CA1074858A

CA1074858A - Lithium-bromine cell and method of making the same

Info

Publication number: CA1074858A
Application number: CA262,100A
Authority: CA
Inventors: Ralph T. Mead; Wilson Greatbatch; Norbert W. Frenz (Jr.); Frank W. Rudolph; Robert L. Mclean
Original assignee: ELEANOR AND WILSON GREATBACH FOUNDATION
Current assignee: ELEANOR AND WILSON GREATBACH FOUNDATION
Priority date: 1975-09-29
Filing date: 1976-09-27
Publication date: 1980-04-01
Also published as: FR2326050A1; FR2326050B1; MX143038A; DE2644417A1; IL50695A; AU503213B2; AU1816176A; SE7610751L; GB1554758A; NL7610804A; JPS5259815A

Abstract

ABSTRACT OF THE DISCLOSURE
A lithium-bromine cell comprising a casing which can be of electrically conducting material and containing a lithium anode element from which a sealed conductor ex-tends through the casing. A filling element which can be of electrically conducting material and which has a passage therethrough is fixed to the sealed casing with one end of the passage in communication with the interior of the casing and the other and externally exposed.
Bromine is introduced through the passage to the interior of the casing into operative relationship with the lithium anode whereupon the passage is closed to complete the cell.
The electrically conducting casing serves as a cathode current collector in operative contact with the bromine cathode, and after closing of the passage the electri-cally conducting filling element serves as an electrical terminal for the cell. An electrical potential difference exists between the terminal and the anode conductor during operation of the cell.

Description

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BACKGROU~V OF THE I~VENTION
_ _ This invention relates to the conversion of chemical energy to electrical energy, and more particularly to a new and improved lithium-bromine cell and method oE making the same.
In the development of solid electrolyte batteries, lithium is recognized as a very desirable material for the negative electrode, i.e. the anode on discharge, in a non-aqueous cell. The cell of the present invention includes a lithium anode and a bromine cathode to utili~e the desirable characteristics of bromine, among which are a significant degree of chemical activity, a moderately low molecular weight, and a significant level of energy density. In making a lithium-bromine cell, it is necessary to consider, among other factors~ that bromine normally is in the form of a liquid which emits vapors.
SUMMARY OF THE INVENTION
It is therefor, an object of this invention eO provide a new and improved lithium-bromine cell and method of making the same.
In one particular aspect the present invention provldes 20 a method of making a lithium-bromine cell comprising the steps of:
a) providing a casing;
b) placing lithium anode means in said casing;
c) providing a filling element having a passage there-through;
d) sealing said casing in a manner such that said filling element is fixed to said casing with one end of said passage in communication with the inter-ior of said casing and the other end externally ex-posed;
e) in~roducing bromine through said passage in said filling element to the interior of said casing into operative relationship with said lithium anode means;
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f) closing said passage of said filling element.
In another particular aspect the present invention provides a lithium-bromine cell comprising: .
a) a casing of electrically conducting material;
b) anode means positioned within said casing and comprising a lithium element having an exposed surface portion and another surface portion;
c) electrical conductor means operatively connected to said other sur~ace portion of said lithium element and 0 extending from said casing;.
d~ means for sealing said conductor means from the remainder of said cell;
e) a bromine cathode within said casing and in operative contact with said exposed surface portion oE said lithium element and with said casing in a manner such that said casing serves as a cathode current collector;
f) terminal means on said casing and comprising a hollow element of electrical conducting material having an internal passage in communication with the interior of said casing and :
0 means closing said passage whereby prior to closing said passage said element functions to allow introduction of bromine : :
to the interior of said casing into operative relationship with .
said lithium anode element and after closing said passage said element functiong as an electrical terminal and an electrical potential difference exists between said terminal and said conductor means during operation of said ce`ll; and g) a solid lithium bromide electrolyte formed between `:
said lithium anode.and said bromine cathode.
In a further particular aspect the present invention .
0 provides a lithium-bromine cell compr:Lsing:
a) a casing of electrically conducting material; .

b) anode means positioned within said casing and comprising a li~hium element having an exposed surface porti.on and another surface portion; :~

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- c) electrical conductor means operatively connected to said other surface portion of said lithium element and extending from said casing;
d) means for sealing said conductor means Erom the remainder of said cell;
e) a bromine cathode within said casing and in operative contact with said exposed surface portion of said lithium element and with said casing in a manner such that said casing serves as a cathode current collector; and f) a solid lithium bromide electrolyte formed between said lithium anode and said bromine cathode.
The foregoing and additional advantages and characterizing features of the present invention will become clearly apparent upon a reating of the ensuing detailed de-cription ..
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1 together with the included drawing wherein:
BR _F DESCRIPTIO~ OF THE DRAWIMG FIGURES
Fig. 1 is a perspective view of a lithium-br~mine cell according to the present inven-tion;
Fig. 2 is a sectional view taken about on line 2-2 in Fig. l;
Fig. 3 is a fragmentary vertical sectional view wi-th parts shown in eleva-tion of the cell of Fig. l;
Fig. 4 is a side elevational view with parts removed illustra-ting a cell at one s-tage in the me-thod of the present invention;
Fig. 5 is a side elevational view with parts removed illustrating a cell at another stage in the method of the present inven-tion;
Fig. 6 is a side eleva-tional view with parts removed illustrating a cell at a stage in the method according to another emobdiment of the present inven-tion; and ;;--Fig. 7 is a fragmentary elevational view illustrating an alternative means closing the filling elemen-t in the cell of the present invention.
DETAILED DESCRIPTIO~ OF THE ILLUSTRATED EMBODIME~TS
Referring now to Fig. 1, a lithium-bromine cell according to the present inven-tion comprises a casing 10 of me-tal such as stainless steel which preferably is shaped or o-therwise formed to be hollow and generally rectangular in shape of an in-tegral cons-truction including a cuxved bo-ttom por-tion 11~ spaced-apart planar side wall por-tions .

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1 123 13 extending from the bottom portionl and spaced-apart curved end wall portions 14, 15 also extending from bottom por-tion 11 and joining corresponding ones of the side wall por-tions 12, 13. The bottom portion 11 is of compound curvature in that i-t is curved both in a direc-tion between -the side wall portions 12, 13 and also is curved in a direc-tion be-tween t~e end wall por-tions 14~ 15. This latter curva-ture of bot-tom port~on 11 is of the same degree as the curvature of the end wall portions 14~ 15 -thereby defining a con-tinuousJ curved surface around c~long the casing. The side wall portions 12~ 13 are generally parallel.
The casing has an opened top or end opposite the bottom por-tion 11 which is sealed closed by means of a lid 17 also of me-tal such as stainless steel.
Referring now to Figs. 2 and 3, the cell of the present invention further includes anode means com-prising a pair of lithium elements or plates 22, 24 having an anode current collector elemen-t 26 sandwiched or positioned therebetween. ~s shown in detail in Fig.
3, current collec-tor 26 is a relatively -thin, preferably a sheet of no. 12 mesh zirconium metal. A conductor strip 28 of nic~el or suitable metal is spot welded to collector element 26 along one edge thereol and an e1ectrical conduc-tor 30 which can be of nickelJ
platinum or suitable metal is welded at one end to the strip 28 and is of su~ficient leng~h allowing it to ~41~S~l 1 extend out from the casing for making external electri-cal connection -thereto. Conductor 30 is sealed from the remainder of -the cell by means including an in-sula-tor element generally designa-ted 32 which surrounds lead 30 and has a first por-tion 34 which is sand-wiched between -the lithium plates 22, 24 and a secondor body portion 36 which is cylindrical and lo-cated between the lithium plates and lid 17 when the cell is completed. The insulator 32 is of a material which in addition to being a non-conduc-tor of electri-city also is non-reactive with bromine. One form of material ~ound to per~orm s-tatifac-torily is a 1uoro-polymer material commercially available under t~e name Halar~ a trademark of -the Allied Chemical Company.
O~ course~ other materials having -these characteris-tics can be used for the insula-tor 32.
The anode assembly comprising -the li-thium elements 22, 24 and current collector 26 is fitted within an anode holding means or frame in the form of a s-trap 40 which embraces the anode assembly in a manner ex-posing at least one lithium surface. Strap 40 is of the aforementîoned Halar material or any similar ma-terial which is non-reac-tive wi-th bromine. In ~he present illus-tration, s-trap 40 surrounds the peri-pheral edges of -the lithit~ elements or plates 22, 24 in a snu~ sealing relationship. The opposi-te ends of s-trap 40 are provided with apertures of a si~e suf~icient to receive the insulator portion 34~ and :

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1 these ends are overlapped adjacent the insulator portion 34 as shown in Fig. 3. A ferrule 44 o~ metal such as stainless s-teel encloses a further portion of lead 30.
Ferxule 44 is threaded at one end ~not shown~ and is con-nected into insulator portion 36, -the inner surface of which also is threaded. Ferrule 44 is of generally hollow cylindrical shape, and the region between ferrule 44 and conductor 30 is filled by a g:Lass seal 46 formed therein to provide a metal-glass hermetic seal.
One illustrative method of forming the anode assembly is as follows. First there is provided a subassembly in-cluding lead 30 within the combination of insulator 32 and ferrule 44. Strap 40 then is assembled into place with the ends overlapped to align -the openings therein -which then are fit-ted onto insulator por-tion 34. The overlapping ends joined to insulator portion 34 can be sealed in place with a suitable cement which is non-reactive with bromine such as cyanoacryla-te cement commercially available under the name Permabond 101.
Similarly, the ~nction between insulator portion 36 and -the bot-tom portion of ferrule 44 can be cemented. Current collector 26~ conducting strip 28 and the end o~ lead 30 are spot welded -toge-ther whereupon -the lithium plates 22, 24 are positioned wi-thin strap 40 on opposite sides of the collector element 26 and insula-tor portion 34.
The subassembly -then is placed wi-thin a suitable fixture or support and is prassed together wi-th a suitable force, for example abou-t 3,000 lbs. The current collector 26, 1 strip 28, insulator portion 34 and the portion of lead 30 con-tained therein are sealed within the lithium elements 22, 24.
The material of strap 40 is pressure bondable to lithium with the result that the peripheral juncture at the edges of the lithium elements 22, 24 is enclosed or sealed by the strap 40.
If desired, the junction between the inner surface of strap 40 and the periphery of lithium elements 22, 24 can be sealed further by the aforementioned cement. The completed anode assembly thus has two exposed surfaces which are oppositely directed or disposed.
When the anode assembly is completed, the exposed surfaces of lithium elements 22 and 24 are provided with coatinys 48 and 50, respectively, of an organic electron donor component material, and the nature of the coatings 48, 50 and their role in the cell of the present invention will be described in further detail presently. The completed anode assembly is positioned in casing 10 as shown in Figs. 2 and 3, with the anode operative surfaces spaced from the inner surface of casing 10 .
The cell of the present invention further comprises a bromine cathode including a reyion of cathode material 54 with-in casing 10 and operatively contacting the exposed surfaces of the lithium^elements22, 24 and operatively contacting the inner surface of casing 10. Casing 10, being of electrically con-ducting material, serves as a cathode current collector. Ac-cording to a preferred mode of the present invention, the cathode material 54 comprises the reaction product of liquid bromine and an organic ~lectron donor material. In particular, the --. : .... . , . ... , :.: ., : , . : . .: . .

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1 cathode material 54 preferably comprises a charge transfer com-plex of bromine and an organic electron donor component materi-al. A preferred form of the organic electron donor component is polyvinyl pyridine polymer and in particular two-vinyl-pyridine polymer.
The cell of the present invention further comprises an element 58 on the casing and having a passage 60 therethrough which at one end thereof is in communication with the interior of casing 10 and which at the other end is externally exposed.
In particular, element 58 is in the form of a metal tube fixed to lid membeE 17. Tube 58 preferably a separate element which is fitted at one end into an aperture provided through lid 17 and welded thereto. Alternatively, the lid 17 and tube 58 could be formed integrally from a single piece of metal. Lid member 17 is fitted into pla~e in the open end of the casing and is ~ welded at 64 around the peripheral edge thereof to the corres-- ponding edge o~ the casing. In making the cell according to the method of the present invention, bromine is introduced through passage 60 in the filling element 58 to the interior of the casing and into operative relationship with the lithium anodeO
Then passage 60 is closed by suitable means, for example an element 66 which can be a plug of material which is non-reactive with bromine and which is sealed in place by sui-table non-reactive cement. Other arrangements for closing passage 60 can of course be employed. The metal tube 58 preferably of nickel also serves as an electrical terminal inasmuch as the casing 10 ser~es as a ~athode curren-t co~ector.

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48~i8 1 invention for making the lithium-bromine cell illustrated in Figs. 1-3. Fig. 4 illustrates a cell at a stage of the method prior to introduction of bromine. Thus, there is provided the casing 10, preferably of electrically conduc-ting material such as stainless steel, and the lithium anode means in the casing including the pair of lithium plates, the one plate 22 being shown in Fig. 4, surrounded by the strap or frame 40 at the peripheral edges thereof and having the anode electrical con-ductor 30 e~tending therefrom and out through the casing being enclosed and insulated by the insulator element 32 and ferrule 44. The exposed or operative surfaces of the lithium plates are coated with an organic electron donor material as previously described. According to a preferred mode of the present in-vention, an organic electron donor material is introduced into operative relationship with the lithium anode means prior to introducing bromine. An organic electron donor material found to perform satisfactorily is polyvinyl pyriding polymer, in particular two-vinyl pyridine polymer, and as shown in Fig. 4 the material is in the form of a pellet or wafer, one of which is designated 70 in Fig. 4. It is preferred to include two such pellets or wafers in a cell, one adjacent each exposed face of the lithium anode. By way of example, in a cell wherein the total weight of li-thium is about 1.0~ grams, each pelle-t or wafer has a weight of about 0.5 gram and is of a size having an outer diameter of about 1 3~32 inches and a thickness of about 0.035 inch. Alternati~ely, the organic electron donor material can be introduced in the form of crystals generally designated 7~ in Fig. 6 placed in the cell in a measured quantity adjacent . . , - , . .: . . . :

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1 both sides of the lithium anode.
After the organic electron donor material is placed in casing 10 in operative relationship with the lithium anode, the casing is sealed in a manner such tha-t the filling element or tube 58 is fixed to the casing with one end of the passage 60 in communication with the interior of the casing and the other end externally exposed. As i~ustrated in Fig. ~, the filling element 58 is fixed to lid 17, which, in turn, is fitted into the open end of casing 10 with the aperture in the lid receiv-ing ferrule 44 whereupon the lid is sealed to the casing bymeans of the weld 64 as previously described.
The next step in the method of the present invention is in-troducing bromine through passage 60 in the filling element 58 to the interior of the casing into operative relationship with the lithium anode. In particular, a small diameter tube or conduit 78 leading from a supply of bromine (not shown) is placed in fluid communication with passage 60, and in the present illus-tration tube 78 is insarted into and along with element 58 so that the open end of the tube 78 is within the casing 10. Liq-uid bromine in a measured quantity or volume is conveyed fromthe supply through the tube 78 into the casing 10, the level of bromine at this illustrative stage of the method being designated 80 in Fig. 5. Tube 78 can have an outer diameter such that it fits relatively snugly within the passage 60 to prevent or mini-mize escape of bromine vapors from within casing 10 to the out-side. If desired, the tube 78 can carry a suita~le seal for engaging the end of filling element 58. One illustrative form of supply and dispenser is a hypodermic syringe where conduit :

8~i3 1 78 is the needle thereof. The amount of liquid bromine intro-duced to casing 10 generally will be sufficient to at least cover the exposed surfaces of the lithium plates, and often will be filled to a level above the anode assembly and below the lid 17. After the predetermined amoun-t of bromine is introduced to casing 10, conduit 78 is removed from the filling element 58 and the passage 60 is closed as previously described. ~nother means for closing tube 5~ is illustrated in Fig. 7 wherein the outer end is pinched or otherwise mechanically formed into a flatened, clamped portion 84 which then can be further sealed by welding.
The liquid bromine in casing 10 reacts at room temperature with the organic electron material, i.e. poly-2-vinyl pyridine, and the reaction product is a charge transfer complex of an organic electron donor component, i.e. poly~2-vinyl pyridine, and bromine. Thus, the bromine-containing cathode material is formed in casing 10 upon introduction or in~ection of bromine to the interior thereof.
The lithium-bromine cell according to the present invention operates in the following manner. As soon as the bromine-containlng cathode material, for example the cathode material ;
54 in Figs. Z and 3, operatively contacts a lithium element, a solid lithium-bromine electrolyte begins to form at the inter-~ace. In the present illustration this occurs at the outer or oppositely-disposed surfaces of the two lithium elements 22 and 24. An electrical~potential difference will exist between the ~ -anode lead 30 and the cathode terminal 58 because casing 10 is of electrically conductive ma-terial and operatively contacts ~0~

1 the bromine-containing cathode material -to serve as a cathode current collector. The mechanism by which the foregoing is accomplished is believed to include migration of lithium ions through the electrolyte whereby lithium is the ionic species in the cell.
The method of the present invention is efficient, effec-tive, relatively easy to perform, and utilizes bromine in its natural or uncombined form as a starting product. Liquid bromine is introduced through a passage in a filling element to the interior of a sealed casing containing other cell components wherein the bromine-containing cathode material, i.e. a charge transfer complex of poly-2-vinyl pyridine and bromine, is formed in situ. Introducing or injecting bromine into a sealed cas-ing, i.e. after the casing lid is welded in place, avoids re-lease of bromine vapor to the surroundings thereby preventing contamination of the atmosphere with bromine vapor and prevent-ing interference of the bromine vapor with the weld.
In the cell of the present invention all parts of the anode -current collector 26 and conductor 30 are shielded or sealed from cathode material 54 and from the metal casin~ 10, 17. As a result, no insulation is needed between the cathode material 54 and the metal casing thereby enabling the metal casing 10, 17 to contact the bromine-containing cathode material and function as a very large cathode current collector. This improves cell performance and increases theoretical energy density due to the relatively large amo~nt of cathode material in contact with the curren~ collector. Another advantage of the foregoing ar rangement is that b~ having the filling element 58 selectri-1 cally conducting material, after in~ection of bromine and the closing of passage 60, the element provides another impor-tant function in serving as a cathode electrical terminal for the cell.
Table I presents electrical data obtained from a lithium-bromine cell according to the present invention as a function of cell life in hours. For example, the data entered in the first row of Table I was obtained sixteen hours after the cell was placed in operation. The impedance quantities indicate impedance measured at 100 hertz, add impedance measurements were made with a 100 kilohm resistance connected in parallel with the cell under test.
TABLE I
Open Circuit Voltage Cell Impedance Cell Life in HoursIn Volts ~n Ohms 16 3.373 90 64 3.417 76 88 3.422 81 112 3.424 84 The cell from which the foregoing data was obtained included a total lithium weight of about 1.2 grams and a total weight of -about 1.0 gram for two pellets of poly-2-vinyl pyridine. The . :
weight of the anode assembly was 2.24 grams prior to coating and

2.28 grams after coating. The completed cell wei~hed 13.09 grams before introduction of bromine and 27.03 grams after in-troduction of bromine. This ne-t weight of 13.94 grams bromine at 0.335 ampere-hours per gram energy density for bromine gives a stoichiometric energy capacity of 4O6 ampere hours. At a 1 utilization ra-te of 76 percen-t, the cell has a nominal energy capacity of 3.5 ampere hours. With an output voltage of 3.4 volts and a cell weight of 27 grams, the energy density of the cell is 450 watt-hours/Kilogram [3.4 volts x 3 5 ampere hours]
The weight ratio of bromine to organic electron donor material, i.e. poly-2-vinyl pyridine, in the completed cell is 13.94 grams: 1:04 grams or 13.3:1.
It is important that the bromine-containing cathode materi-al 54 is not allowed to come in contact directly with any por-tion of the electrical conducting means connected to the lithi-um elements of the anode, in particular anode current collector 26 and leads 28,30. Otherwise, this will cause an electronic conduction between the cathode material 54 and the anode current collector 26 or leads 29, 30 creating an electrical short circuit condition in the cell. In particular, any migration of the bromine-containing cathode material 54 directly to anode cur-; rent co~ector 26 or directly to leads 28, 30 instead of first reacting with a lithium element of the anode will result in a condition of electronic conduction thereby creating a short circuit in the cell. On the other hand, when the bromine-con-taining material 54 contacts only the lithium portion of the anode this gives rise first to a condition of ionic conduction and results in proper cell operation.
In the cell of the present invention, all parts of the anode current collector 26 and leads 28, 30 are sealed from cathode material 54 and from the metal casing. Anode current collector 26 and its connection through strip 28 to lead 30 are sealed within the sandwiched or pressure bonded assembly of ~L07~5~

1 lithium plates 22, 24. This seal is enhanced by the strap 40 which is of Halar or similar material which is non-reactive with bromine.
The foregoing arrangement together with the provision of insulator 32 and ferrule 44 with glass seal 46 provides an anode structure which is comple-tely sealed with the exception of the oppositely-directed operative lithium surface portions ; of the anode which are available to the cathode material 54.
All parts of anode current collector 26 and leads 28, 30 are shielded from the cathode material and from the cell casing. ~ ~ -Furthermore, the sealed anode assembly can be completed before the entire cell is assembled for efficiency in manufacturing.
The foregoing advantages are provided in a cell which is relatively simple in construction.
The material of coatings 48 and 50 on lithium elements 22 ;
and 2~, respectively, is an organic electron donor material of -~
the group of organic compounds known as charge transfer complex donors. The material of the coatings can be the organic elec-; tron donor material introduced into the cell casing prior to introducing bromine which then reacts to form the charge trans-fer complex of the cathode material 54, but other materials can be employed. A preferred material for the coatings is polyvinyl pyridine and it is applied to the exposed surfaces of lithium elements 22 and 24 in the following manner. A solution of poly-2-vinyl pyridine polymer in anhydrous benzene or other suitable solvent is prepared. The poly-2-vinyl pyridine is readily com-mercially available. The solution is prepared ~ith 2-vinyl-pyridine present in the range from about 10% to abou-t 20% by _ 16 -~7~858 1 weight with a strength of about 14% by weight of 2~vinyl-pyridine being preferred. While 2-vinyl pyridine, 4-vinyl pyridine and

3-ethyl 2-vinyl pyridine can be used, 2-vinyl pyridine is pre-ferred because of its more fluid characteristics in solution.
When the solution is prepared at a strenc3th below about 10% the resulting coating can be undesirably too thin and ~hen the solu-tion is prepared at a stren~th greater than about 20% the materi-al becomes difficult to apply. The solution is applied to the exposed surface of each lithium plate in a suitable manner, for example simply by application with a brush. The presence of the anhydrous benzene serves to exclude moisture thereby pre-ventin~ any adverse reaction with the lithium plate. The coated anode then is exposed to a desiccant in a manner sufficient to remove the benzene from the coating. In particular the coated anode is placed in a chamber with barium oxide solid material for a time sufficient to remove the benzene, which can be in the neighborhood of 24 hours. The foregoin~ procedure can be re-peated to provide multiple coatin~s or layers~ for example three, on each lithium plate.
~t is therefore apparent that the present invention ac-complishes its intended objects. While several embodiments of the present invention have been described in detail, this is for the purpose of illustration, not limitation.
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Claims

The embodiments of the invention in which an exclusive property ox privilege is claimed are defined as follows:

1. A method of making a lithium-bromine cell comprising the steps of:
a) providing a casing;
b) placing lithium anode means in said casing;
c) providing a filling element having a passage there-through;
d) sealing said casing in a manner such that said filling element is fixed to said casing with one end of said passage in communication with the interior of said casing and the other end externally exposed;
e) introducing bromine through said passage in said fill-ing element to the interior of said casing into opera-tive relationship with said lithium anode means; and f) closing said passage of said filling element.

2. A method according to claim 1, wherein said casing is of the type having an opening at one end closed by a lid member sealed thereto, said lid member having an opening therein, and wherein said step of providing said filler element comprises fixing said filler element to said lid with said passage in com-munication with said lid opening.

3. A method according to claim 2, wherein said casing is sealed by welding said lid to said casing.

4. A method according to claim 1, wherein said filling element is in the form of a tube and said passage is closed by sealing the exposed end of said tube.

5. A method according to claim 4, wherein said tube is of metal and the exposed end is sealed by pinching and welding.

6. A method according to claim 1, wherein said bromine is introduced in liquid form.

7. A method according to claim 1, further including in-troducing an organic electron donor material into operative relationship with said lithium anode means prior to introducing bromine.

8. A method according to claim 7, wherein said organic electron donor material comprises polyvinyl pyridine polymer.

9. A method according to claim 7, wherein said organic electron donor material is solid in form and placed in said casing adjacent said lithium anode.

10. A method according to claim 9, wherein said organic electron donor material is in the form of a solid wafer of poly-2-vinyl-pyridine.

11. A method according to claim 7, wherein said organic electron donor material comprises poly-2-vinyl pyridine and wherein the ratio weight of bromine to poly-2-vinyl pyridine is about 13:1.

12. A method according to claim 1, wherein said anode means comprises a lithium element having an exposed surface adapted to operatively contact said bromine, and further including the step of applying to said surface a coating of an organic elec-tron donor material prior to said step of introducing bromine.

13. A method according to claim 12, wherein said organic electron donor material comprises polyvinyl pyridine polymer.

14. A method according to claim 1, wherein said casing is of electrically conducting material and wherein said step of in-troducing bromine is performed in a manner placing said bromine into operative relationship with said casing whereby said cas-ing serves as a cathode current collector.

15. A method according to claim 14, wherein said filling element is of electrically conducting material and wherein said step of closing said passage is performed in a manner causing said filling element to serve as an electrical terminal for said cell.

16. A lithium-bromine cell comprising:
a) a casing of electrically conducting material;
b) anode means positioned within said casing and compris-ing a lithium element having an exposed surface por-tion and another surface portion;
c) electrical conductor means operatively connected to said other surface portion of said lithium element and extending from said casing;
d) means for sealing said conductor means from the re-mainder of said cell;
e) a bromine cathode within said casing and in operative contact with said exposed surface portion of said lithium element and with said casing in a manner such that said casing serves as a cathode current col-lector;
f) terminal means on said casing and comprising a hollow element of electrical conducting material having an internal passage in communication with the interior of said casing and means closing said passage whereby prior to closing said passage said element functions to allow introduction of bromine to the interior of said casing into operative relationship with said lithium anode element and after closing said passage said element functions as an electrical terminal and an electrical potential difference exists between said terminal and said conductor means during operation of said cell; and g) a solid lithium bromide electrolyte formed between said lithium anode and said bromine cathode.

17. A cell according to Claim 16, wherein said terminal means comprises a tube fixed at one end to said casing with the interior of said tube being in communication with the interior of said casing and wherein said passage closing means is adjacent the opposite end of said tube.

18. A cell according to Claim 17, wherein said passage closing means comprises a weld at said end of said tube.

19. A cell according to Claim 17, wherein said passage closing means comprises a seal in said tube adjacent said end of said tube.

20. A cell according to Claim 16, wherein said casing is of the type having an opening at one end closed by a lid member sealed thereto, said lid member having an opening therein, and wherein said terminal means is fixed to said lid member with said internal passage being in communication with said lid member opening.

21. A cell according to Claim 16, wherein said bromine cathode comprises a charge transfer complex of an organic donor component material and bromine.

22. A cell according to Claim 16, further including a coating of an organic electron donor material on said exposed surface of said lithium.

23. A lithium-bromine cell comprising:
a) a casing of electrically conducting material;
b) anode means positioned within said casing and comprising a lithium element having an exposed surface portion and another surface portion;
c) electrical conductor means operatively connected to said other surface portion of said lithium element and extending from said casing;
d) means for sealing said conductor means from the remainder of said cell;
e) a bromine cathode within said casing and in operative contact with said exposed surface portion of said lithium element and with said casing in a manner such that said casing serves as a cathode current collector; and f) a solid lithium bromide electrolyte formed between said lithium anode and said bromine cathode.

24. A cell according to Claim 23, wherein said bromine cathode comprises a charge transfer complex of an organic donor component material and bromine.

25. A cell according to Claim 23 further including a coating of an organic electron donor material on said exposed surface of said lithium element.