|United States Patent
|Filatovs , et al.
||March 12, 1985 |
Electrical energy storage
Storage of electrical energy in an oxidation-reduction polymer material is
optimized when the material is lignin and/or hydrazine is added to the material
so as to facilitate bonding of the material to graphite. A preferred embodiment
of the invention includes a storage device having an electron acceptor component
separated from an electron donor component by a barrier which is impregnated
with an electrolyte so as to electrically separate the two components while
serving as an ion conduit. At least one of the layers includes an
oxidation-reduction polymer material which either is lignin or is mixed with
hydrazine, or both. The preferred energy storage material is a mixture of
lignin, hydrazine and graphite, the latter being either added to the mixture or
formed by graphitization upon heating of the lignin.
||Filatovs; George J. (Greensboro, NC);
McGinness; John E. (Houston, TX) |
||MB-80 Energy Corporation (Houston, TX)
||August 31, 1983|
|Current U.S. Class:
||429/304; 252/182.1; 429/213
|Field of Search:
References Cited [Referenced
U.S. Patent Documents
|Foreign Patent Documents|
Chemical Abstracts: Fitzpatrick et al., vol. 76,
Chemical Abstracts: Moskovtsev et al., vol. 87,
Chemical Abstracts: Gurgenidze et al., vol. 84,
Primary Examiner: Walton;
Attorney, Agent or Firm: Epstein & Edell
What is claimed:
1. A rechargeable electrical energy storage
a first electrode;
a component of electron
acceptor material coupled to said first electrode;
a second electrode;
a component of electron donor material coupled to said second electrode;
ion-conducting solid-state barrier means coupled to both said
components of electron acceptor and electron donor material for electrically
separating said components and passing ions through said components;
wherein at least one of said electron donor material and electron
acceptor material includes lignin, an ohmic contact material, and a reducing
agent for bonding the lignin to said ohmic contact material.
rechargeable electrical energy storage device according to claim 1 wherein said
electron acceptor material includes lignin mixed with a salt, and wherein said
electron donor material includes lignin.
3. A rechargeable electrical
energy storage device according to claim 2 wherein said salt is zinc chloride.
4. A rechargeable electrical energy storage device according to claim 1
wherein said electron acceptor material includes lignin mixed with a hydrazine,
and wherein said electron donor material includes lignin.
rechargeable electrical energy storage device according to claim 4 wherein said
hydrazine is hydrazine-monohydrate.
6. A rechargeable electrical energy
storage device according to claim 4 wherein said first and second electrodes are
7. A rechargeable electrical energy storage device according
to claim 4 wherein said electron acceptor material is a mixture of approximately
1:1.5 by weight of lignin at a pH of approximately 10.6 and
8. A rechargeable electrical energy storage
device according to claim 1 wherein said electron acceptor material and said
electron donor material are both a mixture of lignin and hydrazine.
rechargeable electical energy storage device according to claim 1 wherein said
electron acceptor material includes lignin and said electron donor material
10. A rechargeable electrical energy storage device
according to claim 9 wherein said electron acceptor material includes lignin
having a 20% hydration, and wherein said barrier means is a film of plastic
material impregnated with zinc sulfate.
11. A rechargeable electrical
energy storage device according to claim 9 wherein said electron acceptor
material is lignin that has been partially graphitized by heating.
rechargeable electrical energy storage device according to claim 1 wherein said
electron acceptor material is lignin that has been graphitized by heating, and
wherein said electron donor material is a mixture formed by heating lignin
saturated with ammonia.
13. A rechargeable electrical energy storage
device according to claim 1 wherein said electron acceptor material is a mixture
formed by dissolving lignin in methyl alcohol.
14. A rechargeable
electrical energy storage device according to claim 13 wherein said electron
donor material is zinc.
15. A rechargeable electrical energy storage
device according to claim 1 wherein said barrier means includes a film of
plastic material impregnated with an electrolyte.
16. A rechargeable
electrical energy storage device according to claim 1 wherein said electrolyte
is zinc sulfate.
17. A rechargeable electrical energy storage device
according to claim 1 wherein said one of said acceptor and donor materials is a
mixture of lignin, hydrazine monophosphate and graphite.
rechargeable electrical energy storage device according to claim 17 wherein the
other of said acceptor and donor materials is a mixture of hydrazine
monohydrate, diethylamine and hydroquinone.
19. A rechargeable
electrical energy storage device according to claim 1 wherein said one of said
acceptor and donor materials is a mixture of hydrazine monohydrate, diethylamine
20. A rechargeable electrical energy storage device
according to claim 1 wherein said reducing agent is 2, 4-dinitrophenyl
21. A composition of matter comprising a mixture for storing
electrical energy, said mixture including lignin polymer material, a hydrazine
compound, and graphite.
22. A composition of matter according to claim
21 wherein said hydrazine compound is hydrazine monohydrate.
composition of matter according to claim 21 wherein said hydrazine compound is
24. A composition of matter according to claim
21 wherein said polymer material is formed by dissolving lignin in methyl
25. A rechargeable electrical energy storage device comprising:
a pair of spaced electrodes; and
storage means sandwiched
between said electrodes for storing electrical energy in response to passage of
electrical current therethrough, said storage means comprising a mixture of:
an oxidation reduction polymer material;
an ohmic contact
reducing agent means for adding electron-repelling groups
to the polymer material to render the polymer material more anodic and for
facilitating molecular connection between the polymer and ohmic contact
26. The device according to claim 25 wherein said polymer
material is lignin.
27. The device according to claim 25 wherein said
ohmic contact material is graphite.
28. The device according to claim 25
wherein said reducing agent means is a hydrazine compound.
device according to claim 28 wherein said polymer material is lignin.
30. The device according to claim 29 wherein said ohmic contact material
31. The device according to claim 28 wherein said ohmic
contact material is graphite.
32. The device according to claim 25
wherein said polymer material is lignin and said ohmic contact material is
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to devices and methods for storing
electrical energy using organic materials. More particularly, the invention
relates to energy storage in a device which in part comprises organic
semiconducting materials derived by modifying existing polymers or cross-linking
monomers such that they are capable of functioning as electron donors or
acceptors so as to form an assembly which can be repeatedly charged with and
discharge electrical energy. The present invention is an improvement of the
device described and claimed in U.S. Pat. No. 4,366,216 to
McGinness, the disclosure of which is expressly incorporated herein by reference
in its entirety.
2. Discussion of the Prior Art
electrical energy occurs through electron-transfer reactions which permit the
extraction and addition of electrons through an external circuit. Various
methods of storing and extracting this energy have been the focus of
considerable research and development which have taken many approaches, each
with individual success and compromise. Prior to the present invention,
electrical energy storage systems have been devised at various levels of
sophistication, each with sufficient shortcomings to render further research and
It is known in the prior art that semiconducting
materials may be employed as electron donors or acceptors. However, the
operation of such devices is not fully understood and their utilization has been
limited chiefly as electron acceptors (i.e. cathodes) in primary cells,
primarily the halogen-organic charge transfer complexes. Moreover, the organic
complex cathodes are usually coupled with inorganic anodes such as lithium.
Although such batteries have high power and current characteristics and
reasonably long storage life, they suffer from the disadvantages of high
manufacturing cost, toxicity during manufacture and disposal, and dependence on
scarce strategic materials.
A promising breakthrough in electrical
energy storage has been described in the aforementioned McGinness patent which
discloses the use of an oxidation-reduction polymer material, such as a polymer
of quinone, semiquinone and hydroquinone units, as a storage device. The
oxidation-reduction polymer when operated in the solid state was found to have
extremely fast charge time (on the order of twenty times faster than ionic
electrical energy storage devices) at the proper static dielectric constant
while eliminating the requirements for consumable electrodes and liquid phase
materials. In addition, such storage devices have extremely long lifetimes
permitting, in theory, limitless charging and discharging cycles. Moreover, the
oxidation-reduction polymer material storage device can be made of light weight
non-toxic materials and can deliver electrical energy comparable to that of a
conventional ionic battery but using a device of substantially less size and
weight. The oxidation-reduction polymer materials disclosed in the McGinness
patent include melanins, a polymer which is polymerized from hydroquinone and
diethylamine, and others. We have found, however, that the performance
characteristics of the energy storage device can be considerably improved if
other oxidation-reduction polymer materials are employed or if the materials are
treated in a particular manner. In particular, the energy density is improved by
over two orders of magnitude.
SUMMARY OF THE INVENTION
Accordingly, it is the primary object of the present invention to
provide an improvement of the electrical energy storage methods and apparatus
described in the aforementioned McGinness patent.
Another object of the
present invention is to provide an energy storage device employing an
oxidation-reduction polymer material which is available in large quantities and
at very low cost.
A further object of the present invention is to
provide an energy storage device having electron donor and acceptor components,
at least one of which is an organic semiconducting compound, the components
being separated by a barrier which is impregnated with an electrolyte and which
electrically separates the active donor and acceptor materials while acting as
an ion conduit.
A still further object of the present invention is to
provide an electrical energy storage device which includes a pair of spaced
electrodes and storage means including an oxidation-reduction polymer material
coupled between the electrodes and arranged to store electrical energy in
response to passage of electrical current therethrough, and wherein at least one
component of the polymer material is lignin.
The present invention has
another object in that the aforesaid device includes additive means mixed with
the polymer material for bonding the polymer material to graphite in the mixture
so as to thereby increase conductivity of the material. In the preferred
embodiment, the additive means comprises a hydrazine.
Another object of
the present invention is to provide a rechargeable electrical energy storage
device having a pair of spaced electrodes and storage means in the form of an
oxidation-reduction polymer material coupled between the electrodes and mixed
with a hydrazine.
One aspect of the present invention is characterized
by the use of the natural polymer lignin as the oxidation-reduction polymer
material in an energy storage device. While various lignin material has been
utilized in battery systems in the prior art, such use has been limited to
serving as fillers and expanders, passivating agents, antioxidants, etc. There
is no recognition in the prior art that lignin may be utilized as a solid state
electrical energy storage agent, in that it contains an unusually anodic
functional group which can either be blocked or destroyed by titrating acid with
HCl. Finally we have found that other naturally occuring substances such as
squid melanin or melanosomes may also contain these functional groups.
In another aspect of the present invention an oxidation-reduction
polymer has its energy storage capability improved dramatically when it is mixed
with a hydrazine or other reducing agent. Specifically, the hydrazine functions
as an anodic functional group when connected to the conjugated polymer
structure, the activity of the functional groups being enhanced by the double
bond structures in its vicinity. In addition, the hydrazine serves as a
molecular solder which connects the polymer to the electrode of the storage
device. The combination of increased conductivity and enhanced bonding to the
electrode renders the hydrazine ideally suitable as a component of the mixture
which comprises the energy storage material.
BRIEF DESCRIPTION OF THE
These and other objects, features and many of the attendant
advantages of the invention will be better understood upon a reading of the
following detailed description when considered in conjunction with the
The FIGURE is a diagrammatic illustration of one
form of the energy storage device of the present invention.
OF PREFERRED EMBODIMENTS
The present invention is based on the discovery
that lignin, a naturally occurring polymer, is particularly useful for storing
electrical energy. As noted above, lignin has been used in batteries in the
prior art, but only as fillers, expanders, passivating agents, anti-oxidants,
etc. It turns out, however, that lignin can be charged by a charging current so
as to store electrical energy which can be used to drive a load.
is the major non-cellulosic component of wood. In a broader sense, the term
lignin is a generic term which includes other lignin-containing products such as
various paper mill products and effluence, black liquor, commercial lignin and
even ground-up newsprint. The term lignin as used herein is evident from this
context. In general, the present invention operates most efficiently with the
purest form of lignin available; however, one of the advantages of the present
invention resides in the fact that it is capable of utilizing almost any form of
lignin. Due to the broad range of chemical purities in the various
aforementioned lignin products, the necessary modifying treatments and resultant
electronic characteristics may vary. As expected, performance degrades as the
lignin becomes more impure.
In its isolated form, lignin includes many
randomly bonded and cross-linked units, forming macro-molecules with a formula
of the family OCH.sub.3 C.sub.6 O.sub.2 (CH).sub.n SH. Lignins are not a
chemical compound but a material which is statistically describable in terms of
the concentration of functional groups and the kind and frequency of interunit
linkages. The average lignin is known to contain aromatic rings with a side
chain, one or two methoxyls, a phenolic hydroxyl or phenol ether. Prominent
configurations in the chemical structure are the quinoid charge transfer
complexes. While quinoid materials have been previously explored for use as
energy storage materials as described in the aforementioned McGinness patent, it
is the source (i.e. lignin) and modifications of these materials as part of the
present invention which makes them more viable as energy storage devices.
The present invention is also based on the discovery of the aforesaid
modifications to the polymer materials so as to make them more viable for the
intended purpose. One of the principal agents in modifying the polymers
according to the present invention is hydrazine. Hydrazine has heretofore been
widely used for such functions as fuel cell materials and immunology research to
bond tyrosine residues to plastic for mechanical adherance. It has been found,
however, that hydrazine will bond a variety of quinones to graphite with
resulting increase in conductivity. Specifically, hydrazine is employed with the
oxidation-reduction polymer in accordance with the present invention for two
distinct purposes: (1) the addition of electron-repelling groups to render the
base polymer more anodic; and (2) as a molecular solder connecting the polymer
to an ohmic electrode. More specifically, it has been found that
2,4-dinitrophenyl hydrazine can be mixed with an oxidation-reduction polymer
such that the hydrazine functions as an anodic functional group when connected
to the conjugated (phenyl) ring structure. The activity of the functional groups
is enhanced by the double-bond structure in its vicinity.
accordance with the present invention, lignin can be employed in the non-barrier
and barrier structural embodiments of the aforesaid McGinness patent, and
although, in accordance with the present invention, oxidation-reduction polymers
in general may be mixed with hydrazine in the non-barrier and barrier structural
embodiments of the aforesaid McGinness patent, it has been found that the
structure illustrated in the accompany drawing is particularly suitable for
electrical energy storage devices. Referring to that drawing, an electrical
energy storage device 10 includes collector electrodes 11 and 13 which form
ohmic interfaces 12 and 14 with respective electron acceptor 15 and electron
donor 17 components, respectively. A barrier 19 is disposed between the electron
acceptor 15 and the electron donor 17 and is impregnated with an electrolyte.
Barrier 19 serves to separate the active materials of components 15 and 17 into
two compartments while acting as an ion conduit therebetween. An external
circuit 20 operates to withdraw or introduce electrons into the active material
in components 15 and 17. Specifically, series-connected ammeter 22 and resistor
23 are selectively connected across collector electrodes 11 and 13 by a switch
21 in one of its positions. A charging circuit, including a variable voltage
source 24., is selectively connected across these electrodes in another position
of switch 21.
As noted above, the present invention involves certain
modifications which can render an organic semiconducting polymer containing
quinoid subunits suitable as an electron donor or acceptor. Moreover, as noted
above, the present invention recognizes that there is a plentiful and natural
source of such polymer, namely lignin. These materials can be made to function
as one or both of the components 15, 17, depending upon the chemical and
physical modifications employed. In addition, these materials can be made so as
to acquire characteristics which compensate for some of their shortcomings.
The electro-chemical properties of organic semiconducting materials lack
adequate theoretical description. General interpretations and understandings
arise from a combination of considerations based on solid state physics,
chemistry and structure. Therefore, the operational theory described hereinbelow
is only theory and is intended to be illustrative of the present understanding
of the invention operation. In addition, there are simply too many possible
variations in the structure, detail and composition of the materials employed in
the invention to provide an exact theory which covers all of the possibilities.
The discussion which follows inherently includes the role played in the
invention by oxygen (present primarily in the form of lone pair states, such as
in quinones) nitrogen (present primarily in hydrazine) and sulfur (present
primarily in sulfimides, sulfonation and sulfhidrals). Moreover, it should be
recognized that elements of higher order in the chemical periodic table may
The polymeric semiconductive materials which may be
employed in energy storage devices in accordance with the present invention
contain both modifications to the quinone structure and additional sub-units.
When an electrical current is passed through the material, certain sites in the
material can accept or donate electrons while simultaneously reacting with ions,
depending upon the free energy states of the sites before and after the
accepting-donating event. When the device is charged from the external circuit
20, higher energy states are created which can later drive an internal ionic and
external electric current when the device is later discharged through a load. In
this regard, the standard battery terminology of cathode and anode are most
applicable when considering events external to the energy source device.
Internal events can include charge gradients, counter ions, charge transfer
complexes, etc., which render some terminology unclear. In some contexts the
terms anode and cathode are useful, such as the reference to potential voltage
levels described below.
Pure quinones have an electrical potential of
0.7 volts with respect to hydrogen making them cathodic-electron acceptors with
respect to the standard inorganic battery materials, such as zinc. Hydroquinones
are anodic toward hydrogen and donate electrons to strong electron acceptors.
For a battery to be constructed entirely of quinone and hydroquinone units, the
electrical potentials must be changed. The alterations possible are substituents
and modifications to the rings and to the non-ring groups. The effect of these
can be followed qualitatively as alterations in electron density in the vicinity
of oxidizable or reduceable groups. The effect is greatest in alterations of the
quinone ring. Quinone is ordinarily cathodic and accepts electrons when it is
reduced to hydroquinone. The effects of substituents on the ring are that
electron-attracting groups decrease electron density in the vicinity of oxygen,
rendering the compound a stronger oxidizing agent. Electron-repelling groups
have the opposite effect.
Hydroquinone is normally anodic and donates
electrons when oxidized to quinone. The effect of ring substituents is that the
anodic potential is raised if there is a higher electron density, for example,
by adding electron-repelling groups, in the vicinity of an oxidizable group.
Alternatively, the ring substituents make the compound a stronger reducing agent
by rendering the compound more weakly aromatic.
Finally, the voltage
obtained with graphite as the ohmic contact is anomalously high and can exceed
2.5 V in contrast to metal ohmic contacts which provide potentials which
correlate with the 0.7 volt contribution expected from quinones and yields 1.4 V
The general theory of operation within the
oxidation-reduction polymer material used for electron acceptor 15, electron
donor 17, or both, is described in detail in the aforementioned McGinness patent
and is not repeated herein. The present invention is best illustrated by means
of the following examples which show the preparation of oxidation-reduction
polymers for use in electrical storage devices, including the device shown in
the accompanying drawing, according to the present invention:
An energy storage device was constructed using typical pulp mill black
liquor (lignin) at 20% hydration. Black liquor paste was spread on a 32 mm
graphite disc and was in turn covered with a thin paste of zinc chloride. The
combined pastes were then covered with a 32 mm diameter zinc disc, forming a
device in the form of a sandwich of graphite/black liquor/salt/zinc. The device
was charged at 1 ampere for four ten-second cycles. The decay voltage was
monitored and, after the fourth cycle, stabilized. The device was discharged and
then charged at 200 mA for one minute. The resultant total efficiency (available
stored energy versus charging energy) was 12% and the energy density was 125 M
Joules/m.sup.3. The average potential was 1.8 volts. The short circuit current
An energy storage device was constructed
as in Example I with the addition of a Celgard microporous film (Celanese Fibers
Marketing Co.) serving as barrier 19 of the drawing. The liquor/zinc chloride
mixture was spread on the zinc disc, covered with the Celgard film; liquor alone
was spread on the other side of the film, and covered with a graphite disc.
(Devices in which zinc chloride was used without liquor on the zinc disc
component did not function as well as a mixture of zinc chloride with liquor.)
This energy storage device had energy densities of over 100 M Joules/m.sup.3,
with increased total efficiency, typically above 30%, and a significantly
reduced voltage decay rate.
An energy storage device
was constructed by layering a 0.05 mm black liquor coat on a 32 mm graphite
disc, placing a Celgard film on top, and layering a 0.05 mm coat of hydra-
zine-monohydrate treated liquor. A 32 mm graphite disc was placed on top of this
as an ohmic contact. (The liquor was treated with hydrazine by mixing 500 mg (at
a pH 10.6) of liquor with 750 mg of hydrazine and heating the resulting liquor
at 60.degree. C. for ten minutes.) The charging process evaporated excess
liquid; further, the discharge characteristics showed that the liquor was
modified such that it was capable of acting as an electron acceptor toward
untreated liquor. The initial polarity of the energy storage device was negative
with the liquor at pH 12.6, acting cathodic with regard to the liquor with pH
10.5. (The addition of hydrazine monohydrate makes the liquor more basic.) The
charging current reversed this polarity. However, the energy retention was
relatively poor. Twenty-four hours later, the sample was tested at the same
dynamic impedance (125 ohms) and was found to have increased its energy storage
capacity from 2 MJ/m.sup.3 to 8 MJ/m.sup.3. The average potential was 1.4 volts.
Furthermore, the discharge curve of voltage versus time was much flatter than is
usually observed for quinone-containing polymers, including liquor and other
lignins which have not been treated with hydrazine.
An energy storage device was prepared as in Example III from one gram of
black liquor treated by mixing with hydrazine monohydrate at a pH of 12.6. The
liquor was titrated to the desired pH by addition of ten normal NaOH. Two
milliliters of hydrazine were then added. The material was incubated at
60.degree. C. for eighteen hours to remove excess water and allow the reaction
mixture to reach equilibrium. In this example and in some following, the
electronically active polymer was used in a variant form termed a composite
material (abbreviated CM) which is a combination of polymer with an ohmic
contact material, for instance, graphite powder. This composite structure
increased surface area and stabilized the electronic properties, as well as
improving mechanical behavior. The device was constructed from the combination
of a graphite disc, the composite material, and separator in the order:
graphite/CM/Separator/CM/graphite. The effect of adding graphite was to raise
the potential to over 2 volts, lower the internal impedance to 5.7
ohms/cm.sup.2, increase the energy density to over 25 MJ/cm.sup.3, and slow
internal discharge. This device ran a transistor radio at 10MA until the voltage
dropped below the 2 V cutoff of the radio, at which time the device still
contained over 80% of its charge. Short circuit current after charging was
An energy storage device was constructed using
a commercial lignin known as Indulin AT (Polychemicals Department, Westvaco)
which is a kraft pine lignin polymer. The device consisted of an zinc electron
donor (32 mm disc), a ZnS04 saturated Celgard film, and a 20% hydration lignin
paste 0.05 mm thick as the electron acceptor. Tantalum discs, again 32 mm in
diameter, formed the ohmic contacts. The device was charged and discharged
(three times) until the voltage was stabilized and energy density raised, a
procedure which has been found to be beneficial. The device then had an energy
density of 150 MJ/m.sup.3, and an average discharge voltage of 1.2 volts.
Lignin (Indulin AT) was packed in a tantalum foil
envelope and heated to 1200.degree. C. for three hours. The resulting product
was a partly graphitized mass with improved mechanical properties and higher
electrical conductivity. When tested as in Example V, it acted as an electron
acceptor toward zinc and had an energy density of 200 MJ/m.sup.3 at an average
voltage of 1.0 volts.
Lignin (Indulin AT) was
saturated with ammonia and packed in a tantalum foil envelope and heated at
1200.degree. C. for four hours. The resultant product was found to function as
an electron donor against the material in Example VI. Tested in the manner of
Example V, with an electrolyte of NaOH, it produced an energy density of 80
MJ/m.sup.3 at an average voltage of 0.9 volts.
energy storage device was constructed using Indulin AT as the electron acceptor.
The lignin was dissolved in methyl alcohol and a graphite felt was saturated
with the solution using a vacuum funnel. The felt was then dried in a vacuum at
60.degree. C., rehydrated, and tested against a zinc electron acceptor with a
Celgard film impregnated with zinc sulfate as an electrolyte. Due to the large
increase in surface area for electron transfer, there was a corresponding
improvement in charging/discharging kinetics and energy density. The energy
density was approximately 200 MJ/m.sup.3, and the average voltage 1.2 volts.
An energy storage device was constructed as in
Example VI, charged, and then cooled to 10.degree. C. The self-discharge rate
decreased by 83%. Discharging the device through an external circuit at
10.degree. C. reduced the discharge rate by 32%. This demonstrates that even
though the low temperature charging/discharging characterisitics of lignin are
superior to lead-acid systems, for example, there is a temperature dependence
which can be used to lower the self-discharging life.
A composite material (CM1) was formed by mixing one gram of black liquor
with 1 ml of hydrazine monophosphate and incubating the mixture for three
minutes. Graphite powder (500 mg) was mixed into the black liquor and hydrazine
mixture. A second composite material (designated CM2) was formed by first mixing
1 mg of hydrazine monohydrate and 1 ml diethylamine. One gram of hydroquinone
was then mixed into the solution and 300 mg of distilled water was added. The
resultant chemical reaction raised the temperature from 25.degree. C. to
46.degree. C. Several energy storage devices were constructed with graphite as
the ohmic contact and Celgard separators with the configuration:
graphite/CM1/Separator/CM2/graphite. The energy content was highest with the CM1
as the cathode and CM2 as the anode. One energy storage device was reverse
charged; that is, with CM1 the anode and CM2 the cathode. In both cases, the
storage capacity continued to increase from twenty-four hours after initial
charging. The device which was reverse charged was charged twenty-four hours
later in the original charge configuration and found to store only approximately
24% of original capacity. This indicates that initial charging current,
therefore, polarizes the energy storage devices which incorporate hydrazine.
In the previous descriptions, the results were obtained on developmental
devices which used materials such as Teflon, tantalum, sealing materials, and so
forth. These were used for better control and ease of testing and fabrication;
for this reason they were not detailed, along with the test methods of data
gathering and processing, as they are not pertinent to the operation of the
One of the advantages of the present invention over the prior
art is that both the electron acceptor component 15 and the electron donor
component 17 can be made from the same organic semiconducting material. This
confers advantages in processing and in stability. Cross-contamination is
lessened when the anode and cathode are derived from the same material.
A further advantage of the present invention is that a readily available
material, namely lignin, may be employed as the basis for one series of
materials. This material is a by-product of the paper making industry and is
frequently thought of as a waste product. In addition, the non-toxicity of
lignin, as evidenced by its use in animal feed, is another distinct advantage.
The energy storage material which, in the preferred embodiment, is treated in
the manner described, is not suitable for use as food; however, it is clearly
safe to handle. The energy storage materials are also chemically stable,
lightweight and readily moldable to specific shapes.
In addition to the
examples described above, experiments were conducted with the device of the
present invention by titrating black liquor lignin with hydrochloric acid in
order to determine the role of sulfur groups in energy storage devices. A
precipitant was formed, along with the release of sulfur gas, as a result of the
titration. The resulting polymer was markably reduced in energy storage
capacity. Furthermore, it was noted that quinone polymers without sulfur or
other anodic groups are also low in energy storage capacity. This phenomenon can
be prevented by treatments which preserve the sulfur groups in the material. In
such cases, titration with sulfuric acid allows protection if an acidic sample
Finally, the graphite bonded by hydrazine allows the static
dielectric constant to be reduced without appreciably lowering the impedence.
Previously the static dielectric constant was lowered to prevent internal decay.
Although internal decay could be drastically reduced, only a limited reduction
could be achieved before the impedence became too high.
It will be
appreciated that the structure illustrated in the drawing represents a single
cell of an energy storage device and that such cells may be connected in series,
in parallel or in any other manner in which individual cells are connected in
conventional battery devices.
Having described several embodiments of a
new and improved electrical energy storage device and method, it is believed
that other modifications, variations and changes will be suggested to those
skilled in the art in light of the above disclosure. It is therefore to be
understood that all such variations, modifications and changes are believed to
fall within the scope of the invention as defined by the appended claims.
* * * * *