CA1193653A - Electrochemical cell having a alkali metal nitrate electrode - Google Patents
Electrochemical cell having a alkali metal nitrate electrodeInfo
- Publication number
- CA1193653A CA1193653A CA000425221A CA425221A CA1193653A CA 1193653 A CA1193653 A CA 1193653A CA 000425221 A CA000425221 A CA 000425221A CA 425221 A CA425221 A CA 425221A CA 1193653 A CA1193653 A CA 1193653A
- Authority
- CA
- Canada
- Prior art keywords
- alkali metal
- positive electrode
- nitrate
- electrochemical cell
- sodium
- 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
- 229910001963 alkali metal nitrate Inorganic materials 0.000 title claims abstract description 16
- 229910052783 alkali metal Inorganic materials 0.000 claims abstract description 53
- 150000001340 alkali metals Chemical class 0.000 claims abstract description 39
- 239000000203 mixture Substances 0.000 claims abstract description 21
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 claims abstract description 21
- 150000002823 nitrates Chemical class 0.000 claims abstract description 18
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 14
- 239000011734 sodium Substances 0.000 claims abstract description 14
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims abstract description 12
- 239000007774 positive electrode material Substances 0.000 claims abstract description 12
- 239000007773 negative electrode material Substances 0.000 claims abstract description 11
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 10
- 235000010344 sodium nitrate Nutrition 0.000 claims abstract description 10
- 239000011149 active material Substances 0.000 claims abstract description 9
- 239000004317 sodium nitrate Substances 0.000 claims abstract description 7
- 229910001413 alkali metal ion Inorganic materials 0.000 claims abstract description 6
- 239000004020 conductor Substances 0.000 claims abstract description 6
- 239000007787 solid Substances 0.000 claims abstract 5
- 230000004888 barrier function Effects 0.000 claims abstract 3
- 210000004027 cell Anatomy 0.000 claims description 57
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims description 18
- 150000003839 salts Chemical class 0.000 claims description 15
- -1 alkali metal nitrite Chemical class 0.000 claims description 14
- 229910001948 sodium oxide Inorganic materials 0.000 claims description 9
- 239000011521 glass Substances 0.000 claims description 8
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 239000007784 solid electrolyte Substances 0.000 claims description 7
- 229910000272 alkali metal oxide Inorganic materials 0.000 claims description 6
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 claims description 6
- 229910002651 NO3 Inorganic materials 0.000 claims description 5
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 5
- 229910052810 boron oxide Inorganic materials 0.000 claims description 5
- 239000007789 gas Substances 0.000 claims description 5
- 239000003792 electrolyte Substances 0.000 claims description 4
- 150000002500 ions Chemical class 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims description 4
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 150000002826 nitrites Chemical class 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 235000010288 sodium nitrite Nutrition 0.000 claims description 3
- 229910002001 transition metal nitrate Inorganic materials 0.000 claims description 3
- 229910001964 alkaline earth metal nitrate Inorganic materials 0.000 claims description 2
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Inorganic materials [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 claims description 2
- 229910021645 metal ion Inorganic materials 0.000 claims description 2
- 210000000352 storage cell Anatomy 0.000 claims description 2
- 238000013022 venting Methods 0.000 claims description 2
- 239000003365 glass fiber Substances 0.000 claims 2
- 229910019016 NaNO3—KNO3 Inorganic materials 0.000 claims 1
- YIXJRHPUWRPCBB-UHFFFAOYSA-N magnesium nitrate Inorganic materials [Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O YIXJRHPUWRPCBB-UHFFFAOYSA-N 0.000 claims 1
- 239000012768 molten material Substances 0.000 abstract 1
- KEAYESYHFKHZAL-UHFFFAOYSA-N Sodium Chemical compound [Na] KEAYESYHFKHZAL-UHFFFAOYSA-N 0.000 description 5
- 238000005260 corrosion Methods 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- PXIPVTKHYLBLMZ-UHFFFAOYSA-N Sodium azide Chemical compound [Na+].[N-]=[N+]=[N-] PXIPVTKHYLBLMZ-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- BNOODXBBXFZASF-UHFFFAOYSA-N [Na].[S] Chemical compound [Na].[S] BNOODXBBXFZASF-UHFFFAOYSA-N 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 229910001882 dioxygen Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 239000010963 304 stainless steel Substances 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- FUJCRWPEOMXPAD-UHFFFAOYSA-N Li2O Inorganic materials [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- 229910013555 LiNO3—KNO3 Inorganic materials 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 229910000589 SAE 304 stainless steel Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- XUCJHNOBJLKZNU-UHFFFAOYSA-M dilithium;hydroxide Chemical compound [Li+].[Li+].[OH-] XUCJHNOBJLKZNU-UHFFFAOYSA-M 0.000 description 1
- BTYPWVDULNVBHU-UHFFFAOYSA-N disodium;dinitrate Chemical compound [Na+].[Na+].[O-][N+]([O-])=O.[O-][N+]([O-])=O BTYPWVDULNVBHU-UHFFFAOYSA-N 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 239000002001 electrolyte material Substances 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229910001947 lithium oxide Inorganic materials 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910001510 metal chloride Inorganic materials 0.000 description 1
- 229910001960 metal nitrate Inorganic materials 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Inorganic materials [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 1
- 230000036647 reaction Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 229910001538 sodium tetrachloroaluminate Inorganic materials 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
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
- H01M10/39—Accumulators not provided for in groups H01M10/05-H01M10/34 working at high temperature
-
- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
-
- 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
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
ELECTROCHEMICAL CELL HAVING A ALKALI METAL NITRATE ELECTRODE ABSTRACT OF THE DISCLOSURE A power producing secondary electrochemical cell includes a molten alkali metal as the negative electrode material and a molten nitrate salt as the positive electrode material. The molten material in the respective electrodes are separated by a solid barrier of alkali metal ion conducting material. A typical cell includes active materials of molten sodium separated from molten sodium nitrate and other nitrates in mixture by a layer of sodium .beta." alumina.
Description
'336~3 ELECT~OCHEMICAL CELL H~VING A
ALKALI METAL NITRATE ELECTRODE
The invention relates to high temperature, secondary electrochemical cells for producing power that includes a molten alkali metal and nitrate salts. The invention particularly relates to the use of molten sodium metal and salts including sodium nitrate as the active materials.
It was previously believed that electrochemical cells involving molten alkali metals and their nitrate salts were only of interest as unrechargable primary cells or as cells for the electrolytic production of alkali metal.
Electrochemical reactions such as for the production of molten sodium metal from sodium nitrate have involved the release of gases for instance, nitrogen dioxide and oxygen gas which impose substantial difficulties in incorporating such a reaction in a secondary rechargable electrochemical cell. Furthermore, the nitrates within molten nitrate salts were thought to be decomposed to nitrite plus oxygen gas thus preventing the recharge of the cell to this original state.
The principal positive electrode material presently ~0 under consideration for secondary sodium cells is sulfur.
At the high operating temperature of these cells a very ' ~ 7 ~!
,`' ' , ';~.,'. ~
~1~33~i~3 corrosive environment is developed that requires expensive current collector materials such as titanium oxide or chrome plated steel. Other positive electrodes for molten sodium cells that have been considered include sodium tetrachloro-aluminate solvent containing sulfur species or metal chlorides.
These systems also exhibit severe corrosion problems and have relatively low theoretical specific energies on the order of 30OWh/kg.
It is an ob~ect of the present invention to provide an improved secondary electrochemical power producing cell that can employ molten alkali meta] as the negative electrode material.
It is a further object to provide a new positive electrode for use in combination with an alkali metal negative electrode within a secondary rechargable electro-chemical cell.
It is also an object to provide a high temperature secondary power producing electrochemical cell with a reactive alkali metal as negative electrode material with reduced corrosion problems in the positive electrode.
In accordance with the present invention, there is provided a secondary electrochemical storage cell comprising a negative electrode containing elemental alkali metal as active material, a positive electrode containing a salt including metal ions of the alkali metal as active material, the salt including a nitrate, a mixture of nitrates or a mixture of a nitrate and a nitrite; a solid electrolyte including and being capable of conducting ions of the alkali metal between the positive and negative ~3~3 electrodes; discharge means for conducting an electrical current through an electrical load connected in series between the positive and negative electrodes as alkali metal oxidizes to alkali metal ions in the negative electrode and alkali metal nitrate reduces to alkali metal nitrite in the positive electrode; recharge means for applying a source of electrical potential between the positive and negative electrodes sufEicient to oxidize alkali metal nitrite to alkali metal nitrate in the positive electrode and reduce alkali metal ions to alkali metal in the negative electrode; and sealing means for retaining the salt of alkali metal in the positive electrode as the cell discharges through the electrical load and as the cell is recharged for storing electrical energy.
In more specific aspects of the invention the negative electrode contains molten sodium and the positive electrode contains a molten salt including sodium nitrate. In such a cell the electrolyte separating the electrodes can be of a sodium oxide and alumina composition, for example one of the well known sodium ~ aluminasO These compositions permit the conduction of sodium ions from the negative to the positive electrodes during discharge of the cell.
In one other aspect of the invention the nitrate salt is selected from a mixture oE nitrate salts that permit reduced melting points below that of sodium nitrate salt.
Mixtures of alkali metal nitrates, alkaline earth metal nitrates and transition metal nitrates are contemplated with eutectic compositions generally providing low melting points ~3~
for a particular selec-tion of molten salts. In one other aspect of the invention, at least the positive electrode is contained within a sealed chamber to prevent incidental venting of nitrogen dioxide or of oxygen gases that may arise from the decomposition of the various nitrate salts.
In a further embodiment an alkali metal is included in the negative electrode and nitrate salts in the positive electrode each in communication with a plurality of qlass fibers extending between the positive and negative electrodes and in contact with the molten alkali metal and the molten metal nitrate salts. The glass Eibers consist essentially of an alkali metal ion conducting material including such as sodium oxide and boron oxide.
Further in accordance with the present invention there is provided a rechargeable electrochemical cell in at least a partially uncharged state comprising a negative electrode chamber containing elemental alkali metal as negative electrode material and means for collecting electronic current in contact with the alkali metal; a sealed positive electrode chamber containing a salt of alkali metal including nitrites and oxides as positive electrode material and means for collecting electronic current in contact with the alkali metal salt; a solid electrolyte wall forming at least a portion of the sealed positive electrode chamber and being in contact at one surface with the elemental alkali metal 4 .
and its opposite surface with the alkali metal salt, the solid electrolyte wall being capable of conducting ions of the alkali metal between the active materials of the positive and negative electrodes; and electrical recharge means or connecting a source of electrical potential across the current collecting means of the negative and the positive electrodes to oxidize alkali metal nitrite to alkali metal nitrate in the positive electrode.
The present invention is illustrated in the accompanying drawin~s wherein:
Fig. 1 is a schematic elevation view o~ an electro-chemical cell including a molten alkali metal and a molten nitrate salt as active materials.
Fig. 2 is a graph of volts vs. capacity over two charge and discharge cycles of a sodium-sodium nitrate secondary electrochemical cell.
Fig. 1 shows a laboratory style electrochemical cell used in demonstrating the electrochemical cell of this invention. It will be understood that this cell is presented merely by way of example and that various forms and constructions of cells more appropriate for commercial and industrial applications are also contem-plated within the scope of the present invention.
A cell container or housing 11 of corrosion resistant material, such as stainless steel, is illustrated as both the current collector and container for the negative electrode material 13. ~olten sodium metal is of principle interest as the negative electrode material 13. However ~`! .
3~53 other alkali metals such as potassium and lithium may be appropriate in molten mixture with sodium or as a separate electrode material.
A container 15 for the positive electrode material 17 is shown with its outer surfaces partially immersed in the molten alkali metal 13. Container 15 can be provided with some or all of its walls of a solid electrolyte material to establish means for ionic conduction between the positive 17 and negative electrode materials during cell operation.
The electrolyte material is advantageously selected from one of the sodium ~ aluminas of the type commonly used in sodium-sulfur cells. The ~ aluminas are poly-crystalline composition of sodium oxide and alumina having typically 8-20 mole percent Na2O and the balance alumina. Small amounts of lithia, magnesia and other constituents also may be included as stabilizer or to attribute other properties. A preferred form is that of ~ alumina (nominally Na2O:5A12O3) stabilizers with up to about one weight percent of Li2O.
Various ionic cond~ctive glasses such as those formed of boron oxide with a sodium oxide or other alkali metal oxide modifiers also are contemplated for use.
Such glasses may include 94-96~ by weight boron oxide modified by 4-6~ sodium oxide, Na2O:2~2O3:~.2SiO2 and Na2O:2B2O3:0.2SiO2:0.16NaCl as well as other sodium oxide modified glasses of boron oxide and silicon oxide.
The positive electrode material 17 within container 3~r~3 -- 6 ~
15 includes molten alkali metal salts, particularly the alkali metal nitrate of the negative electrode material.
Sodium nitrate or various mixtures of alkali metal nitrates and in some cases transition metal nitrates including NaN2~KN3' NaN3~KN3~ Mg(N3)2, NaNO3-LiNO3, LiNO3-KNO3 are contemplated as positive electrode material.
Mixtures with melting points less than 350 C advantageously can be selected. During operation of the cell through charge and discharge cycles, the positive electrode also is expected to contain alkali metal nitrites and alkali metal oxides that occur in the partially charged and uncharged states. Accordingly nitrites and oxides can be included in the initial positive electrode formulation.
Positive electrode 17 is illustrated as having a suitable current collector 19 in the shape of a screen or grid that may be of stainless steel, nickel or other inert metal. Certain nitrate compositions such as NaNO2-KNO3 have been found to be compatable with mild steel containment thus making this inexpensive current collector material available for use.
A closure 21, with an electrical feedthrou~h, is illustrated sealing the positive electrode compartment to prevent escape of any gases such as NO2 and 2 that may incidentally be evolved during cycling of the cell.
The cell chemistry does not contemplate evolution of these gases, but should it occur as a result of undesirable side reactions, closure 21 or other means can advantageously be employed to restrict loss of constituents.
3~
The electrochemical cell of Fig. 1 is provided with electrical conductors 23 and 25 connected to the current collectors of the positive and negative electrodes. These conductors are illustrated coupled to an electrical load 27 and a recharger means 29 employed in cycling the Fig. 1 electrochemical cell through charge and discharge cycles.
The electrochemical cell described herein has been found to be a reversible secondary electrochemical cell operating at about 1.7 volts. The cell reaction is thought to be:
2Na + NaNO3 = Na2O + NaNO2 However, under certain circumstances, the sodium oxide and sodium nitrite may combine to form the species Na3NO3 within the molten salt, positive electrode material.
The following e~ample is presented merely as an illustration of the electrochemical cell of this invention.
A sodium ~ alumina tube of about 8 cm length and about 1.5 cm diameter were assembled within a stainless steel cup to form an annulus for the negative electrode material. About 10 gm of molten sodium was filled into the annulus and about 2 gm of sodium nitrate was used as the positive electrode active material within the ~ alumina tube. Electrical conductors were connected to the stainless steel cup as a negative electrode current collector and a spool of type 304 stainless steel screen employed within the ~ alumina tube as the positive electrode current collector material. The cell was operated in a helium blanketed furnace at about 325-335C for 14 cycles over a period of a~out 500 hours.
Fig. 2 illustrates charge and discharge curves from two cycles operated at 10 and ~ hour rates that is at S0 and 80 milliamps respectfully. From these cycles the voltage is estimated to be at about 1.75 V and theoretical specific energy at this EMF is about 720Wh/kg.
It is therefore seen that the present invention provides a new improved secondary electrochemical power producing cell that can employ molten alkali metal in the negative electrode opposite a molten salt containing alkali metal nitrate in the positive electrode. The cell has potential for reduced corrosion problems over that of the traditional high temperature sodium-sulfur cell and can employ various known sodium-ion-conductive electrolytes.
Although the present invention is described in terms of specific embodiments it would be clear to one skilled in the art that various modifications in the structures, materials and procedures can be made within the scope of the following claims.
ALKALI METAL NITRATE ELECTRODE
The invention relates to high temperature, secondary electrochemical cells for producing power that includes a molten alkali metal and nitrate salts. The invention particularly relates to the use of molten sodium metal and salts including sodium nitrate as the active materials.
It was previously believed that electrochemical cells involving molten alkali metals and their nitrate salts were only of interest as unrechargable primary cells or as cells for the electrolytic production of alkali metal.
Electrochemical reactions such as for the production of molten sodium metal from sodium nitrate have involved the release of gases for instance, nitrogen dioxide and oxygen gas which impose substantial difficulties in incorporating such a reaction in a secondary rechargable electrochemical cell. Furthermore, the nitrates within molten nitrate salts were thought to be decomposed to nitrite plus oxygen gas thus preventing the recharge of the cell to this original state.
The principal positive electrode material presently ~0 under consideration for secondary sodium cells is sulfur.
At the high operating temperature of these cells a very ' ~ 7 ~!
,`' ' , ';~.,'. ~
~1~33~i~3 corrosive environment is developed that requires expensive current collector materials such as titanium oxide or chrome plated steel. Other positive electrodes for molten sodium cells that have been considered include sodium tetrachloro-aluminate solvent containing sulfur species or metal chlorides.
These systems also exhibit severe corrosion problems and have relatively low theoretical specific energies on the order of 30OWh/kg.
It is an ob~ect of the present invention to provide an improved secondary electrochemical power producing cell that can employ molten alkali meta] as the negative electrode material.
It is a further object to provide a new positive electrode for use in combination with an alkali metal negative electrode within a secondary rechargable electro-chemical cell.
It is also an object to provide a high temperature secondary power producing electrochemical cell with a reactive alkali metal as negative electrode material with reduced corrosion problems in the positive electrode.
In accordance with the present invention, there is provided a secondary electrochemical storage cell comprising a negative electrode containing elemental alkali metal as active material, a positive electrode containing a salt including metal ions of the alkali metal as active material, the salt including a nitrate, a mixture of nitrates or a mixture of a nitrate and a nitrite; a solid electrolyte including and being capable of conducting ions of the alkali metal between the positive and negative ~3~3 electrodes; discharge means for conducting an electrical current through an electrical load connected in series between the positive and negative electrodes as alkali metal oxidizes to alkali metal ions in the negative electrode and alkali metal nitrate reduces to alkali metal nitrite in the positive electrode; recharge means for applying a source of electrical potential between the positive and negative electrodes sufEicient to oxidize alkali metal nitrite to alkali metal nitrate in the positive electrode and reduce alkali metal ions to alkali metal in the negative electrode; and sealing means for retaining the salt of alkali metal in the positive electrode as the cell discharges through the electrical load and as the cell is recharged for storing electrical energy.
In more specific aspects of the invention the negative electrode contains molten sodium and the positive electrode contains a molten salt including sodium nitrate. In such a cell the electrolyte separating the electrodes can be of a sodium oxide and alumina composition, for example one of the well known sodium ~ aluminasO These compositions permit the conduction of sodium ions from the negative to the positive electrodes during discharge of the cell.
In one other aspect of the invention the nitrate salt is selected from a mixture oE nitrate salts that permit reduced melting points below that of sodium nitrate salt.
Mixtures of alkali metal nitrates, alkaline earth metal nitrates and transition metal nitrates are contemplated with eutectic compositions generally providing low melting points ~3~
for a particular selec-tion of molten salts. In one other aspect of the invention, at least the positive electrode is contained within a sealed chamber to prevent incidental venting of nitrogen dioxide or of oxygen gases that may arise from the decomposition of the various nitrate salts.
In a further embodiment an alkali metal is included in the negative electrode and nitrate salts in the positive electrode each in communication with a plurality of qlass fibers extending between the positive and negative electrodes and in contact with the molten alkali metal and the molten metal nitrate salts. The glass Eibers consist essentially of an alkali metal ion conducting material including such as sodium oxide and boron oxide.
Further in accordance with the present invention there is provided a rechargeable electrochemical cell in at least a partially uncharged state comprising a negative electrode chamber containing elemental alkali metal as negative electrode material and means for collecting electronic current in contact with the alkali metal; a sealed positive electrode chamber containing a salt of alkali metal including nitrites and oxides as positive electrode material and means for collecting electronic current in contact with the alkali metal salt; a solid electrolyte wall forming at least a portion of the sealed positive electrode chamber and being in contact at one surface with the elemental alkali metal 4 .
and its opposite surface with the alkali metal salt, the solid electrolyte wall being capable of conducting ions of the alkali metal between the active materials of the positive and negative electrodes; and electrical recharge means or connecting a source of electrical potential across the current collecting means of the negative and the positive electrodes to oxidize alkali metal nitrite to alkali metal nitrate in the positive electrode.
The present invention is illustrated in the accompanying drawin~s wherein:
Fig. 1 is a schematic elevation view o~ an electro-chemical cell including a molten alkali metal and a molten nitrate salt as active materials.
Fig. 2 is a graph of volts vs. capacity over two charge and discharge cycles of a sodium-sodium nitrate secondary electrochemical cell.
Fig. 1 shows a laboratory style electrochemical cell used in demonstrating the electrochemical cell of this invention. It will be understood that this cell is presented merely by way of example and that various forms and constructions of cells more appropriate for commercial and industrial applications are also contem-plated within the scope of the present invention.
A cell container or housing 11 of corrosion resistant material, such as stainless steel, is illustrated as both the current collector and container for the negative electrode material 13. ~olten sodium metal is of principle interest as the negative electrode material 13. However ~`! .
3~53 other alkali metals such as potassium and lithium may be appropriate in molten mixture with sodium or as a separate electrode material.
A container 15 for the positive electrode material 17 is shown with its outer surfaces partially immersed in the molten alkali metal 13. Container 15 can be provided with some or all of its walls of a solid electrolyte material to establish means for ionic conduction between the positive 17 and negative electrode materials during cell operation.
The electrolyte material is advantageously selected from one of the sodium ~ aluminas of the type commonly used in sodium-sulfur cells. The ~ aluminas are poly-crystalline composition of sodium oxide and alumina having typically 8-20 mole percent Na2O and the balance alumina. Small amounts of lithia, magnesia and other constituents also may be included as stabilizer or to attribute other properties. A preferred form is that of ~ alumina (nominally Na2O:5A12O3) stabilizers with up to about one weight percent of Li2O.
Various ionic cond~ctive glasses such as those formed of boron oxide with a sodium oxide or other alkali metal oxide modifiers also are contemplated for use.
Such glasses may include 94-96~ by weight boron oxide modified by 4-6~ sodium oxide, Na2O:2~2O3:~.2SiO2 and Na2O:2B2O3:0.2SiO2:0.16NaCl as well as other sodium oxide modified glasses of boron oxide and silicon oxide.
The positive electrode material 17 within container 3~r~3 -- 6 ~
15 includes molten alkali metal salts, particularly the alkali metal nitrate of the negative electrode material.
Sodium nitrate or various mixtures of alkali metal nitrates and in some cases transition metal nitrates including NaN2~KN3' NaN3~KN3~ Mg(N3)2, NaNO3-LiNO3, LiNO3-KNO3 are contemplated as positive electrode material.
Mixtures with melting points less than 350 C advantageously can be selected. During operation of the cell through charge and discharge cycles, the positive electrode also is expected to contain alkali metal nitrites and alkali metal oxides that occur in the partially charged and uncharged states. Accordingly nitrites and oxides can be included in the initial positive electrode formulation.
Positive electrode 17 is illustrated as having a suitable current collector 19 in the shape of a screen or grid that may be of stainless steel, nickel or other inert metal. Certain nitrate compositions such as NaNO2-KNO3 have been found to be compatable with mild steel containment thus making this inexpensive current collector material available for use.
A closure 21, with an electrical feedthrou~h, is illustrated sealing the positive electrode compartment to prevent escape of any gases such as NO2 and 2 that may incidentally be evolved during cycling of the cell.
The cell chemistry does not contemplate evolution of these gases, but should it occur as a result of undesirable side reactions, closure 21 or other means can advantageously be employed to restrict loss of constituents.
3~
The electrochemical cell of Fig. 1 is provided with electrical conductors 23 and 25 connected to the current collectors of the positive and negative electrodes. These conductors are illustrated coupled to an electrical load 27 and a recharger means 29 employed in cycling the Fig. 1 electrochemical cell through charge and discharge cycles.
The electrochemical cell described herein has been found to be a reversible secondary electrochemical cell operating at about 1.7 volts. The cell reaction is thought to be:
2Na + NaNO3 = Na2O + NaNO2 However, under certain circumstances, the sodium oxide and sodium nitrite may combine to form the species Na3NO3 within the molten salt, positive electrode material.
The following e~ample is presented merely as an illustration of the electrochemical cell of this invention.
A sodium ~ alumina tube of about 8 cm length and about 1.5 cm diameter were assembled within a stainless steel cup to form an annulus for the negative electrode material. About 10 gm of molten sodium was filled into the annulus and about 2 gm of sodium nitrate was used as the positive electrode active material within the ~ alumina tube. Electrical conductors were connected to the stainless steel cup as a negative electrode current collector and a spool of type 304 stainless steel screen employed within the ~ alumina tube as the positive electrode current collector material. The cell was operated in a helium blanketed furnace at about 325-335C for 14 cycles over a period of a~out 500 hours.
Fig. 2 illustrates charge and discharge curves from two cycles operated at 10 and ~ hour rates that is at S0 and 80 milliamps respectfully. From these cycles the voltage is estimated to be at about 1.75 V and theoretical specific energy at this EMF is about 720Wh/kg.
It is therefore seen that the present invention provides a new improved secondary electrochemical power producing cell that can employ molten alkali metal in the negative electrode opposite a molten salt containing alkali metal nitrate in the positive electrode. The cell has potential for reduced corrosion problems over that of the traditional high temperature sodium-sulfur cell and can employ various known sodium-ion-conductive electrolytes.
Although the present invention is described in terms of specific embodiments it would be clear to one skilled in the art that various modifications in the structures, materials and procedures can be made within the scope of the following claims.
Claims (15)
1. A secondary electrochemical storage cell comprising:
a negative electrode containing elemental alkali metal as active material, a positive electrode containing a salt including metal ions of said alkali metal as active material, said salt including a nitrate, a mixture of nitrates or a mixture of a nitrate and a nitrite;
a solid oxide electrolyte including and being capable of conducting ions of said alkali metal between said positive and negative electrodes;
discharge means for conducting an electrical current through an electrical load connected in series between said positive and negative electrodes as alkali metal oxidizes to alkali metal ions in said negative electrode and alkali metal nitrate reduces to alkali metal nitrite in said positive electrode;
recharge means for applying a source of electrical potential between said positive and negative electrodes sufficient to oxidize alkali metal nitrite to alkali metal nitrate in said positive electrode and reduce alkali metal ions to alkali metal in said negative electrode; and sealing means for retaining said salt of alkali metal in said positive electrode as said cell discharges through said electrical load and as said cell is recharged for storing electrical energy.
a negative electrode containing elemental alkali metal as active material, a positive electrode containing a salt including metal ions of said alkali metal as active material, said salt including a nitrate, a mixture of nitrates or a mixture of a nitrate and a nitrite;
a solid oxide electrolyte including and being capable of conducting ions of said alkali metal between said positive and negative electrodes;
discharge means for conducting an electrical current through an electrical load connected in series between said positive and negative electrodes as alkali metal oxidizes to alkali metal ions in said negative electrode and alkali metal nitrate reduces to alkali metal nitrite in said positive electrode;
recharge means for applying a source of electrical potential between said positive and negative electrodes sufficient to oxidize alkali metal nitrite to alkali metal nitrate in said positive electrode and reduce alkali metal ions to alkali metal in said negative electrode; and sealing means for retaining said salt of alkali metal in said positive electrode as said cell discharges through said electrical load and as said cell is recharged for storing electrical energy.
2. An electrochemical cell as claimed in claim 1, wherein said alkali metal in the negative electrode and the salt in the positive electrode are in the molten state.
3. An electrochemical cell as claimed in claim 1, wherein the alkali metal is sodium.
4. An electrochemical cell as claimed in claim 1, wherein the solid electrolyte comprises a tubular barrier of sodium oxide and alumina containing the positive electrode active material, said tubular barrier disposed in a container of elemental alkali metal to form an annular negative electrode.
5. An electrochemical cell as claimed in claim 1, wherein the positive electrode includes a nitrate salt selected from an alkali metal nitrate, an alkaline earth metal nitrate, a transition metal nitrate or a mixture thereof.
6. An electrochemical cell as claimed in claim 5, wherein the nitrate salt comprises a mixture of salts having a melting point less than 350°C.
7. An electrochemical cell as claimed in claim 5, wherein the nitrate salt is selected from the group of nitrate salts consisting of NaNO3, NaNO2-KNO3-NaNO3KNO3-Mg(NO3)2, NaNO3-LiNO3, LiNO3-NaNO3-KNO3 and mixtures thereof.
8. An electrochemical cell as claimed in claim 1, wherein the solid oxide electrolyte is a solid media communicating with both the positive electrode active material and the negative active material, the solid media is selected from the group of alkali metal conducting materials consisting of sodium .beta." alumina and a glass including an alkali metal oxide.
9. An electrochemical cell as claimed in claim 8, wherein said glass comprises Na2O and B2O3.
10. An electrochemical cell as claimed in claim 8, wherein said glass including an alkali metal oxide comprises a plurality of glass fibers between the positive and negative electrodes, said glass fibers selected from the group of glass material consisting of 94-96% by weight boron oxide modified by 4-6% by weight sodium oxide, Na2O:2B2O3:0.2SiO2 or Na2O:2 B2O3:02SiO2:0.16NaCl.
11. An electrochemical cell as claimed in claim 1, wherein the positive electrode is contained within a sealed chamber adequate to restrict venting of NO2 or O2 gases.
12. An electrochemical cell as claimed in claim 1, wherein the positive electrode in the partially charged state includes a molten mixture of alkali metal nitrates, alkali metal nitrites, and alkali metal oxides.
13. A rechargeable electrochemical cell in at least a partially uncharged state comprising:
a negative electrode chamber containing elemental alkali metal as negative electrode material and means for collecting electronic current in contact with said alkali metal;
a sealed positive electrode chamber containing a salt of alkali metal including nitrites and oxides as positive electrode material and means for collecting electronic current in contact with said alkali metal salt;
a solid electrolyte wall forming at least a portion of said sealed positive electrode chamber and being in contact at one surface with said elemental alkali metal and at its opposite surface with said alkali metal salt, said solid electrolyte wall being capable of conducting ions of said alkali metal between the active materials of said positive and negative electrodes; and electrical recharge means for connecting a source of electrical potential across the current collecting means of said negative and said positive electrodes to oxidize alkali metal nitrite to alkali metal nitrate in said positive electrode.
a negative electrode chamber containing elemental alkali metal as negative electrode material and means for collecting electronic current in contact with said alkali metal;
a sealed positive electrode chamber containing a salt of alkali metal including nitrites and oxides as positive electrode material and means for collecting electronic current in contact with said alkali metal salt;
a solid electrolyte wall forming at least a portion of said sealed positive electrode chamber and being in contact at one surface with said elemental alkali metal and at its opposite surface with said alkali metal salt, said solid electrolyte wall being capable of conducting ions of said alkali metal between the active materials of said positive and negative electrodes; and electrical recharge means for connecting a source of electrical potential across the current collecting means of said negative and said positive electrodes to oxidize alkali metal nitrite to alkali metal nitrate in said positive electrode.
14. An electrochemical cell as claimed in claim 13, wherein said sealed positive electrode chamber contains a mixture of alkali metal nitrate, alkali metal nitrite and alkali metal oxide as positive electrode material.
15. An electrochemical cell as claimed in claim 13, wherein said alkali metal is sodium and wherein said cell charges in accordance with the reaction Na2O + NaNO2 ? 2Na + NaNO3 with the sodium nitrate formed in the positive electrode chamber as sodium is formed in the negative electrode chamber.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US38520282A | 1982-06-04 | 1982-06-04 | |
| US385,202 | 1982-06-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1193653A true CA1193653A (en) | 1985-09-17 |
Family
ID=23520454
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000425221A Expired CA1193653A (en) | 1982-06-04 | 1983-04-05 | Electrochemical cell having a alkali metal nitrate electrode |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS58216367A (en) |
| CA (1) | CA1193653A (en) |
| DE (1) | DE3319951A1 (en) |
| FR (1) | FR2528237A1 (en) |
| GB (1) | GB2121597B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017143088A1 (en) * | 2016-02-18 | 2017-08-24 | Sandia Corporation | Radical-ion battery and operation thereof |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9111982D0 (en) * | 1991-06-04 | 1991-07-24 | Chloride Silent Power Ltd | An alkali metal energy conversion cell |
| EP3238297A1 (en) * | 2014-12-23 | 2017-11-01 | Battery Consult GmbH | Molten salt electrochemical flow cell |
| EP3637510B1 (en) | 2018-10-08 | 2021-08-11 | Battery Consult AG | Alkaline battery with ceramic solid electrolytes |
| CN113654936B (en) * | 2021-06-28 | 2024-01-23 | 浙江安力能源有限公司 | Na-beta' -Al 2 O 3 Method for measuring sodium content in solid electrolyte |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2081926A (en) * | 1933-07-17 | 1937-06-01 | Gyuris Janos | Primary element |
| US3847667A (en) * | 1972-09-26 | 1974-11-12 | Esb Inc | Alkali metal-porous conductive carbon battery having a molten alkali metal chloraluminate electrolyte |
-
1983
- 1983-04-05 GB GB08309198A patent/GB2121597B/en not_active Expired
- 1983-04-05 CA CA000425221A patent/CA1193653A/en not_active Expired
- 1983-05-25 FR FR8308637A patent/FR2528237A1/en active Pending
- 1983-05-26 JP JP58093305A patent/JPS58216367A/en active Pending
- 1983-06-01 DE DE19833319951 patent/DE3319951A1/en not_active Withdrawn
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017143088A1 (en) * | 2016-02-18 | 2017-08-24 | Sandia Corporation | Radical-ion battery and operation thereof |
| US20190088971A1 (en) * | 2016-02-18 | 2019-03-21 | National Technology & Engineering Solutions Of Sandia, Llc | Radical-ion battery and operation thereof |
| EP3417503A4 (en) * | 2016-02-18 | 2019-09-25 | Sandia Corporation | RADIAL ION BATTERY AND ITS OPERATION |
| US10879552B2 (en) | 2016-02-18 | 2020-12-29 | National Technology & Engineering Solutions Of Sandia, Llc | Radical-ion battery and operation thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58216367A (en) | 1983-12-16 |
| DE3319951A1 (en) | 1983-12-08 |
| FR2528237A1 (en) | 1983-12-09 |
| GB2121597A (en) | 1983-12-21 |
| GB2121597B (en) | 1986-01-29 |
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