MOLTEN SODIUM BATTERY AND PARTITION WALL FOR MOLTEN SODIUM BATTERY

Abstract

A molten sodium battery includes molten sodium making an anode active material, a cathode active material, a sodium container accommodating the molten sodium therein, a partition wall including an anode chamber in an interior thereof, and a cathode container air-tightly accommodating the cathode active material and the partition wall therein. The molten sodium battery further includes the cathode container including a joint having an Opening communicating an inside of the cathode container with an outside thereof, and the partition wall containing a partition-wall body within the cathode container having a plate shape which contains the anode chamber at around central site thereof in a thickness direction, and a through bore connecting the anode chamber with an outside of the anode chamber, and a head fitted into the opening in the joint and bonded integrally with the partition-wall body which is communicated with the anode chamber by the through bore.

Claims

1. A molten sodium battery comprising: molten sodium making an anode active material: a cathode active material: a sodium container accommodating the molten sodium therein: a partition wall including an anode chamber in an interior thereof: and a cathode container air-tightly accommodating the cathode active material and the partition wall therein, the molten sodium. battery further comprising: the cathode container including joint which. has an opening communicating an inside of the cathode container with an outside thereof, and made of a metal: and the partition wall comprising: a partition-wall body within the cathode container having a plate shape which comprises the anode chamber at around central site thereof in a thickness direction thereof, and a through bore connecting the anode chamber with an outside of the anode chamber, and made of beta-alumina: and a head fitted into the opening in the joint and bonded integrally with the partition-wall body which is communicated with the anode chamber way of the through bore, comprising a passage bore and a groove wherein the lower end of the passage bore opens and an end portion of the partition-wall body in which the through bore is formed is mounted in the groove.

2. The molten sodium battery according to claim 1, further comprising a metallic tubule communicated with the passage bore in the head to communicate the sodium container with the anode chamber.

3. The molten sodium battery according to claim 1, wherein: the joint comprises a part including the opening, and an annular attachment face demarcating the opening; and the head comprises a central part including the passage bore, and another part present around the central part, and including an annular attachment face joined to the attachment face of the joint.

4. The molten sodium battery according to claim 1, wherein: the joint has a hat shape comprising a top-face portion including a part which has the annular attachment face, and a cylindrical walled portion extending downward from a circumferential edge of the top-face portion; and the head comprises an upper staged portion including the passage bore, and a lower stage portion present around the upper staged portion, and including an annular attachment face joined to the attachment face of the joint.

5. The molten sodium battery according to claim 1, wherein the cathode active material comprises molten sulfur or metal halide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG. 1 is a vertical cross-sectional diagram of a sodium-sulfur battery according to the First Embodiment;

[0044] FIG. 2 is a cross-sectional diagram in which FIG. 1 is enlarged partially;

[0045] FIG. 3 is a partial plan view of a partition. wall whose cross-sectional diagram is illustrated in FIG. 2.

[0046] FIG. 4 is a vertical cross-sectional diagram of a major part in a sodium-sulfur battery according to Second Embodiment;

[0047] FIG. 5 is vertical cross-sectional diagram of a cross section of major part in a partition wall whose cross-sectional diagram is illustrated in FIG. 4, and which is viewed in such a direction as turning the partition wall shown in FIG. 4 by 90 degrees; and

[0048] FIG. 6 is a vertical cross-sectional diagram of a major section sodium-sulfur battery according to Third Embodiment.

MODE FOR CARRYING OUT THE INVENTION

Description of Embodiment Modes

[0049] The present invention will be hereinafter described more specifically while presenting embodiments of a sodium-sulfur battery according to the present invention.

First Embodiment

[0050] A sodium-sulfur battery 1 according to First Embodiment of the present invention will be hereinafter described based on FIGS. 1 through 3. Note herein that FIG. 1 illustrates vertical cross section in the sodium-sulfur battery 1; FIG. 2 illustrates an enlarged cross section of its major part; and FIG. 3 illustrates a plane of its partition wall 11 partially.

[0051] The battery 1 comprises the following major constituent elements: a partition wall 11; a cathode container 12; a sodium container 13; an anode chamber 110 formed as an internal space in the partition wall 11; a cathode chamber 120 enclosing the partition wall 11 within an internal space in the cathode container 12; molten sodium 14 accommodated inside the anode chamber 110 and inside the sodium container and making an anode active material; molten sulfur 15 accommodated in the cathode chamber 120, and making a cathode active material; a fine-tubed fitting 16 communicating the anode chamber 110 with the internal space in the sodium container 12; and an insulator 17 intervening between the cathode container 12 and the sodium container 13, and insulating the two electrically. The battery 1, which uses the molten sulfur 15 as cathode active material, makes a sodium-sulfur battery.

[0052] The partition wall 11 comprises a plate-shaped partition-wall body 111, and a nipple-shape head 117, both of which are formed of beta-alumina integrally. The partition-wall body 111 includes: a front-side member 112; a rear-side member 113; a frame-shaped member 114; a pillar-shaped member 115 in a quantity of 81 pieces. The partition-wall body 111 has a squared plate shape having 100 mm approximately in each of length and width, and 2 mm approximately in thickness. The front-side member 112 and rear-side member 113 have a squared configuration having 100 mm in each of length and width, and 2 mm in thickness. The frame-shaped member 114 has a squared configuration having 100 mm approximately each of length and width, 2 mm in the breadth, and 2 mm in thickness, and is located. between the front-side member 112 and the rear-side member 113. The pillar-shaped members 115 have a columnar shape having 2 mm in outside diameter and 2 mm in thickness, and are located between the front-side member 112 and the rear-side member 113 at equal intervals.

[0053] The nipple-shaped head 117 includes an upper member 118, and a Tower member 119, making a configuration formed as columnar protuberance, as its outer side face is shown in FIG. 3. The upper member 118 has a columnar shape having 10 mm approximately in outside diameter, and 8 mm in height. The lower member 119 has a columnar shape having 13 mm approximately in outside diameter, and 12 mm approximately in height. Note that the lower member 119, which is formed integrally with the partition-wall body 111, is covered on some of the outer peripheral face partially with the partition-wall body 111, as illustrated in FIG. 3. Moreover, the nipple-shaped head 117 further includes a passage bore 1175 composed of an upper axial-bore portion 1176 and lower axial-bore portion 1177. The upper axial-bore portion 1176 has 4 mm approximately in inside diameter, and 5 mm approximately in length. The lower axial-bore portion 1177 has 3 mm approximately in inside diameter, and 7 mm approximately in length. The lower axial-bore portion 1177 is opened to the anode chamber 110.

[0054] The nipple-shaped head 117 includes the lower member 119 that is integrated rust only with side end face in the partition-wall body 111 but also with surfaces in the front-side member 112 and rear-side member 113 linking to the side end face. Thus, the lower member 119 appears to make some of the partition-wall body 111. As a result, the nipple-shaped head 117, and the partition-wall body 111 are integrated to a higher degree.

[0055] The partition wall 11 is produced as follows: sodium oxide and alpha-alumina are calcined to synthesize beta-alumina in advance; the resulting beta-alumina is granulated obtain a beta-alumina fine powder; the resultant beta-alumina fine powder used to mold a front-side green compact and rear-side green compact, which divide the partition-wall body 11 into halves at around the middle in the thickness direction, the resulting front-side green compact and rear-side green compact are combined with one another to make a partition-wall green compact; and the resultant partition-wall green compact is sintered. Note that an adaptable production process preferably comprises the steps of: molding each of the half-divided faces in the front-side green compact and rear-side green compact with a mold; and compression molding the front face and rear face with a rubber mold. In the as-sintered partition wall 11, the nipple-shaped head 117 molded preferably to have a slightly larger outer peripheral face; the passage bore 1175 is molded preferably to have a slightly smaller inner peripheral face: and the stepped faces, which are located between the outer peripheral faces in the upper member 118 and lower member 119 of the nipple-shaped head 117, and the. passage bore 1175 are preferably machined to higher dimensional accuracy by grinding, or the like.

[0056] The cathode chamber 12 comprises a container body 121 formed the shape of a rectangular parallelepiped, and a cap 122 formed integrally on the top face in the container body 121. The container body 121 has 105 mm approximately in each of length and width, and 50 mm approximately in thickness. The cap 122 has 12 mm approximately in outside diameter, 10 mm approximately in inside diameter, and 10 mm approximately in height. The cathode container 12 is formed of a stainless-steel plate whose thickness is 1 mm approximately. To be more concrete, the cathode container 12 is formed of three portions, namely, a top lidded portion 123 involving the cap 122, a bottom lidded portion (not shown) in the container body 121, and a trunked portion 124, other than the top lidded portion 123 and bottom lidded portion, in the container body 121.

[0057] The top lidded portion 123, and the partition wall are integrated with one another as follows: the top lidded portion 123 involving the cap 122 is first mounted onto the upper member 118 of the nipple-shaped head 117 until the lower end of the cap 122 comes in contact with the upper the end face in the lower member 119 of the nipple-shaped head 117; and then the outer peripheral face in the upper member 118, and the inner peripheral face in the cap 122 are joined to one another by thermal shrink fitting and thermal pressure bonding.

[0058] Note that, before or after the joining operation, the free end of a shorter portion 162 in the fine-tubed fitting 16 is inserted into the upper axial-bore portion 1176 of the passage bore 1175 in the upper member 110 of the head 117 in the partition wall 11, and then then shorter portion 162 and the upper axial-bore portion 1170 are joined to one another.

[0059] Moreover, the top lidded portion 123 to which the partition wall 11 is joined, and the trunked portion 124 are integrated with one another by laser welding. In addition, a felt-like current collector (not shown), which has 100 mm approximately in each of length and width and 18 mm approximately in thickness and which is composed of carbon fibers with sulfur impregnated, is prepared. The thus prepared felt-like current collector is inserted into the opposite sides of the partition wall 11, which retained within the container body 121, through the opened bottom of the trunked portion 124. Finally, the trunked portion 124, and the bottom lidded portion are integrated with one another by laser welding, forming the cathode container 12.

[0060] The sodium container 13 is a container which is provided with a cutout. The sodium container 13 is formed in the shape of a rectangular parallelepiped, and has 50 mm approximately in each of length and thickness and 105 mm width. The cutout is disposed at one of the opposite ends on the lower side of the sodium container 13, and is formed in the shape of a rectangular parallelepiped having 20 mm approximately in height, 25 mm approximately it length and 50 mm approximately in breadth. The sodium container 13 is formed of a stainless-steel plate whose thickness 1 mm approximately.

[0061] The fine-tubed fitting 16 is a fine tube having 3 mm in diameter and 1 mm approximately in thickness, and made of a stainless steel fine-tubed fitting 16 comprises: a longer portion 161 with an end one of whose opposite ends has widened diameter; and the shorter portion 162 with an end whose diameter is narrowed down and is inserted into the widened-diameter end of the longer portion 161. As illustrated in FIG. 1, the fine-tubed fitting 16 is welded air-tightly at one of the opposite ends to the sodium container 13 so that the longer portion 161 penetrates through the upper face of the sodium container 13 with the cutout provided; and bent in an inverted letter-“U” shape to make the other one of the opposite ends locate adjacent to an inner bottom face of the sodium container 13. As illustrated in FIG. 2, the fine-tubed fitting 16 is further joined air-tightly so that the shorter portion 162 is inserted into the axial-bore portion 1176 of the passage bore 1175 in the nipple-shaped head 117. When the sodium container 13 is assembled with the cathode container 12, the longer portion 161 and shorter portion 162 of the fine-tubed fitting 16, and the sodium container 13 and nipple-shaped head 117 are joined to each other as follows: each of the longer portion 161 a shorter portion 162 is fitted at the free end into the mating member coaxially; and thereafter each of the coaxially-fitted free ends and the mating member are adhered together by heating.

[0062] The insulator 17, which comprises a sheet having 3 mm approximately thickness and is made of inorganic fibers, intervenes between the cathode container 12 and the sodium container 13 to electrically insulate between the two.

[0063] After the cathode container 12 has been assembled with the sodium container 13, molten sodium is injected into the sodium container 13 through a not-shown injector pipe. Then, the interiors of the sodium container 13 and anode chamber 110 are put in a near-vacuum state by deaerating the sodium container 13 and anode chamber 110 and finally closing the injector pipe.

[0064] Thereafter, the interior of the cathode container 12 is deaerated through a not-shown deaerator pipe. Then, the deaerator pipe is closed after the anode chamber 110 has been depressurized more than the cathode chamber 120 is depressurized.

[0065] The sodium-sulfur battery according to First Embodiment constructed as described above. The present sodium-ion battery, which is heated to 300° C. approximately and whose cathode container and sodium chamber 13 making cathode terminal and anode terminal respectively are connected to ah external load, functions in the same manner as ordinary sodium-sulfur batteries do.

[0066] The sodium-sulfur battery according to First Embodiment seals the cathode chamber 120 air-tightly from the outside at one location, namely, the sealing between the outer peripheral face in the nipple-shaped head 117 of the partition wall 11 and the inner peripheral face in the cap 122 of the cathode container 12. That is, the cathode chamber 120 is sealed air-tightly from the outside at one location, namely, the coaxially cylindrical simple sealing between a pillar-shaped nipple and a cylindrical cap. It is easy not only to finish a cylindrical sealing face but also to give enhanced dimensional accuracy. Consequently, it easy to seal the cathode chamber 120 air-tightly from the outside particular, the nipple-shaped head 117, and the cap 122 which is subjected to thermal shrink fitting to mechanically tighten the nipple-shaped head 117, provide an advantage of making the sealing faces less likely to peel off from the substrates.

[0067] Moreover, the top lidded portion 123 involving the cap 122 according to First Embodiment is attached to the upper member 118 in the nipple-shaped head 117 of the partition wall until the lower end of the cap 122 comes in contact with the upper end face in the lower member 119 of the nipple-shaped head 117. Accordingly, strains, which occur between the partition wall 11 and the cathode container 12, concentrate on the lower end of the cap 122, and on the upper end face in the lower member 119 of the nipple-shaped head 117, but are less likely to arise in the outer peripheral face in the upper member 118 of the nipple-shaped head 117 joined to the cap 122, and in the inner peripheral face in the cap 122 joined to the nipple-shaped head 117. Consequently, the joinder faces between the cap 122 and the nipple-shaped head 117 are less likely to peel off from one another.

[0068] In addition, the nipple-shaped head 117, which is composed of the upper member 118 joined to the cap 122 and the lower member 119 made thicker than is the upper member 118, integrated at the thicker lower member 119 with the partition-wall body 111. Thus, the nipple-shaped head 117 gives a sturdy configuration against stresses between the nipple-shaped head 117 and the partition-wall body 111.

[0069] Moreover, the plate-shaped partition-body 111, which might be weak to mechanical stresses, is retained in such a state as floating within the anode chamber 110. According, the plate-shaped partition-wall body 111 is held under a condition where tensile stresses, such as bending or flexural stresses, are less likely partially act on it, Consequently, the plate shaped partition-wall body 111 constitutes a novel partition wall, which is so durable that chances of being broken down are low.

Second Embodiment

[0070] A sodium-sulfur battery 2 according to Second Embodiment of the present invention will be hereinafter described based on FIGS. 4 and 5. The sodium-sulfur battery 2 comprises, instead of the partition wall 11 of the sodium-sulfur battery 1 according to First Embodiment a modified partition wall 21. The partition wall 21 will be hereinafter described mainly, because the sodium-sulfur battery comprises the same constituent elements as those of the sodium-sulfur battery 1, other than the partition wall 21.

[0071] FIG. 4 illustrates a vertical cross section of a major part of the sodium-sulfur battery 2. FIG. 5 illustrates a chief constituent element of the major part illustrated in the cross-sectional diagram shown in FIG. 4, namely, the partition wall 21, in another cross section in which the sodium-sulfur battery 2 illustrated in FIG. 4 is viewed in such a direction as turning it by 90 deg. from the cross-sectional diagram shown in FIG. 4.

[0072] The partition wall 211 comprises a plate-shaped partition-wall body 211 formed of beta-alumina, and a nipple-shaped head 217 formed of alpha-alumina. The partition-wall body 211 and head 217 are integrated by joining them integrally to one another with a glass solder.

[0073] The partition-wall body 211 comprises front-side member 212, a rear-side member 213, a frame-shaped member 214, and a pillar-shaped member 215 in a quantity of 81 pieces. The front-side member 212 and rear-side member 213 are formed the shape of a squared plate having 100 mm approximately in each of length and width and 6 mm approximately in thickness. The frame-shaped member 214 is formed in the shape of squared plate having 100 mm in each of length and width, 2 mm in breadth, and 2 mm in thickness, and is located between the front-side member 212 and the rear-side member 213. The pillar-shaped members 215 are formed in the shape of a pillar having 2 mm in outside diameter, and 2 mm in thickness, and are located at equal intervals between the front-side member 212 and the rear-side member 213. An interspace between the front-side member 212 and the rear-side member makes an anode chamber 210. A passage bore 2140, which makes a passage communicating the anode chamber 210 with the outside is formed in the frame-shaped member 214.

[0074] The same manufacturing method as that described in First Embodiment for manufacturing the partition wall 11 allows manufacturing the partition-wall body 211.

[0075] The nipple-shaped head 217 comprises a pillar-shaped upper member 218 and a pillar-shaped lower member 219, forming the configuration of a two-staged pillar-shaped protuberance, as its vertical cross section is illustrated in FIG. 5. The upper member 218 has 10 mm approximately in outside diameter, and 8 mm approximately in height. The lower member 219 has 13 mm approximately in outside diameter, and 12 mm approximately in height.

[0076] A groove 2190 is formed at around the middle in the lower face of the lower member 219. The groove 2190 pierces the both cross-sectionally rectangular side faces of the lower member. The groove 2190 has 6 mm approximately in width, and 10 mm approximately in depth. To the groove the partition-wall body 211 is attached at one of the opposite ends in which the passage bore 2140 is formed.

[0077] A passage bore 2175 is formed in the upper member 218 of the nipple-shaped head 217. The passage bore 2175 is opened at one of the opposite ends to the upper member 218 of the nipple-shaped head 217, and is opened at the other one of the opposite ends to the groove 2190. The passage bore 2175 is composed of an upper axial-bore portion 2176, and a lower axial-bore portion 2177. The upper axial-bore portion 2176 has 4 mm approximately in inside diameter, and 5 mm approximately in depth. The lower axial-bore portion 2177 has 3 mm approximately inside diameter, and 7 mm approximately in depth.

[0078] The following manufacturing processes make it possible to produce the nipple-shaped head 217: forming a pillar-shaped green compact made of alpha-alumina and having a size that is a bit larger than the predetermined dimensions; shaping the green compact machining; sintering the shaped green compact; and then finishing the sintered green compact the predetermined dimensions by machining.

[0079] The partition wall 21 is available by joining the nipple-shaped head 217 at one of the opposite ends, in which the passage bore 2140 is formed, to the partition-wall body 211 with a glass solder.

[0080] In the same manner as the partition wall 11 according to First Embodiment, the partition wall 21 likewise comprises the nipple-shaped head 217 integrated at the thick lower member 219 with the partition-wall body 211. Thus, the thick lower member 219 enhances the integrality between the nipples-shaped head 217 and the partition-wall body 211.

[0081] Descriptions on how the sodium-sulfur battery 2 according to Second Embodiment is constructed are abbreviated herein because it is constructed identically with that of the sodium-sulfur battery 1 according to First Embodiment.

[0082] The method for manufacturing the partition wall 21 of the sodium-sulfur battery method which comprises the steps of: dividing the partition wall 21 into two components parts, the partition-wall body 21 and nipple-shaped body 217; and thereafter integrating the two component parts is effective in adopting a forming method in which an electrophoretic deposition process produces only a green compact with a substantially equal wall thickness.

Third Embodiment

[0083] A sodium-sulfur battery 3 according to Third Embodiment of the present invention will be hereinafter described based on FIG. 6. The sodium-sulfur battery 3 comprises a modified partition wall 31, a modified cathode container 32, and a modified fine-tubed fitting 36, instead of the partition wall 11, cathode container 12 and fine-tubed fitting 16 of the sodium-sulfur battery according to First Embodiment. The other constituent elements of the sodium-sulfur battery 3 are identical with those of the sodium-sulfur battery 1. FIG. 6 illustrates a vertical cross section of a major part of the sodium-sulfur battery 3. Note that the cross section shown in FIG. 6 corresponds to a cross section viewed in such a direction as turning the cross section shown in FIG. 4 by 90 deg. That is, the viewing direction is identical with the direction in which FIG. 5 is viewed.

[0084] The partition wall 31 comprises a plate-shaped partition-wall body 311 formed of beta-alumina, and a nipple-shaped head 317 formed of alpha-alumina. The partition-wall body 311 and head 317 are joined integrally to one another with a glass solder.

[0085] The partition-wall body 311 has the shape of a squared plate, and comprises a front-side member 312, a rear-side member 313, a frame-shaped member 314, and pillar-shaped members 315. An interspace between the front-side member 312 and the rear-side member 313 makes an anode chamber 310. A passage bore 3140, which makes some of a passage communicating the anode chamber 310 with an external sodium tank or container, is formed in the framed member 314. Note that the partition-wall body 311 identical with the partition-wall body 211 according to Second Embodiment.

[0086] The head 317 has the shape of a two-staged mound-shaped head, and comprises an upper staged portion 318, and a lower staged portion 319. The upper staged portion 318 includes an axial bore 3170 along with a top face 3181. The lower staged portion 319 includes an annular shouldered face 3191.

[0087] The axial bore 3170 in the head 317 include an upper axial bore 3171, and a lower axial bore 3172. The upper axial bore 3171 has 6 mm in inside diameter, and 7 mm in depth. The lower axial bore 3172 extends downward concentrically with the upper axial bore 3171, and has 3 mm in inside diameter, and 3 mm in depth. The upper staged portion 318 of the head 317 has 16 mm in outside diameter, and 5 mm in height. The lower staged portion 319 of the head 317 has 27 mm in outside diameter, and 26 mm in height. The annular shouldered face 3191 in the lower staged portion 319 has 16 mm in inside diameter, 27 mm in outside diameter, and 5.5 mm in width.

[0088] The lower staged portion 319 is provided with an engagement groove 3190 at the lower end. The engagement groove 3190 has center coinciding with the axial center of the lower staged portion 319, has 6 mm in width, and 16 mm in depth, and is opened at the opposite ends., The axial bore 3170 is opened in the upper face in the engagement groove 3190. The head 317 has a line-symmetric configuration with respect to the axial center of the axial bore 3170, and makes a two-staged head mound-shaped with 31 mm in height.

[0089] The head 317 is also produced by the same manufacturing method as the above-described method for the head 217 according to Second Embodiment. The partition wall 31 is obtained by joining the head 317 with a glass solder to one of the opposite ends of the partition-wall body 311 in which the through bore 3140 is formed. The partition wall 31 likewise comprises the head 317 integrated the thick lower stage 319 with the partition-wall body 311 in the same manner as the partition wall according to Second Embodiment. Thus, the thick lower staged portion 319 enhances the integrality between the head 317 and the partition-wall body 311.

[0090] The cathode container 32 comprises a container body 321, and a hat-shaped joint 322 formed integrally with a top-face site in the container body 321. The container body 321 formed in the shape of a rectangular parallelepiped with 105 mm approximately in each length and width, and 50 mm approximately in height. The hat-shaped joint 322 includes top-face portion 3221, and a cylindrically-walled portion 3222. The top-face portion 3221 with 28 mm in outside diameter is provided with an opening having 16 mm diameter. The cylindrically-walled portion 3222 with 28 mm in outside diameter and 5 mm in height extends downward from the circumferential rim of the top-face portion 3221. Moreover, the cathode container 32 is formed of a stainless-steel plate with 1 mm approximately in thickness.

[0091] To be more concrete, the cathode container 32 comprises two parts, namely, a top lidded part involving the hat-shaped joint 322, and a container-body part excluding the top lidded part an/or the hat-shaped joint 322. Note herein that the hat-shaped joint 322 includes the top-face portion 3221, and the cylindrically-walled portion 3222.

[0092] The following method achieves the joining between the top lidded part involving the hat-shaped joint 322 and the head 317 of the partition wall 31. First, the top lidded part is put at the hat-shaped joint 322 onto the head 317 of the partition wall 322. Then, the head 317 is protruded at the upper staged portion 318 through the opening in the top-face portion 3221 of the hat-shaped joint 322. Moreover, the top-face portion 3221 is brought into contact at the lower face with the annular shouldered face 3191 in the lower-staged portion 319 of the head 317, attaching the hat-shaped joint 322 to the head 317 of the partition wall 31. Under the circumstances, the inner peripheral face in the cylindrical-walled portion 3222 of the hat-shaped joint 322, and the outer peripheral face in the lower staged portion 319 of the head 317 are fitted coaxially with one another. Moreover, the top lidded part involving the hat-shaped joint 322 is fixed to and retained on the head 317 of the partition wall 31. In this way, the top-face portion 3221 in the thus fixed and retained hat-shaped joint 322 is held firmly on the annular shouldered face 3191 in the lower staged portion 319 of the head 317.

[0093] A predetermined pressing force is applied to the hat-shaped joint 322, which put under the above-described conditions, from an upward face in the top-face portion 3221 of the hat-shaped joint 322, pressing the top-face portion 3221 onto the annular shouldered face 3191 in the lower staged portion 319 of the head 317. The hat-shaped joint 322 and head 317, which are put under the pressed condition, are heated to a predetermined temperature, and are then kept under the heated condition for a predetermined time, joining the hat-shaped joint 322 at the lower face in the top-face portion 3221 and the head 317 at the annular face in the lower staged portion 319 to one another by thermal diffusion. Thus, the partition wall 31 is joined to the top lid of the cathode container 32.

[0094] Simultaneously with the above-described joining, a shorter portion 352 in the fine-tubed fitting 36 is joined to the annular top face 3181 in the upper staged portion 318 of the head 317 by thermal diffusion. The fine-tubed fitting 36 is composed of two portions, namely, a longer portion 351, and the shorter portion 362. The longer portion 361 is identical with a longer portion in the fine-tubed fitting 16 according to First Embodiment. As illustrated in FIG. 6, the shorter portion 362 in the fine-tubed fitting 36 comprises an end segment 363 formed in the shape of a flanged funnel, and a fine-tubed segment 354 formed in the shape of a tubule. The funnel-shaped end segment 363 includes an annular flange 3631, and a leg 3632 whose outer peripheral configuration is formed as a circular truncated cone. The leg 3632 integrated at the lower segment end with the lower end of the fine-tubed segment 354 by welding under such a condition as locating its core site concentrically with the fine-tubed segment 364.

[0095] As illustrated in FIG. 6, the fine-tubed fitting is joined at the shorter portion to the upper staged portion 318 of the head 317 by thermal diffusion. Specifically, the leg 3632 of the funnel-shaped end segment 363 is inserted into the upper axial bore 3171 in the upper staged portion 318 of the head 317. Then, the downward face in the flange 3631 of the shorter portion is brought into contact with the annular top face 3181 in the upper staged portion 318. Finally, the thus sub-assembled fine-tubed fitting 36 and head are heated at a predetermined temperature while applying a predetermined pressing force onto the upward face in the flange 3631, joining the flange 3631 at the downward face to the annular top face 3181 in the upper staged portion 318 by thermal diffusion.

[0096] The top lid and container body 321 of the cathode container 32 are integrated with one another in the following manner. First, felt made of carbon fibers impregnated with sulfur is put into the container body 321. Subsequently, the partition wall 31 is inserted into the container body 321, and then the top lid is put on the container body 321. Thereafter, the container body 321, and the top lid are integrated by laser welding, or are joined by crimping.

[0097] The sodium-sulfur battery 3 according to Third Embodiment is constructed as described above. The partition wall 31 and cathode container 32 of the sodium-sulfur battery 3 are integrated by the hat-shaped joint 322 of the cathode container 32. The hat-shaped joint 322 comprises the top-face portion 3221, and the cylindrically-walled portion 3222. The top-face portion 3221 is integrated with the annular shouldered face 3191 in the lower staged portion 319 in the head 317 of the partition wall 31, and the cylindrically-walled portion 3222 is integrated with the upper site of outer peripheral face in the lower staged portion 319. Accordingly, the upper side of the outer peripheral face in the lower staged portion 319, and the cylindrically-walled portion 3222 of the hat-shaped joint 322 first come to be subjected to strains, such as relative deformations, which act between the partition wall 31 and the cathode container 32. Consequently, strains, like relative deformations, which act between the partition wall 31 and the cathode container 32, do not act directly on the annular shouldered face 3191 and top-face portion 3221 making the joinder faces. Thus, the hat-shaped joint 322 lowers the possibilities of the integrated partition wall 31 and cathode container 32 being broken down at the joinder faces.

[0098] Likewise, the upper axial bore 3171 in the upper staged portion 318, and the circular truncated cone-shaped leg 3632 in the fine-tubed fitting 36 at first come to be subjected to strains, such as relative deformations, which act between the partition wall 31 and the sodium container 13.

[0099] Consequently, strains, like relative deformations, which act between the partition wall 31 and the sodium container 13, do not act directly on the joinder faces made between the annular top face 3181 in the upper staged portion 318 and the flange 3631 in the funnel-shaped end segment. Thus, the upper axial bore 3171 and leg 3632 lower the possibilities of the integrated partition wall 31 and sodium container 13 being broken down at the joinder faces.

Explanation on Reference Numerals

[0100] (1, or 3): Sodium-sulfur Battery;

[0101] (11, 21 or 31): Partition Wall;

[0102] (12 or 32): Cathode Container;

[0103] 13: Sodium Container;

[0104] (16 or 36): Fine-tubed Fitting;

[0105] (111, 211 or 311): Partition-wall Body;

[0106] (117 or 217): Nipple;

[0107] 121: Container Body; and

[0108] 122: Cap