JP2001093570A - Electro-chemical battery separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of fabricating a polycrystalline ceramic solid electrolyte separator for a high temperature electro chemical battery by sintering a particulate starting material. SOLUTION: A method of fabricating a polycrystalline ceramic solid electrolyte separator comprises the steps of mixing a particulate starting material with a binder, forming a raw artifact consisting of at least 5 tubes connected in parallel to each other, and sintering the raw artifact to form the polycrystalline ceramic solid electrolyte separator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates generally to separators for high temperature rechargeable electrochemical cells. More particularly, the invention relates to a method of making such a separator.

According to the present invention, there is provided a method of making a ceramic solid electrolyte separator for a high temperature electrochemical cell from a particulate starting material that may be sintered to form an integral polycrystalline solid electrolyte ceramic artifact, comprising: Mixing the particulate starting material with a binder to form a possible mixture; and an integral sinterable raw artifact comprising at least five multiple interconnected tubes arranged in a side-by-side relationship Forming a moldable mixture to form a sintered polycrystalline ceramic solid electrolyte artifact to form a sintered polycrystalline ceramic solid electrolyte artifact. The polycrystalline ceramic solid electrolyte artifacts are interconnected together by sintering, At least 5 arranged in Do relationship
A method is provided for making a ceramic solid electrolyte separator for a high temperature electrochemical cell that includes a number of ceramic solid electrolyte separator tubes.

It is advantageous if the solid electrolyte is a conductor of sodium ions, such as β-alumina or preferably β ″ alumina. The particulate starting material may be in the form of particles of the solid electrolyte, or It may be in the form of a precursor mixture that is transformed or transformed into a solid electrolyte when heated to a sintering temperature, known in the art when the solid electrolyte is β or β ″ alumina, A powder mixture comprising a suitable oxide or hydroxide of aluminum of the type that forms β or β ″ alumina when heated to a sintering temperature, together with a composition selected from soda and lithium oxide or magnesia. Alumina oxide, soda, lithium oxide or mag which is a substance that becomes the oxide when heated to 700 ° C. in air. Precursors may be used in shear. In this regard, aluminum hydroxide, effectively a precursor of aluminum oxide of this type.
Thus, in a particular embodiment of the present invention, the particulate material may be a precursor of a solid electrolyte selected from the group of solid electrolytes consisting of sodium beta alumina, beta sodium sodium, and mixtures thereof; The binder is selected from the group consisting of a binder having thermoplastic properties, a binder having thermosetting properties, a binder having both thermoplastic and thermosetting properties, and a mixture of those binders.

[0004] The binder has both thermoplastic properties and thermosetting properties, and has thermoplastic properties upon initial heating.
It may be an organic binder that becomes thermoset in nature when heated to a temperature higher than the temperature at which it is thermoplastic. Suitable binders in the form of a binder formulation are described, for example, in GB 1 274 211. As described in GB 1 274 211, a single binder compound can be provided and used as exhibiting the required thermoplastic and thermoset properties.

A suitable binder is polyvinyl butyral because it has both thermoplastic and thermosetting properties, and it is combined with a plasticizer such as dibutyl phthalate and a solvent such as methyl ethyl ketone. Solvents and plasticizers may be used to facilitate mixing of the binder with the finely divided starting material, such as β or β ″ alumina or a precursor mixture thereof, to form a sufficiently uniform moldable mixture. However, if a high energy mixer such as a Banbury mixer is used, plasticizers and solvents can be omitted in principle.

In practice, molding provides a tube of green artifact in a somewhat compact side-by-side relationship in which adjacent tubes are adjacent and integral with each other, or alternatively, In the tube
Arranged in spaced-apart relationship with one another by spacers extending longitudinally in the form of webs of material to be molded, each web having a side edge integrated around two adjacent tubes. By multiple tubes is meant in this regard at least 5 tubes, typically at least 10 tubes, and preferably at least 25 tubes. Thus, in one embodiment, the molding is performed in such a manner that adjacent tubes have adjacent perimeters adjacent to each other, and after sintering are integrated together in a closely packed, side-by-side relationship such that unsintered artifacts May work to provide a tube. And in another embodiment, the molding is such that the tubes are spaced apart from each other by spacers that extend longitudinally in the form of a web of raw material to be molded, each web being the two adjacent tubes. Peripheries may be integrated into the periphery to serve to provide a tube of green artifact in spaced apart side-by-side relationship.

In use, the separator forms part of an assembly with a header (for connection of the separator to the battery housing), at least a portion of which is electronically and electrochemically. The header may be insulated, for example, as described in International Patent Application No. PCT / GB98 / 0, published as WO 98/35400.
As described in No. 0389, the interior is communicated to the interior of the tube by glassing, ie, glass welding, and is integrated or hermetically connected to the open end of the tube. The sintered separator may be glass welded to a suitable header that has such required electronic and electrochemical insulating properties. The tube will be closed at the opposite end of the separator, i.e. at the end of the separator remote from the header, but will extend between and alongside the tube and open at its end at the end of the separator remote from the header. May be present. Molding involves sealing a plurality of separator tubes having open ends integrally molded with the header to the header after the tubes have been sintered, the header communicating with the interior of the tubes. Has an interior,
And the header may serve to provide that it is made of a material that is electronically and electrochemically insulated. Instead, the molding has an opening to the periphery to which the open end of the tube is coupled, and the header comprises a floor that allows the interior of the tube to communicate with the interior of the header through the opening, the method comprising: The method may include providing an upright rim on the floor having a lower edge extending along the periphery of the floor, and providing the header with a lid on which the upper edge of the rim extends along the periphery.

[0008] Typically, the header is hermetically sealed around a metal seal ring having a pair of gaps, conveniently by thermocompression bonding, in a location that is electronically and electrochemically insulated from the tube. A lid having a central opening coupled therewith, the header having a floor with an opening leading to the open end of the tube, and a rim extending between the perimeter of the floor and the perimeter of the lid. It will be integral with the part or glass welded to the floor opening. The electronic and electrochemical insulation of the header may be comprised of sintered alpha alumina, and any one or more of the header floor, rim or lid may be comprised of alpha alumina. It may be. In particular, it has a rim and a floor integrated with each other and with the tube, having a lid made of α-alumina, and the rim, floor and tube are made of β or β ″ alumina and the lid is made of glass on top of the rim. Having a lid and rim integral with each other and made of alpha alumina, integrated with the tube at the bottom of the rim and glass welded to the floor made of beta or beta "alumina; or The rim and floor together form an integrated sintered article of alpha alumina, and the floor can be glass welded to the tube. In one embodiment, the method may include sealing and glass-welding the lower edge of the rim to the periphery of the floor after the rim and lid are integrally molded together and integrally. . Alternatively, it may include sealing the upper edge of the rim to the lid and glass welding after the floor and rim are integrally molded as a single piece.

Tube arrangements for separators include rectangular compact or rectangular spaced arrays, and hexagonal compact or hexagonally spaced arrays. Next, the tube may have various cross-sections as desired. Thus, the tubes may have a circular cross-section, the spacing being defined between the tubes, depending on whether the tubes are spaced or compacted, or the tubes may be square, rectangular or hexagonal in cross-section. They may be square, in which case they are in principle separated from one another by spacer webs, but usually they will be closely packed with no spacing between them.

Hereinafter, the present invention will be described by embodiments with reference to the accompanying drawings.

1 and 2, there is shown a separator assembly generally designated by the reference numeral 10 and comprising separators indicated by headers 12 and 14, comprising 23 hexagonal arrays arranged in a spaced apart hexagonal arrangement. From a number of spaced side-by-side separator tubes 16. The tubes 16 extend side by side and a web 18
Are separated by Header 12 is in the form of a cup and is made of alpha alumina, and tube 16 and web 18 are made of beta "alumina.

The tube 16 has a circular cross-sectional profile,
It has an end remote from the header 12 which is closed in the form of a closing panel by a closing object 20 integrally formed with the tube 16. The end of the tube 16 adjacent to the header 12 is open. The cup of the header 12 is a floor 22,
And an upright peripheral rim or wall 24 surrounding a header space 26 above the tube 16, and the assembly 10 is shown in a vertical working position in FIG. The open ends of the tubes 16 open into the header space 26 through openings 28 in the floor 22 of the header 12, to which the headers 12 are tightly sealed by glass welding or they are integrally molded. Have been. The floor 22 has a rectangular outer shape, the periphery of which is indicated by a dashed line 30 in FIG. The header 12 has a lid not shown in FIG. 1 and will be described in more detail below with reference to FIG.

In FIG. 3, the separator assembly comprises:
Similar to the separator assembly of FIGS. 1 and 2, the same reference numbers are used in FIG. 3 for the same parts as in FIG. The difference between the assembly of FIG. 3 and the assembly of FIGS. 1 and 2 is that the assembly of FIG. 3 has 25 tubes 16 and instead of the hexagonally spaced tube arrangement of the assembly of FIGS. The third assembly has a rectangular (square) spaced tube arrangement.

Referring again to FIG. 4, the same reference numerals are used for the same parts as in FIG. The tube arrangement of FIG. 4 is hexagonal, as in FIGS.
Instead of being separated from one another by 8, the tubes can be considered as a compact hexagonal array. Thus, in FIG. 4 there is no spacer or web and the tubes 16 are welded together at the point 32 where they meet.

5, the same reference numerals are used for the same parts as in FIG. The difference between the assembly of FIG. 5 and the assembly of FIG. 4 is that the assembly of FIG. 5 has 25 tubes 16 instead of the 23 tubes 16 of the assembly of FIG. While the tubes 16 are arranged closely together, such as the arrangement of tubes of the assembly of FIG. 4, the tube arrangement of FIG. 5 is rectangular, like the tubes of the assembly of FIG. Was omitted from the assembly of
The tubes are welded together at 32.

In the case of the assembly 10 of FIG. 6, in general, the same reference numbers are used for the same parts as in FIGS. The difference between the tube 16 of FIG. 6 and the tube 16 of FIGS.
However, as shown in FIGS. 2 to 5, instead of a circular cross-sectional outer shape, a regular hexagonal outer shape is used. Therefore, the tubes 16 of the assembly 10 of FIGS. 2-5 extend alongside them,
While having a longitudinally extending space 34 bounded by tube 16 and web 18 (FIGS. 2 and 3) or simply tube 16 (FIGS. 4 and 5), tube 16 of FIG. Hexagonal compact arrangement, where there is no space 34 between the tubes and adjacent tubes have a common wall where they border, as at 36. The assembly 10 of FIG. 6 is shown having 18 tubes 16.

The assembly 10 of FIG. 7 is similar to the assembly of FIG. 6 and the same reference numerals as in FIG. 6 are used in FIG. 7 unless otherwise indicated. The difference between the two assemblies of FIGS. 6 and 7 is that there are 25 tubes 16 in the assembly of FIG. 7, and FIG. 7 has the tubes 16 arranged in a square compact arrangement. .

In the case of FIG. 8, a simplified view of a variant of the assembly of FIG.
6, ie, four rows 38 of five larger tubes 16 each providing 20 larger tubes, and three rows 40 of five smaller tubes each providing 15 smaller tubes 16. are doing. The larger tubes consist of a square outline, and the smaller tubes consist of an elongated rectangular outline, the tubes alternate between larger and smaller rows of tubes, and the two outermost rows are: Bigger tube 1
It is arranged in a compact rectangular array of six rows 38.

According to the process of the invention, for example, similar to the moldable mixtures described in US Pat. No. 5,057,384, a ratio of β ″ of 80 to 120 by mass with a particle size of 10 to 50 μm is present. Alumina powder is a British patent GB 14-14 by weight.
A binder such as the thermoplastic and thermoset polyvinyl butyral binder of No. 1 274 211, and
British Patent No. GB 1 274 2 at a rate of 10 to 10
No. 11 dibutyl phthalate and GB 1
By mixing with a plasticizer, such as the 274 211 methyl ethyl ketone solvent, a moldable mixture is formed. The components are mixed until a substantially homogeneous mixture is formed.

The mixture is then formed of a bundle of integral interconnected tubing 16 of the desired length (see FIG. 1) molded separately from the header cup 12 to be joined, ie, a monolithic, monolithic green artefact. Injection molded to provide In this regard, the method is intended to formulate a second moldable mixture in which the β ″ alumina described above is replaced by a similar proportion of α-alumina, and otherwise the same. Injection molding involves molding a mixture comprising β ″ alumina to form a bundle of tubes 16 all of which are open at one end and occluded by occlusion panels 20 integrally molded at the other end. And, optionally, the tube will also be integrally molded with a portion of the header cup 12 from the mixture. The mixture having α-alumina is molded to form a molded article that forms part or all of the header cup 12. The two moldings are then hermetically sealed together by glassing or glass welding (after their sintering), as described hereinafter with reference to FIG.

In the case of FIGS. 6-8, some selected tubes have open ends remote from the header, and the ends adjacent to the header can be closed and molded, while others are remote from the header 12. It is closed at the end and molded to open into the header space 26 at the opening 28.

In FIG. 9, unless explicitly stated otherwise, FIG.
The same reference numerals are used for the same parts. The header cup 12 is shown with only the upper end of the tube 16, and the header cup 12 is shown with a lid 42 having a central opening 44. On the outer (upper) surface of the lid 42, a hermetically sealed thermocompression bonded metal seal ring 46 is shown at 48, along the periphery of the opening 44. The ring 46 has a flange 50 radially projecting outward and extending peripherally and joined to the lid 42 and an upright rim 52 extending along the inner circumference of the flange 50.

Similarly, the metal seal ring 54 is
At the inner (lower) surface of, is hermetically sealed at 56 along the periphery of the opening 44. Ring 54
Are radially outwardly projecting and extending circumferentially, inside and concentric with the flange 58 joined to the lid 42 and the rim 52 of the opening 44 and ring 46,
It has an upright rim 60 extending along the inner circumference of the flange 58.

The outer periphery of lid 42 is shown to be glass welded to the upper edge of rim 24 of header cup 12 by a glass bead or fillet 62.

In fact, in making assembly 10 (see also FIG. 1), floor 22 and rim 24 are molded together with each other and with tube 16 from a mixture comprising β ″ alumina, and lid 42 is , Α-alumina are molded separately, and the two moldings are then sintered and then the rings 46 and 54
Is joined to the lid 42, which is then glass welded to the upper edge of the bead 62.

In a variant of this method, the floor 22
Is molded integrally with the tube 16 by a mixture including β ″ alumina, and the lid 42 and the rim 24 are integrally molded by the mixture including α-alumina. In this case, the glass weld is formed around the floor 22. At location 64, it will be done to glass weld it to the lower edge of rim 24.

In another variant of the method, the lid 4
2, the floor 22 with the rim 24 and the opening 28 can be integrally molded with a mixture comprising α-alumina and only the tubes 16 are molded with a mixture comprising β ″ alumina with their closure 20. In that case, the open upper end of tube 16 would be glass welded to opening 28.

In the case of FIGS. 1 to 5, the tubes 16 can be clearly distinguished by the spaces 34 between the tubes. When used in an electrochemical cell, the tube 16 is expected to contain an electrochemical electrode active material, such as a cathode or anode material. When tube 16 contains the cathode material, space 34 will contain the anode material. And when the tube 16 contains the anode material, the space 34 will contain the cathode material.

However, in the case of FIGS. 6 to 8, the space 34 does not exist. Thus, if it is desired to have the cathode material in close proximity to the anode material, separated by the solid electrolyte walls of the tubes, some tubes will contain the cathode material and others will contain the anode material. Will do. Possible anodes /
The cathode arrangement is shown in FIG. 7, where the tube containing the cathodic material is indicated by "C" and the tube containing the anodic material is indicated by "A".
In the case of FIG. 8, for example, a smaller tube may contain the anode material and a larger tube may contain the cathode material.

In FIGS. 1-5 (and for similar considerations also for FIGS. 6-8), all tubes containing one electrode material (cathode or anode depending on the circumstances) are typically In particular, the ends that open into the header 12 from which they are opposite and will be remote from the header will be closed by the closing panel 20. And other electrode materials (anode material or cathode material depending on the circumstances)
Will open at the end remote from the header 12 while their ends proximate to the header 12 will be closed by the header floor 22.

In each case, it is in close proximity to, and possibly surrounded by, the wall of the tube (FIG. 2).
5) A separator assembly 10 is provided that provides the anode active material to be separated from the cathode active material by the wall of the tube. The header 12 has one electrode material in a tube communicating with the header space 26 in place in the housing of the electrochemical cell and the separator assembly 10 and the battery housing at the end of the tube bundle closed from the header and remote from the header. Provided to connect the assembly 10 with other electrode material in the space between tubes or other tubes communicating with the interspace.
The method of the present invention comprises a separator assembly including an injection molded header and an interconnected tube bundle that can be easily sintered, if desired, after assembly by molding, as described with reference to at least the figures. Provides a convenient and desirable method for mass-producing.

[Brief description of the drawings]

FIG. 1 is a schematic side elevational sectional view of a separator assembly including a header made in accordance with the method of the present invention in the direction of the line II of FIG.

2 is a schematic sectional plan view of the assembly of FIG. 1 in the direction of the line II-II in FIG. 1;

FIG. 3 is a schematic view of a separator assembly corresponding to FIG. 2 made according to the method of the invention and having a different tube arrangement than the tube arrangement of the assembly of FIGS. 1 and 2;

FIG. 4 is a schematic view of a separator assembly corresponding to FIG. 2 made according to the method of the present invention and having a different tube arrangement than the tube arrangement of the assembly of FIGS. 1 and 2;

FIG. 5 is a schematic view of the separator assembly corresponding to FIG. 2 made according to the method of the present invention and having a different tube arrangement than the tube arrangement of the assembly of FIGS. 1 and 2;

FIG. 6 is a schematic view of the separator assembly corresponding to FIG. 2 made according to the method of the present invention and having a different tube arrangement than the tube arrangement of the assembly of FIGS. 1 and 2;

FIG. 7 is a schematic view of the separator assembly corresponding to FIG. 2 made according to the method of the present invention and having a different tube arrangement than the tube arrangement of the assembly of FIGS. 1 and 2;

FIG. 8 is a schematic view of the separator assembly corresponding to FIG. 2 made according to the method of the present invention and having a different tube arrangement than the tube arrangement of the assembly of FIGS. 1 and 2;

FIG. 9 shows an enlarged detail of the header of the assembly of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Separator assembly 12 Header 14 Separator 16 Separator tube 18 Web 20 Closure 22 Floor 24, 52, 60 Rim 26 Header space 28 Opening 30 Perimeter of floor 34 Space between tubes 36 Wall 38, 40 rows 42 Cover 44 Central opening 46, 54 Metal seal ring 50, 58 Flange 62 Bead

Claims (8)

[Claims] A method of making a ceramic solid electrolyte separator for a high temperature electrochemical cell from a particulate starting material that can be sintered to form an integral polycrystalline ceramic solid electrolyte artifact, comprising: Mixing the particulate starting material with a binder to form; and forming an integral sinterable raw artifact comprising at least five multiple interconnected tubes arranged in a side-by-side relationship. Forming a moldable mixture; and sintering the unsintered artifact to form a sintered polycrystalline ceramic solid electrolyte artifact, wherein the sintered polycrystalline ceramic comprises: Solid electrolyte artifacts are interconnected together by sintering and in a parallel relationship. At least 5 arranged
A method of making a ceramic solid electrolyte separator for a high temperature electrochemical cell comprising a number of ceramic solid electrolyte separator tubes. 2. The particulate starting material is a precursor of a solid electrolyte selected from the group of solid electrolytes consisting of sodium beta-alumina, sodium beta "-alumina, and mixtures thereof, wherein the binder is a binder having thermoplastic properties. The method of claim 1, wherein the binder is selected from the group consisting of: a binder having thermosetting properties, a binder having both thermoplastic and thermosetting properties, and a mixture of those binders. 3. The molding is to provide a tube of unsintered artifact in a closely juxtaposed side-by-side relationship in which adjacent tubes are adjacent to each other and integrated after sintering. 3. A method according to claim 1 or claim 2, which works for. 4. The molding wherein the tubes are spaced apart from each other by spacers extending longitudinally in the form of a web of green material to be molded, each web being integral around two adjacent tubes. 3. A method as claimed in claim 1 or claim 2 having a side edge that is textured and operative to provide a tube of green artifact in spaced-apart, side-by-side relationship. 5. The molding serves to provide a plurality of separator tubes having open ends that are integrally molded with the header such that the tubes are hermetically bonded to the header after sintering. 5. A header, the interior of which communicates with the interior of the tubes, and the header is made of a material that is electrically and electrochemically insulating.
The method according to any one of the preceding claims. 6. The shaping serves to provide the header with a floor having an opening to the periphery to which the open end of the tube is coupled, wherein the interior of the tube communicates with the interior of the header through the opening. 6. The method of claim 5, comprising providing an upright rim on the floor having a lower edge extending along the perimeter of the floor, and providing a header on the header with an upper edge extending along the perimeter of the rim. 7. The method of claim 6, including after the rim and lid have been integrally molded together as a single piece, the lower edge of the rim is hermetically sealed around the floor and glass welded. 8. The method according to claim 6, comprising sealing the upper edge of the rim to the lid and glass welding after the floor and the rim are integrally formed as one piece together.