CA1093149A - Metal halogen battery of improved efficiency - Google Patents
Metal halogen battery of improved efficiencyInfo
- Publication number
- CA1093149A CA1093149A CA294,116A CA294116A CA1093149A CA 1093149 A CA1093149 A CA 1093149A CA 294116 A CA294116 A CA 294116A CA 1093149 A CA1093149 A CA 1093149A
- Authority
- CA
- Canada
- Prior art keywords
- metal
- electrolyte
- chloride
- halogen
- cation
- 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
- H01M10/36—Accumulators not provided for in groups H01M10/05-H01M10/34
- H01M10/365—Zinc-halogen accumulators
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Secondary Cells (AREA)
- Hybrid Cells (AREA)
- Primary Cells (AREA)
- Conductive Materials (AREA)
Abstract
Abstract of the Disclosure The energy efficiency of a metal-halogen battery is im-proved by increasing the halide ion concentration in the metal halide electrolyte.
Description
93~
BACKGROUND OF THE INVENTION
A variety of electrical energy storage devices have here-tofore been used or proposed for use either as a principal or as a backup source of electrical energy. Electric storage batteries of a type which are capable of supplying at least 50 watt hours of electric power per pound of weight have been conventionally classi-fied as high energy density storage batteries which, because of their compactness and high energy capacity, are emminently satis-factory for use in a variety of stationary and mobile power plan-t systems.
Numerous patents describe the use of aqueous me~allic halide solutions as electrolyte with halogen as electroactive material. A good description of the use of such a system in se-condary batteries can be found in Symons Patent 3,713,888. Symons stores the halogen which evolves at the positive electrode during charging by converting it into a halogen hydrate. The halogen can also be stored in other forms such as, for example, as a liquid.
The energy efficiency of a battery is equal to the product of the voltaic efficiency and the coulombic efficiency. In the metal halide battery, the worst efficiency is usually the coulombic efficienc~ on charge. During charging, the metallic ion in the electrolyte plates out on the negative electrode as the metal and halogen is formed from the halide at the positive electrode. It has been discovered that the poor charge coulombic efficiency is due to the partial recombination of the metal and halogen fo~med during the charging. It has further been discovered that the chemical re-combination ràte, or corrosion rate, is proportional to the - ,~
,: :
. ': , ' :,',` '::: ,' ,, , :, ' .
. ~ , ., :. ' , . ..
~a31~9 concentration of dissolved halogen in the electrolyteO It is there-fore apparent that it would be desirable to decrease the amount of dissolved halogen in the electrolyte and thereby improve charge coulombic efficiency.
An apparent means of decreasing the concentration of dis-solved chlorine in the electrolyte is to establish a partial vacuum on the electrolyte. This procedure, however, requires the use of a relatively costly gas pump and much of the improvement in energy efficiency of the battery is negated by the additional energy which is required for the gas pump. Another apparent alternative would be to increase the temperature since it is well known that solubil-ity of dissolved gases can be reduced thereby. However, in the metal halide battery system, it has been observed that increasing the temperature does not provide any significant improvement. It is believed that this is the result of the decreased solubility being offset by increased diffusion of the dissolved chlorine and/
or the kinetics of recombination.
Accordingly, it is the object of this invention to pro-vide a means for reducing the concentration of dissolved halogen ~0 in the electrolyte of a metal halide battery system in such a way to provide a significant improvement in coulombic efficiency with-out requiring the use of costly and energy wasteful auxiliary equipment. This and other objects of the invention will be apparent to those skilled in the art from the following detailed description.
SUMMARY OF THE INVENTION
This invention relates to a metal halide battery of improved efficiency in which the concentration of dissolved halogen in the metal halide electrolyte is reduced by adding an appropriate - : , :: :~
. ', . ~ b . .
3~
salt thereto so as to increase the halide concentration thereof.
DETAILED DESCRIPTION OF THE INVENTION
The electrolyte of the present battery system is a sol-ution of a metal halide. The choice o~ the metal is primarily de-pendent upon its ability to plate out to an electrode surface during charging. Zinc is the most pre~erred metal and is desirable because of its ease of being deposited from an aqueous solution and the zinc deposit is smooth and large surfaces can be deposited. The most pre~erred embodiment is an aqueous solution of zinc chloride. Other preferred metal halides are halides of Group IIb metals or halides o iron, cobalt, nickel or other group VIII metals of the periodic tablè listed in the Handbook of Chemistry & Physics, 43rd Edition (1961-1962)~ The most pre~erred halides are the chlorides and bromides. Other metal halides that can be employed are the halides of the lanthanide and actinide series as well as the halides of Sc, Ti, V, Cr, Mn, Cu, Ga, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Nf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pd, or Bi.
The electrolyte solutions employed can have a variety of other components therein to decrease corrosion, reduce dendrite ~oxmation, increaseelectrolytic conductivity, etc. In secondary batteries,` the most preferred electrolyte is an aqueous one although other electrolyte systems can be used. Generally these systems are polar systems. For primary batteries, some electrolyte systems in addition t~ the aqueous ones that can be employed are lower aliphatic alcohols and ketones, such as methanol, ethanol, acetone, etc. as well as monomethylformamide, dimethyl sulfoxide and propy-lene carbonate.
The concentration of the pre~erred aqueous metal halide ` `:.-.,`.' ', ,- , ,, :
., - , , - . . ; ~ ,: .
.
3~9 electrolyte employed in this in~ention ranges from about 5% to saturation and most preferably about 10 to 35% by weight.
In order to decrease the amount of dissolved halogen in the electrolyte during charging, an appropriate amount of a metal salt is added to the electrolyte so as to increase the halide ion concentration. It will thus be appreciated that the anion of the added salt will be the same as the halide of the metal halide electrolyte. The cation of the added salt is chosen so that the salt will be solub~e in the electrolyte and the cation will not plate out or otherwise interfere with the plating out of the metal `o~ the metal halide. In general, any cation whose oxidation pot-ential in a molal solution of ions in contact with metal at 25 is greater than 1.50 are appropriate for use as the cation of the added salt. ~uch cations include the alkali metals, the alkaline earth metals and aluminum. The preferred salt is NaCl.
The added salt is employed in an amount which can range from about 0.1 weight percent up to saturation of the electrolyte.
It is usually sufficient to employ about 0.5-5 moles of added salt per mole of metal halide ln the electrolyte, and preferably about 1 to 2 moles of added salt per mole of metal halide are used.
The e~fect of the addition of the salt to the electrolyte is shown in the following table in which the number of grams per liter of dissolved chlorine in a chlorine saturated aqueous zinc chloride solution are set forth:
.
;
, . . .
.: :
~3~
Moles of Added Salt ZnC12 and Amount g/l of C12 1 - 3.1
BACKGROUND OF THE INVENTION
A variety of electrical energy storage devices have here-tofore been used or proposed for use either as a principal or as a backup source of electrical energy. Electric storage batteries of a type which are capable of supplying at least 50 watt hours of electric power per pound of weight have been conventionally classi-fied as high energy density storage batteries which, because of their compactness and high energy capacity, are emminently satis-factory for use in a variety of stationary and mobile power plan-t systems.
Numerous patents describe the use of aqueous me~allic halide solutions as electrolyte with halogen as electroactive material. A good description of the use of such a system in se-condary batteries can be found in Symons Patent 3,713,888. Symons stores the halogen which evolves at the positive electrode during charging by converting it into a halogen hydrate. The halogen can also be stored in other forms such as, for example, as a liquid.
The energy efficiency of a battery is equal to the product of the voltaic efficiency and the coulombic efficiency. In the metal halide battery, the worst efficiency is usually the coulombic efficienc~ on charge. During charging, the metallic ion in the electrolyte plates out on the negative electrode as the metal and halogen is formed from the halide at the positive electrode. It has been discovered that the poor charge coulombic efficiency is due to the partial recombination of the metal and halogen fo~med during the charging. It has further been discovered that the chemical re-combination ràte, or corrosion rate, is proportional to the - ,~
,: :
. ': , ' :,',` '::: ,' ,, , :, ' .
. ~ , ., :. ' , . ..
~a31~9 concentration of dissolved halogen in the electrolyteO It is there-fore apparent that it would be desirable to decrease the amount of dissolved halogen in the electrolyte and thereby improve charge coulombic efficiency.
An apparent means of decreasing the concentration of dis-solved chlorine in the electrolyte is to establish a partial vacuum on the electrolyte. This procedure, however, requires the use of a relatively costly gas pump and much of the improvement in energy efficiency of the battery is negated by the additional energy which is required for the gas pump. Another apparent alternative would be to increase the temperature since it is well known that solubil-ity of dissolved gases can be reduced thereby. However, in the metal halide battery system, it has been observed that increasing the temperature does not provide any significant improvement. It is believed that this is the result of the decreased solubility being offset by increased diffusion of the dissolved chlorine and/
or the kinetics of recombination.
Accordingly, it is the object of this invention to pro-vide a means for reducing the concentration of dissolved halogen ~0 in the electrolyte of a metal halide battery system in such a way to provide a significant improvement in coulombic efficiency with-out requiring the use of costly and energy wasteful auxiliary equipment. This and other objects of the invention will be apparent to those skilled in the art from the following detailed description.
SUMMARY OF THE INVENTION
This invention relates to a metal halide battery of improved efficiency in which the concentration of dissolved halogen in the metal halide electrolyte is reduced by adding an appropriate - : , :: :~
. ', . ~ b . .
3~
salt thereto so as to increase the halide concentration thereof.
DETAILED DESCRIPTION OF THE INVENTION
The electrolyte of the present battery system is a sol-ution of a metal halide. The choice o~ the metal is primarily de-pendent upon its ability to plate out to an electrode surface during charging. Zinc is the most pre~erred metal and is desirable because of its ease of being deposited from an aqueous solution and the zinc deposit is smooth and large surfaces can be deposited. The most pre~erred embodiment is an aqueous solution of zinc chloride. Other preferred metal halides are halides of Group IIb metals or halides o iron, cobalt, nickel or other group VIII metals of the periodic tablè listed in the Handbook of Chemistry & Physics, 43rd Edition (1961-1962)~ The most pre~erred halides are the chlorides and bromides. Other metal halides that can be employed are the halides of the lanthanide and actinide series as well as the halides of Sc, Ti, V, Cr, Mn, Cu, Ga, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Nf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pd, or Bi.
The electrolyte solutions employed can have a variety of other components therein to decrease corrosion, reduce dendrite ~oxmation, increaseelectrolytic conductivity, etc. In secondary batteries,` the most preferred electrolyte is an aqueous one although other electrolyte systems can be used. Generally these systems are polar systems. For primary batteries, some electrolyte systems in addition t~ the aqueous ones that can be employed are lower aliphatic alcohols and ketones, such as methanol, ethanol, acetone, etc. as well as monomethylformamide, dimethyl sulfoxide and propy-lene carbonate.
The concentration of the pre~erred aqueous metal halide ` `:.-.,`.' ', ,- , ,, :
., - , , - . . ; ~ ,: .
.
3~9 electrolyte employed in this in~ention ranges from about 5% to saturation and most preferably about 10 to 35% by weight.
In order to decrease the amount of dissolved halogen in the electrolyte during charging, an appropriate amount of a metal salt is added to the electrolyte so as to increase the halide ion concentration. It will thus be appreciated that the anion of the added salt will be the same as the halide of the metal halide electrolyte. The cation of the added salt is chosen so that the salt will be solub~e in the electrolyte and the cation will not plate out or otherwise interfere with the plating out of the metal `o~ the metal halide. In general, any cation whose oxidation pot-ential in a molal solution of ions in contact with metal at 25 is greater than 1.50 are appropriate for use as the cation of the added salt. ~uch cations include the alkali metals, the alkaline earth metals and aluminum. The preferred salt is NaCl.
The added salt is employed in an amount which can range from about 0.1 weight percent up to saturation of the electrolyte.
It is usually sufficient to employ about 0.5-5 moles of added salt per mole of metal halide ln the electrolyte, and preferably about 1 to 2 moles of added salt per mole of metal halide are used.
The e~fect of the addition of the salt to the electrolyte is shown in the following table in which the number of grams per liter of dissolved chlorine in a chlorine saturated aqueous zinc chloride solution are set forth:
.
;
, . . .
.: :
~3~
Moles of Added Salt ZnC12 and Amount g/l of C12 1 - 3.1
2 - 2.75
3 - 2.5
4 - 2.3
5.3 - 2.15 2 3M KCl 2.4 2 3M NaCl 1.9 2 4M NaCl 1.7 2 lM AlC13 2.6 2 1.5M MgC12 2.5 2 1.5M CaC12 2.3 2 2M CaC12 2.~
3 2M KCl 2.6 From the foregoing data, it will be appreciated that by the addition of the salt, particularly sodium chloride, to the zinc chlorideelectrolyte, the dissolved chlorine concentration can be reduced to the point where the charging coulombic efficiency is the same as if a gas pump was used.
In addition to improving the coulombic efficiency, it has been found that the addition of the salt, whether alone or in ~arious combinations, produces other beneficial results in the battery system. For example, the conductivity of an aqueous 10-35%
~inc chloride electrolyte is about 0.06-0.12 mhos/cm and addition of the salt results in an increased conductivity o~ about 0.1-0.2 mhos/cm. In addition, the morphology of the zinc deposit is im-proved, particularly at higher operating temperatures t35-60C).
- ~ . . ,- .-The latter improvement makes it possible to employ higher charging current densities and/or longer charging times and, in turn, results in an improvement in energy efEiciency of the battery system as well as higher capacitiesO It has further been found that by operating at such higher temperatures, the activation (polarization) over-potential is decreased so that in addition to increased charge coul-ombic efficiency, higher voltaic efficienices are achieved during both the charging and discharging of the battery.
Various changes and modifications can be made in the electrolyte and battery systems of the present invention without departing from the spirit and scope thereof. The various embodiments disclosed herein were set forth for the purpose further illustrating the invention but were not intended to limit it.
~: . . .: : -., , . - :
3 2M KCl 2.6 From the foregoing data, it will be appreciated that by the addition of the salt, particularly sodium chloride, to the zinc chlorideelectrolyte, the dissolved chlorine concentration can be reduced to the point where the charging coulombic efficiency is the same as if a gas pump was used.
In addition to improving the coulombic efficiency, it has been found that the addition of the salt, whether alone or in ~arious combinations, produces other beneficial results in the battery system. For example, the conductivity of an aqueous 10-35%
~inc chloride electrolyte is about 0.06-0.12 mhos/cm and addition of the salt results in an increased conductivity o~ about 0.1-0.2 mhos/cm. In addition, the morphology of the zinc deposit is im-proved, particularly at higher operating temperatures t35-60C).
- ~ . . ,- .-The latter improvement makes it possible to employ higher charging current densities and/or longer charging times and, in turn, results in an improvement in energy efEiciency of the battery system as well as higher capacitiesO It has further been found that by operating at such higher temperatures, the activation (polarization) over-potential is decreased so that in addition to increased charge coul-ombic efficiency, higher voltaic efficienices are achieved during both the charging and discharging of the battery.
Various changes and modifications can be made in the electrolyte and battery systems of the present invention without departing from the spirit and scope thereof. The various embodiments disclosed herein were set forth for the purpose further illustrating the invention but were not intended to limit it.
~: . . .: : -., , . - :
Claims (9)
1. The method of improving the energy efficiency of a platable metal-halogen-aqueous metal halogen electrolyte electrical energy storage system which comprises adding to said aqueous metal electrolyte a soluble metal halide whose cation doss not substantially plate out during the charging of said system, whereby the amount of dissolved halogen in the electrolyte upon charge is decreased.
2. The method of claim 1 wherein the halogen is chlorine and the halide is chloride.
3. The method of claim 1 wherein said cation has an oxidation potential of at least 1.50.
4. The method of claim 2 wherein said cation is an alkali metal, alkaline earth metal or aluminum.
5. The method of claim 4 wherein said cation is sodium.
6. The method of claim 2 wherein said metal chloride is an aqueous solution of zinc chloride and wherein said soluble metal chloride is sodium chloride.
7. The method of claim 6 wherein said soluble metal chloride concentration is about 1.2 moles per mole of zinc chloride.
8. The method of claim 2 wherein said soluble metal chloride is present in an amount of about 0.5 to 5 moles per mole of said metal chloride in said electrolyte.
9. The method of claim 8 wherein said soluble metal chloride concentration is about 1.2 moles per mole of metal chloride.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US78174477A | 1977-03-28 | 1977-03-28 | |
| US781,744 | 1977-03-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1093149A true CA1093149A (en) | 1981-01-06 |
Family
ID=25123779
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA294,116A Expired CA1093149A (en) | 1977-03-28 | 1977-12-29 | Metal halogen battery of improved efficiency |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS53120141A (en) |
| BE (1) | BE863201A (en) |
| BR (1) | BR7800030A (en) |
| CA (1) | CA1093149A (en) |
| DE (1) | DE2758511A1 (en) |
| ES (1) | ES465662A1 (en) |
| FR (1) | FR2386151A1 (en) |
| GB (1) | GB1598834A (en) |
| IT (1) | IT1089289B (en) |
| MX (1) | MX148501A (en) |
| NL (1) | NL7800202A (en) |
| SE (1) | SE500450C2 (en) |
| SU (1) | SU679169A3 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0636375B2 (en) * | 1982-04-23 | 1994-05-11 | 古河電気工業株式会社 | Zinc-halogen battery |
| GB2177251B (en) * | 1985-06-19 | 1988-12-07 | Furukawa Electric Co Ltd | Battery |
| US12100803B2 (en) | 2018-10-10 | 2024-09-24 | Oregon State University | Aqueous zinc-metal batteries comprising “water-in-salt” electrolyte |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR499498A (en) * | 1917-04-05 | 1920-02-12 | Guglielmo Marconi | Improvements to electric accumulators |
| GB320916A (en) * | 1928-04-27 | 1929-10-28 | Leonard Angelo Levy | Improvements in and relating to secondary electric cells |
| BE364349A (en) * | 1928-11-05 | |||
| US3682703A (en) * | 1971-02-02 | 1972-08-08 | Zito Co | Metal bromide system |
| US3855089A (en) * | 1972-11-27 | 1974-12-17 | Deepsea Ventures Inc | Process for the electrolytic refining of heavy metals |
| US3929506A (en) * | 1973-05-18 | 1975-12-30 | Dow Chemical Co | Zinc-bromide secondary cell |
| US4049886A (en) * | 1976-12-13 | 1977-09-20 | General Electric Company | Rechargeable aqueous metal-halogen cell |
-
1977
- 1977-12-28 DE DE19772758511 patent/DE2758511A1/en not_active Withdrawn
- 1977-12-29 CA CA294,116A patent/CA1093149A/en not_active Expired
- 1977-12-30 IT IT31488/77A patent/IT1089289B/en active
-
1978
- 1978-01-02 ES ES465662A patent/ES465662A1/en not_active Expired
- 1978-01-03 BR BR7800030A patent/BR7800030A/en unknown
- 1978-01-05 SE SE7800144A patent/SE500450C2/en unknown
- 1978-01-05 FR FR7800242A patent/FR2386151A1/en active Granted
- 1978-01-06 NL NL7800202A patent/NL7800202A/en not_active Application Discontinuation
- 1978-01-06 GB GB545/78A patent/GB1598834A/en not_active Expired
- 1978-01-09 MX MX171984A patent/MX148501A/en unknown
- 1978-01-16 SU SU782571756A patent/SU679169A3/en active
- 1978-01-23 BE BE184541A patent/BE863201A/en not_active IP Right Cessation
- 1978-02-15 JP JP1636078A patent/JPS53120141A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| BR7800030A (en) | 1978-10-24 |
| DE2758511A1 (en) | 1978-10-12 |
| SE7800144L (en) | 1978-09-29 |
| SE500450C2 (en) | 1994-06-27 |
| ES465662A1 (en) | 1978-09-16 |
| IT1089289B (en) | 1985-06-18 |
| MX148501A (en) | 1983-04-27 |
| SU679169A3 (en) | 1979-08-05 |
| FR2386151B1 (en) | 1984-05-25 |
| GB1598834A (en) | 1981-09-23 |
| JPS53120141A (en) | 1978-10-20 |
| NL7800202A (en) | 1978-10-02 |
| FR2386151A1 (en) | 1978-10-27 |
| BE863201A (en) | 1978-05-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 19980106 |