CN1976108A

CN1976108A - Solid porous supporting body flat-plate series micro solid oxide fuel battery

Info

Publication number: CN1976108A
Application number: CNA2006101242342A
Authority: CN
Inventors: 刘江; 高鸿波
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2006-12-15
Filing date: 2006-12-15
Publication date: 2007-06-06
Anticipated expiration: 2026-12-15
Also published as: CN100495793C

Abstract

A micro-solid oxide fuel cell of flat series connected type with solid porous support body is prepared as forming fuel cell unit by porous positive electrode layer, compact electrolyte film and porous negative electrode; connecting porous positive electrode in one unit to porous negative electrode in another unit on two adjacent units to form cell set, using insulated solid porous support body with porosity being greater then 50% as said support body and setting position of compact electrolyte film to porous positive electrode and position of compact electrolyte film to porous negative electrode to be staggered for avoiding short-circuit between two said electrodes.

Description

Solid porous support flat plate series connection type micro solid oxide fuel cell

Technical Field

The invention relates to a screen printing process, a technology for printing a porous ceramic support body by a wax slurry casting method and a fuel cell technology, in particular to a solid porous support body flat plate series connection type micro solid oxide fuel cell pack.

Background

With the development of the technology, the miniature electronic products have more functions, such as a color screen and a multimedia message of a mobile phone, a PDA combined with communication equipment, an integrated digital camera and the like. These functions require higher energy consumption, and conventional MH-Ni batteries and lithium ion batteries have been gradually unable to meet the increasingly high energy consumption requirements of electronic products. The specific energy of the fuel cell is higher than that of a storage battery theoretically, and charging is not needed, so that the micro fuel cell is expected to replace the traditional battery to become a new energy source of micro electronic products.

Miniaturized fuel cells, which are in the mW-W range, can power portable electronic devices and military appliances, and have higher efficiencies and energy densities than conventional cells are difficult to compare. Small low temperature Proton Exchange Membrane Fuel Cells (PEMFCs) have been the focus of research because they do not require complex heat integration for efficiency improvement. However, the high cost of manufacture, the complex equipment, and the technical difficulties that have been difficult to solve to date have necessitated many PEMFC systems to bypass the fuel reforming and hydrogen purging processes using hydrogen storage methods. Direct Methanol Fuel Cells (DMFCs) have advantages in that fuel can be directly used, and micro DMFCs have been developed for use in portable electronic devices. However, in order to achieve the power density required for portable electronic devices, highly concentrated methanol solutions are required, and penetration of methanol fuel under such conditions has been a problem. Due to the above-mentioned problems with these polymer electrolyte based fuel cells, solid oxide electrolyte based fuel cells (SOFC) may be more advantageous than for the application areas of portable electronic devices. Solid Oxide Fuel Cell (SOFC) units (or single cells) are composed of an anode, a cathode and an electrolyte sandwiched between the two electrodes, the output current is proportional to the area (also called effective area) of the overlapping portion of the anode, the cathode and the electrolyte, the open-circuit voltage of each SOFC unit is about 1V, and the operating voltage is 0.7V. The SOFC stack consists of SOFC cells in appropriate series and parallel connections. SOFC's operate by providing a fuel gas, such as hydrogen, to the anode and an oxidant gas, such as air, to the cathode. The fuel gas and the oxidant gas generate current through electrochemical reaction, and the current flows through an external circuit and flows through a load to obtain electric energy.

SOFC anodes can also be fuelled without hydrogen by using inexpensive, high energy density hydrocarbons directly, thus eliminating the steps of fuel pre-reforming, purging, hydrogen storage, or water recycling, and overcoming the above disadvantages of polymer electrolyte based fuel cells. In order to avoid degradation of SOFC performance or even direct combustion damage to the SOFC due to direct contact between the fuel gas on the anode side and the oxidant gas on the cathode side, it is necessary that the electrolyte of the SOFC be very dense in order to providea tight separation between the fuel gas on the anode side and the oxidant gas on the cathode side. The electrolyte material is generally Yttrium Stabilized Zirconia (YSZ), which is a pure oxygen ion conductor and is stable in both oxidizing and reducing atmospheres, but its conductivity is only 10 ℃ at 800 ℃ (the SOFC operating temperature)^-2Of the order of Scm. To minimize the ohmic resistance of the electrolyte, the electrolyte may be formed as a ceramic membrane 10-50 microns thick. However, the electrolyte membrane is too thin to be self-supporting and can only be fabricated on a substrate having sufficient mechanical strength.

The existing micro SOFC structure types are mainly divided into a micro-pipe type design and a flat plate serial type design. Microtubular SOFCs (washio Suzuki, Toshiaki Yamaguchi, Yoshinobu Fujishiro, Masanobu Awano, "Fabrication and characterization of micro structural SOFCs in the interfacial temperature," Journal of Power Sources 160(2006)73-77) with a diameter of 0.8mm have been printed, but such techniques have had some difficulty in achieving electrical connection of the individual cells. Another planar tandem SOFC is a series of SOFC cells (Tammy s.lai, Jiang Liu, and scott a. barnettz, "Effect of Cell Width on segmented-in-series SOFCs," Electrochemical and Solid-State Letters, 7(4) a78-a81(2004)) which are all membrane structures and are serially connected to each other by screen printing on porous hollow flat tubes, wherein fuel gas is supplied from the inside of the tubes during operation of the Cell, and air is directly used as an oxidant from the outside. The battery has higher integration degree and small air resistance, can use the screen printing technology commonly adopted by the electronic industry, and is suitable for mass production. The micro SOFC is small in size, the walls of the hollow porous flat tubes are thin, the manufacturing difficulty is high, and the hollow flat tubes are easy to collapse due to applied pressure during the screen printing process, so that the hollow porous support tube becomes a main factor limiting the development of the flat serial micro SOFC.

Disclosure of Invention

In order to overcome the deficiencies of the prior art, it is an object of the present invention to provide a solid porous support. The solid porous support body is easy to manufacture, has high mechanical strength, is suitable for mass production, can play a role in supporting an electrolyte membrane, and can be used as a catalyst carrier for realizing internal reforming of hydrocarbon fuel in an SOFC (solid oxide fuel cell) or inhibiting carbon deposition reaction.

The purpose of the invention is realized by the following technical scheme:

a solid porous support plate series connection type micro solid oxide fuel cell comprises a support body, compact electrolyte membranes, porous anode layers, porous cathode layers, connecting materials and insulating sealing materials, wherein the porous anode layers are printed on the upper surface and the lower surface of the support body at intervals in parallel, the compact electrolyte membranes are respectively printed on the surfaces of the porous anode layers, the porous cathode layers are respectively printed on the electrolyte membranes, the porous anode layers, the compact electrolyte membranes and the porous cathode layers form unit bodies of the fuel cell, the porous anode layers of one unit body in two adjacent unit bodies are connected with the porous cathode layers of the other unit body through the connecting materials and are connected in series to form a battery pack, and charge collectors are arranged on the connecting materials at one end of the upper surface and one end of the lower surface of the support body; the side wall of the porous support body of the battery pack is sealed by an insulating material; one side wall of the porous support body is provided with a fuel and tail gas guide tube, the support body is an insulating solid porous support body, the porosity is more than 50%, the position of the compact electrolyte membrane is staggered with the position of the porous anode layer, and part of porous anodes are reserved to realize series connection among the cells; the porous cathode layer and the compact electrolyte membrane are staggered in position, so that short circuit with the porous anode layer is avoided.

The solid porous support body is cuboid-shaped insulating ceramic or foamed ceramic; the solid porous support body is prepared by mixing zirconia foamed ceramic or zirconia powder PSZ with 3 mol% yttria partially stabilized and pore-forming agent (high molecular organic matter such as beeswax or starch) according to the weight ratio of 70: 30 and adopting a wax slurry casting method or a slip casting method.

The porous anode layer is prepared by mixing nickel protoxide and yttrium stabilized zirconia powder according to the weight ratio of 7: 3 and adopting a brushing or screen printing method; the compact electrolyte membrane is prepared from yttrium stabilized zirconia by adopting a screen printing method or a centrifugal method; the porous cathode layer is prepared by mixing strontium-doped lanthanum manganate and yttrium stabilized zirconia powder according to the weight ratio of 1: 1 and adopting a brushing or screen printing method.

The side wall of the porous support body of the battery pack is sealed by an insulating material to prevent fuel gas from leaking; three gas-guide tubes are led out from the porous support body, fuel gas is led in through the gas-guide tube positioned in the center, and tail gas after cell reaction is discharged from the gas-guide tubes at two sides.

Compared with the prior art, the invention has the beneficial effects that: (1) the flat-plate serial connection type micro SOFC adopts solid porous ceramics as a support body, is easy to manufacture, has good strength and is suitable for mass production; (2) the space occupied by the hollow of the hollow support body in the prior art is saved, and the whole battery can be made thinner and more intensive; (3) the solid porous support body can also play a role of a catalyst carrier, so that the SOFC can realize the reformation of hydrocarbon fuel in the SOFC or directly use the hydrocarbon fuel without carbon deposition, thereby greatly improving the specific energy of the micro SOFC; (4) the SOFC battery pack prepared by the invention can adjust the number of the single batteries connected in series according to the required voltage, and is particularly suitable for the application of portable electronic equipment power supplies.

Drawings

Fig. 1 is a cross-sectional view of a battery of the present invention;

fig. 2 is a schematic view of the operating principle of the present invention and fuel gas diffusion.

The figures show that: 1. an air duct; 2. a charge collector; 3. a dense conductive connection material; 4. a porous support; 5. a porous anode layer; 6. a dense electrolyte membrane; 7. a porous cathode layer.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the scope of the present invention is not limited to the examples.

As shown in fig. 1, the solid porous support plate serial micro solid oxide fuel cell of the present invention comprises an insulating solid porous support 4, a dense electrolyte membrane 6, a porous anode layer 5, a porous cathode layer 7, a connecting material 3 and an insulating sealing material, wherein a plurality of porous anode layers 5 are printed on two largest surfaces of the porous support 4 at intervals in parallel, the dense electrolyte membrane 6 is printed on the surfaces of the plurality of porous anode layers 5, respectively, and the porous cathode layer 7 is printed on all the electrolyte membranes 6, respectively. The porous anode layer 5, the dense electrolyte membrane 6 and the porous cathode layer 7 constitute a fuel cell unit. The position of the compact electrolyte membrane 6 is staggered with that of the porous anode layer 5, the porous anode layer 5 cannot be completely covered, and part of anodes are reserved to realize series connection among the cells; the porous cathode layer 7 is offset from the dense electrolyte membrane 6 to avoid shorting to the porous anode layer 5. The porous cathode layer 7 of the single cell and the adjacent porous anode layer 5 are connected in series by the connecting material to form the battery pack.

The battery pack selects the number of the battery monomers connected in series according to the required voltage, and selects the size of the battery monomers according to the required current.

The invention uses cuboid solid porous ceramics as the support body of SOFC, the support body is made of insulating ceramics, the porosity is more than 50%, and foamed ceramics can also be adopted; when preparing the SOFC, first, the porous anode layer 5 is printed in parallel on the surface of the porous support 4 with the largest area on both surfaces at a certain interval; then printing a compact electrolyte membrane 6 on the surface of the anode layer 5, wherein the position of the electrolyte membrane 6 is staggered with the position of the anode layer 5 a little so as to reserve part of anodes to realize the series connection between the cells, therefore, the electrolyte membrane 6 can not completely cover the anode layer 5, and a part for leading out anode current is reserved; dense conductive connecting materials are printed on the reserved anode layer and the porous support body 4 between the electrolyte membranes, and the dense conductive connecting materials 3 are electronic conductive dense materials and play a role in isolating fuel gas and air together with the electrolyte membranes besides playing a role in electrical connection. The porous cathode layer 7 is printed on the electrolyte membrane, and the electrolyte membrane 6 cannot be completely covered by the cathode layer 7 so as not to cause short circuit with the anode layer 5; the porous anode layer 5 is prepared by mixing nickel oxide and yttrium stabilized zirconia powder according to the weight ratio of 7: 3 and printing by adopting a coating or screen printing method, the compact electrolyte membrane 6 is prepared by mixing yttrium stabilized zirconia powder according to the weight ratio of 1: 1 and printing or screen printing method, and the porous cathode membrane 7 is prepared by mixing strontium-doped lanthanum manganate powder and yttrium stabilized zirconia powder according to the weight ratio of 1: 1; connecting the cathode layer of a SOFC single cell (consisting of a stacked anode-electrolyte-cathode) with the anode layer of an adjacent SOFC by using a conductive connecting material containing silver to form a battery pack; the battery pack on the porous support body 4 is electrically connected with the battery pack below through a connecting material; the current generated by the total battery pack on the upper and lower surfaces is led out through a connecting material and a charge collector (platinum conductive adhesive is coated on the cathode layer in a grid form so as to collect and lead out a large amount of charges generated by the cathode, and silver conductive adhesive is also available); the side walls of the porous support of the batterywere sealed with an insulating material (pyrex). Three gas-guide tubes 1 are led out from the porous support body at the end of the charge collector, fuel gas is led in through the gas-guide tube 1 at the center, and tail gas after cell reaction is discharged from the gas-guide tubes at two sides.

As shown in FIG. 2, when the battery pack is in operation, the flat plate serial connection type micro solid body supported by the solid porous ceramicsProviding fuel gas, e.g. inside porous support of oxide fuel cell stackHydrogen H₂The fuel gas diffuses within the porous support and reaches the anode reaction site. The cathode is exposed in the air, and after oxygen molecules in the air reach the cathode, electrons are obtained under the electrocatalytic action of the cathode to be changed into oxygen ions O^2-The electrolyte YSZ is oxygen ion conductive, thus O^2-Passes through the electrolyte to reach the anode under the action of concentration difference on two sides of the electrolyte, and reacts with hydrogen of the anode to generate water H₂And O emits electrons, the emitted electrons generate current through an external circuit, and the tail gas after the battery reaction is discharged through the gas guide tube. The specific reaction formula is as follows:

and (3) cathode reaction:

and (3) anode reaction:

and (3) total reaction:

example (b):

the solid porous ceramic supported plate serial connection type micro SOFC has the advantages that the size of a porous support body is 20mm multiplied by 15mm multiplied by 3mm, 4 SOFC cells which are connected in series are respectively manufactured on two surfaces with the size of 20mm multiplied by 15mm, and the cell groups on the two surfaces are connected in series through connecting materials to form a cell group with 8 cells connected in series. The effective working area of each single cell is 10mm × 2mm ═ 0.2cm2, the open circuit voltage of each single cell is 1V, the working voltage is 0.7-0.8V, and this micro SOFC can give a working voltage of about 6V. Typical power densities of SOFC single cells are 0.3W/cm2, and this SOFC can reach 0.48W.

The invention combines the screen printing technology commonly adopted in the electronic industry with the traditional ceramic manufacturing technology, and the design mode of the flat serial connection type micro SOFC supported by the solid porous ceramic saves the space occupied by the hollow of the hollow support body in the prior art, has high space utilization rate, can manufacture thinner and more intensive integral cells, and is easy to realize sealing; the cells may be small and are particularly suited for use as a power source for portable electronic devices. The actual size and power of the battery can also be specifically designed according to actual needs.

Claims

1. A solid porous support plate series connection type micro solid oxide fuel cell comprises a support body, compact electrolyte membranes, porous anode layers, porous cathode layers, connecting materials and insulating sealing materials, wherein the porous anode layers are printed on the upper surface and the lower surface of the support body at intervals in parallel, the compact electrolyte membranes are respectively printed on the surfaces of the porous anode layers, the porous cathode layers are respectively printed on the electrolyte membranes, the porous anode layers, the compact electrolyte membranes and the porous cathode layers form unit bodies of the fuel cell, the porous anode layers of one unit body in two adjacent unit bodies are connected with the porous cathode layers of the other unit body through the connecting materials and are connected in series to form a battery pack, and charge collectors are arranged on the connecting materials at one end of the upper surface and one end of the lower surface of the support body; the side wall of the porous support body of the battery pack is sealed by an insulating material; a porous supporter lateral wall sets up fuel and tail gas air duct, its characterized in that: the support is an insulating solid porous support, the porosity is more than 50%, the position of the compact electrolyte membrane is staggered with the position of the porous anode layer, and part of porous anodes are reserved to realize series connection among the cells; the porous cathode layer and the compact electrolyte membrane are staggered in position, so that short circuit with the porous anode layer is avoided.

2. The solid porous support plate serial micro solid oxide fuel cell of claim 1, wherein the solid porous support is an insulating porous ceramic or a foamed ceramic.

3. The solid porous support plate serial micro solid oxide fuel cell of claim 1 or 2, wherein the solid porous support is prepared by mixing zirconia ceramic foam or 3 mol% yttria partially stabilized zirconia powder with pore forming agent according to the weight ratio of 70: 30 and adopting a wax slurry casting method or a slip casting method.

4. The solid porous support plate series micro solid oxide fuel cell of claim 3, wherein the porous anode layer is prepared by mixing nickel oxide and yttrium stabilized zirconia powder in a weight ratio of 7: 3 and by painting or screen printing.

5. The solid porous support plate serial micro solid oxide fuel cell of claim 4, wherein the dense electrolyte membrane is made of yttrium stabilized zirconia by screen printing or centrifugation.

6. The solid porous support plate series connection type micro solid oxide fuel cell as claimed in claim 5, wherein the porous cathode layer is prepared by mixing strontium-doped lanthanum manganate and yttrium stabilized zirconia powder in a weight ratio of 1: 1 and applying a painting or screen printing method.