RU2310256C2 - Tubular cell (alternatives) for batteries of high-temperature electrochemical devices using thin-layer solid electrolyte and method for its manufacture - Google Patents

Abstract

FIELD: electrical engineering; manufacture of tubular cells for batteries of high-temperature electrochemical devices.

SUBSTANCE: intermediate layer of micron particles is formed in each electrode-electrolyte interface to enlarge effective surface area of microrelief solid electrolyte. Solid-oxide cell can be made with supporting electrolyte, 100 =- 150 μm thick, with one of electrolytes, with one supporting electrode, or with both supporting electrodes. Proposed method for manufacturing tubular cells includes production of tubular-cell multilayer structures with different alternatives of microrelief, and with layers differing in microstructure using film-forming technology, for instance with micron and nanometric-size high-temperature ceramic powder based polyvinyl butyral drosses, followed by joint molding and sintering of all tubular-cell components.

EFFECT: enhanced strength, heat-resistance, and gas-tightness, enlarged effective surface area of electrode-to-electrolyte interface.

9 cl, 6 dwg

Description

The group of the present invention relates to high-temperature electrochemical devices (ECUs) with solid electrolyte, such as electrochemical generators (fuel cells), electrolyzers, converters, pumps, etc. devices. More precisely, to the design of the element of these devices and to the method of its manufacture.

Known elements used in electrochemical devices, for example, high-temperature fuel cells with a solid oxide electrolyte based on zirconia, having a planar, tubular or block structure of a solid electrolyte coated with a gas diffusion anode and cathode ("High-temperature electrolysis of gases" M.V. Perfilyev, A. K. Demin, B.L. Kuzin, A.S. Lipilin, ISBN 5-02-001399-4, M .: Nauka, 1988, 232 p.). An element can be considered an element according to the patent of the Russian Federation No. 2027258, H01M 8/12, “HIGH TEMPERATURE ELECTROCHEMICAL GENERATOR” Somov SI, Demin AK, Lipilin AS, Kuzin BL, Perfilyev MV Application filing date 07/03/1990, publ. Date formula 01.20.1995, in which a tubular element with a supporting solid electrolyte, gas diffusion electrodes is used.

The closest analogue of the device, the prototype, the authors consider a fuel cell with a thin-layer solid oxide electrolyte based on zirconia of a tubular design, with a supporting cathode and a supported gas diffusion anode, with an anode and cathode chambers for supplying fuel and oxidizer reagents and a current path through the generatrix (A.O. .Isenberg, in 1982 National Fuel Cell Seminar Abstracts, November 14-18, 1982, Newport Beach, CA, Courtesy Associates, Washington, DC, 1982, p. 154). The authors consider the prototype of the method to be the well-known, traditional, powder, ceramic technology described in the monograph ("High-temperature electrolysis of gases" M.V. Perfiliev, A.K. Demin, B.L. Kuzin, A.S. Lipilin, ISBN 5-02 -001399-4. M .: Nauka, 1988, 232 pp.), Which consists in the fact that a prefabricated powder is formed into a product blank and is sintered, as a rule in furnaces, at high temperatures. Ceramic technologies are the cheapest, so it is advisable to use them in the manufacture of ceramic components of high temperature solid oxide fuel cells.

The solid electrolyte itself, the most frequently used and more durable, based on yttrium stabilized zirconia (YSZ), and alternative ones based on cerium, galate or bismuth, is a ceramic that by its nature has rather low strength and heat resistance at high temperatures . These disadvantages are compounded by the fact that for devices with solid electrolyte, for example YSZ, operating temperatures (700-1000 ° C) are in the hot zone of solid electrolyte (i.e., they are quite sensitive to mechanical stress). The zone of plastic deformation, in which mechanical loads do not cause the initiation of cracks and fractures, lies above 1300 ° C, above the operating temperature. At the same time, electrochemical devices (ECUs) in the range of operating temperatures in devices with gaseous fuels and oxidizing agents require inter-cavity gas density in the working area, do not allow cracks and local damage. One of the disadvantages of the elements of such ECUs is the low mechanical strength of the solid electrolyte, which does not allow its use as a carrier, with a thickness of less than 0.15-0.2 mm in a tubular structure. Several foreign firms in the UK, Switzerland, Japan, and the United States use a carrier electrolyte of this thickness for planar fuel cell designs. The fuel elements of a tubular structure with such an electrolyte thickness are not known to the authors. Moreover, well-known technologies do not allow to obtain a tubular structure of a supporting electrolyte with such a wall thickness. The analogue element (RF Patent No. 2027258, Н01М 8/12, “HIGH TEMPERATURE ELECTROCHEMICAL GENERATOR” Somov SI, Demin AK, Lipilin AS, Kuzin BL, Perfilyev MV) thickness the wall of the tubular solid electrolyte was 0.4-0.5 mm The prototype (A.O. Isenberg, in 1982 National Fuel Cell Seminar Abstracts, November 14-18, 1982) has 40 μm, but a support cathode about a millimeter thick is used there. Thus, the thick cell wall used in known cells with a supporting electrolyte two or more times not only significantly increases the consumption of electrolyte material, but also increases the internal resistance of the cell, thereby reducing specific characteristics. Another disadvantage is the relatively low working surface of the solid electrolyte electrode boundary. Recent studies to determine the real working area of a solid electrolyte have shown that only the area in contact with the gas diffusion electrode, which is only 1-4% of the visible area, works. Activation of the electrodes by substances with mixed conductivity (CeO ₂ , Pr ₂ O ₃ ) increase the contact area to 8-10%. This suggests that about 90% of the surface of the solid electrolyte does not perform its main function of generating current, i.e. as if it is "superfluous", i.e. It performs the function not of a solid electrolyte, but of the hermetic separation of the anode and cathode gas spaces. The disadvantage of this technology is the impossibility of the well-known ceramic technologies used today: extrusion, slip casting into gypsum molds, hot casting into metal molds to produce tubes or test tubes with a wall thickness of less than 200 microns.

An object of the invention is the design and manufacturing technology of an element devoid of the above disadvantages. The authors propose a tubular design of an element with a supporting thin-layer solid electrolyte with a supporting electrode or electrodes, structurally having increased strength, heat resistance, gas density while increasing the working surface of the boundary between the electrodes and electrolyte, which leads to improved specific characteristics, more functional use of solid electrolyte and longer life service item.

The problem is solved due to the fact that we form an intermediate layer of micron particles on the boundary of each electrode with the electrolyte, as a result, the working surface of the solid electrolyte is more than doubled due to such microroughness. In addition, we even more than double the working area due to the design - the solid electrolyte of the tubular element is made macro-relief (sections of solid electrolyte, macro-relief options are presented in figures 1-3). Such a technical solution leads both to an increase in the area of a single element (improvement of specific characteristics) and to an increase in strength, which, on the one hand, leads to an increase in heat resistance, the service life of the element, and, on the other hand, makes it possible to produce a tubular element with a thinner bearing electrolyte, which in turn also leads to improved specific characteristics. The proposed design of the solid oxide ECU element can be implemented both with a supporting electrolyte with a thickness of 0.15 mm (Figs. 1-3), and with a supporting one of the electrodes (Figs. 4, 5) or supporting both electrodes (Fig. 6). A method of manufacturing such an element is based on the creation of multilayer structures with layers that differ both in composition (components of the ECM element) and in microstructure:

- porous anode;

- porous interface layer;

- micro-rough layer of solid electrolyte;

- a thin layer of gas-tight solid electrolyte;

- micro-rough layer of solid electrolyte;

- porous interface layer;

- porous cathode.

The implementation of the proposed element design became possible due to the combination of two technologies: film watering technology, for example, using polyvinyl butyral slips from powders of the above-mentioned components of different sizes (from nanometric to micron) and molding technology, layer bonding, for example, magnetic pulse pressing.

This application proposes the following design options for the element.

1. An element with a supporting solid electrolyte, for example YSZ, with a thickness providing sufficient strength, for example 100-150 microns, having "corrugations" along the generatrix of the tube (cylinder) in the form of a "wave" (figure 1), in the form of a "trapezoid" (figure 2), in the form of a "triangle" (figure 3). Thin electrodes, for example 20-50 microns, are located on the outer and inner surfaces of the electrolyte and are applied in the usual way, for example by burning electrode pastes, onto a pre-sintered, tubular solid electrolyte.

2. An element with a supporting solid electrolyte, for example YSZ, with a thickness providing sufficient strength, for example 100-150 microns, with spherical, pyramidal bulges located along the generatrix of the tube or with a shift of each row relative to the neighboring ones in a “checkerboard pattern”. Thin electrodes, for example 20-50 microns, are located on the outer and inner surfaces and are applied in the usual way, for example by burning electrode pastes, onto a pre-sintered, tubular solid electrolyte.

3. An element with a supporting internal electrode, for example, of LSM (strontium lanthanum manganite) or Ni cermet, of a tubular structure has an internal, smooth cylindrical surface and an external "macro-relief" surface in the form of corrugations along a wave-shaped, "trapezoid" shape, A "triangle" or spherical, pyramidal bulges located along the generatrix or with a shift of each row relative to the neighboring ones in a "checkerboard pattern" (Fig. 4 is a variant of a wave-like relief) on which a thin solid electric wire is arranged and connected in series ktrolit, e.g., 2-50 microns thick and thin outer electrode, for example, 20-50 microns thick.

4. An element with a supporting external electrode, for example, of LSM or Ni cermet, a tubular structure having an external, smooth cylindrical surface and an internal "macro-relief" surface in the form of corrugations along a generatrix in the form of a "wave", "trapezoid", "triangle" or spherical, pyramidal bulges located along the generatrix or with a shift of each row relative to the neighboring ones in a “checkerboard pattern” (figure 5 is a variant of a wave-like relief) on which a thin solid electrolyte, for example, YSZ thick, is arranged and connected in series 2-50 microns and a thin outer electrode, for example of LSM or Ni cermet 20-50 microns thick.

5. An element with supporting external and internal electrodes, for example, of LSM or Ni cermet, having respectively external and internal smooth cylindrical surfaces and located between them and connected with them a thin solid electrolyte, for example, YSZ with a thickness of 2-50 μm, made in the form corrugation along the generatrix in the form of a "wave", "trapezoid", "triangle" or spherical, pyramidal bulges located along the generatrix or with a shift of each row relative to the neighboring ones in a "checkerboard pattern" (Fig.6 is a variant of a wavy relief).

The present application provides methods for manufacturing the above-mentioned design options for a tubular element, comprising the following operations:

- the formation of thin films of a solid electrolyte, for example, YSZ, with a thickness of 5-30 μm, with a thermoplastic binder, for example polyvinyl butyral, according to a technology, for example, casting films on a lavsan substrate or extrusion followed by colondization, using nano-sized and micro-sized powders for slip;

- the formation of thin films from electrode materials, for example, from LSM or Ni cermet, 5-100 microns thick, with a thermoplastic binder, for example polyvinyl butyral, according to the technology, for example, casting films on a polyester substrate or extrusion followed by colondization, using nano-sized and micro-sized slips powders;

- the formation of thin films of interface, transition layers, for example, of cerium doped with gadolinium (GDC), a thickness of 5-10 microns, with a thermoplastic binder, for example polyvinyl butyral, by technology, for example, casting films on a lavsan substrate or extrusion, followed by colondization, using for slurries, nanoscale and microsize powders;

- cutting from films of the required compositions and sizes of patterns of all the components of the element;

- winding (folding) the required number of layers of films from the necessary components of the element;

- the molding of all components of the element of the required design under conditions that ensure homologation of thermoplastic layers: temperature, for example, for PVB - 90-125 ° C and pressure of comprehensive pressing, for example magnetic pulse pressing (MIL), 0.1-1.8 GPa;

- joint sintering of the multilayer structure of the element is carried out under conditions providing a gas-tight, thin layer of solid electrolyte and porous gas diffusion electrodes, for example, for YSZ layers of solid electrolyte from nanopowder with specific surface area S = 62 ± 4 m ² / g, apparent density 97-98 % of the theoretical value is achieved in the temperature range of 950-1300 ° C with an exposure of 100 hours - 20 minutes, respectively.

Execution example

Polyvinyl butyral-based slurries (10-14 wt.%) Were cast onto a dacron substrate (film) by films from weakly agglomerated nanopowders (S = 60-6 m ² / g) of solid electrolytes based on zirconium dioxide and cerium with a thickness of 10-20 μm . From agglomerated micropowders (S = 12-14 m ² / g) of the same materials, films about 5-10 microns thick were cast. A film 20–30 μm thick was cast from micropowder of the electrode material of strontium lanthanum manganite. From nanopowder films, separated from the mylar ribbon, patterns were cut that were wound in 6, 12 and 18 layers on a steel core of the mold. Then, after evacuation and heating to 125 ° C, magnetic pulse pressing was performed (monolithic thermoplastic layers) at a pressure of about 0.3 GPa and sintering in an atmosphere of air at a temperature of 1150 ° C for one hour. As a result, gas-tight tubes of solid electrolyte with a diameter of about 10 mm and a wall thickness of about 60, 120, and 180 μm with a grain size of ceramic of about 100 nm were obtained.

Claims (9)

1. A tubular element for batteries of high-temperature electrochemical devices with a supporting thin-layer solid electrolyte, gas diffusion electrodes and interface layers, in which the carrying thin-layer solid electrolyte is made of nanopowder, for example, based on zirconium stabilized with yttrium (YSZ), with a thickness that provides sufficient strength, for example, 100-150 microns, along the generatrix of which there are corrugations in the form of a wave, or a trapezoid, or a triangle in the form of a corrugated surface, with thin interiors applied to it clear layers of micropowder, for example, cerium doped with gadolinium (GDC), or (YSZ), and thin, for example, 20-50 μm, gas diffusion electrodes, for example, of strontium manganite (LSM) or Ni cermet, deposited on the corrugated outer and the inner surface of the solid carrier electrolyte with interface layers. 2. A tubular element for batteries of high-temperature electrochemical devices with a supporting thin-layer solid electrolyte, gas diffusion electrodes and interface layers, in which the carrying thin-layer solid electrolyte is made with spherical, pyramidal bulges located along the generatrix tube, or with a shift of each row relative to staggered neighboring ones with thin interface layers deposited on the corrugated surface of a solid supporting electrolyte made of micropowder, for example, cer I, doped with gadolinium (GDC), or zirconium stabilized with yttrium (YSZ), and thin, for example, 20-50 μm, gas diffusion electrodes, for example, strontium manganite (LSM) or Ni cermet, located on the corrugated outer and inner surface carrier electrolyte with interface layers. 3. A tubular element for batteries of high-temperature electrochemical devices with a supporting internal electrode, a thin layer solid electrolyte, interface layers, and an external thin electrode, in which the supporting internal electrode is made of, for example, LSM or Ni cermet, with an internal smooth cylindrical surface and an external macrorelief surface in the form of corrugations along the generatrix in the form of a wave, trapezoid, triangle or spherical, pyramidal bulges located along the generatrix or with a shift of each row of relative adjacent in a checkerboard pattern, and connected in series through the interface layer with a thin layer solid electrolyte, for example, 2-50 microns thick, an interface layer and a thin external electrode, for example, 20-50 microns thick. 4. A tubular element for batteries of high-temperature electrochemical devices with a supporting external electrode, a thin layer solid electrolyte, interface layers, and a thin internal electrode, in which the supporting external electrode is made, for example, of LSM or Ni cermet, with an external smooth cylindrical surface and an inner macrorelief surface in the form of corrugations along the generatrix, in the form of a wave, trapezoid, triangle or spherical, pyramidal bulges located along the generatrix or with a shift of each row relative adjacent a "checkerboard pattern", and is connected in series via an interface layer with a thin solid electrolyte, e.g., 2-50 microns in thickness, an interface layer and a thin inner electrode, e.g., 20-50 microns thick. 5. A tubular element for batteries of high-temperature electrochemical devices with supporting external and internal electrodes, with a thin-layer solid electrolyte and interface layers, in which the supporting external and internal electrodes are made, for example, of LSM or Ni cermet, and have respectively external and internal smooth cylindrical surfaces between which a thin solid electrolyte, for example, from YSZ, with a thickness of 2-50 μm, made in the form of corrugations along a generatrix in the form of a wave, is located and connected to them through interface layers tion, triangular or spherical, pyramidal protuberances disposed along a generatrix or shift relative to each adjacent row are staggered. 6. A method of manufacturing a tubular element for batteries of high-temperature electrochemical devices with a supporting thin-layer solid electrolyte, gas diffusion electrodes and interface layers, including the formation of thin films from a suspension for the manufacture of components of the tubular element: electrolyte, interface layers and electrodes, while for the manufacture of a carrier thin-layer solid electrolyte, the suspension contains nanopowder, and for the manufacture of interface layers and electrodes - micropowder; winding thin films into a roll in the required sequence and the required number of layers: thin films of the inner electrode, the interface layer, solid electrolyte, the interface layer and the outer electrode, forming the components of the tubular element necessary to obtain the desired design, under conditions providing monolithic layers made on the basis of a thermoplastic binder: at a temperature, for example, 90-125 ° C, for a polyvinyl butyral (PVB) binder and a pressure of 0.1-1, 8 GPa, for example, for magnetic pulse pressing, sintering of the components of the tubular element under conditions providing a gas-tight, thin layer of solid electrolyte and porous gas diffusion electrodes, for example, for YSZ layers of solid electrolyte from weakly agglomerated nanopowder with specific surface area S = 62 ± 4 m ² / g, in the temperature range 950-1300 ° C, with a shutter speed of 100 - 0.33 h, respectively. 7. A method of manufacturing a tubular element for batteries of high-temperature electrochemical devices with a supporting inner electrode, with a thin layer solid electrolyte, and interface layers, in which the supporting inner electrode is made, for example, of LSM or Ni cermet, including the formation of thin films for the manufacture of the components of the tubular element, for example, by casting from a suspension containing a powder of the desired composition with a binder, while the film of electrodes and interface layers are cast from micropowder, and solid electrolyte from nanopowder, winding thin films into a roll in the required sequence: a supporting internal electrode, such as an anode or cathode, an interface layer, a solid electrolyte, an interface layer, an external electrode, such as a cathode or anode, with the required number of layers, molding the components of the tubular element necessary to obtain the desired design under conditions that ensure homologation of layers based on a thermoplastic binder: at a temperature of 90-125 ° C, for example, for polyvinyl butyral (PVB) as a binder, and a pressure of 0.1-1, 8 GPa, for example, for magnetic pulse pressing, sintering of the components of the tubular element under conditions providing a gas-tight, thin layer of solid electrolyte and porous gas diffusion electrodes, for example, for YSZ layers of solid electrolyte from weakly agglomerated nanopowder with specific surface area S = 62 ± 4 m ² / g, in the temperature range 950-1300 ° C, with a shutter speed of 100 - 0.33 h, respectively. 8. A method of manufacturing a tubular element for batteries of high-temperature electrochemical devices with a supporting external electrode, with a thin-layer solid electrolyte and interface layers, in which the supporting external electrode is made, for example, of LSV or Ni cermet, including the formation of thin films for the manufacture of the components of the tubular element, for example, by casting from a suspension containing a powder of the desired composition with a binder, while the film of electrodes and interface layers are cast from micropowder, and solid electrolyte from nanopowder, winding thin films into a roll in the required sequence: an internal electrode, such as an anode or cathode, an interface layer, a solid electrolyte, an interface layer supporting an external electrode, such as a cathode or anode, with the required number of layers, forming the components of the tubular element to obtain the desired design under conditions that ensure monolithic layers based on a thermoplastic binder: at a temperature of 90-125 ° C, for example, for polyvinyl butyral (PVB) as a binder, and a pressure of 0.1-1.8 GPa, for example, for magnetic pulse pressing, sintering of the components of the tubular element under conditions providing a gas-tight, thin layer of solid electrolyte and porous gas diffusion electrodes, for example, for YSZ layers of solid electrolyte from weakly agglomerated nanopowder with specific surface area S = 62 ± 4 m ² / g, in the temperature range 950-1300 ° C, with a shutter speed of 100 - 0.33 h, respectively. 9. A method of manufacturing a tubular element for batteries of high-temperature electrochemical devices with supporting external and internal electrodes, with a thin-layer solid electrolyte and interface layers, in which the supporting external and internal electrodes are made, for example, of LSM or Ni cermet, including the formation of thin films for the manufacture of the components of the tubular element, for example, by molding from a suspension containing a powder of the desired composition, while the film of the supporting electrodes and interface layers are cast from micropowder, and solid electrolyte from nanopowder, winding films into a roll in the required sequence: an internal supporting electrode, for example an anode or cathode, an interface layer, a solid electrolyte, an interface layer, an external supporting electrode, such as a cathode or anode, with the required number of film layers, pre-forming or corrugating the electrode-electrolyte-electrode films, placing them in a mold, filling the gaps between the blank of the element and the micropowder shape of the corresponding electrode with a binder, pressing the necessary components of the tubular element, providing the required design of the tubular element, under conditions that ensure monolithic layers due to the thermoplasticity of the binder: at a temperature of 90-125 ° C, for example, for polyvinyl butyral (PVB) as a binder and a pressure of 0.1-1, 8 GPa, for example, for magnetic pulse pressing, sintering of the components of the tubular element under conditions providing a gas-tight, thin layer of solid electrolyte and porous gas diffusion electrodes, for example, for YSZ layers of solid electrolyte from weakly agglomerated nanopowder with specific surface area S = 62 ± 4 m ² / g, in the temperature range 950-1300 ° C with an exposure of 100 - 0.33 h, respectively.