SE535245C2 - Fuel cells without octrolytes - Google Patents

Abstract

The invention relates to a completely new type of fuel cell (FC), without a single anode, electrolyte or cathode construction, but made of a single component with both ionic and electronic conductivity. Two-component versions are also possible. With this configuration without electrolyte, the conventional three-component FC technology is not needed. Instead, the one- or two-component design is constructed using materials of suitable porosity, which makes this FC technology completely different from conventional FC technology, which requires a dense electrolyte and porous electrodes (anode and cathode). The new one- or two-component FC has demonstrated excellent and stable function that gives 200 to 900 mWcmJ between 400 and 600 ° C. This new technology has also demonstrated good results with large areas such as 6x6 cmz, then with a contribution of 10-20 watts. The new F C technology described here will have major advantages in terms of overhead production, costs, performance and competitiveness and has the potential to revolutionize future FC technology, development and markets.

Description

535 245 zirconia) to achieve sufficient high ion conductivity fl. This has historically severely limited the choice of construction materials, which has resulted in excessive costs for a commercialization.

As a consequence, great efforts have been made to develop new, alternative electrolyte materials for SOF Cs with the intention of lowering the working temperature "to reduce costs and make the choice of materials easier, etc. Examples of materials are fl unoritated iodopathic ceriumw, oxides", of sample kite type 02 'conductive oxidant and proton conducting ceramics "as well as other complex materials such as LagMozOgu, BalnO-based oxides, apatite-type oxides and others. SOFC electrolytes can be developed by design from structures based on various new materials".

The new invention described here presents a breakthrough and a completely new fuel cell technology that does not require an MEA design / technology. It is electrolyte free and instead uses only one or two components. The materials in FCn are either based on cerium composites consisting of nanocomposites of metal oxides or industrial products with mixed earth oxides.

Figure 1 shows a conventional FC constructed of three components. la) The invention - an FC technology without electrolyte, lb) Without anode and cathode with only a single component.

When the FC without electrolyte is placed in H2 and luñ, both H2 and O2 can be catalytically separated as H * and O2 'and generate electricity by a double catalytic function of the component. H * and 02 'become one on the surface of the particle and produce H20. During this process, the contact side of H2 acts as an anode which releases electrons by creating the contact side of H * and the air (02) as a cathode which receives electrons which means that the FC reaction is immediately completed as long as IY and 02 'are in suitable or close connection. In this invention, the ion transport that takes place within the electrolyte in a conventional FC is replaced by ionization on the surface, movement and reaction in a F C reactor without electrolyte. All reactions and processes are completed on the surface of the particles by a direct combination of H * and O2 'ions. The reaction process for the claimed FC is described below. on the H2 side: H2 - + 2H + + 2e '(1) at the lu fi side (o2); 1/20, + 2 e '_ »02' (2) general reactions: H2 + 1/202 -> 2H + + 02 '(3-a) 2 H * + 02' -» H20 (sb) This should be compared with FC reactions / processes, e.g. in the case but an I-f -conducting electrolyte. at the anode: H2 -> ZH * + 2e '(4) at the cathode: 1/202 + 2 l-Ü + 2e' -v H2O (5) general reactions: H2 + I / 202 -> H2O. (6) And in the case of the 02 '-conducting electrolyte: at the anode; H2 + o2 '- + H2O - ze' (7) at the cotton; 1 / 2o2 + 2 e '_ »02' (s) general reactions: H2 + 1/202 - + H20. (9) The significant difference between other FCs and this invention is that this FC does not comprise ion (1-Ü or O 2 -) transport through the electrolyte. The FC reaction instead takes place directly with the H * and O 2 'ions on the surface of the particles. In this way, the invented FC is a reactor and not like an ordinary fuel cell apparatus.

There has been an invention, a single body SOFC with patent number US 5298235, 1994, Worrell et al. However, the FC apparatus was still based on an electrolyte and electrode three-component function.

Another U.S. patent, 20090258276, 2009, discloses a fuel cell constructed of materials having P-N functions. For this there was no need to construct an electrolyte but it was irradiated with light later.

A Summary of the Invention This invention relates to a revolutionary new fuel cell technology FC without electrolyte and technology. The FC was constructed based on one or two components which have a mixed electronic conductor and ionic conductor, where mixed earth metals (oxides) are both natural and synthesized as ion-conducting materials mixed with metal oxides as electronically conductive materials. All existing fuel cell technologies and devices have three basic fuel cell components: anode, electrolyte and cathode. These form a so-called MEA (membrane and electrolyte assembly). The electrolyte should offer electronic insulation but fully permeable to ions, e.g. 02 'or PF' line to completely separate the propellant and oxidant. Existing SOFC technologies require all constructions with complete detailed dryness between the components both mechanically and electrochemically. They must also offer good chemical stability. In particular, the electron-transporting ßrmàga or conduction fl inlet of the electrolyte has limited the drive functions. For example, in the case of SOFCs, “yttrium stabilized zirconia” (Y SZ) currently reaches a desired conductivity of 0.] S / cm at 1000 ° C, resulting in dri fi at high temperatures. In this invention, the FC without electrolyte has no separate anode, electrolyte and cathode.

Instead, only one or two components are used. The FC consists of at least two electronic and ionic functions, such as l-fl / Oz conductivity and catalytic to both H2 and 02.

The FC is constructed of either one or two components of a homogeneous material or two components with different materials and an interface between the two components.

No electrolyte. The components have mixed ionic and electronic conductive (MIEC) materials made from pure MIE conductors or a mixture / composite of electronic and ionic conductors / materials. The components are made with the appropriate structure and necessary porosity which is necessary for all fuel cell technologies. Normal ceramic sintering or ceramic molding technologies have been used.

According to this invention, the ion-conducting materials are proton or oxygen-ion-conducting materials, usually i) doped Ba (Ce, Zr) O3 ceramics; ii) ion doped cerium (SDC: samarium doped cerium; GDC: gadolinium doped cerium; yttrium doped cerium; calcium dopated cerium; Sm-Pr or Gd-Pr doped cerium; iii) mixed earth metals (oxides), e.g. DCP (patented in Sweden..xxx); iv) YSZ, ScSZ; v) LaGaMgO3 etc .; vi) 535,245 cerium-based including LCP composites previously patented, PCT and Swedish patent number 0101424-0.

According to another preferred concrete form of the invention, the electronically conductive phase materials are based on metal oxides, in particular, M (M = Li, Na, K, Cu, Ni, Zn, Mg, Ag, Fe, Sn, Al, Co, Mn , Mo, Cr, In, Ca, Ba, Sr) oxides and their complex oxides with two or fl of these oxides in a mixture or composite.

These metal oxides can be deposited in various metal oxide systems, e.g. Fe oxide systems, such as undoped BiFeO 2;, single doped BiFeO 3 (eg BiO oxide system with both an n- and p-type of ZnO. Al, Ga, and in such substitutional ingredients as Zn and Cl and I such substitutional ingredients as O can be used as n-type dopants; p-type ZnO with Li, Na, and K, Cu, Ag, and N, P, As.

According to another more intricate concrete form of the invention, certain materials naturally contain both ionic and electronic conductivity based on sample kite oxides of Ba0.5Sr0.5-Co0.8Fe0.2032d (BSCF), (Ba / Sr / Ca / lßW6MxNbl-xO3-å). (M: Mg, Ni, Mn, Cr, Fe, ln, Sn); doped LaMO3 (M = Ni, Cu, Co, Mn), eg LaNiO_, Fe ,,,, Cu., _ ,, 0, etc.

Compared to other FC technologies, the technology for the fuel cell without electrolyte designed with one or two components has advantages especially in terms of chemical stability, mechanical properties and compatibility (the electrolyte's problems with compatibility between the anode and electrolyte as well as the electrolyte and cathode are thus avoided). The new one-component FC without electrolyte has shown extraordinary FC performance, between zoo and iooo mwcm * below soo-sooo mAcm-Z within the belt range (400 m1 600 ° C).

The fuel cell technology without electrolyte can offer an extremely cheap FC technologies with a large market potential. There is a great potential for further development with a person who is skilled in the field. The key lies in optimizing materials, blends, synthesizing and manufacturing technologies using ceramic membrane technologies. 535 245 Brief Description of the Drawing and Figures Some typical FC performance with a one- or two-component design is shown in the figures and is also listed in Table 2 below.

Figure 1. A conventional fastener FC (left) with three components (including cathode, electrolyte and anode). To the right FCs without electrolytes.

Figure 2 illustrates typical characteristics; I-V (current density-volt) and I-P (power density) for a one-component designed FC unit with different material compositions: a) and b). b) refers to commercial GDC and SDC as ion-conducting materials, mixed metal oxides, of Ni-Cu-Zn oxide as the electronic; c) LCP-LiNiCu oxide; d) SDC-LiNaCO3 composite LiNiCu oxide; e) Na2CO3-SDC-nanocomposite-LiCuZnNi oxide.

Fuel: H2, Oxidant: luñ. Gas fl fate: 80 to 120 ml / min, gas pressure: I atm; Cell size: 13 mm in diameter with an active area of 0.7 cmz.

Figure 3 shows increased performance by improving the catalytic function of the metal oxide in the LiCuZnNi-Fe oxide and the nanocomposite Na2CO3-SDC ion conductor.

Fuel: H; Oxidant: lu fi. Gas fl fate: 80 to 120 ml / min, gas pressure: 1 atm; Cell size: 13 mm in diameter with an active area of 0.7 cmz.

Figure 4 shows the I-V / I-P characteristics of a bicomponent FC without electrolyte. a, b and c are at 480, 520 and 560 ° C respectively.

Fuel: H; Oxidant: lu fi. Gas fl fate: 150 to 200 ml / min, gas pressure: 1 atm; Cell size: 20 mm in diameter with an active area of 2.l cmz.

Figure 5 shows the I-V / I-P characteristics of the best FC by improving both ion and electronic conductivity. a, b and c are at 480, 500 and 520 ° C respectively.

Fuel: H; Oxidant: air. Gas fl fate: 80 to 120 ml / min, gas pressure: 1 atm; Cell size: 13 mm in diameter with an active area of 0.7 cmz. Figure 6 shows the 1-V / 1-P characteristic of F Cn with membranes made by slurry casting process and hot pressing at 550 ° C.

Fuel: H2_ Oxidant: lu fi. Gas fl fate: 1000 to 2000 ml / min, gas pressure: 1 atm; Cell size: 6 x 6 cmzi diameter with an active area of 25 cmz.

Detailed Description of the Intended Embodiments Materials and Preparations The ion-conducting materials: i) iii) SDC (cerium doped with samarium), GDC (cerium doped with gadolinium) and YSZ (yttrium stabilized zirconia) oxygen ion conductors were purchased from (Seattle Specialty Ceramics, Seattle, WA, USA).

Nanostructured SDC-NagCQ i.e. nanocomposite electrolytes were synthesized in an assembly process. In the synthesis of the urium carbonate composites, the following chemicals were used in 1.0 M solutions, Ce (NO;) 3 '6H2O (Sigma-Aldrich) and Sm (NO3);' 6H2O (Sigma-Aldrich). According to the desired molar ratios, the solution of Sm (NO 3) 3 '6H 2 O was mixed with a solution of Ce (NO 3); 6H 2 O. As for the metal ion carbonate ion 1: 2 in molar ratio, a significant amount of NazCO was added; solution (1.0 M) slowly (10 ml / min) to completely make the cerium carbonate composites with a wet chemical precipitation process. In the same process, a mixture of SDC and carbonates is used. After this process, the mixture was filtered by suction filtration method. The precipitate was dried overnight in an oven at 50 ° C. Finally, the dry solid was crushed in a mortar and sintered at 800 ° C for one hour.

The LCP was purchased from Baotou rare-earth plant, Inner Mongolia, China, a world-renowned soil producer. Table 1 lists the contents of the LCP after heat treatment at 800 ° C for 2 hours. By heat treating the LCP directly at this temperature, the resulting materials created earth metal oxides in a 535,245 mixture / composite with the main components consisting of CeO 2, LagO 2 and procent your percent Pr fi On, see Table 1. These LCPs were used as electrolytes for lTSOFCs. The LCP can be further modified by adding other alkaline or alkaline earth carbonates, e.g., MXCO; (M = Li, Na, K, Ca, Sr, Ba, x = 1, 2). During the heat treatment, parts of CeOg and MXCO; form some form of ion-doped cerium, MxCenxOg, the resulting materials became even better SOFC electrolytes.

Table I Composition of an industrial LCP product is 2 hours heat treatment at 800 ° C LCP TREO LagOg CeOg PróOn NdgOg Sm-2O3 Y2O3 Re2 (C03) 3 43.25 36.55 57.69 5.59 0.18 <0.0l <0.04 Electronic conductive material: The electronically conductive metals was prepared by the usual solid state reaction method. Stoichiometric amounts of Li2CO3, NiCO; . 2Ni (OH) 2-61-120 (Sigma Aldrich, USA) and Zn (I103) 2-6H 2 O (Sigma Aldrich, USA) and CuCO 3 (99.99%, Aldrich) were mixed, ground and sintered at 700-800 ° C for 3 hours.

The BSCFn (Ba0.2SrCo0.4Fe0.60x) was synthesized in a precipitation process. The following chemicals were used for 1.0 M solutions, Ba (N 03); (Sigma-Aldrich), Sr (NO3) 2, Co (NO3) s'6H2O (Sigma-Aldrich) and Fe (NO;); 9H2O. To achieve the desired molar ratios, all these nitrates were mixed to be prepared in 1.0 M solution. Metallic ionic carbonate ions in the appropriate molar ratio to make a complete precipitation of Ba, Sr, Co and Fe as carbonates, a considerable amount of NazCO 3 solution (1.0 M) was added slowly (10 ml / min to complete the precipitation process. After this, the precipitate was filtered and dried overnight in an oven at 50 ° C. Finally, the dried solid was dried at 800 ° C for 12 hours.

Preparation of the FC component without electrolyte and FC constructions 535 245 The resulting electronically conductive materials described above were mixed with the above-described ion conductors in the weight ratio 1: 3 and 3: 1.

The resulting powder was uniaxially pressed into pellets in one step at a pressure of 300 MPa into a tablet of the one-component, both surfaces of which were coated with silver as current absorbers. Its size was at least 13 mm or 20 mm in diameter and 0.60-1.0 mm thick. The larger, 6x6 cm2 one-component FCs were constructed using hot press technology with 600 ° C heat and 10-20 tons of pressure to form the materials. Silver-plated metal nets were used on both sides as current collectors.

Fuel cell measurements Cell performance was tested by computerized instruments (L43, Tianjin, China) at temperatures of 400-600 ° C where the hydrogen and air were at 80-110 ml min * at 1 atm pressure on both sides for the 13 mm cells and 1-2 liters min -l for the cells of 6x6 cm2.

Example 1: 1 g of commercial GDC was mixed with 1 g of LiO.1Ni0.5ZnO.4 oxide.

The mixture was pressed with 200 kg pressure in a 13 mm mold to create pellets with 0.6-0.8 mm thickness. FC performance is shown in Figure 2a.

Example 2: 1 g of commercial SDC was mixed with 1 g of LiO.1Ni0.5ZnO.4 oxide. The mixture was further heated at 700 ° C for 2 hours and pressed at 200 kg pressure in a shape of 13 mm to create pellets 0.6-0.8 mm thick, see Figure 2b.

Example 3: 10 g of LCP was mixed with sodium carbonate in a weight ratio of from 20:] to 4: 1 followed by the addition of 0.5-1.0 g of NiCO 3. 2Ni (OH) 2- 6H2O, Zn (NO;) 2-6H2O, CuCOg 0.5-1.0 g Fe (NO3) 9H2O, and 0.5-1.0 g LiNO3 mixed thoroughly. The mixture was heated at 720 ° C for 2 hours. The resulting material was then pressed at 200 kg pressure in a 13 mm mold to create pellets 0.6-0.8 mm thick, Figure 2c. Example 4: 10 g of SDC-NaCO 3 nanocomposites as ionic conductors were mixed with LiO.1Cu0.4ZnO.5 oxide made in the above-mentioned synthesis. The mixture was sintered at 700 ° C for 2 hours and then pressed with 200 kg pressure in a 13 mm mold to create pellets 0.6-0.8 mm thick, Figure 2d.

Example 5: 10 g were mixed with 5 g of LiO.2Ni0.3Cu0.2ZnO.3 oxide. The mixture was further heated at 70 ° C for 2 hours and then pressed with 200 kg pressure in a 13 mm mold to create pellets 0.6-0.8 mm thick, Figure 2e.

Example 6: For improved catalytic function of the metal oxide catalyst, Fe was added. 1.2 g Na 2 CO 3 -SDC -0.6 g Lin 2 NiCuZn oxide was further mixed with 0.6 g Fe (NO 2) 9 H 2 O and mixed completely. The mixture was heated at 720 ° C for 2 hours. The resulting material was then pressed with 200 kg pressure in a 13 mm mold to create pellets 0.6-0.8 mm thick. The FC performance is shown in Figure 2, effect of catalyst function by adding Fe elements 3b) compared to non-Fc, 3a).

Example 7: Constructing two-component FC without electrolyte. One component was made using a Li0.2Ni0.3Cu0.2Zn0.30x -SDC mixture and another using a BSCF-SDC mixture. The powder mixtures were pressed in a two-layer configuration with a pressure of 300 kg in a 20 mm mold to create pellets 0.6-0.8 mm thick. The FC performance is shown in Figure 4.

Example 8: The best one-component FC performance of this invention was improved by carefully fitting the parts between the ionic and electronic conductors using the samples from Example 6. The 1: 1.5 weight ratios between Na 2 CO 3 -SDC and the LtNiCulnFe oxide were used. The FC performance shown in Figure 5. a, b, c and d are at 480, 500, 520 and 540 ° C respectively. Example 9: The one component was made using the best composition of Example 8 which was further processed by slurry casting process to produce membranes and followed by hot pressing at 550 ° C and 20 tons of pressure. The final I- V / I-P characteristics of the FC are shown in Figure 6.

More examples are listed in Table 2, with indications of their corresponding ITSOFC performance.

Those skilled in the art will appreciate that the above-mentioned examples are intended to be exemplary only and are not intended to limit the present invention. 535 245 Table 2. More examples of one-component materials Ion conducting Electronic conductive material FC Temperature performance material (mwcmq) (° C) i) LiNi0.6Cu0.40x 200-600 450 - 600 LCP oxides ii) LiCu0.4Zn0.60x 200- 500 450-600 iii) LaMO 3 (M = Ni, Cu, Co, Mn) 150-400 400-650 The weight ratios between the electronic 300-1000 conductor and the LCP are 1: 1 400-650 Ion doped 200-700 500-700 M, .Ce1 - ,. O2 iv) LiNi0.6Cu0.40x Substance M <20 mol% * and v) BSCF 120-540 500-700 = ef, SF, Gas * smsi v ”** BCY vi) LiNi0.6Cu0.40x 220-880 450 - 700 240-800 450-700 Note to Table 2: * mol% means molar ratio, wt% are weight ratios References cited U.S. Patent 5298235, Worrell et al, 1994 Electrochemical devices based on single-component solid oxide fuel bodies 535 245 U.S. Patent, 20090258276, Kenneth Ejike Okoye Emenike Chinedozi Ejiogu Sachio Matsui, 2009 Fuel cell unit, fuel cell unit array, fuel cell module and fuel cell system Other publications 1.

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Claims (10)

1. A fuel cell comprising a porous body having a first side arranged to be incontact with H2 and a second side arranged to be in contact with air (02), andmeans for collecting current at said first and second side, wherein the bodycomprises one or two components for catalyzing dissociation of H2 and 02and comprising at least one ionic conducting material and at least one electron conducting material.

2. A fuel cell according to claim 1, wherein the component or components area composite of at least one ionic conducting material and at least one electron conducting material.

3. A fuel cell according to claim 1 or 2, wherein the component or componentsare a mixture of at least one ionic conducting material and at least one electron conducting material.

4. A fuel cell according to any previous claim, wherein at least one ionic conducting material is a proton or oxygen ion conducting material.

5. A fuel cell according to claim 4, wherein the at least one ionic conductingmaterial is selected from - doped Ba(Ce,Zr)O3 ceramics, - ion doped ceria, such as SDC (samarium doped ceria) GDC,(gadolinium doped ceria) yttrium doped ceria, calcium doped ceria, Sm-Pr orGd-Pr doped ceria, - mixed rare-earth oxides, such as LCP, -YSZ (yttrium stabilized zirconia), ScSZ (Scandia stabilized zirconia), - LaGaMgOg,

6. 26. A fuel cell according to any previous claim, wherein at least one electron conducting material is a metal oxide, such as oxides of Li, Na, K, Cu, Ni, Zn, Mg, Ag, Fe, Sn, Al, Co, Mn, Mo, Cr, ln, Ca, Ba, Sr and their complex oxides.

7. A fuel cell according to claim 6, wherein the at least one electron conducting material further comprises Fe.

8. A fuel cell according to any previous claim, wherein the weight ratiobetween the at least one electron conducting material and the at least oneionic conducting material is between 1:3 and 3:1.

9. A fuel cell according to any one of claims 1, wherein the at least one ionicconducting material and the at least one electron conducting material is the one and the same material.

10. A fuel cell according to claim 9, wherein the material is -proveskite oxides of Ba05Sr0_5-Co0_8Fe0_2O32d (BSCF),(Ba/Sr/Ca/La)O.6MxNb1-xO3-ö in which M is selected from Mg, Ni, Mn, Cr,Fe, ln and Sn, or -doped LaMO3 in which M =(Ni, Cu, Co, Mn), such as LaNiozFeoßscUotsøs -