CA1084110A - Zinc electrodes and methods of making same - Google Patents
Zinc electrodes and methods of making sameInfo
- Publication number
- CA1084110A CA1084110A CA283,579A CA283579A CA1084110A CA 1084110 A CA1084110 A CA 1084110A CA 283579 A CA283579 A CA 283579A CA 1084110 A CA1084110 A CA 1084110A
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- Canada
- Prior art keywords
- weight
- zinc
- electrode
- improvement
- titanate compound
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/24—Electrodes for alkaline accumulators
- H01M4/244—Zinc electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Hybrid Cells (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Improvements in cell capacity maintenance and reductions in electrode shape change are obtained in rechargeable zinc (-) cells by the inclusion of limited amounts of a titanate compound in the negative zinc electrode.
Improvements in cell capacity maintenance and reductions in electrode shape change are obtained in rechargeable zinc (-) cells by the inclusion of limited amounts of a titanate compound in the negative zinc electrode.
Description
iO84110 This invention relates to electrodes which are useful in electrochemical generators and, more particularly, to zinc -electrodes for use in rechargeable electrochemical cells.
It is believed that shape change occurs in the negative plates or electrodes of cells which include zinc electrodes in alkaline electrolytes, e.g., silver/zinc and nickel/zinc cells, whenever any part of the negative plate becomes zinc limiting.
The latter appears to occur at any discontinuity in the negative plate such as the plate edges and fissures within the plate.
At the locations of diæcontinuity in the negative plate, the zincate concentration becomes dilute during charge while at other locations of the negative plate, e.g., the center, -~
there can be an excess of zinc oxide which will maintain the electrolyte at the latter location at saturation with respect to zincate. Thus, a concentration cell can develop between the locations in the negative plate which are dilute in zincate and those locations which are associated with a high concentration of zincate. Such concentration cells can result in a transfer of ~incate from one portion of the negative plate to another thereby producing shape change. ;~
A number of methods to reduce or eliminate electrode shape change in the aforementioned cells presently exist.
One of these methods involves cell construction features which function to reduce the possibility of concentration polarization build-up at the negative electrode during charge. Such a method is described in U.S. Patent No. 3,505,115, issued April 7, 1970, and assigned to the instant assignee. This patent describes the sizing of the negative plate so that it i9 larger than and overlaps the positive electrode.
1~84110 1 Another method involves preventing the solubilization of the zinc as it is anodized. Such a method is described in `
U.S. Patent No. 3,536,537, issued February 3, 1970, and assigned to the instant assignee. The latter patent teaches the addition of a small quantity of a fluorocarbon polymer to the negative ;
zinc electrode.
Although the methods described in the aforementioned patents provide a substantial increase in cell life, they do not completely eliminate the problems of zinc electrode edge erosion -and shape change, particularly after prolonged cycling of theelectrode. Additionally, whereas cells built with extended edge negative electrodes and fluorocarbon impregnated negative electrodes exhibit the benefits (although to a lesser degree) of the hereindescribed invention only after numerous charge/discharge cycles, e.g., on the order of 90 such cycles, cells containing negative electrodes as described herein exhibit improved capacity ;~
maintenance after only a few charge/discharge cycles, e.g., on the order of three (3) cycles. Therefore, there remains a need for a technique which will provide further improvements in zinc electrode edge erosion and shape change.
The incorporation of various types of fibers, both organic and inorganic, in both positive and negative electrodes for the purpose of providing a physically stronger electrode is described in U.S. Patent l~o. 3,271,195, issued September 6, 1966, which is assigned to the instant assignee. Although the herein-described invention can provide improvements in the strength of electrodes similar to that described in the latter patent, the fibrous materials identified in the latter patent are not capable of providing the improvements in cell capacity maintenance and electrode shape change which are obtainable from the herein-described invention.
1~84llo .:
1 U.S. Patent No. 3,476,601, issued November 4, 1969 discloses the use of about 2% to about 50% by weight of a titanate compound in or against either electrode in a high ~-~
density battery for the purpose of mechanically strengthening the electrodes. There is no recognition in that patent of ~`
the electrochemical improvements obtainable from such titanate compounds. This lack of recognition is reflected in both the concentration range given for the titanate compound and in the location of the latter.
The charging current densities normally employed for charging silver/zinc cells range between 1.5 and 3.0 ma/cm2.
However, the limiting current density (LCD) for a cell incorporating 5~ (wt.) titanate in the zinc electrode is only 0.77 ma/cm . Since the LCD decreases with increasing percent titanate in the negative electrode, it will be understood that the titanate range recommended in U.S. Patent No. 3,476,601 is unrealistic in electrochemical terms although it may be quite acceptable in mechanical terms. In fact, mechanically strength- -ening the negative (and positive) electrode s~ems to have been ~ ;
the only object of the 3,476,601 patent since it discloses either incorporation of the titanate in the electrode or placement of the titanate against the electride in order to achieve greater mechanical strength. As is well known,-placement of the titanate against an electrode is not normally recommended for improvement in electrochemical properties.
SU~MARY OF THE INVENTION
_ This invention comprises the inclusion in negative zinc electrodes in rechargeable alkaline electrochemical cells of about 0.2% to about 1.8~ by weight of the weight of the zinc oxide of an inorganic titanate compound.
1~84llo 1 The inclusion of such a titanate in the negative zinc electrode improves the cell maintenance capacity while at the same time decreasing negative electrode shape change. Additionally, if the titanate is employed in fiber form, it provides improve-ments in electrode mechanical strength similar to the improve-ment provided by the fibers disclosed in U.S. Patent Na.
3,271,195. Furthermore, the foregoing benefits are obtained when using the titanate compound in the aforementioned concentration range while maintaining a commercially acceptable limiting 10 charging current density. -DES~RIPTION OF THE PREFERRED EMBODIMENT
This invention will be hereinafter described with respect~to a silver/zinc cell although other electro-chemical cells which employ zinc as the negative electrode, such as, for example, nickel/zinc, zinc/air, zinc/oxygen and mercuric oxide/zinc cells, will also be improved by this invention.
The improvement in zinc electrodes comprises the inclusion of limited amounts of an inorganic titanate compound in the mixture which is employed to fabricate the zinc electrode.
The titanate compounds which are useful herein include sodium, potassium, calcium, magnesium and barium titanates. It is presently preferred to use sodium or potassium titanate.
Mixtures of these titanates can also be used.
The titanate compound can be used in various physical forms, including powders and fibers. However, it is preferred to use the titanate compound in fiber form because of the improvement in mechanical strength of the electrode which is derived from the fibers.
~` The amount of the titanate compound to be included in the negative zinc electrode varies between about 0.2% and - , .
. ~ , 1 about 1.8% by weight of the weight of the zinc oxide in the electrode. Below about 0.2% of titanate, there is little or no improvement in cell capacity maintenance and there is little or no effect on electrode shape change. Above about 1.8%, the electrical conductivity of the finished electrode is affected, and plates containing amounts beyond this level exhibit difficulty in charging. Additionally, about about 1.8%, the limiting charging current density of a cell utilizing ~
electrodes incorporating the titanate compound is reduced to a -level which becomes commercially unacceptable. Preferably, the titanate compound is used in amounts between about 1.0%
and about 1.5~ with 1.25~ being most preferred. Within this preferred range, there is an optimum balance between limiting charging current density ~which increases with decreasing ` *
amounts of titanate compound) and electrode resistance to shape change (which increased to a point with increasing amounts of titanate compound).
To obtain the benefits from the titanate compounds which have been described hereinbefore, it is necessary to incorporate a titanate compound in the electrode admixture so that it is substantially homogeneously dispersed in the electrode mixture. While this result may be accomplished in several ways, it is presently preferred to use the following procedure which is essentially the same procedure as that which is described in the applicant's U.S. Patent No. 3,271,195, which issued Septem~er 6, 1966. In brief, a viscous mixture is formed comprising zinc oxide powder, potassium titanate fibers, mercuric oxide powder, distilled water and carboxymethyl cellulose binder.
This mixture is placed in a blender and agitated until a substantially uniform thixo-tropic suspension is obtained. The B
108~110 1 resulting suspension or slurry is cast between two layers of carrier paper, e.g., Aldex paper, and passed under an oscillating doctor blade to form long strips of papered electrode material.
These strips are then dried at elevated temperature, for example, on the order of 93~C. after which electrode plates are cut from them as desired. Each electrode plate is then pressed to the desired electrode thickness using, e.g., a hydraulic press. Thereafter, a conductive grid, which may be expanded metal, mesh, perforated metal or solid sheet and Which is provided with an electrode terminal, is sandwiched between two electrode plates to form an electrode assembly.
The latter is pressed together in a suitable press to form a unitary composite electrode.
The electrodes so made may be used in the "green" or unformed condition to be then "formed" or charged in situ in the rechargeable zinc (-) cell. On the other hand, the electr,ode may be formed outside the cell in order to convert at ~ -lea~t some of the zinc oxide to active zinc metal. In the latter condition, ~he electrode may be used in the dry-charged condition in the previously identified rechargeable electro-chemical cells.
In summary, there has hereinbefore been described an improvement in rechargeable electrochemical generators or cells having a negative electrode formed from an electro-chemically active zinc material, e.g., zinc oxide, which is ~ -reduced to elemental metallic zinc in the charged state of the electrochemical generator, a positive electrode formed from a material which is electropositive with respect to the active zinc material and which is present in its oxidized form in the charged state of the cell, and including an alkaline electrolyte 1 in electrochemical contact with the aforementioned electrodes.
That improvement comprises the inclusion of an inorganic titanate compound within the zinc electrode mixture in a `~
specific concentration range of about 0.2 - 1.8% by weight of the weight of the active negative electrode material.
This invention will be further described by the following examples.
As used in the Examples, the term "parts" means "parts by weight".
10EX~PLE 1 A slurry was prepared consisting of 100 parts of zinc oxide, 2.2 parts of FIBEX 'L' (Dupont Co.; approximately 57% by wt. potassium titanate fibers), 40 parts of 1~ solution of Carboxymethylcellulose (Hercules Powder Co., Grade CMC 7HF) and 33 parts of distilled water. The slurry constituents were blended until a uniform, thixo-tropic blend was obtained. The pasting operation was performed by a pasting machine which spread the material uniformly between two layers of ALDEX* paper by means of two oscillating doctor blades. The resulting zinc oxide strips were dried at about 93C. The weight per unit area of each strip was 0.9 grams per square inch. The strips were cut to size by means of a die, one layer of the A~DEX paper was removed, the current collector (2 mil perforated copper sheet) was placed between two strips on the paper-free side and the assembly pressed to a thickness of 42 mils. The total active mix weight per electrode was 10.4 grams.
Test cells were fabricated using the above-described electrodes. The cells consisted of four positive (silver) electrodes, each 1.975 in. wide x 3.00 in. high x 0.021 in.
thick and five rlegative (zinc) electrodes measuring 1.975 in.
*Txade Mark ~.,~. .
1 wide x 3.00 in. high x 0.042 in. thick, made into an LR10-5 cell assembly. The cell pack was placed in a plastic cell case which was sealed with a cover terminal assembly and the cell was filled with a 45 weight percent solution of potassium hydroxide.
Exact replicates of the test cells just described were built except that the negative electrodes in these cells contained no additive. These cells were designated "Controls".
The test regime which consisted of charging at 0.6 amps to a cut-off voltage of 2.05 V. and discharging at 4 amps to 1.0 volt per cell (100% DOD). The results are shown in Table 1.
CONTROLS TEST CELLS
(Average of 3 Cells)(Average of 3 Cells) Cycle No.Capacity (amp.hr.)Capacity (amp.hr.) 1 15.5 15.0 12.5 14.5 12.0 14.0 11.2 14.0 9.0 11.~ -The procedure of Example 1 was repeated except that potassium titanate fibers were employed which differed dimen-sionally from the Fibex L fibers employed in Example 1 as shown in Table 2.
Trademark Avg. Fiber Dia. Avg. Fiber Length Density (microns) (microns) (gm/cc) "PKT" 0.1 - 0.2 3 - B 3.3 1 Trademark Avg. Fiber Dia. Avg. Fiber Length Density ~microns) _ (microns) (gm/cc)~
"Tipersul" 1.0 100 3.58 - -~
"Fibex D" 0.1 - 0.15 5 - 10 3.3 ~;
"Fibex L" 0.1 - 0.15 5 - 10 3.3 (hydrated) Substantially no difference in results were found among the fibers listed in Table 1.
Silver/~inc cells were fabricated which consisted of two positive (silver) electrodes and three negative (zinc) ~-electrodes made in an HR2X cell assembly. The zinc electrodes were pasted zinc oxide plates made up of 100 parts of zinc oxide, 1.5 parts of zinc titanate powder and 1.0 part of mercuric - -oxide. The total mix weight per electrode was 6 grams and the electrode thickness was 45 mils. The positive electrodes were wrapped in two layers of clear, unplasticized CELLOPHANE (DuPont ~-Code No. PuDO-193) separator material. The cell pack was placed in a plastic ~TYRENE -acrylonitrile polymer) cell case which was sealed with a cover-terminal assembly. The cell was then filled with a 45 weight percent of potassium hydroxide soiution.
Each such cell was designated a "test" cell.
Exact replicates of the cells just described were built except that the negative-electrodes in these cells contained no ~inc titanate. They did, however, contain rayon fibers for strengthening the negatives in the manner disclosed in U.S.
Patent No. 3,271,195. These cells were designated "Controlsl.
Each cell was subjected to the same discharge/charge cycling regime, namely, charging at 0.25 amp. for 10 hr. and discharging at 1 amp. to 1 volt (100~ DOD), until 50% of the initial cell capacity was reached~ The results are shown in Table 3.
*Trade Mark 1~84110 ;~ ::
Avg . % capac ity Designation Cycles to Short Loss at ~alf Cvcle ._ :
Controls 23-28 35 Test 47-52 2 ~' , , ,, ~
~,,~, .
', `'~.
. :
-:
It is believed that shape change occurs in the negative plates or electrodes of cells which include zinc electrodes in alkaline electrolytes, e.g., silver/zinc and nickel/zinc cells, whenever any part of the negative plate becomes zinc limiting.
The latter appears to occur at any discontinuity in the negative plate such as the plate edges and fissures within the plate.
At the locations of diæcontinuity in the negative plate, the zincate concentration becomes dilute during charge while at other locations of the negative plate, e.g., the center, -~
there can be an excess of zinc oxide which will maintain the electrolyte at the latter location at saturation with respect to zincate. Thus, a concentration cell can develop between the locations in the negative plate which are dilute in zincate and those locations which are associated with a high concentration of zincate. Such concentration cells can result in a transfer of ~incate from one portion of the negative plate to another thereby producing shape change. ;~
A number of methods to reduce or eliminate electrode shape change in the aforementioned cells presently exist.
One of these methods involves cell construction features which function to reduce the possibility of concentration polarization build-up at the negative electrode during charge. Such a method is described in U.S. Patent No. 3,505,115, issued April 7, 1970, and assigned to the instant assignee. This patent describes the sizing of the negative plate so that it i9 larger than and overlaps the positive electrode.
1~84110 1 Another method involves preventing the solubilization of the zinc as it is anodized. Such a method is described in `
U.S. Patent No. 3,536,537, issued February 3, 1970, and assigned to the instant assignee. The latter patent teaches the addition of a small quantity of a fluorocarbon polymer to the negative ;
zinc electrode.
Although the methods described in the aforementioned patents provide a substantial increase in cell life, they do not completely eliminate the problems of zinc electrode edge erosion -and shape change, particularly after prolonged cycling of theelectrode. Additionally, whereas cells built with extended edge negative electrodes and fluorocarbon impregnated negative electrodes exhibit the benefits (although to a lesser degree) of the hereindescribed invention only after numerous charge/discharge cycles, e.g., on the order of 90 such cycles, cells containing negative electrodes as described herein exhibit improved capacity ;~
maintenance after only a few charge/discharge cycles, e.g., on the order of three (3) cycles. Therefore, there remains a need for a technique which will provide further improvements in zinc electrode edge erosion and shape change.
The incorporation of various types of fibers, both organic and inorganic, in both positive and negative electrodes for the purpose of providing a physically stronger electrode is described in U.S. Patent l~o. 3,271,195, issued September 6, 1966, which is assigned to the instant assignee. Although the herein-described invention can provide improvements in the strength of electrodes similar to that described in the latter patent, the fibrous materials identified in the latter patent are not capable of providing the improvements in cell capacity maintenance and electrode shape change which are obtainable from the herein-described invention.
1~84llo .:
1 U.S. Patent No. 3,476,601, issued November 4, 1969 discloses the use of about 2% to about 50% by weight of a titanate compound in or against either electrode in a high ~-~
density battery for the purpose of mechanically strengthening the electrodes. There is no recognition in that patent of ~`
the electrochemical improvements obtainable from such titanate compounds. This lack of recognition is reflected in both the concentration range given for the titanate compound and in the location of the latter.
The charging current densities normally employed for charging silver/zinc cells range between 1.5 and 3.0 ma/cm2.
However, the limiting current density (LCD) for a cell incorporating 5~ (wt.) titanate in the zinc electrode is only 0.77 ma/cm . Since the LCD decreases with increasing percent titanate in the negative electrode, it will be understood that the titanate range recommended in U.S. Patent No. 3,476,601 is unrealistic in electrochemical terms although it may be quite acceptable in mechanical terms. In fact, mechanically strength- -ening the negative (and positive) electrode s~ems to have been ~ ;
the only object of the 3,476,601 patent since it discloses either incorporation of the titanate in the electrode or placement of the titanate against the electride in order to achieve greater mechanical strength. As is well known,-placement of the titanate against an electrode is not normally recommended for improvement in electrochemical properties.
SU~MARY OF THE INVENTION
_ This invention comprises the inclusion in negative zinc electrodes in rechargeable alkaline electrochemical cells of about 0.2% to about 1.8~ by weight of the weight of the zinc oxide of an inorganic titanate compound.
1~84llo 1 The inclusion of such a titanate in the negative zinc electrode improves the cell maintenance capacity while at the same time decreasing negative electrode shape change. Additionally, if the titanate is employed in fiber form, it provides improve-ments in electrode mechanical strength similar to the improve-ment provided by the fibers disclosed in U.S. Patent Na.
3,271,195. Furthermore, the foregoing benefits are obtained when using the titanate compound in the aforementioned concentration range while maintaining a commercially acceptable limiting 10 charging current density. -DES~RIPTION OF THE PREFERRED EMBODIMENT
This invention will be hereinafter described with respect~to a silver/zinc cell although other electro-chemical cells which employ zinc as the negative electrode, such as, for example, nickel/zinc, zinc/air, zinc/oxygen and mercuric oxide/zinc cells, will also be improved by this invention.
The improvement in zinc electrodes comprises the inclusion of limited amounts of an inorganic titanate compound in the mixture which is employed to fabricate the zinc electrode.
The titanate compounds which are useful herein include sodium, potassium, calcium, magnesium and barium titanates. It is presently preferred to use sodium or potassium titanate.
Mixtures of these titanates can also be used.
The titanate compound can be used in various physical forms, including powders and fibers. However, it is preferred to use the titanate compound in fiber form because of the improvement in mechanical strength of the electrode which is derived from the fibers.
~` The amount of the titanate compound to be included in the negative zinc electrode varies between about 0.2% and - , .
. ~ , 1 about 1.8% by weight of the weight of the zinc oxide in the electrode. Below about 0.2% of titanate, there is little or no improvement in cell capacity maintenance and there is little or no effect on electrode shape change. Above about 1.8%, the electrical conductivity of the finished electrode is affected, and plates containing amounts beyond this level exhibit difficulty in charging. Additionally, about about 1.8%, the limiting charging current density of a cell utilizing ~
electrodes incorporating the titanate compound is reduced to a -level which becomes commercially unacceptable. Preferably, the titanate compound is used in amounts between about 1.0%
and about 1.5~ with 1.25~ being most preferred. Within this preferred range, there is an optimum balance between limiting charging current density ~which increases with decreasing ` *
amounts of titanate compound) and electrode resistance to shape change (which increased to a point with increasing amounts of titanate compound).
To obtain the benefits from the titanate compounds which have been described hereinbefore, it is necessary to incorporate a titanate compound in the electrode admixture so that it is substantially homogeneously dispersed in the electrode mixture. While this result may be accomplished in several ways, it is presently preferred to use the following procedure which is essentially the same procedure as that which is described in the applicant's U.S. Patent No. 3,271,195, which issued Septem~er 6, 1966. In brief, a viscous mixture is formed comprising zinc oxide powder, potassium titanate fibers, mercuric oxide powder, distilled water and carboxymethyl cellulose binder.
This mixture is placed in a blender and agitated until a substantially uniform thixo-tropic suspension is obtained. The B
108~110 1 resulting suspension or slurry is cast between two layers of carrier paper, e.g., Aldex paper, and passed under an oscillating doctor blade to form long strips of papered electrode material.
These strips are then dried at elevated temperature, for example, on the order of 93~C. after which electrode plates are cut from them as desired. Each electrode plate is then pressed to the desired electrode thickness using, e.g., a hydraulic press. Thereafter, a conductive grid, which may be expanded metal, mesh, perforated metal or solid sheet and Which is provided with an electrode terminal, is sandwiched between two electrode plates to form an electrode assembly.
The latter is pressed together in a suitable press to form a unitary composite electrode.
The electrodes so made may be used in the "green" or unformed condition to be then "formed" or charged in situ in the rechargeable zinc (-) cell. On the other hand, the electr,ode may be formed outside the cell in order to convert at ~ -lea~t some of the zinc oxide to active zinc metal. In the latter condition, ~he electrode may be used in the dry-charged condition in the previously identified rechargeable electro-chemical cells.
In summary, there has hereinbefore been described an improvement in rechargeable electrochemical generators or cells having a negative electrode formed from an electro-chemically active zinc material, e.g., zinc oxide, which is ~ -reduced to elemental metallic zinc in the charged state of the electrochemical generator, a positive electrode formed from a material which is electropositive with respect to the active zinc material and which is present in its oxidized form in the charged state of the cell, and including an alkaline electrolyte 1 in electrochemical contact with the aforementioned electrodes.
That improvement comprises the inclusion of an inorganic titanate compound within the zinc electrode mixture in a `~
specific concentration range of about 0.2 - 1.8% by weight of the weight of the active negative electrode material.
This invention will be further described by the following examples.
As used in the Examples, the term "parts" means "parts by weight".
10EX~PLE 1 A slurry was prepared consisting of 100 parts of zinc oxide, 2.2 parts of FIBEX 'L' (Dupont Co.; approximately 57% by wt. potassium titanate fibers), 40 parts of 1~ solution of Carboxymethylcellulose (Hercules Powder Co., Grade CMC 7HF) and 33 parts of distilled water. The slurry constituents were blended until a uniform, thixo-tropic blend was obtained. The pasting operation was performed by a pasting machine which spread the material uniformly between two layers of ALDEX* paper by means of two oscillating doctor blades. The resulting zinc oxide strips were dried at about 93C. The weight per unit area of each strip was 0.9 grams per square inch. The strips were cut to size by means of a die, one layer of the A~DEX paper was removed, the current collector (2 mil perforated copper sheet) was placed between two strips on the paper-free side and the assembly pressed to a thickness of 42 mils. The total active mix weight per electrode was 10.4 grams.
Test cells were fabricated using the above-described electrodes. The cells consisted of four positive (silver) electrodes, each 1.975 in. wide x 3.00 in. high x 0.021 in.
thick and five rlegative (zinc) electrodes measuring 1.975 in.
*Txade Mark ~.,~. .
1 wide x 3.00 in. high x 0.042 in. thick, made into an LR10-5 cell assembly. The cell pack was placed in a plastic cell case which was sealed with a cover terminal assembly and the cell was filled with a 45 weight percent solution of potassium hydroxide.
Exact replicates of the test cells just described were built except that the negative electrodes in these cells contained no additive. These cells were designated "Controls".
The test regime which consisted of charging at 0.6 amps to a cut-off voltage of 2.05 V. and discharging at 4 amps to 1.0 volt per cell (100% DOD). The results are shown in Table 1.
CONTROLS TEST CELLS
(Average of 3 Cells)(Average of 3 Cells) Cycle No.Capacity (amp.hr.)Capacity (amp.hr.) 1 15.5 15.0 12.5 14.5 12.0 14.0 11.2 14.0 9.0 11.~ -The procedure of Example 1 was repeated except that potassium titanate fibers were employed which differed dimen-sionally from the Fibex L fibers employed in Example 1 as shown in Table 2.
Trademark Avg. Fiber Dia. Avg. Fiber Length Density (microns) (microns) (gm/cc) "PKT" 0.1 - 0.2 3 - B 3.3 1 Trademark Avg. Fiber Dia. Avg. Fiber Length Density ~microns) _ (microns) (gm/cc)~
"Tipersul" 1.0 100 3.58 - -~
"Fibex D" 0.1 - 0.15 5 - 10 3.3 ~;
"Fibex L" 0.1 - 0.15 5 - 10 3.3 (hydrated) Substantially no difference in results were found among the fibers listed in Table 1.
Silver/~inc cells were fabricated which consisted of two positive (silver) electrodes and three negative (zinc) ~-electrodes made in an HR2X cell assembly. The zinc electrodes were pasted zinc oxide plates made up of 100 parts of zinc oxide, 1.5 parts of zinc titanate powder and 1.0 part of mercuric - -oxide. The total mix weight per electrode was 6 grams and the electrode thickness was 45 mils. The positive electrodes were wrapped in two layers of clear, unplasticized CELLOPHANE (DuPont ~-Code No. PuDO-193) separator material. The cell pack was placed in a plastic ~TYRENE -acrylonitrile polymer) cell case which was sealed with a cover-terminal assembly. The cell was then filled with a 45 weight percent of potassium hydroxide soiution.
Each such cell was designated a "test" cell.
Exact replicates of the cells just described were built except that the negative-electrodes in these cells contained no ~inc titanate. They did, however, contain rayon fibers for strengthening the negatives in the manner disclosed in U.S.
Patent No. 3,271,195. These cells were designated "Controlsl.
Each cell was subjected to the same discharge/charge cycling regime, namely, charging at 0.25 amp. for 10 hr. and discharging at 1 amp. to 1 volt (100~ DOD), until 50% of the initial cell capacity was reached~ The results are shown in Table 3.
*Trade Mark 1~84110 ;~ ::
Avg . % capac ity Designation Cycles to Short Loss at ~alf Cvcle ._ :
Controls 23-28 35 Test 47-52 2 ~' , , ,, ~
~,,~, .
', `'~.
. :
-:
Claims (8)
1. In a rechargeable electrochemical generator having a negative electrode comprising a relatively electronegative zinc electrode material which is in essentially elemental metallic form in a charged state of said generator, a positive electrode comprising a relatively electropositive electrode material in oxidized form in said charged state, and including an alkaline electrolyte in electrochemical contact with said electrodes, the improvement which comprises:
an inorganic titanate compound dispersed in said zinc electrode material in an amount between about 0.2% by weight and about 1.8% by weight of the weight of said zinc electrode material in an uncharged state.
an inorganic titanate compound dispersed in said zinc electrode material in an amount between about 0.2% by weight and about 1.8% by weight of the weight of said zinc electrode material in an uncharged state.
2. The improvement of claim 1 wherein said inorganic titanate compound is a material selected from the group consisting of sodium, potassium, calcium, magnesium and barium titanates, and mixtures thereof.
3. The improvement of claim 1 wherein said inorganic titanate compound is present in the form of fibers.
4. The improvement of claim 1 wherein said inorganic titanate compound is present in an amount between about 1.0% by weight and 1.5% by weight of the weight of said zinc electrode material in its uncharged state.
5. The improvement of claim 1 wherein said electro-negative zinc electrode material is zinc oxide when in its uncharged state.
6. In a rechargeable electrochemical generator having a negative electrode comprising electrochemically active zinc oxide, a positive electrode comprising a material which is electropositive relative to said zinc oxide, and including an alkaline electrolyte in electrochemical contact with said electrodes, the improvement which comprises:
an inorganic titanate compound substantially homo-geneously dispersed in said zinc oxide, said inorganic titanate compound being a material selected from the group consisting of sodium, potassium, calcium, magnesium and barium titanates, and mixtures thereof, and being present in said negative electrode in an amount between about 0.2% by weight and about 1.8% by weight of the weight of said zinc oxide.
an inorganic titanate compound substantially homo-geneously dispersed in said zinc oxide, said inorganic titanate compound being a material selected from the group consisting of sodium, potassium, calcium, magnesium and barium titanates, and mixtures thereof, and being present in said negative electrode in an amount between about 0.2% by weight and about 1.8% by weight of the weight of said zinc oxide.
7. The improvement of claim 6 wherein said inorganic titanate compound is present in the form of fibers.
8. In the improvement of claim 7 wherein said inorganic titanate compound is present in an amount between about 1.0%
by weight and about 1.5% by weight of the weight of said zinc oxide.
by weight and about 1.5% by weight of the weight of said zinc oxide.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US709,138 | 1976-07-27 | ||
| US05/709,138 US4041221A (en) | 1976-07-27 | 1976-07-27 | Zinc electrodes and methods of making same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1084110A true CA1084110A (en) | 1980-08-19 |
Family
ID=24848641
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA283,579A Expired CA1084110A (en) | 1976-07-27 | 1977-07-27 | Zinc electrodes and methods of making same |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4041221A (en) |
| JP (1) | JPS5319537A (en) |
| CA (1) | CA1084110A (en) |
| DE (1) | DE2733691C3 (en) |
| FR (1) | FR2360182A1 (en) |
| GB (1) | GB1533698A (en) |
| IL (1) | IL52569A (en) |
| IN (1) | IN147971B (en) |
| IT (1) | IT1079378B (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IL50024A (en) * | 1976-07-12 | 1979-05-31 | Israel State | Secondary cells |
| US4358517A (en) * | 1979-10-30 | 1982-11-09 | General Motors Corporation | Nickel-zinc cell |
| US4339512A (en) * | 1980-03-19 | 1982-07-13 | General Motors Corporation | Battery having electrode with hydrophilic polymer binder |
| US4304828A (en) * | 1980-06-27 | 1981-12-08 | Energy Research Corporation | Zinc electrode |
| US4312931A (en) * | 1980-09-02 | 1982-01-26 | General Motors Corporation | Zinc electrode containing porous calcium silicate |
| JPS6277162A (en) * | 1985-09-30 | 1987-04-09 | Hitachi Zosen Corp | Slab cooling device in continuous casting equipment |
| US5556720A (en) * | 1994-08-18 | 1996-09-17 | Energy Research Corporation | Sealed zinc secondary battery and zinc electrode therefor |
| US5863676A (en) * | 1997-03-27 | 1999-01-26 | Energy Research Corporation | Calcium-zincate electrode for alkaline batteries and method for making same |
| JP3653410B2 (en) * | 1998-03-24 | 2005-05-25 | 三洋電機株式会社 | Sealed alkaline zinc storage battery |
| FR2828335B1 (en) * | 2001-08-03 | 2004-09-17 | Conseil Et De Prospective Scie | ZINC ANODE FOR ALKALINE SECONDARY ELECTROCHEMICAL GENERATORS |
| FR2828336B1 (en) * | 2001-08-03 | 2006-07-07 | Conseil Et De Prospective Scie | ZINC ANODE ALKALINE SECONDARY ELECTROCHEMICAL GENERATORS |
| US7074509B2 (en) | 2001-11-13 | 2006-07-11 | Eldat Communication Ltd. | Hydrogen generators for fuel cells |
| US6770186B2 (en) | 2001-11-13 | 2004-08-03 | Eldat Communication Ltd. | Rechargeable hydrogen-fueled motor vehicle |
| FR2843235B1 (en) * | 2002-07-30 | 2006-07-28 | Conseil Et De Prospective Scie | OXIDATION-CONDUCTIVE CONDUCTIVE CERAMIC FOR ZINC ANODE OF ALKALI SECONDARY ELECTROCHEMICAL GENERATORS |
| US20060162879A1 (en) * | 2003-07-13 | 2006-07-27 | Tinker Larry C | Compounding of fibrillated fiber |
| US20050183243A1 (en) * | 2003-07-13 | 2005-08-25 | Tinker Larry C. | Fibrillation of natural fiber |
| WO2007116413A1 (en) | 2006-04-12 | 2007-10-18 | Thothathri Sampath Kumar | A nanosized electrochemical dispersion for rechargeable alkaline zinc batteries |
| US20100062347A1 (en) * | 2008-09-09 | 2010-03-11 | Lin-Feng Li | Rechargeable zinc cell with longitudinally-folded separator |
| US20120171535A1 (en) | 2010-12-31 | 2012-07-05 | Fuyuan Ma | Nickel-zinc battery and manufacturing method thereof |
| CN106654213A (en) * | 2016-12-30 | 2017-05-10 | 大连理工大学 | Preparation method of negative electrode material for nickel-zinc cell |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3476601A (en) * | 1964-06-29 | 1969-11-04 | Mc Donnell Douglas Corp | Battery including inorganic fibrous material |
| JPS5033421A (en) * | 1973-07-26 | 1975-03-31 | ||
| JPS5435293B2 (en) * | 1974-06-18 | 1979-11-01 |
-
1976
- 1976-07-27 US US05/709,138 patent/US4041221A/en not_active Expired - Lifetime
-
1977
- 1977-07-18 GB GB30055/77A patent/GB1533698A/en not_active Expired
- 1977-07-21 IL IL52569A patent/IL52569A/en unknown
- 1977-07-22 IN IN1128/CAL/77A patent/IN147971B/en unknown
- 1977-07-26 IT IT50445/77A patent/IT1079378B/en active
- 1977-07-26 DE DE2733691A patent/DE2733691C3/en not_active Expired
- 1977-07-26 FR FR7722986A patent/FR2360182A1/en active Granted
- 1977-07-27 JP JP8937377A patent/JPS5319537A/en active Granted
- 1977-07-27 CA CA283,579A patent/CA1084110A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| IN147971B (en) | 1980-08-30 |
| IL52569A (en) | 1979-09-30 |
| JPS5319537A (en) | 1978-02-22 |
| US4041221A (en) | 1977-08-09 |
| FR2360182B1 (en) | 1980-04-18 |
| DE2733691C3 (en) | 1979-08-30 |
| JPS5751229B2 (en) | 1982-10-30 |
| FR2360182A1 (en) | 1978-02-24 |
| GB1533698A (en) | 1978-11-29 |
| DE2733691A1 (en) | 1978-02-02 |
| IL52569A0 (en) | 1977-10-31 |
| IT1079378B (en) | 1985-05-08 |
| DE2733691B2 (en) | 1979-01-04 |
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