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
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
• • 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
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
  • H01M10/0562—Solid materials
• • 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
  • 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
  • H01M10/3909—Sodium-sulfur cells
  • H01M10/3918—Sodium-sulfur cells characterised by the electrolyte
• • 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
  • H01M4/368—Liquid depolarisers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0065—Solid electrolytes
  • H01M2300/0068—Solid electrolytes inorganic
  • H01M2300/0071—Oxides
  • H01M2300/0074—Ion conductive 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
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
• • 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

Definitions

• the present invention relates to electrochemical cells utilizing a solid alkali ion conductive electrolyte membrane and to methods of protecting such membranes from degradation by dissolution. More particularly, the present invention discloses systems and methods for operating an electrochemical cell comprising a alkali ion conductive electrolyte membrane and an aqueous catholyte (or positive electrode) solution. Generally, the described systems and methods act to protect the membrane from degradation by dissolution.
• Electrochemical cells comprising solid alkali ion conductive electrolyte membrane that selectively transport alkali ions are known in the art.
• alkali ion- selective membrane in the electrochemical cell, alkali ions are allowed to pass between the cell's anolyte compartment (or negative electrode compartment) and catholyte compartment (or positive electrode compartment) while other chemicals are maintained in their original compartments.
• an electrochemical cell can be engineered to be more efficient and to produce different chemical reactions than would otherwise occur without the membrane.
• Solid alkali ion conductive electrolyte membranes are used in electrochemical cells for various reasons, including, but not limited to, being ion conductive, ion selective, water impermeable, chemically stable, electronic insulator, and so forth.
• NaSICON Na Super Ion CONducting
• LiSICON Li Super Ion CONducting
• KSICON K Super Ion CONducting
• Other examples of solid alkali ion conductive electrolyte membranes include beta alumina, sodium- conductive glasses, etc.
• Electrochemical cells comprising solid alkali ion conductive membranes are used to produce a variety of different chemicals and to perform various chemical processes. Electrochemical cells may convert alkali salts into their corresponding acids. In other cases, such electrochemical cells may also be used to separate alkali metals from mixed alkali salts.
• FIG. 1 illustrates an electrochemical cell 110 which comprises an negative electrode compartment 112 and a positive electrode compartment 114 that are separated by a NaSICON membrane 116.
• the negative electrode compartment 112 comprises an aqueous sodium salt solution (NaX, wherein X comprises an anion capable of combining with a sodium cation to form a salt) and current is passed between an anode 118 and a cathode 120.
• Fig. 1 illustrates an electrochemical cell 110 which comprises an negative electrode compartment 112 and a positive electrode compartment 114 that are separated by a NaSICON membrane 116.
• the negative electrode compartment 112 comprises an aqueous sodium salt solution (NaX, wherein X comprises an anion capable of combining with a sodium cation to form a salt) and current is passed between an anode 118 and a cathode 120.
• NaX aqueous sodium salt solution
• Fig. 1 shows that as the cell 110 operates, water (H 2 0) is split at the anode 118 to form oxygen gas (0 2 ) and protons (H + ) through the reaction 2H 2 0 ⁇ 0 2 + 4H + + 4e ⁇ .
• Fig. 1 further shows that the sodium salt NaX in the anolyte (or negative electode) solution is split (according to the reaction NaX + H + ⁇ HX + Na + ) to (a) allow sodium cations (Na + ) to be transported through the NaSICON membrane 116 into the positive electrode compartment 114 and (b) to allow anions (X " ) to combine with protons to form an acid (HX) that corresponds to the original sodium salt.
• the above-mentioned electrochemical cell may be modified for use with other alkali metals and acids corresponding to the alkali salts used in the anolyte solution.
• other electrochemical reactions may occur which result in hydroxyl formation and a corresponding rise of pH within the positive electrode compartment 114.
• High pH catholyte solutions in such electrochemical cells have shortcomings.
• certain alkali ion-conductive ceramic membranes, such as NaSICON membranes begin to structurally degrade by dissolution.
• base produced in the positive electrode compartment 114 can actually damage the alkali ion conductive membrane, such as a NaSICON membrane, and thereby shorten its useful lifespan.
• Batteries are a class of electrochemical cells that are used to store and release electrical energy for a variety of uses. In order to produce electrical energy, batteries typically convert chemical energy directly into electrical energy. Generally, a single battery includes one or more galvanic cells, wherein each of the cells is made of two half-cells that are electrically isolated except through an external circuit. During discharge, electrochemical reduction occurs at the cell's positive electrode, while electrochemical oxidation occurs at the cell's negative electrode. While the positive electrode and the negative electrode in the cell do not physically touch each other, they are generally chemically connected by at least one (or more) ionically conductive and electrically insulative electrolyte(s), which can either be in a solid or a liquid state, or in combination. When an external circuit, or a load, is connected to a terminal that is connected to the negative electrode and to a terminal that is connected to the positive electrode, the battery drives electrons through the external circuit, while ions migrate through the electrolyte.
• Batteries can be classified in a variety of manners. For example, batteries that are completely discharged only once are often referred to as primary batteries or primary cells. In contrast, batteries that can be discharged and recharged more than once are often referred to as secondary batteries or secondary cells. The ability of a cell or battery to be charged and discharged multiple times depends on the Faradaic efficiency of each charge and discharge cycle.
• Rechargeable batteries based on sodium and lithium can employ a solid primary electrolyte separator, such as a solid alkali ion conductive electrolyte membrane.
• a solid primary electrolyte separator such as a solid alkali ion conductive electrolyte membrane.
• the principal advantage of using a solid ion conductive electrolyte membrane is that the Faradaic efficiency of the resulting cell approaches 100%. Indeed, in almost all other cell designs, the electrode solutions in the cell are able to intermix over time and, thereby, cause a drop in Faradaic efficiency and loss of battery capacity.
• the electrochemical cells may be operated using molten salts which may be chemically reactive to the alkali ion conductive electrolyte membrane.
• the halide ion or polyhalide ions or pseudohalide ions or sulfide ions or polysulfide ions concentration is greater than 1.5M. In other non-limiting embodiments, the halide ions or polyhalide ions or pseudohalide ions or sulfide ions or polysulfide ions concentration is greater than 6M.
• the halide ions or polyhalide ions or pseudohalide ions or sulfide ions or polysulfide ions concentration is between 3M and a saturation concentration for the halide ions or polyhalide ions or pseudohalide ions or sulfide ions or polysulfide ions at an operating temperature of the positive electrode compartment.
• the halide ions or polyhalide ions or pseudohalide ions or sulfide ions or polysulfide ions concentration is between 6M and 10M.
• the halide ion is selected from chloride, bromide, and iodide.
• the pseudohalide ion is selected from azide, thiocyanate, and cyanide.
• Other known pseudohalide ions may also be used herein.
• the solid alkali ion conductive electrolyte membrane material may include, but is not limited to, an alkali Metal Super Ion Conductive (MeSICON) material, where "Me” represents an alkali metal.
• MeSICON materials include ceramic NaSICON, NaSICON-type materials, LiSICON, LiSICON-type materials, KSICON, and KSICON-type materials.
• the electrochemical cell is a molten sodium rechargeable cell, wherein the anode comprises molten sodium metal in contact with the alkali ion conductive electrolyte membrane as the cell operates.
• the alkali ion conductive membrane may include a NaSICON or NaSICON-type sodium ion conductive membrane.
• the molten sodium rechargeable cell may function at an operating temperature between about 100° C and about 150° C. In other non- limiting embodiments, the cell functions at an operating temperature between about 110° C and about 130° C.
• the present invention provides methods for protecting a solid alkali ion-conductive electrolyte material from degradation by dissolution.
• the method comprises obtaining and operating an electrochemical cell as described above, wherein the presence of halide ions or complex halide ions or pseudohalide ions or sulfide ions or polysulfide ions protects the solid alkali ion conductive electrolyte membrane from degradation.
• Figure 2 depicts a schematic diagram of a representative embodiment of a molten sodium secondary cell, wherein the cell is in the process of being discharged.
• Figure 3 depicts a schematic diagram of a representative embodiment of the molten sodium secondary cell, wherein the cell is in the process of being recharged.
• Figure 4 depicts a graph of percent weight loss for various NaSICON samples in
• Figure 5 depicts a graph of percent weight loss per week for various NaSICON samples in 50 wt.% NaOH at 100° C over a nine week period.
• Figure 6 depicts a graph of percent weight loss per week for various NaSICON samples in three different sodium halide solutions at 100° C over a nine week period.
• Figure 7 depicts a graph of the average weekly weight percent loss of the samples in the different sodium halide solution as reported in Figure 4.
• Figure 8 depicts a graph of percent weight loss per week for a given NaSICON sample in four different sodium iodide solutions at 120° C over a nine week period.
• Figure 9 depicts a graph of cell potential over time of the various charge/discharge cycles of a molten sodium secondary cell having a NaSICON membrane and 10 M Nal catholyte solution.
• elevated temperatures means a temperature greater than room temperature.
• an elevated temperature includes a temperature greater than 40°C.
• an elevated temperature includes a temperature greater than 60°C.
• an elevated temperature includes a temperature greater than 80°C.
• an elevated temperature includes a temperature greater than 100°C.
• the halide ion is selected from chloride, bromide, and iodide.
• the pseudohalide ion is selected from azide, thiocyanate, and cyanide. Other known pseudohalide ions may also be used herein.
• the halide ion or pseudohalide ion concentration is greater than 3M. In other non-limiting embodiments, the halide ion or pseudohalide ion concentration is greater than 6M. In other non-limiting embodiments, the halide ion or pseudohalide ion concentration is between 3M and a saturation concentration for the halide ion or pseudohalide ion at an operating temperature of the positive electrode compartment. In yet other non-limiting embodiments the halide ion or pseudohalide ion concentration is between 6M and 10M.
• FIG. 2 shows a representative embodiment in which the molten sodium secondary cell 210 comprises an negative electrode compartment 215 that includes a metal sodium negative electrode 220, a positive electrode compartment 225 that comprises a positive electrode 230 that is disposed in a liquid positive electrode solution 235, a sodium ion conductive electrolyte membrane 240 that separates the negative electrode from the positive electrode solution, a first terminal 245, and a second terminal 250.
• the molten sodium secondary cell 210 comprises an negative electrode compartment 215 that includes a metal sodium negative electrode 220, a positive electrode compartment 225 that comprises a positive electrode 230 that is disposed in a liquid positive electrode solution 235, a sodium ion conductive electrolyte membrane 240 that separates the negative electrode from the positive electrode solution, a first terminal 245, and a second terminal 250.
• Figure 2 illustrates that as the cell 210 is discharged and electrons (e ⁇ ) flow from the negative electrode 220 (e.g., via the first terminal 245), sodium is oxidized from the negative electrode 220 to form sodium ions (Na + ).
• Figure 2 shows that these sodium ions are respectively transported from the sodium negative electrode 220, through the sodium ion conductive membrane 240, and to the positive electrode solution 235.
• the cell can comprise a negative electrode compartment 215 and a positive electrode compartment 225.
• the two compartments can be any suitable shape and have any other suitable characteristic that allows the cell 210 to function as intended.
• the negative electrode and the positive electrode compartments can be tubular, rectangular, or be any other suitable shape.
• the two compartments can have any suitable spatial relationship with respect to each other.
• FIG. 3 shows that the negative electrode compartment 215 and the positive electrode compartment 225 can be adjacent to each other, in other embodiments (not shown), one compartment (e.g., the negative electrode compartment) is disposed, at least partially, in the other compartment (e.g., the positive electrode compartment), while the contents of the two compartments remain separated by the electrolyte membrane 40 and any other compartmental walls.
• one compartment e.g., the negative electrode compartment
• the other compartment e.g., the positive electrode compartment
• the cell 210 can comprise any suitable sodium negative electrode 220 that allows the cell 210 to function (e.g., be discharged and recharged) as intended.
• suitable sodium negative electrode materials include, but are not limited to, a sodium sample that is substantially pure and a sodium alloy comprising any other suitable sodium-containing negative electrode material.
• the negative electrode comprises or consists of an amount of sodium that is substantially pure. In such embodiments, because the melting point of pure sodium is around 98° C, the sodium negative electrode will become molten above that temperature.
• the cell 210 can comprise any suitable positive electrode that allows the cell to be charged and discharged as intended.
• the positive electrode can comprise virtually any positive electrode material that has been successfully used in a sodium-based rechargeable battery system.
• the positive electrode comprises a wire, felt, plate, tube, mesh, foam, and/or other suitable positive electrode configuration.
• the positive electrode comprises a nickel foam, nickel hydroxide (Ni(OH) 2 ), nickel oxyhydroxide (NiOOH), sulfur composites, sulfur halides, including sulfuric chloride, and/or another suitable material. Furthermore, these materials may coexist or exist in combinations.
• the positive electrode comprises copper and copper iodide and the catholyte solution comprises sodium iodide.
• a suitable positive electrode material may be nickel oxyhydroxide (NiOOH) (e.g., when the cell is at least partially charged) and nickel hydroxide (Ni(OH) 2 ) (e.g., when the cell is at least partially discharged).
• the positive electrode comprises a nickel oxyhydroxide (NiOOH) electrode. It is understood that a nickel oxyhydroxide electrode, even when fully charged, will contain some amount of nickel hydroxide.
• the positive electrode comprises copper and copper iodide and the catholyte solution comprises sodium iodide.
• the positive electrode 230 comprises a nickel oxyhydroxide (NiOOH) electrode
• the negative electrode 220 comprises sodium
• the positive electrode solution 235 (as discussed below) comprises an aqueous solution
• the reactions that occur at the negative electrode and at the positive electrode and the overall reaction as the cell 210 is discharged may occur as illustrated below:
• the above embodiment of the describe cell 210 are capable of producing about 3.2V ⁇ 0.5V at standard temperature and pressure.
• the positive electrode comprises and the catholyte solution comprises sodium iodide.
• the positive electrode 230 comprises copper and copper iodide
• the negative electrode 220 comprises sodium
• the positive electrode solution 235 comprises sodium iodide

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• 2013
  • 2013-11-05 EP EP13865228.4A patent/EP2935655B1/en active Active
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