries, the
electrons are released at the electrodes. Such conventional ionic batteries have
the disadvantages of being slow to charge, being able to discharge large
currents for only brief periods, requiring electrodes made of specific and
usually rare metals, and consuming the electrodes thereby limiting battery
lifetime.
Many attempts have been made to increase the efficiency,
charging rate and lifetime of ionic batteries; however, such attempts have not
met with success in that, while they have improved some characteristics of such
batteries, they still rely on the ionic process of energy storage thereby
retaining relatively long charge times and consumable electrodes due to the
inherent low mobility of ions in the electrolyte.
One area where
substantial efforts have been made to improve electrical energy storage is for
use with electric vehicles, and most of these efforts have been directed toward
improving batteries to provide efficient operation of electric motors and
conservation of energy. To date, however, while many sophisticated battery
systems have been devised, such systems still suffer from decreased lifetimes
relative to charging and discharging cycles, long charging times, and the
requirement of materials expensive to produce and, in many cases, hazardous to
produce.
Research in melanins has resulted in the discovery of switching
characteristics providing high and low resistance states in response to voltage
as described by John E. McGinness et al. in an article entitled "Amorphous
Semiconductor Switching in Melanins," 1974, Science, Vol. 183, pp. 853-855, by
C. H. Culp et al. in an article in the Journal of Applied Physics, 1975, Vol.
46, pp. 3658-3659, by J. Filatous et al. in an article entitled "Thermal and
Electronic Contributions to Switching in Melanins," 1976, Biopolymers, Vol. 15,
pp. 2309-2312, and by F. W. Cope in an article entitled "Inversions of Emulsions
of Aggregated Electrons as a Possible Mechanism for Electrical Switching in Wet
Melanin," 1977, Physiological Chemistry and Physics, Vol. 9, pp. 543-546. V.
Horak et al. discuss oxidation reduction of dopa melanin in an article entitled
"A Study of The Oxygen Reduction State of Synthetic Dopa Melanin," 1971,
Molecular Pharmacology, Vol. 1, pp. 429-433, and characteristics of melanin are
further discussed by P. R. Crippa in an article "Struttura Electronica e
Proprieta Funzionali Delle Malanine," Att. Accademia Gioenia de Catania, Serie
VII, Vol. XI, 1979. Studies of melanin and their electrical characteristics have
produced only the recognition of the switching characteristics thereof; and,
after disclosure of such switching characteristics, studies of the electrical
characteristics of melanins failed to yield any information leading to other
beneficial electrical characteristics of melanins even by those on the forefront
of the semiconductor field.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to overcome
the above-mentioned disadvantages of conventional ionic batteries by providing
an electrical energy storage device and method operating on an electronic rather
than ionic basis.
Another object of the present invention is to utilize
the oxidation-reduction characteristics of organic polymers to store electrical
energy and discharge the stored electrical energy.
A further object of
the present invention is to utilize a polymer of randomly recurring quinone,
semiquinone and hydroquinone units to form an electrical energy storage device.
The present invention has another object in that electrical energy is
stored by a method including the step of supplying an electrical current to a
polymer of quinone, semiquinone and hydroquinone units to create a proton
gradient in the polymer.
Yet a further object of the present invention
is to form an electrical energy storage device of an oxidation-reduction polymer
material coupled between a pair of electrodes with one or more barrier
laminations of an electrically conductive material preventing ion passage
therethrough disposed in spaced relation in the polymer material.
Another object of the present invention is to increase the charge
gradient across the electrodes of an electrical energy storage device having an
oxidation-reduction polymer material coupled between the electrodes by arranging
a plurality of spaced, electrically conductive barrier laminations.
The
present invention has a further object in the use of an oxidation-reduction
polymer to store an electrical charge wherein the polymer has a hydration range
of 1 to 25% by weight, the hydration range being preferably between 10 and 15%
by weight.
An additional object of the present invention is to provide
an electrical energy storage device that operates on an electronic basis to
permit extremely fast charging, the electrical energy storage device including
an oxidation-reduction polymer material having electrons injected therein
followed by an ionic release.
In accordance with a further object of the
present invention, electrical energy is stored by passing an electrical current
through a polymer of quinone, semiquinone and hydroquinone units such that
quinone units at a negative end of the polymer are reduced and hydroquinone
units at a positive end of the polymer are oxidized to create a proton gradient
across the polymer.
The present invention has another object in that a
method of storing and discharging electrical energy includes passing an
electrical current through an oxidation-reduction polymer to create an energy
containing gradient thereacross by withdrawing electrons from lower energy sites
and storing the electrons at higher energy sites, the stored energy being
discharged to deliver a current from the oxidation-reduction polymer material by
withdrawing the electrons from the higher energy sites and returning the
electrons to the lower energy sites.
Some of the advantages of the
present invention over the prior art are that electrical energy storage devices
according to the present invention do not have consumable electrodes, have
extremely fast charge times on the order of twenty times faster than ionic
electrical energy storage devices, operate on an electronic basis rather than an
ionic basis, require no liquid phase materials, have extremely long lifetimes
permitting, theoretically, limitless charging and discharging cycles, can be
made of readily available, light weight, non-toxic materials, and can deliver
electrical energy the same as that of a conventional ionic battery via an energy
storage device of substantially less size and weight. The electrical storage
device of the present invention is particularly advantageous for use in powering
electrically driven vehicles in that the electrical storage device can be
charged very quickly and can, accordingly, be more fully charged via systems
operating on vehicle momentum thereby minimizing loss by increasing efficiency.
The electrical storage device is light in weight due to the oxidation-reduction
polymer and the non-consumption of electrodes permitting their construction of
light weight materials, such as aluminum, and the electrical storage device can
have any desirable shape facilitating incorporation into the vehicle body
construction.
The present invention is generally characterized in a
method of storing electrical energy including the step of passing an electrical
current through an oxidation-reduction polymer material containing functional
groups reversibly oxidizable and reducible by electron withdrawal and acceptance
to produce an energy containing gradient across the polymer material.
The present invention is further generally characterized in an
electrical energy storage device including a pair of spaced electrodes, and an
oxidation-reduction polymer material coated on the electrodes to store a charge
when an electrical current is supplied thereto.
The present invention is
further generally characterized in a method of storing and discharging
electrical energy including the steps of storing charge by passing a current
through an oxidation-reduction polymer material to withdraw electrons from
reversibly oxidizable functional groups of the oxidation-reduction polymer
material and injecting electrons in reversibly reducible functional groups of
the oxidation-reduction polymer material to store electrons possessing increased
energy, and discharging the stored charge to deliver a current by withdrawing
the increased energy electrons from the previously reduced functional groups of
the oxidation-reduction polymer material and returning the increased energy
electrons to the previously oxidized functional groups of the
oxidation-reduction polymer material.
The present invention is further
generally characterized in an electrical energy storage device including a pair
of spaced electrodes, an oxidation-reduction polymer material coupled with the
electrodes, and a plurality of barrier laminations made of an electrically
conductive material preventing ion passage therethrough, the barrier laminations
being disposed in spaced relation in the oxidation-reduction polymer material to
define layers of the oxidation-reduction polymer material whereby the charge
gradient across the layers is cumulative.
Other objects and advantages
of the present invention will become apparent from the following description of
the preferred embodiment taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1, 2 and 3 are
diagrammatic drawings illustrating the theory of operation of the electrical
storage device of the present invention.
FIG. 4 is a schematic drawing
of an electrical storage device according to the present invention.
FIGS. 5, 6 and 7 are diagrammatic drawings illustrating the theory of
operation of the electrical storage device of FIG. 4.
DESCRIPTION OF THE
PREFERRED EMBODIMENT
The present invention is based on the discovery
that, when an electrical current is passed through an oxidation-reduction
polymer material, such as a polymer of quinone, semiquinone and hydroquinone
randomly recurring units, an electrical charge will be stored at sites in the
polymer where the electrons gain a usable potential energy due to a
concentration gradient generated by oxidized and reduced functional groups
produced by electrons binding protons upon reduction and releasing protons upon
oxidation as well as the energy contained in the charge gradient consisting of
protons and hydroxyl ions which have been left behind. Electrical energy storage
devices formed of an oxidation-reduction polymer coupled with a pair of
electrodes in accordance with the present invention can, accordingly, be charged
by passing a current therethrough and thereafter discharged by coupling a load
with the electrical energy storage device to be supplied with current discharged
by the electrical storage device as protons are released and reabsorbed in the
polymer. The charge gradient created across an oxidation-reduction polymer
material was discovered by measuring pH at the ends of an oxidation-reduction
polymer after a current was passed therethrough, it being noted that current had
been passed through similar materials as reported by John E. McGinness et al. in
an article entitled "Amorphous Semiconductor Switching in Melanins," 1974,
Science, Vol. 183, pp. 853-855, by C. H. Culp et al. in an article in the
Journal of Applied Physics, 1975, Vol. 46, pp. 3658-3659, by J. Filatous et al.
in an article entitled "Thermal and Electronic Contributions to Switching in
Melanins," 1976, Biopolymers, Vol. 15, pp. 2309-2312, and by F. W. Cope in an
article entitled "Inversions of Emulsions of Aggregated Electrons as a Possible
Mechanism for Electrical Switching in Wet Melanin," 1977, Physiological
Chemistry and Physics, Vol. 9, pp. 543-546, with only the switching
characteristics of the material recognized.
While the operation of
oxidation-reduction polymers in storing electrical energy is not precisely
understood, it is theorized that upon application of a current to the polymer,
oxidation and reduction occur at opposite ends of the polymer to produce a
charge gradient. Where the polymers are formed of quinone, semiquinone and
hydroquinone units, quinone units at the negative end of the polymer are reduced
thereby gaining electrons and hydroquinone units at the positive end of the
polymer are oxidized thereby losing electrons while a finite number of
semiquinones exist in the middle of the oxidation-reduction cycle to shift to a
quinone state at the positive end and to a hydroquinone state at the negative
end.
The oxidation-reduction process takes place in accordance with the
following formula:
______________________________________
At The Negative End
At The Positive End
______________________________________
Q + H.sup.+ + e.sup.- .fwdarw. Q. H
QH.sub.2 .fwdarw. Q. H + H + e.sup.-
. QH + H.sup.+ + e.sup.- .fwdarw. QH.sub.2
. QH .fwdarw. Q + e.sup.- + H
______________________________________
An explanation of the theory upon which the present invention is
believed to operate is described with respect to FIG. 1 wherein an
oxidation-reduction polymer material 10 is shown coupled at opposite ends 12 and
14 to electrodes 16 and 18, respectively, which are adapted to be connected with
an electrical energy charging source, not shown. The polymer material 10
contains quinone, semiquinone and hydroquinone randomly recurring units with the
functional groups only thereof illustrated to facilitate understanding. Quinone
functional groups are illustrated as ".dbd.O" while hydroquinone functional
groups are illustrated as "--OH," it being appreciated that semiquinones contain
a quinone functional group and a hydroquinone functional group. Prior to the
supply of an electrical current through the polymer material, the quinone,
semiquinone and hydroquinone units will be randomly distributed throughout the
polymer material as indicated in FIG. 1 by the distribution of functional
groups.
When an electrical current is supplied to the polymer material
10, electrons (e-) are supplied to the polymer material at electrode 18, as
shown in FIG. 2; and, since electrons are more mobile in a given applied field
than ions, the electrons are shown passing through the polymer material 10
without functional group change in FIG. 2. Thereafter, protons are released to
produce quinones adjacent electrode 16, which can be considered the anode of the
electrical storage device, and bound to produce hydroquinones adjacent electrode
18, which can be considered the cathode of the electrical storage device.
Accordingly, a proton or charge gradient and a concentration or
oxidation-reduction gradient is formed across the polymer material, and these
gradients can be discharged through a load connected across the electrodes 16
and 18 by release of protons as electrons are withdrawn from the polymer
material and binding of protons where they are returned.
Only electron
current involving functional groups is illustrated in FIGS. 1, 2 and 3 and FIGS.
5, 6 and 7, to be discussed hereinafter, to simplify the drawings and facilitate
understanding of the present invention. It should be understood that these
drawings are symbolic and abstract in nature to facilitate understanding of the
theory of operation of the present invention and that all functional groups
adjacent regions 12 and 14 will not necessarily be oxidized and reduced.
It has been found that the charge gradient established across the
polymer material can be increased by forming an electrical energy storage device
of a plurality of layers of polymer material 20, 22, 24 and 26 with a plurality
of barrier laminations 28, 30 and 32 disposed therebetween, the barrier
laminations being formed of a material forming a barrier to ion movement while
permitting passage of electrons therethrough, such as copper, aluminum, titanium
or graphite. Electrodes 34 and 36 are disposed in contact with opposite ends of
the laminated polymer material and can be made of any suitable electrically
conductive material. A housing 38 surrounds the electrical storage device to
provide an hermetic seal therearound, and leads 40 and 42 extend through the
ends of the housing to contact the electrodes 34 and 36, respectively.
The laminated electrical energy storage device of FIG. 4 is believed to
operate, in theory, in the manner illustrated in FIGS. 5, 6 and 7 wherein only a
single barrier lamination 44 is illustrated as being positioned between layers
of polymer material 46 and 48 sandwiched on their opposite sides by electrodes
50 and 52, respectively. The number of barrier laminations shown in FIGS. 4, 5,
6, 7 and 8 are exemplary only, and it is noted that any number of laminations
can be used in the electrical energy storage device of the present invention,
the number of laminations being preferably as great as possible to create a
maximum charge gradient. Prior to an electrical current being supplied to the
electrical energy storage device, the quinones, semiquinones and hydroquinones
are in a random distribution as illustrated by the functional groups shown in
FIG. 5; and, once a current is supplied to the electrical energy storage device
by supplying electrons at electrode 52, which can be considered the cathode, the
electrons (e-) will initially pass through the polymer materials 46 and 48 and
the barrier laminations 44 without functional group change since electrons are
more mobile in a given applied field than ions, as shown in FIG. 6. As
illustrated in FIG. 7, the result of the barrier lamination 44 is to double the
charge separation produced by the releasing and binding of protons relative to
the example of FIGS. 1, 2 and 3. That is, the region near the anode has excess
protons and the region near the cathode has excess hydroxyls while a new region
of excess hydroxyls is created adjacent the anode side of the barrier lamination
and a new region of excess protons is created adjacent the cathode side of the
barrier lamination. Accordingly, to maximize stored charge, it is desirable to
have as many laminations as possible within a fixed volume.
Looking at
the charge gradient alone, it will be appreciated that intrinsic charge decay
occurs if the protons and hydroxyls are free to move and recombine; and, in
order to stabilize the charge separation, it is desirable to reduce the liquid
content or hydration of the polymer material to reduce mobility. Another method
of stabilizing charge separation is to leave the charge on the polymer material
itself. For example, a polymer containing functional groups, such as primary or
secondary amines, like NH.sub.2, which can bind protons to become charged
amines, like NH.sub.3 +, or carboxyls like COO.sup.- which can become COOH, will
trap protons to prevent recombination. Such polymers are modified or selected to
bind protons and hydroxyls, either chemically or electrostatically, in the
regions where they are formed to minimize recombination.
Electrical
energy storage devices according to the present invention utilize
oxidation-reduction polymers which are defined as polymers containing functional
groups which can be reversibly oxidized by removing one or more electrons from
each functional group and thereafter reduced by adding one or more electrons to
each functional group. Examples of functional groups that can be involved in
oxidation-reduction within an oxidation-reduction polymer, in addition to
phenolic oxygen functional groups, are organic acids including carboxylic acid
functional groups, nitrogen functional groups, such as amines, sulfur-containing
functional groups, the family of alcohol, aldehyde and carboxylic acid
functional groups and combinations of the above functional groups, such as an
alpha ketone next to a carboxylic acid.
The present invention is further
illustrated by means of the following examples showing the preparation of
oxidation-reduction polymers for use in electrical storage devices according to
the present invention and the construction and operation of electrical storage
devices according to the present invention:
EXAMPLE I
50 grams
of dopamine were added to 500 ml of water and 100 ml of 0.05 molar NAOH in a
2000 ml beaker at 22.degree. C. The solution was left stirring with a Fisher
Scientific magnetic stirrer at 22.degree. C. and 70% humidity for three weeks.
The remaining water was removed by subjecting the beaker containing the solution
for 24 hours to a vacuum at 37.degree. C. supplied by a vacuum pump. The
resulting polymer material was a black powder of a very fine consistency which
was then placed in a storage bottle by shaking the powder out of the beaker.
EXAMPLE II
50 grams of dopamine were added to 500 ml of water
and 100 ml of diethylamine (DEA) in a 1000 ml beaker at 22.degree. C. The
solution was left stirring with a Fisher Scientific magnetic stirrer at
22.degree. C. and 70% humidity for three weeks. The remaining water was removed
by subjecting the beaker containing the solution for 24 hours to a vacuum at
37.degree. C. supplied by a vacuum pump. The resulting polymer material was a
black powder of a very fine consistency which was then placed in a storage
bottle by shaking the powder out of the beaker.
EXAMPLE III
100
grams of hydroquinone were added to 1000 ml of solution containing 1 ml
tetranitromethane, 100 ml of diethylamine (DEA) and 900 ml of water in a 2000 ml
beaker at 22.degree. C. The hydroquinone gradually entered the solution as
polymerization proceeded the solution was stirred with a Fisher Scientific
magnetic stirrer continuously at 22.degree. C. After 21 days, the stirring
action was stopped and the polymer had a uniform density and was of a black
color. The polymer was left in the beaker without stirring for seven days and
the polymer precipitated as a sludge at the bottom of the beaker. The sludge was
removed from the beaker with a spatula and had a granular consistency, was black
in color, had a molasses-like viscosity and adhered readily to metal and plastic
surfaces.
EXAMPLE IV
An electrical storage device was
constructed using DEA dopamine melanin (DEADM) prepared in accordance with
Example II as the polymer material. DEAM powder was rehydrated by exposing the
powder to steam to produce 20% water content by weight and 100 mgs of the
rehydrated polymer material was coated on titanium metal plates measuring 2.5 cm
by 2.5 cm surface area and 0.90 mm thickness. Nine plates were coated on both
sides and two plates were coated on one side. The DEADM coated plates were
pressed together sandwiching 200 mg of DEAM between adjacent metal plates to
produce an electrical storage device having ten layers of DEAM, nine barrier
laminations and two electrodes measuring 2 cm in length. The electrical storage
device was encased in a plexiglass housing measuring 4 cm by 4 cm by 3 cm.
Contacts were formed on the electrical storage device by threading a screw into
opposite plexiglass faces of the housing to contact the end plates or electrodes
of the electrical storage device. The plexiglass was sealed with #3 Weld.On
plastic cement manufactured by the Industrial Polychemical Service to prevent
hydration of the DEAM from changing from the 20% value at the time of
construction.
The electrical storage device was charged by applying 200
v for 10 seconds across the electrodes at an average current of 25 ma. The
energy storage device was monitored with a voltmeter connected across the
electrodes and a milliammeter connected in series between one electrode and one
terminal of a piezoelectric buzzer having an impedance of 15 K.OMEGA., the other
terminal of the buzzer being connected to the opposite electrode of the
electrical storage device. The buzzer emitted a sound for a four-minute period
after connection. When the buzzer was connected, the voltage across the
electrical storage device was 6 v and the current delivered was 4 ma, and during
a two-minute period immediately after connection, the voltage fell from 6 v to 3
v and the current fell from 0.4 ma to 0.2 ma. During the following two-minute
interval, the voltage fell from 3 v to 1.8 v and the current fell from 0.2 ma to
0.1 ma. The buzzer possessed a 2 v cutoff and no longer was audible although
energy was still stored in the electrical storage device.
Using the same
voltmeter and ammeter connections with various loads, the following results were
obtained for the cited charging conditions:
______________________________________
Measured Upon Connection with Load
CHARGING LOAD LOAD LOAD LOAD
CONDITIONS 100K 10K 1K 0.1K
______________________________________
250V
10MA 2.3V 1.5V 0.2V .04V
10 sec. .02MA .08MA .25MA .3MA
200V
10MA 5.6V 2.3V .3V .03V
1 Min. .06MA .23MA .4MA .4MA
200V
10MA 6V 2.5V .4V .03V
1 Min. .06MA .26MA .4MA .3MA
50% Duty Cycle
10 Sec. on/
10 Sec. off
54V
2.5MA 5.0V 1.2V .2V .01V
5 Min. .02MA .2MA .2MA .1MA
111V
10MA 4.5V 2V .3V .03V
5 Min. .04MA .2MA .4MA .2MA
50% Duty Cycle
10 Sec. on/
10 Sec. off
______________________________________
From the above, it was noted that the electrical storage device
was most efficiently charged by application of high power for a short period of
time, it being appreciated that increase of charging time from 10 seconds to 1
minute did not produce a concomitant increase of stored charge. Additionally,
interrupted or pulsed application of charging electricity was at least as
effective as continuous charging over the same charging interval.
EXAMPLE V
An energy storage device was constructed using heavy
duty Reynolds wrap aluminum cut in 20 cm by 20 cm square sheets. A polyethylene
sheet of 0.1 mm thickness was cut into 20 cm by 20 cm square sheets and the
inside 19.5 cm by 19.5 cm square section was removed. The polyethylene was glued
to both sides of one aluminum sheet and one side each of two other aluminum
sheets with epoxy glue. The aluminum was coated inside the polyethylene with
DEADM prepared in accordance with Example II, the DEADM having been rehydrated
to 30% water content by weight. The wet surface of the DEADM was dusted with dry
dopamine melanin prepared in accordance with Example I, and the melanin coated
aluminum sheets were pressed together with the polyethylene preventing the
aluminum edges from making contact.
The electrical storage device was
tested by charging at 200 v with 25 ma for 10 seconds and monitoring the voltage
developed. The electrical storage device would not store more than 0.4 v which
discharged completely in one minute. The electrical storage device was
dehydrated by placing in an incubator at 50.degree. C. for 24 hours and retested
as before. The voltage developed was 0.78 v and discharged over a ten-minute
period with no load. The electrical storage device was returned to the incubator
for 48 hours for dehydration after which it developed the following voltage-time
characteristics:
______________________________________
TIME VOLTAGE
______________________________________
0 Min. 1.5 V
5 Min. 1.06 V
10 Min. .93 V
15 Min. .84 V
20 Min. .77 V
25 Min. .71 V
30 Min. .67 V
40 Min. .58 V
60 Min. .45 V
1Hr.20 Min. .35 V
______________________________________
The voltage decay time was measured with a 100 K.OMEGA. load and
developed the following voltage-time characteristics:
______________________________________
TIME VOLTAGE
______________________________________
0 Min. 1 V
4 Min. .5 V
8 Min. .3 V
16 Min. .23 V
30 Min. .16 V
______________________________________
EXAMPLE VI
An electrical storage device was constructed
from the polymer material prepared in accordance with Example III (HQDEA) and
three titanium metal plates of 2.5 cm by 2.5 cm area and 0.90 mm thickness. The
HQDEA sludge was coated on both sides of one plate and one side of the other
plates at a thickness of 0.2 mm. The plates were combined to form two
laminations. The electrical storage device formed measured 3.5 mm in thickness
and was allowed to remain at room temperature for ten days. After this period,
the electrical storage device was charged at 200 v with 100 ma for ten seconds
via electrodes formed by the end plates of the electrical storage device, and
the voltage across the electrical storage device was measured with a voltmeter
connected across the electrodes while current was measured with an ammeter
connected in series with one electrode and one terminal of a piezoelectric
buzzer having an impedance of 15 K.OMEGA. the other terminal of the buzzer being
connected to the opposite electrode of the electrical storage device. As the
electrical storage device commenced discharging through the buzzer, the voltage
across the electrical storage device was 2 v and the current discharged was 0.4
ma. The buzzer was audibly operated for two minutes, and at the end of two
minutes, the current discharged was 0.1 ma.
Oxidation-reduction polymers
containing quinone and hydroquinone functional groups are insulators in their
pure form and do not show appreciable electrical activity. When a liquid is
adsorbed by the polymer, the electrical activity increases in proportion to the
static dielectric constant of the liquid introduced to produce the
oxidation-reduction polymer as a polymer-adsorbed liquid mixture. A given
conductivity or electrical activity can be reached by introducing a moderate
amount of high dielectric constant liquid or a larger amount of lower dielectric
constant liquid. For water, a desired range of electrical activity is reached
with a hydration range of 1% to 25% water by weight depending on the activity
desired and the polymerization procedure with a preferred range of 10% to 15%
water by weight allowing the best mechanical stability.
Electrical
energy storage devices in accordance with the present invention can be
constructed using mixtures of various oxidation-reduction polymers to form the
oxidation-reduction polymer material; and, accordingly, it will be appreciated
that the term "oxidation-reduction polymer material" as used herein is meant to
include materials containing one or more oxidation-reduction polymers.
The storage of energy in the oxidation-reduction polymer material is not
dependent on the switching characteristics of the polymer but rather is
accomplished by removing electrons from less energetic sites and storing the
electrons in higher energy sites in response to the supply of electrical energy
delivered to the polymer material by an external source. The potential energy
possessed by an electron depends upon the concentration of charge in its
vicinity. The potential energy difference between two sites depends upon the
difference in the potential energy of the electron at the site surrounded by a
higher negative charge and the potential energy of the electron at the site
containing less negative or even positive charge. The electrons from the cathode
which bind protons are surrounded by negative hydroxyl ions. The sites at the
anode which have lost an electron during charging are surrounded by positive
proton ions. The site surrounded by hydroxyl or other negative charges released
in the process of storing energy is the high energy site. The site surrounded by
protons or other positive charges released in the process of storing charge is
the low energy site.
Inasmuch as the present invention is subject to
many variations, modifications and changes in detail, it is intended that all
subject matter discussed above or shown in the accompanying drawings be
interpreted as illustrative and not in a limiting sense.
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