CA1100183A - Mercury-free secondary alkaline battery and improved negative interseparator therefor - Google Patents
Mercury-free secondary alkaline battery and improved negative interseparator thereforInfo
- Publication number
- CA1100183A CA1100183A CA311,379A CA311379A CA1100183A CA 1100183 A CA1100183 A CA 1100183A CA 311379 A CA311379 A CA 311379A CA 1100183 A CA1100183 A CA 1100183A
- Authority
- CA
- Canada
- Prior art keywords
- negative
- interseparator
- electrode
- additive
- zinc
- 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.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/24—Alkaline accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/24—Alkaline accumulators
- H01M10/26—Selection of materials as electrolytes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
- H01M50/417—Polyolefins
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
- H01M50/423—Polyamide resins
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
- H01M50/429—Natural polymers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/44—Fibrous material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
-
- 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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Cell Separators (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Hydrogen gas evolution in secondary alkaline batteries which utilize zinc electrodes is reduced by incorporating mercury-free additives in the negative interseparators of such batteries. The additives disclosed herein are certain electrolyte-soluble compounds of lead, cadmium and tin.
Hydrogen gas evolution in secondary alkaline batteries which utilize zinc electrodes is reduced by incorporating mercury-free additives in the negative interseparators of such batteries. The additives disclosed herein are certain electrolyte-soluble compounds of lead, cadmium and tin.
Description
BACKGROU21D OE' THE INVENTION
m is invention relates to alkaline secondary electro-chemical batteries which utilize zinc as the active electrode material and, more particularly, it relates to the use of mercury-free zinc electrodes in such cells and to improved negative interseparators for use in such cells.
Zinc is used as the negative electrode material in alkaline electrochemical cells and batteries for a number of reasons includîng its high half-cell voltage, its low polari-zation, and its high limiting current density on discharge.
However, a number of ad~erse effects result from such use of zinc. Thus, because it is thermodynamically unstable in alkaline media, zinc self-discharges significantly while standing.
Such discharge is accompanied b~ the e~olution of hydrogen.
Together, these reactions produce electrode corrosion and shortened shelf life.
In order to overcome the aforementioned disadvantages while still taking advantage of the benefi~s derived from the use of zinc, battery manufacturers normally include small amounts o~ ~ercury in zinc electrodes to reduce self-discharging of the latter and to reduce evolution of hydrogen. Such reductions are made possible by the ~act that mercury has a substantially higher hydrogen over-voltage than does zinc.
- Although the use o~ mercury in zinc electrodes is advantageous! lts presehce in such cells and batteries and the processes associated with the introduction of mercury into such cells and batteries present hoth environmental and health hazards. Therefore, it would be deslrable to be able to produce mercury-free zinc electrodes having electrochemical character-istics similar to or better than mercury-containing zinc electrodes.
: ~ , 1 Inorganic additives other than mercury have been included in zinc electrodes for some time in order to reduce the corrosion of such electrodes by reducing their self-discharge in alkaline solution. Suggested additives have included: lead, lead oxide, lead hydroxide, lead sulfide, indium hydroxide, stannous chloride and thallium oxide. The aforementioned additives may be used in the absence of or in combination with mercury in zinc electrodes. Exemplary of the use of such additives in zinc electrodes are U.S Patents No. 3r639,176, 3,642,539, 3,847,669, 3,816,178 and 3,785,868.
Although these additives have been ~ound to be partially effective in reducing sel~-discharge of zinc electrodes in alkaline media, the same additives may adversely affect the potential-current curve on discharge, particularly at high battery drain rates.
SUMMARY OF THE INVENTION
This invention is embodied in a secondary alkaline battery utilizing zinc as the active negative Plectrode material and including a negative interseparator positioned between the ~0 negative electrode and a main separator. The invention com prises the use o~ electrolyte-soluble salts in the negative inter~
separator to avoid the necessity for using mercury in the negative electrode for the suppression of h~drogen gas evolution.
The aforementioned salts are materials which, in addition to being at least slightly soluble in the alkaline medium, provide cations which can be reduced to an adherent species in the battexy environment to form a protective coating on the zinc electrode. The a~orementioned salts are compounds o~ lead, cadmium and tin having the above-noted characteristics.
- The coating produced on the negative electrode by the 1 herein-employed salts serves to reduce hydrogen gas evolution upon standing, i.e. upon self-discharge of the battery.
Additionally, such reduction of hydrogen gas evolution is realized even after numerous charge/discharge cycles which are accompanied by some "loss" of cations due to the irreversible nature of the reactions involved because the :interseparator provides a reservoir of cations to replace those lost in the referenced reactions.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The described invention relates to secondary alkaline electrochemical cells and batteries which utilize zinc as the active (negative) electrode material, a material which is more electropositive than zinc as the active positive electrode material, and an alkaline electrol~te. When ~abricated, the negative electrode may include zinc in its metallic (charged) form, i.e. Zn, or in its oxidized (discharged) form/ i.e. ZnO. The positive electrode in such cells may include as the active electrode material nickel, manganese, or silver. The alkaline electrolyte is an aqueous solution of an hydroxide such as ~0 lithium hydroxide, potassiu~ hydroxide, sodium hydroxide and cesium hydroxide, and mixtures thereo.
Commonly, such secondary alkaline cells include separators disposed between the elect.rodes. For example, a separator system may include a main separator and negativa and positive interseparators disposed between the main separator and the negative and positive electrodes, respectively. Such separator systems are well known and do not form an essential feature of this invention except to the extent that the negative interseparator is utilized as a carrier or reser~oir ~or the herein-described additives and is novel in composition.
.
- ~ 33 ~- 1 Therefore, for exemplary purposes only, a positive in-~e~-- separator may be formed fro~ n~lon (Pellon) and a main separator may be formed from cellophane or silverized cellophane.
Fabrication of a negative interseparator in accordance with the invention will be described hereina~ter with reference to incorporation therein of the described additives.
l~pically, the secondary alkaline battery includes a casing with one or more negative electrodes and one or more positive electrodes disposed therein in intimate contact with the alkaline electrolyte. The s~parator system may be utilized in the form of a "U"-wrap, as is well known; with the main separator disposed between confronting surfaces of adjacent positive and negative electrodes so that it forms a "U"
around a positive electrode, with neyative and positive inter-separators positioned on opposite sides of the main separator in paraliel relationship therewith.
Turning now to the essential elements of this invention, the novel negative interseparators o~ the aforementioned secondary alkaline cells or batteries of the invention are ~ provided with an effective amount of an additive having certain characteristics. First, the additive must be at least slightly soluble in the alkaline electrolyte employed in a given application. Such solubi1ity is required to facilitate electrodialytic transport of cations (derived from the addi-~ive) to the negative electrode. Secondly, the additive must be capable of generating ca-tions which are eleckro-reducible to an insoluble adherent species (preferably the metal ~orm) on the zinc-containing el~ckrode at potentials normally encountered in the electrode environment o~ the described secondary alkaline cells, i.e. at potentials positive (nobl~!) to the L8~
1 zinc electrode. ~hirdly, the reduced species ~e.g. the metal form) must have either a high hydrogen overvoltage (on the order of one volt or more) or a reversible potential which is positive with respect to hydroyen.
The additive comprises a salt selected from the group consisting of a cadmium-containing salt, a lead-containing salt, a tin-containing salt, and mixtures thereo~ having the previously described necessary characteristics. of these salts the preferred species are ~elected from the group consisting of lead titanate, lead aceta~e, lead zirconate, cadmium acetate, cadmium zirconate, cadmium titanate, and tin zirconate.
Mixtures of these additives may also be used.
The additive can be incorporated into the negative interseparator when the latter is fabricated or the negative interseparator sheet can be impregnated with a solution con-taining the additive. Alternatively, the additive can be sprayed from a solution on to the negative interseparator. The negative interseparator can be fabricated of any suitable material such as nylon and polyprop~lene non~woven felt, long fiber as~estos ~alumino-silicate) mats, glass fiber and zirconia ~iber mats and the like.
In general, the amount of additive carried on or in-corporated in the negative interseparator will depend upon the characteristics~and function of each battery in which the additive is incorporate~. As the amount of additive approaches zero, there will be less than an efective amount of addi.tive to accomplish the hereinbefore-described purposes, particularly after many charge-discharge cycles. on the other hand, as ~he amount of additive utilized increases, a level will be reached where there i8 more than enough additive to accomplish 1 those purposes and to serve as a reservoir. Since an excess amount ef~ectively serves no function while occupying some space within a battery, it is preferable not to use an e~cess amount so that the volume available for the active electrode materials, etc., is not significantly diminished.
Typically, the amount of additive (as the metal) utilized can range from about 0.5 to about 5% per unit weight of the inorganic fibrous laminate.
In operation, the zinc electrode is plated with a layer of the protective material (the reduced ~orm of the cations derived from the additive) when the battery containing the additive is charged or when on open circuit (i.e. on stand).
After the initial discharge, zinc will also be deposited on the zinc electrode along with the protective material during the charging phase of each charge/discharge cycle. When the circuit is closed, i.e., upon discharge, the battery potential drops to the oxidation potential of the protective material which is consumed (oxidized) and returns to the electrolyte as ions.
When the protective material has been removed as a coating from the zinc electrode, the zinc can then freely oxidize at its usual voltage so that power can be withdrawn from the battery.
When the circuit is again opened or the battery charged, the zinc electrode will again become coated with the protective material. The foregoing sequence of coating or plating followed by`dissolution of the coating will be repeated with every charge/discharge cycle.
When the protective material is dissolved back into the electrolyte, it does so at least to some extent in a form (plumbate ions in the case of lead) which cannot be reduced to again coat the zinc electrode during the next charge. Therefore, :
.
1 some of the protective material is "lost" ~or electrode coating purposes; however, because the negative interseparator includes an ample supply o~ additive, the cations lost as des-cribed will be replaced by a new supply of cations from the additive remaining in the negative interseparator. There~ore, in spite of some loss with each charge/discharge cycle, a re~
latively constant supply of cations will be available in the electrolyte fvr reduction and for coating of the zinc surface.
This is an advantage which is not obtained if the additive is merely included in the electrode or electrolyte. In those latter instances, after a limited number of charge/discharge cycles the active metal species from the additive in close contact with the zinc active material of the electrode is used up, due to the dissolution/dissociation process.
This invention will be further described by the following specific Examples:
EXAMPLE I
An inorganic fibrous laminate (IFL) containing lead titanate was made by dispersing 672 gm. of an admLxture con-sisting of 85g by weight potassium titanate, 9~ by weight asbestos flbers, 2% by weight carboxymethylcelLulose gumr and ~% by weight lead titanate into 8,000 ml of deionized water.
The resultant slurry was then cast into a sheet, which was dried and rolled down to final thickness (5 t~ 6 mils). This sheet was used as a negative interseparator against the zinc electrode in silver/zinc cells.
Ten ampere hour silvex/zinc tesk cells were fabricated utilizing the lead titanate-bearing IFL negative inter-separator material~ The cqlls consisted of 4 positive silverelectrodes and flve negative zinc oxide electrodes. The negative - 7 _ , .. . . . .. .
1 electrodes contained 99.5% by weight ZnO and 0.5% by weight CMC. The separator system consisted of a layer o~ porous polypropylene material as the positive interseparator, four (4) layers of silver-impregnated cellophane against ~he positive electrode as the main separator, followed by one layer of the IFL/lead titanate material against the negative electrode.
The cell pack was placed in a 10 ampere-hour cell case. The cover was sealed to the case and the resultant cell activated with 65 cc of 40 weight % aqueous potassium hydroxide~
Following two formation cycles, the then fully charged cells were placed on wet stand and connected to eudiometers to measure hydrogen gas evolution. The gassin~ rate at room temperature was determined to be 0.028 cc/day/in of negative electrode surface.
Control cells made without the lead titanate in the IFL and with negative electrodes containing 1% by weight mercuric oxide exhibited a gasslng rate equivalent to 0.05 cc/day/in2 of negative electrode surface. Accordingly t the lead titanate produced lower hydrogen gas evolution than the mercuric oxide. Moreover, tests on the cells indicated that the electrical performance of the cells containing lead titanate additive was better than that of the controls containing mercuric oxide.
An inorganic fibrous laminate ~IFL) of the same com position as set forth in Example I, except for the substitution of ca~nium titanate for lead titanate in a concentration o~
5% by weight, was prepared in accordance with the procedure of Example I. This laminate was utilized as a negatiue inter~
separator in cells otherwise identical to those specified`in 1 E~ample I. Control cells were also made in an identical mann~r except that the negative electrodes in these cells contained 1% by weight of mercuric oxide and there was no cadmium titanate additive in ~he negative interseparator.
The test cells and the co~trol cells were all charged at 15 m.a. per square inch rate for 16 hours and then discharged at the 2-hour ra~e to 1.0 volt p~r cell. Cells containing the 1% mercuric oxide additive to the negative electrode had an avera~e output of 10 ampere hours while the cadmium titanate-containing cells had an output of 9.4 ampere hours. Accordingly, the electrical characteristics and the performance of thecadmium titanate-containing cells was comparable to those containing the mercuric oxide, while avoiding the hazards connected with mercuric oxide.
Comparable results can be obtained through the use of other concentrations, preferably between about 0.5 and about 5%, of the selected additive, by weight of the negative interseparator in the zinc electrode-containing cells. In ~ -parallel tests, when lead acetate, lead zirconate, cadmium acetate, 20 ~ cadmium zirconate and tin zirconate are substituted for the cadmium titanate in a concentration between 0.5 and 5%, by weight of the negative interseparator, results comparable to those set forth above for the cadmium titanate-containing test cells and the lead titanate-containing test cells of Example I are obtained. Tests also indicate that substitution of other forms of negative interseparator materials in place :
of those called for in Examples I a~d II produce comparable results so long as the addi.tive is present ~hus, when nylon, or polypropylene non-woven felts, or glass fiber mats or zirconia mats axe used in place of the asbestos fibers called for _ g ~ ' -. . :
1 in Examples I and II, effective negative interseparators can be fabricated.
Various other modifications, changes, alterations and additions can be made in the improved negative interseparator of the present invention and the improved zinc electrode-containing cells employing the negative interseparator. All such modifications, changes, alterations and addltions as are within the scope of the appended claims form part of the present invention.
1`0 ' ,
m is invention relates to alkaline secondary electro-chemical batteries which utilize zinc as the active electrode material and, more particularly, it relates to the use of mercury-free zinc electrodes in such cells and to improved negative interseparators for use in such cells.
Zinc is used as the negative electrode material in alkaline electrochemical cells and batteries for a number of reasons includîng its high half-cell voltage, its low polari-zation, and its high limiting current density on discharge.
However, a number of ad~erse effects result from such use of zinc. Thus, because it is thermodynamically unstable in alkaline media, zinc self-discharges significantly while standing.
Such discharge is accompanied b~ the e~olution of hydrogen.
Together, these reactions produce electrode corrosion and shortened shelf life.
In order to overcome the aforementioned disadvantages while still taking advantage of the benefi~s derived from the use of zinc, battery manufacturers normally include small amounts o~ ~ercury in zinc electrodes to reduce self-discharging of the latter and to reduce evolution of hydrogen. Such reductions are made possible by the ~act that mercury has a substantially higher hydrogen over-voltage than does zinc.
- Although the use o~ mercury in zinc electrodes is advantageous! lts presehce in such cells and batteries and the processes associated with the introduction of mercury into such cells and batteries present hoth environmental and health hazards. Therefore, it would be deslrable to be able to produce mercury-free zinc electrodes having electrochemical character-istics similar to or better than mercury-containing zinc electrodes.
: ~ , 1 Inorganic additives other than mercury have been included in zinc electrodes for some time in order to reduce the corrosion of such electrodes by reducing their self-discharge in alkaline solution. Suggested additives have included: lead, lead oxide, lead hydroxide, lead sulfide, indium hydroxide, stannous chloride and thallium oxide. The aforementioned additives may be used in the absence of or in combination with mercury in zinc electrodes. Exemplary of the use of such additives in zinc electrodes are U.S Patents No. 3r639,176, 3,642,539, 3,847,669, 3,816,178 and 3,785,868.
Although these additives have been ~ound to be partially effective in reducing sel~-discharge of zinc electrodes in alkaline media, the same additives may adversely affect the potential-current curve on discharge, particularly at high battery drain rates.
SUMMARY OF THE INVENTION
This invention is embodied in a secondary alkaline battery utilizing zinc as the active negative Plectrode material and including a negative interseparator positioned between the ~0 negative electrode and a main separator. The invention com prises the use o~ electrolyte-soluble salts in the negative inter~
separator to avoid the necessity for using mercury in the negative electrode for the suppression of h~drogen gas evolution.
The aforementioned salts are materials which, in addition to being at least slightly soluble in the alkaline medium, provide cations which can be reduced to an adherent species in the battexy environment to form a protective coating on the zinc electrode. The a~orementioned salts are compounds o~ lead, cadmium and tin having the above-noted characteristics.
- The coating produced on the negative electrode by the 1 herein-employed salts serves to reduce hydrogen gas evolution upon standing, i.e. upon self-discharge of the battery.
Additionally, such reduction of hydrogen gas evolution is realized even after numerous charge/discharge cycles which are accompanied by some "loss" of cations due to the irreversible nature of the reactions involved because the :interseparator provides a reservoir of cations to replace those lost in the referenced reactions.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The described invention relates to secondary alkaline electrochemical cells and batteries which utilize zinc as the active (negative) electrode material, a material which is more electropositive than zinc as the active positive electrode material, and an alkaline electrol~te. When ~abricated, the negative electrode may include zinc in its metallic (charged) form, i.e. Zn, or in its oxidized (discharged) form/ i.e. ZnO. The positive electrode in such cells may include as the active electrode material nickel, manganese, or silver. The alkaline electrolyte is an aqueous solution of an hydroxide such as ~0 lithium hydroxide, potassiu~ hydroxide, sodium hydroxide and cesium hydroxide, and mixtures thereo.
Commonly, such secondary alkaline cells include separators disposed between the elect.rodes. For example, a separator system may include a main separator and negativa and positive interseparators disposed between the main separator and the negative and positive electrodes, respectively. Such separator systems are well known and do not form an essential feature of this invention except to the extent that the negative interseparator is utilized as a carrier or reser~oir ~or the herein-described additives and is novel in composition.
.
- ~ 33 ~- 1 Therefore, for exemplary purposes only, a positive in-~e~-- separator may be formed fro~ n~lon (Pellon) and a main separator may be formed from cellophane or silverized cellophane.
Fabrication of a negative interseparator in accordance with the invention will be described hereina~ter with reference to incorporation therein of the described additives.
l~pically, the secondary alkaline battery includes a casing with one or more negative electrodes and one or more positive electrodes disposed therein in intimate contact with the alkaline electrolyte. The s~parator system may be utilized in the form of a "U"-wrap, as is well known; with the main separator disposed between confronting surfaces of adjacent positive and negative electrodes so that it forms a "U"
around a positive electrode, with neyative and positive inter-separators positioned on opposite sides of the main separator in paraliel relationship therewith.
Turning now to the essential elements of this invention, the novel negative interseparators o~ the aforementioned secondary alkaline cells or batteries of the invention are ~ provided with an effective amount of an additive having certain characteristics. First, the additive must be at least slightly soluble in the alkaline electrolyte employed in a given application. Such solubi1ity is required to facilitate electrodialytic transport of cations (derived from the addi-~ive) to the negative electrode. Secondly, the additive must be capable of generating ca-tions which are eleckro-reducible to an insoluble adherent species (preferably the metal ~orm) on the zinc-containing el~ckrode at potentials normally encountered in the electrode environment o~ the described secondary alkaline cells, i.e. at potentials positive (nobl~!) to the L8~
1 zinc electrode. ~hirdly, the reduced species ~e.g. the metal form) must have either a high hydrogen overvoltage (on the order of one volt or more) or a reversible potential which is positive with respect to hydroyen.
The additive comprises a salt selected from the group consisting of a cadmium-containing salt, a lead-containing salt, a tin-containing salt, and mixtures thereo~ having the previously described necessary characteristics. of these salts the preferred species are ~elected from the group consisting of lead titanate, lead aceta~e, lead zirconate, cadmium acetate, cadmium zirconate, cadmium titanate, and tin zirconate.
Mixtures of these additives may also be used.
The additive can be incorporated into the negative interseparator when the latter is fabricated or the negative interseparator sheet can be impregnated with a solution con-taining the additive. Alternatively, the additive can be sprayed from a solution on to the negative interseparator. The negative interseparator can be fabricated of any suitable material such as nylon and polyprop~lene non~woven felt, long fiber as~estos ~alumino-silicate) mats, glass fiber and zirconia ~iber mats and the like.
In general, the amount of additive carried on or in-corporated in the negative interseparator will depend upon the characteristics~and function of each battery in which the additive is incorporate~. As the amount of additive approaches zero, there will be less than an efective amount of addi.tive to accomplish the hereinbefore-described purposes, particularly after many charge-discharge cycles. on the other hand, as ~he amount of additive utilized increases, a level will be reached where there i8 more than enough additive to accomplish 1 those purposes and to serve as a reservoir. Since an excess amount ef~ectively serves no function while occupying some space within a battery, it is preferable not to use an e~cess amount so that the volume available for the active electrode materials, etc., is not significantly diminished.
Typically, the amount of additive (as the metal) utilized can range from about 0.5 to about 5% per unit weight of the inorganic fibrous laminate.
In operation, the zinc electrode is plated with a layer of the protective material (the reduced ~orm of the cations derived from the additive) when the battery containing the additive is charged or when on open circuit (i.e. on stand).
After the initial discharge, zinc will also be deposited on the zinc electrode along with the protective material during the charging phase of each charge/discharge cycle. When the circuit is closed, i.e., upon discharge, the battery potential drops to the oxidation potential of the protective material which is consumed (oxidized) and returns to the electrolyte as ions.
When the protective material has been removed as a coating from the zinc electrode, the zinc can then freely oxidize at its usual voltage so that power can be withdrawn from the battery.
When the circuit is again opened or the battery charged, the zinc electrode will again become coated with the protective material. The foregoing sequence of coating or plating followed by`dissolution of the coating will be repeated with every charge/discharge cycle.
When the protective material is dissolved back into the electrolyte, it does so at least to some extent in a form (plumbate ions in the case of lead) which cannot be reduced to again coat the zinc electrode during the next charge. Therefore, :
.
1 some of the protective material is "lost" ~or electrode coating purposes; however, because the negative interseparator includes an ample supply o~ additive, the cations lost as des-cribed will be replaced by a new supply of cations from the additive remaining in the negative interseparator. There~ore, in spite of some loss with each charge/discharge cycle, a re~
latively constant supply of cations will be available in the electrolyte fvr reduction and for coating of the zinc surface.
This is an advantage which is not obtained if the additive is merely included in the electrode or electrolyte. In those latter instances, after a limited number of charge/discharge cycles the active metal species from the additive in close contact with the zinc active material of the electrode is used up, due to the dissolution/dissociation process.
This invention will be further described by the following specific Examples:
EXAMPLE I
An inorganic fibrous laminate (IFL) containing lead titanate was made by dispersing 672 gm. of an admLxture con-sisting of 85g by weight potassium titanate, 9~ by weight asbestos flbers, 2% by weight carboxymethylcelLulose gumr and ~% by weight lead titanate into 8,000 ml of deionized water.
The resultant slurry was then cast into a sheet, which was dried and rolled down to final thickness (5 t~ 6 mils). This sheet was used as a negative interseparator against the zinc electrode in silver/zinc cells.
Ten ampere hour silvex/zinc tesk cells were fabricated utilizing the lead titanate-bearing IFL negative inter-separator material~ The cqlls consisted of 4 positive silverelectrodes and flve negative zinc oxide electrodes. The negative - 7 _ , .. . . . .. .
1 electrodes contained 99.5% by weight ZnO and 0.5% by weight CMC. The separator system consisted of a layer o~ porous polypropylene material as the positive interseparator, four (4) layers of silver-impregnated cellophane against ~he positive electrode as the main separator, followed by one layer of the IFL/lead titanate material against the negative electrode.
The cell pack was placed in a 10 ampere-hour cell case. The cover was sealed to the case and the resultant cell activated with 65 cc of 40 weight % aqueous potassium hydroxide~
Following two formation cycles, the then fully charged cells were placed on wet stand and connected to eudiometers to measure hydrogen gas evolution. The gassin~ rate at room temperature was determined to be 0.028 cc/day/in of negative electrode surface.
Control cells made without the lead titanate in the IFL and with negative electrodes containing 1% by weight mercuric oxide exhibited a gasslng rate equivalent to 0.05 cc/day/in2 of negative electrode surface. Accordingly t the lead titanate produced lower hydrogen gas evolution than the mercuric oxide. Moreover, tests on the cells indicated that the electrical performance of the cells containing lead titanate additive was better than that of the controls containing mercuric oxide.
An inorganic fibrous laminate ~IFL) of the same com position as set forth in Example I, except for the substitution of ca~nium titanate for lead titanate in a concentration o~
5% by weight, was prepared in accordance with the procedure of Example I. This laminate was utilized as a negatiue inter~
separator in cells otherwise identical to those specified`in 1 E~ample I. Control cells were also made in an identical mann~r except that the negative electrodes in these cells contained 1% by weight of mercuric oxide and there was no cadmium titanate additive in ~he negative interseparator.
The test cells and the co~trol cells were all charged at 15 m.a. per square inch rate for 16 hours and then discharged at the 2-hour ra~e to 1.0 volt p~r cell. Cells containing the 1% mercuric oxide additive to the negative electrode had an avera~e output of 10 ampere hours while the cadmium titanate-containing cells had an output of 9.4 ampere hours. Accordingly, the electrical characteristics and the performance of thecadmium titanate-containing cells was comparable to those containing the mercuric oxide, while avoiding the hazards connected with mercuric oxide.
Comparable results can be obtained through the use of other concentrations, preferably between about 0.5 and about 5%, of the selected additive, by weight of the negative interseparator in the zinc electrode-containing cells. In ~ -parallel tests, when lead acetate, lead zirconate, cadmium acetate, 20 ~ cadmium zirconate and tin zirconate are substituted for the cadmium titanate in a concentration between 0.5 and 5%, by weight of the negative interseparator, results comparable to those set forth above for the cadmium titanate-containing test cells and the lead titanate-containing test cells of Example I are obtained. Tests also indicate that substitution of other forms of negative interseparator materials in place :
of those called for in Examples I a~d II produce comparable results so long as the addi.tive is present ~hus, when nylon, or polypropylene non-woven felts, or glass fiber mats or zirconia mats axe used in place of the asbestos fibers called for _ g ~ ' -. . :
1 in Examples I and II, effective negative interseparators can be fabricated.
Various other modifications, changes, alterations and additions can be made in the improved negative interseparator of the present invention and the improved zinc electrode-containing cells employing the negative interseparator. All such modifications, changes, alterations and addltions as are within the scope of the appended claims form part of the present invention.
1`0 ' ,
Claims (11)
1. An improved secondary alkaline battery, said battery being mercury-free and comprising:
A. at least one positive electrode;
B. at least one zinc negative electrode;
C. a main separator;
D. a positive interseparator;
E. a negative interseparator between said zinc electrode and said main separator and containing a reservoir of electrolyte-soluble additive which, during operation of said battery, yields cations forming a protective coating on said zinc electrode and exhibiting either a hydrogen overvoltage of the order of at least about 1 volt or a reversible potential positive with respect to hydrogen; and F. an alkaline electrolyte, the concentration of said additive in said negative interseparator being sufficient to protect said zinc electrode during the normal operation life of said electrode.
A. at least one positive electrode;
B. at least one zinc negative electrode;
C. a main separator;
D. a positive interseparator;
E. a negative interseparator between said zinc electrode and said main separator and containing a reservoir of electrolyte-soluble additive which, during operation of said battery, yields cations forming a protective coating on said zinc electrode and exhibiting either a hydrogen overvoltage of the order of at least about 1 volt or a reversible potential positive with respect to hydrogen; and F. an alkaline electrolyte, the concentration of said additive in said negative interseparator being sufficient to protect said zinc electrode during the normal operation life of said electrode.
2. The improved battery of claim 1 wherein said cations are electro-reducible to adherent species plating out on said zinc electrode at potentials positive to said zinc electrode.
3. The improved battery of claim 2 wherein said additive is selected from the group consisting of a lead-containing salt, cadmium-containing salt, tin-containing salt, and mixtures thereof wherein said salt is sufficiently soluble in said battery environment to generate said cations.
4. The improved battery of claim 3 wherein said salts preferably are selected from the group consisting of lead titanate, lead acetate, lead zirconate, cadmium acetate, cadmium zirconate, cadmium titanate, tin zirconate, and mixtures thereof.
5. The improved battery of claim 3 wherein the con-centration of said additive in said negative interseparator is about 0.5 - 5%, by weight of said negative interseparator.
6. The improved battery of claim 3 wherein said positive electrode comprises silver and wherein said alkaline electrolyte comprises aqueous alkali metal hydroxide.
7. An improved negative interseparator for a secondary alkaline battery containing a zinc negative electrode, said negative interseparator being mercury-free and comprising:
A. a fibrous laminate; and B. an additive which generates cations electro-reducible to insoluble adherent species on a zinc-containing electrode in an alkaline secondary battery at potentials positive to the zinc electrode, and exhibiting a hydrogen over-voltage of the order of at least about 1 volt or a reversible potential positive with respect to hydrogen, for protection of said zinc electrode, the concentration of said additive in said negative interseparator being sufficient to protect said zinc electrode during the normal operation life of said electrode.
A. a fibrous laminate; and B. an additive which generates cations electro-reducible to insoluble adherent species on a zinc-containing electrode in an alkaline secondary battery at potentials positive to the zinc electrode, and exhibiting a hydrogen over-voltage of the order of at least about 1 volt or a reversible potential positive with respect to hydrogen, for protection of said zinc electrode, the concentration of said additive in said negative interseparator being sufficient to protect said zinc electrode during the normal operation life of said electrode.
8. The improved negative interseparator of claim 7 wherein said additive is present in said negative interseparator in a concentration of about 0.5 - 5%, by weight of said negative interseparator.
9. The improved negative separator of claim 7 wherein said additive is selected from the group consisting of a lead-containing salt, cadmium-containing salt, tin-containing salt, and mixtures thereof.
10. The improved negative interseparator of claim 9 where-in said additive is preferably selected from the group con-sisting of lead titanate, lead acetate, lead zirconate, cadmium acetate, cadmium titanate, cadmium zirconate, tin zirconate, a mixtures thereof.
11. The improved negative separator of claim 10 wherein said additive is present in a concentration of about 0.5 - 5%, by weight of said negative interseparator.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/841,864 US4124743A (en) | 1977-10-13 | 1977-10-13 | Mercury-free secondary alkaline battery and improved negative interseparator therefor |
| US841,864 | 1977-10-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1100183A true CA1100183A (en) | 1981-04-28 |
Family
ID=25285886
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA311,379A Expired CA1100183A (en) | 1977-10-13 | 1978-09-15 | Mercury-free secondary alkaline battery and improved negative interseparator therefor |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4124743A (en) |
| JP (1) | JPS6051780B2 (en) |
| CA (1) | CA1100183A (en) |
| DE (1) | DE2835836C3 (en) |
| FR (1) | FR2406314A1 (en) |
| GB (1) | GB2006512B (en) |
| IL (1) | IL55295A (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4192908A (en) * | 1979-06-15 | 1980-03-11 | The United States Of America As Represented By The Secretary Of The Navy | Mass-transport separator for alkaline nickel-zinc cells and cell |
| US4418130A (en) * | 1981-06-10 | 1983-11-29 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Additive for zinc electrodes |
| JPS5928588A (en) * | 1982-08-09 | 1984-02-15 | Meidensha Electric Mfg Co Ltd | Inhibitor for dendrite of zinc |
| US4812375A (en) * | 1988-06-27 | 1989-03-14 | The United States Of America As Represented By The Secretary Of The Army | Separator for lithium batteries and lithium batteries including the separator |
| US5700599A (en) * | 1996-01-12 | 1997-12-23 | Danko; Thomas | High absorption rate battery separator |
| US5700600A (en) * | 1996-01-12 | 1997-12-23 | Danko; Thomas | Long life battery separator |
| US8139343B2 (en) * | 2010-03-08 | 2012-03-20 | Wisys Technology Foundation | Electrical energy storage device containing an electroactive separator |
Family Cites Families (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE514901A (en) * | 1951-10-07 | |||
| BE557265A (en) * | 1956-05-07 | |||
| US2982806A (en) * | 1956-11-15 | 1961-05-02 | Pertrix Union Ges Mit Beschrae | Electric cell |
| DE1496355A1 (en) * | 1962-05-18 | 1969-05-14 | Yardney International Corp | Separator for electric batteries |
| FR1485539A (en) * | 1965-12-30 | 1967-06-23 | Accumulateurs Fixes | Improvement in electrochemical cells comprising negative zinc-based electrodes |
| US3553027A (en) * | 1968-02-02 | 1971-01-05 | Leesona Corp | Electrochemical cell with lead-containing electrolyte and method of generating electricity |
| US3580740A (en) * | 1968-09-04 | 1971-05-25 | Esb Inc | Zinc electrode containing lead sulfide to reduce gassing at the zinc electrode in heat sterilized silver zinc alkaline battery |
| DE1903168A1 (en) * | 1969-01-23 | 1970-07-30 | Bayer Ag | Preparation of o-(2,2-dichlorovinyl)- - phosphoric acid ester dichloride |
| CA935510A (en) * | 1969-04-08 | 1973-10-16 | J. Van Der Grinten Willen | Rechargeable alkaline-zinc cell |
| JPS485185B1 (en) * | 1969-05-16 | 1973-02-14 | ||
| JPS4813775B1 (en) * | 1970-04-17 | 1973-04-28 | ||
| CA989937A (en) * | 1970-10-28 | 1976-05-25 | Gates Rubber Company (The) | Cadmium lining for alkaline cells having highly electronegative electrodes |
| FR2134302A1 (en) * | 1971-04-30 | 1972-12-08 | Comp Generale Electricite | Additives for electrolytes - for accumulators with zinc electrode giving uniform zinc deposit |
| US3905833A (en) * | 1973-08-08 | 1975-09-16 | Union Carbide Corp | Cyanide and mercury corrosion inhibitors for zinc alkaline galvanic cells |
| JPS5461B2 (en) * | 1973-11-21 | 1979-01-05 | ||
| JPS5096835A (en) * | 1973-12-28 | 1975-08-01 | ||
| US4022953A (en) * | 1975-08-22 | 1977-05-10 | Energy Research Corporation | Zinc electrodes for secondary batteries |
-
1977
- 1977-10-13 US US05/841,864 patent/US4124743A/en not_active Expired - Lifetime
-
1978
- 1978-08-07 IL IL55295A patent/IL55295A/en unknown
- 1978-08-11 GB GB7833007A patent/GB2006512B/en not_active Expired
- 1978-08-16 DE DE2835836A patent/DE2835836C3/en not_active Expired
- 1978-09-05 FR FR7825491A patent/FR2406314A1/en active Granted
- 1978-09-15 CA CA311,379A patent/CA1100183A/en not_active Expired
- 1978-10-13 JP JP53125210A patent/JPS6051780B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2835836A1 (en) | 1979-04-19 |
| JPS6051780B2 (en) | 1985-11-15 |
| DE2835836C3 (en) | 1981-12-03 |
| DE2835836B2 (en) | 1981-01-08 |
| JPS5463333A (en) | 1979-05-22 |
| GB2006512B (en) | 1982-03-03 |
| IL55295A0 (en) | 1978-10-31 |
| FR2406314A1 (en) | 1979-05-11 |
| IL55295A (en) | 1981-09-13 |
| US4124743A (en) | 1978-11-07 |
| FR2406314B1 (en) | 1982-12-10 |
| GB2006512A (en) | 1979-05-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3785868A (en) | Zinc electrode | |
| US6033343A (en) | Iron-based storage battery | |
| US5453336A (en) | Rechargeable zinc cell with alkaline electrolyte which inhibits shape change in zinc electrode | |
| US3516862A (en) | Rechargeable alkaline-zinc cell with porous matrix containing trapping material to eliminate zinc dendrites | |
| Dodson | The Composition and Performance of Positive Plate Material in the Lead‐Acid Battery | |
| US4592974A (en) | Active material for negative poles of alkaline dry cells, and method for making said material | |
| CA1100183A (en) | Mercury-free secondary alkaline battery and improved negative interseparator therefor | |
| US4735870A (en) | Lead-acid battery construction | |
| US3976502A (en) | Nickel-zinc alkaline storage battery | |
| US3847668A (en) | Alkaline accumulator operated in gas-tightly sealed condition | |
| US4152224A (en) | Inorganic additives for zinc-alkaline secondary batteries and alkaline zinc-plating baths | |
| US3607437A (en) | Electrolyte for use in alkaline storage batteries having a zinc negative electrode | |
| Amlie et al. | Adsorption of Hydrogen and Oxygen on Electrode Surfaces | |
| JPH01319261A (en) | Alkaline-zinc storage battery | |
| JPS60220555A (en) | electrochemical cell | |
| JPH1079246A (en) | Method for producing nickel hydroxide electrode for alkaline storage battery | |
| JPH0550814B2 (en) | ||
| JPH0338702B2 (en) | ||
| KR102306925B1 (en) | Reversible manganese dioxide electrode, method for making same, use thereof, and rechargeable alkaline manganese-cell comprising the electrode | |
| JPS5814026B2 (en) | iron alkaline storage battery | |
| CA1174728A (en) | Electrolyte for electro-chemical cells | |
| US3936318A (en) | Electrical energy storage battery means | |
| JPH0821420B2 (en) | Open type alkaline storage battery | |
| Sathyanarayana | Ideally rechargeable cadmium electrodes for alkaline storage batteries | |
| Dmitrenko et al. | The Difference in the Poisoning With Zincate of the Positive Electrodes of Nickel--Zinc and Silver--Zinc Cells |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |