Sulfate/sulfide based rechargeable battery and uses thereof

Abstract

The present disclosure relates to the development and improvement of a High-Temperature Sulfate/Sulfide device, in particular a High-Temperature battery using a Sulfate/Sulfide redox couple (HTSSB) for electrical energy storage at elevated temperatures and the like, and electrical energy storage device comprising the same.

Claims

1. A rechargeable battery having a solid-state device for oxygen storage and release, the rechargeable battery comprising: a gas-tight shell that contains or is made in its entirety of an oxygen-ion conducting electrolyte and defines a contained volume; an oxygen storage material consisting of a sulfate/sulfide redox couple, contained in said contained volume; a first electrode in contact with said electrolyte on a first side and in contact with said contained volume; a second electrode in contact with said electrolyte on a second side of the electrolyte and in contact with an oxygen containing atmosphere; an electrical contact made with each electrode; wherein the electrodes are selected from an electronically conducting material; wherein the oxygen exchanged with the atmosphere outside the gas tight container, may or may not be involved in further chemical reactions or be utilised as a source of pure oxygen; wherein the oxygen storage material is selected from a list consisting of the following elements: gadolinium, lanthanum, cerium, neodymium, samarium, dysprosium, erbium, europium, holmium, terbium, ytterbium, yttrium, scandium, lutetium, magnesium, calcium, strontium, barium, lithium, sodium, potassium, and combinations thereof; and wherein the oxygen storage material is sealed inside the shell, and wherein the electrolyte membrane is an oxide-ion conducting ceramic comprising CeO.sub.2, ZrO.sub.2, LaGaO.sub.3, or mixtures thereof.

2. The rechargeable battery of claim 1, wherein the oxygen storage material is in powder, porous, or molten form, or mixtures thereof.

3. The rechargeable battery of claim 1, wherein the contained volume further comprises a shuttle gas for increase the kinetics of oxygen transfer to the storage material.

4. The rechargeable battery of claim 3, wherein the shuttle gas comprises: a steam/hydrogen (H.sub.2O/H.sub.2) gas mixture, a carbon dioxide/carbon monoxide (CO.sub.2/CO2) gas mixture, or a mixture thereof.

5. The rechargeable battery of claim 4, wherein the shuttle gas further comprises an inert gas for diluting.

6. The rechargeable battery of claim 1, wherein the sulfate/sulfide redox couple is rare earth oxysulfate Ln.sub.2O.sub.2SO.sub.4/Ln.sub.2O.sub.2S based oxygen storage material, wherein Ln comprises: gadolinium, lanthanum, cerium, neodymium, samarium, dysprosium, erbium, europium, holmium, terbium, ytterbium, yttrium, scandium, lutetium, promethium, or thulium, or combinations thereof, and wherein Ln is rare earth element or combination of rare earth elements.

7. The rechargeable battery of claim 1, wherein the sulfate/sulfide redox couple is an alkaline earth metal sulfate MSO.sub.4/MS based oxygen storage material, wherein M comprises: magnesium, calcium, strontium, or barium, or combinations thereof, and wherein M is an alkaline earth metal element or combination of alkaline earth metal elements.

8. The rechargeable battery of claim 1, wherein the sulfate/sulfide redox couple is an alkali metal sulfate A.sub.2SO.sub.4/A.sub.2S based oxygen storage material, wherein A comprises: lithium, sodium, or potassium, or combinations thereof, and wherein A is an alkali metal element or combination of alkali metal elements.

9. The rechargeable battery of claim 1, wherein the oxygen storage material is a mixture of Ln.sub.2O.sub.2SO.sub.4/Ln.sub.2O.sub.2S and/or MSO.sub.4/MS and/or A.sub.2SO.sub.4/A.sub.2S in any ratio, either as independent phases or as a combined phase, wherein Ln is rare earth element or combination of rare earth elements, wherein M is an alkaline earth metal element or combination of alkaline earth metal elements; and wherein A is an alkali metal element or combination of alkali metal elements.

10. The rechargeable battery of claim 1, wherein the oxygen storage material further comprises a metal catalyst for altering sulfate/sulfide redox kinetics, wherein the metal catalyst comprises a powder of one or more metals, selected from the group consisting of: iron, nickel, platinum, palladium, cobalt, copper, and combinations thereof.

11. The rechargeable battery of claim 1, wherein the oxygen storage material is combined with an oxide catalyst to alter sulfate/sulfide redox kinetics, wherein the oxide catalyst comprises at least one metal oxide of iron, nickel, cobalt, copper, vanadium, manganese, molybdenum, praseodymium, or mixtures thereof.

12. The rechargeable battery of claim 1, wherein the oxide-ion conducting ceramic is doped by at least one acceptor rare earth dopant wherein the at least one acceptor rare earth dopant is Gd, Y, or any alkaline earth metal, or mixtures thereof.

13. The rechargeable battery of claim 1, wherein the oxide-ion conducting ceramic is LaGaO.sub.3 and is doped by at least one acceptor dopant of lower valence, where the at least one acceptor dopant comprises any alkaline earth metal or mixtures thereof.

14. The rechargeable battery of claim 1, wherein the electronically conducting material comprises a metal selected from the group consisting of: platinum, gold, silver, copper, and mixtures thereof.

15. The rechargeable battery of claim 1, wherein the gas-tight shell is a ZrO.sub.2 ceramic doped with 8% (mol/mol) of Y.sub.2O.sub.3, or a CeO.sub.2 ceramic doped with 10% (mol/mol) of Gd.sub.2O.sub.3.

16. The rechargeable battery of claim 1, wherein one or more of the electrodes comprises platinum, nickel, gold, silver, or copper, or mixtures thereof.

17. The rechargeable battery of claim 1, wherein one or more of the electrodes comprises ceramic oxides of perovskite or perovskite related structural families, offering mixed oxygen ion and electronic conductivity.

18. The rechargeable battery of claim 1, wherein the first electrode on the side of the oxygen storage material is a cermet material consisting of an oxygen-ion conducting ceramic oxide combined with a metallic phase, wherein the metallic phase comprises Ni, Co, Fe or Cu, Pt, Ag or mixtures or alloys thereof.

19. An electrochemical cell battery comprising the device according to claim 1.

20. An oxygen pump comprising the device according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The following figures provide preferred embodiments for illustrating the description and should not be seen as limiting the scope of invention.

(2) FIG. 1 is a representation of the design and components of an embodiment of the battery wherein (1) represents Pt oxygen pump, (2) represents the electrolyte, in particular yttria stabilised zirconia or gadolinia doped CeO.sub.2 electrolyte, (3) represents an gas-tight container, containing a solid oxygen-ion conducting electrolyte, in particular yttria stabilised zirconia or gadolinia doped CeO.sub.2, (4) represents a Ln.sub.2O.sub.2SO.sub.4/Ln.sub.2O.sub.2S or A.sub.2SO.sub.4/A.sub.2S or MSO.sub.4/MS, oxygen storage material contained in said contained volume, or an oxygen storage material made from their mixtures; (5) represents a sealing material, (6) represents the electrodes, in particular Pt or Au electrical contacts.

(3) FIGS. 2A-2B are a graphics showing the working charge/discharge conditions of the battery with the battery at 600° C. using a H.sub.2/H.sub.2O sweep gas, diluted with 90% N.sub.2.

(4) FIGS. 3A-3C are representations of the design and components of several embodiments of the battery of the present disclosure.

DETAILED DESCRIPTION

(5) The device, in particular a battery, of the present disclosure comprises: an gas-tight container that includes or that is entirely formed from a solid state oxygen-ion conducting electrolyte, which has electronically conducting electrode layers on its both sides, electrical contacts, and an oxygen storage/release material, prepared from a Sulfate/Sulfide redox compound consisting of Ln.sub.2O.sub.2SO.sub.4/Ln.sub.2O.sub.2S or A.sub.2SO.sub.4/A.sub.2S or MSO.sub.4/MS redox couples, or an oxygen storage material made from their mixtures, sealed inside the container.

(6) The separation and reunion of oxygen ions and electrons happen at the interface between the electrodes and the oxygen-ion conducting electrolyte. The oxygen is pumped out of the chamber during charging process using electricity, preferably from a direct current power source. Ln.sub.2O.sub.2SO.sub.4 releases oxygen by the reduction of the sulfate ion.
Ln.sub.2O.sub.2SO.sub.4.fwdarw.Ln.sub.2O.sub.2S+2O.sub.2  (1) MSO.sub.4 releases oxygen by the reduction of the sulfate ion.
MSO.sub.4.fwdarw.MS+2O.sub.2  (2) A.sub.2SO.sub.4 releases oxygen by the reduction of the sulfate ion.
A.sub.2SO.sub.4.fwdarw.A.sub.2S+2O.sub.2  (3)

(7) The pumping oxygen out from the cell stops when the oxygen partial pressure inside the cell, and respective electromotive force (EMF), reach some critical temperature-dependent values. In embodiments containing La.sub.2O.sub.2SO.sub.4, CaSO.sub.4, or K.sub.2SO.sub.4, as the oxygen storage material these values are shown by Table 1, Table 2 and Table 3, respectively. These values can be determined by the coulombic titration technique (FIGS. 2A-2B). For example, La.sub.2O.sub.2SO.sub.4 reduction at 900° C. stops at the oxygen partial pressure of ˜10.sup.−12 atm inside the container (corresponding EMF value of ˜0.7 V, (with respect to reference gas of oxygen)). Also, to avoid the yttria-stabilised zirconia and/or oxygen storage material disintegration, the charging voltage shall be kept below the absolute value of 2.2 V.

(8) TABLE-US-00001 TABLE 1 Represents the battery of embodiment 1 operational conditions. Temperature 900° C. 850° C. 800° C. 750° C. 700° C. Reduction 0.70 ± 0.02 V 0.72 ± 0.02 V 0.74 ± 0.02 V 0.76 ± 0.02 V 0.78 ± 0.02 V voltage

(9) TABLE-US-00002 TABLE 2 Represents the battery of embodiment 4 operational conditions. Temperature 900° C. 850° C. 800° C. 750° C. 700° C. Reduction 0.70 ± 0.02 V 0.72 ± 0.02 V 0.74 ± 0.02 V 0.77 ± 0.02 V 0.79 ± 0.02 V voltage

(10) TABLE-US-00003 TABLE 3 Represents the battery of embodiment 5 operational conditions. Temperature 900° C. 850° C. 800° C. 750° C. 700° C. Reduction 0.87 ± 0.02 V 0.89 ± 0.02 V 0.91 ± 0.02 V 0.93 ± 0.02 V 0.958 ± 0.02 V voltage

(11) On completion of the charging process and by connection of an external workload to the battery, the reoxidation process occurs, for the Ln.sub.2O.sub.2SO.sub.4/Ln.sub.2O.sub.2S or A.sub.2SO.sub.4/A.sub.2S or MSO.sub.4/MS redox couples, respectively:
Ln.sub.2O.sub.2S+2O.sub.2.fwdarw.Ln.sub.2O.sub.2SO.sub.4  (4)
MS+2O.sub.2.fwdarw.MSO.sub.4  (5)
A.sub.2S+2O.sub.2.fwdarw.A.sub.2SO.sub.4  (6)

(12) Oxygen molecules in the surrounding atmosphere, driven by the chemical potential gradient across the electrolyte, dissociate into ions consuming electrons on the electrode-electrolyte surface and conduct across the oxygen-ion conducting electrolyte, while electrons pass over an external load. The recombination of electrons with the oxygen-ions at the electrode at the opposing side of the electrolyte membrane, inside the container, combine with Ln.sub.2O.sub.2S to form Ln.sub.2O.sub.2SO.sub.4 or with MS to form MSO.sub.4 or with A.sub.2S to form A.sub.2SO.sub.4, respectively.

(13) As it is clear from formulae (1-4), the sulfate/sulfide redox couple is advantageous as an oxygen storage/release material because theoretically, 1 mole of rare earth sulfate can provide 2 moles of O.sub.2, which involve 8 moles of electrons in the charging/discharging process. The electricity is stored in the form of oxygen integrated into the sulfate structure, which enables such oxygen storage/release through the oxidation/reduction of sulfur. Additionally, a powdered or porous structure of the oxysulfate/oxysulfide facilitates oxygen diffusion inside the cell, thus increasing charging/discharging rates. The MSO.sub.4/MS, A.sub.2SO.sub.4/A.sub.2S embodiments are advantageous as a battery material over that of the aforementioned oxysulfate embodiments, due to their lower weight and availability.

(14) In an embodiment, La.sub.2O.sub.2SO.sub.4/La.sub.2O.sub.2S which are lanthanum oxysulfate and lanthanum oxysulfide can be prepared by a suitable solid state reaction or soft chemical or pyrolysis method. According to the present disclosure, La.sub.2O.sub.2SO.sub.4/La.sub.2O.sub.2S can be prepared, for example, by the pyrolysis of a lanthanum sulfate octahydrate (La.sub.2(SO.sub.4).sub.3.8H.sub.2O), at the temperature of 850-1050° C. in air or 850-1100° C. in oxygen.

(15) In an embodiment, yttria stabilised zirconia is advantageous as the electrolyte of the battery because it is mechanically and chemically stable, and it is a fast oxygen ionic conductor. Yttria stabilised zirconia can be prepared by the mechanical synthesis process. For example, Yttria (Y.sub.2O.sub.3) and Zirconia (ZrO.sub.2) may be mixed stoichiometrically and transferred into the milling vials, where the powder is high energy milled at a rotation rate of 650 rpm. The nanopowder thereby produced is shaped into cylinder and discs with subsequent firing at 1400-1550° C. in air for 2 hours, at heating and cooling rates of 2° C./min.

(16) In an embodiment, note that platinum paste will not be poisoned or damaged during the operation of the battery, not like in the PEMFCs where it is easily poisoned and cannot be reused. In an actual battery targeted for the market, we can replace platinum with traditional electrode of SOFCs, such as mixed conducting perovskite or perovskite-based electrodes to act as electrocatalytically active electrode materials. These materials can be applied easily by a person skilled in the art.

(17) The present disclosure is described in detail below based on embodiment, but the present invention is not limited thereto.

(18) In the following embodiments, the battery was prepared by sealing the oxygen storage/release materials inside the yttria stabilised zirconia container. The oxygen storage/release materials, Ln.sub.2O.sub.2SO.sub.4, were prepared by pyrolysis of lanthanum sulfate octahydrate (La.sub.2(SO.sub.4).sub.3.8H.sub.2O) or other lanthanide equivalents. The yttria stabilised zirconia container was prepared via solid state reaction. Platinum paste was purchased from HERAEUS. Platinum wire was purchased from PI-KEM. Ceramic sealant was purchased from AREMCO. The oxygen storage material for the CaSO.sub.4 embodiment was a commercial powder purchased from Sigma Aldrich.

Embodiment 1

(19) Step 1: Lanthanum oxysulfate La.sub.2O.sub.2SO.sub.4 used in the following embodiment was prepared as follows. First, lanthanum sulfate octahydrate (La.sub.2(SO.sub.4).sub.3.8H.sub.2O) was heated in air from room temperature to 550° C. and kept for 5 hours, and then heated to 900° C. and kept for 5 hours to decompose it. The heating and cooling rates were 2° C./min. The powder was then pulverized in the planetary ball mill with absolute ethanol at a speed of 200 rpm, for 10 hours. At last, it was dried in the oven at 50° C. overnight.

(20) Step 2: The container of the battery in the current embodiment was made completely of yttria stabilised zirconia, which is prepared by the mechanical synthesis process. Yttria (Y.sub.2O.sub.3) and Zirconia (ZrO.sub.2) were mixed stoichiometrically and transferred into the milling containers, where the powder was high energy ball-milled at a rotation rate of 650 rpm. Then it was pressed into cylinder and disc forms. The cylinder dimensions were: wall thickness 2 mm, length 15 mm, and external diameter 12 mm. The disc dimensions were: thickness 2 mm, diameter 10 mm. All of the yttria stabilised components were fired at 1450° C. in air for 5 hours, with heating and cooling rates of 2° C./min.

(21) Step 3: Commercial platinum paste was diluted with 96% vol. ethanol and painted on both sides of the cylinder and disc, platinum wire was adhered to the painted surfaces at the same time and dried at 950° C. for 30 mins. The heating and cooling rates were 2° C./min.

(22) Step 4: 5 g of the lanthanum oxysulfate La.sub.2O.sub.2SO.sub.4 was sealed inside the yttria stabilised zirconia container with a commercial ceramic sealant hermetically at 1115° C. for 20 minutes, with heating and cooling rates of 2° C./min.

Embodiment 2

(23) The battery was obtained in the same manner as in Embodiment 1, except that the yttria stabilised zirconia cylinder was instead replaced by a tube of hastelloy.

Embodiment 3

(24) The battery was obtained in the same manner as in Embodiment 2, except that the thickness of the electrolyte was below 50 μm.

Embodiment 4

(25) The battery was obtained in the same manner as in Embodiment 1, except that the oxygen storage material of step 4 was CaSO.sub.4.

Embodiment 5

(26) The battery was obtained in the same manner as in Embodiment 1, except that the oxygen storage material of step 4 was K.sub.2SO.sub.4.

Embodiment 6

(27) The battery was obtained in the same manner as in Example 1, except that the oxygen liberated on the discharging step was used to oxidize the external gases CO or NOx.

(28) In an embodiment, FIG. 1 is a representation showing the design and components of the battery. All the components are solid, preventing short-circuit from happening and is more stable than conventional liquid electrolytes used in Li-ion and Li-air batteries. Volatilization and flammability problems are also overcome with the choice of pure solid and inflammable material. The size of the battery can be easily enlarged to hold more oxygen storage material and hence the total capacity of the actual battery is adjustable to a big extent.

(29) In an embodiment, FIGS. 2A-2B are graphs showing the working behaviour of an A.sub.2SO4/A.sub.2S version of the battery where A is potassium (K.sub.2SO4/K.sub.2S) with the battery at 600° C. using a H.sub.2/H.sub.2O sweep gas, diluted with 90% N.sub.2. In this case the open circuit voltage of the battery is 0.99V (with respect to oxygen) and the charging and discharging voltages are shown to be 0.70±0.02 V and 0.70±0.02 V, respectively.

(30) The term “comprising” whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

(31) The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof. The above described embodiments are combinable. The following claims further set out particular embodiments of the disclosure.