Abstract:
An economical method for manufacturing an electrode assembly of virtually any shape to fit into a similarly shaped casing without compromising volumetric efficiency is described. This is accomplished by providing an electrode assembly of multiplate anode and cathode plates that substantially match the internal shape of the casing. A layer of adhesive membrane is provided between the plates to keep them together and provide adequate alignment and spacing between electrodes. That way, no matter what shape the device being powered by the cell dictates the electrode assembly assumes, as little internal volume as possible is left unoccupied by electrode active materials.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. provisional application Ser. No. 61/500,722 filed Jun. 23, 2011. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to the conversion of chemical energy to electrical energy, and more particularly, to an alkali metal electrochemical cell. The cell can be of either a primary chemistry, for example a lithium/silver vanadium oxide (Li/SVO) cell, or a secondary chemistry, for example a lithium-ion secondary cell. 
     Currently, lithium-based primary and secondary cells are used in a large number of medical and commercial applications including implantable medical devices, telephones, camcorders and other portable electronic equipment. They come in a variety of shapes, sizes and configurations as coin, button, and cylindrical and prismatic cells. There are several other applications, however, for which lithium-containing cells may be used but for which present day constructions are unsuitable. Such applications include the next generation of medical instruments, implantable medical devices and surgical tools. For many of these applications, the use of prior art lithium-containing cells is unacceptable because of their shape and construction. In certain types of medical applications, irregularly shaped prismatic cells that are sized for use within the human body are most preferred. 
     2. Prior Art 
     Currently, lithium-containing cells are used to power a number of implantable medical devices including ventricular assist devices, artificial hearts and implantable hearing aids, among others. The predominantly used method for manufacturing such cells is to position a single anode and a single cathode overlaying each other with an intermediate separator sandwiched between them. This electrode assembly is then wound together about a mandrel. 
     A representative wound cell electrode assembly  10  is shown in  FIG. 1 . The electrode assembly  10  comprises an anode electrode  12  and a cathode electrode  14  disposed on either side of an intermediate separator  16 . This anode/separator/cathode structure is then positioned on a plate-shaped mandrel having opposed planar sides (not shown) that is rotated to provide the wound assembly shown. The resulting wound electrode assembly  10  has relatively planar opposed sides  18  and  20  extending to curved ends  22  and  24 . The upper and lower edges (only upper edge  26  is shown) of the anode  12 , cathode  16  and intermediate separator  14  are also relatively planar. 
     The electrode assembly  10  is then housed in a prismatic-shaped casing  28  ( FIG. 2A ) of a deep drawn type. Casing  28  is comprised of opposed major face walls  30  and  32  extending to and meeting with generally planar end walls  34  and  36  at curved corners. The face walls  30 ,  32  and end walls  34 ,  36  connect to a planar bottom wall  38 . A lid  40  secured to the upper edges of face walls  30 ,  32  and end walls  34 ,  36 , such as by welding, closes the casing. The lid  40  supports a terminal lead  42  insulated from the lid and casing  28  by a glass-to-metal seal  44 . There is also a fill opening  46  in the lid closed by a closure means  48 , as is well known by those skilled in the art. The lead  42  is connected to one of the electrodes, typically the cathode, while the casing  28  and lid  40  serve as the lead for the other electrode, typically the anode. This describes a case-negative cell design. 
       FIG. 25  shows a cylindrically-shaped casing  50  closed by a lid  52  supporting a glass-to-metal seal  54  insulating a terminal lead  56  from the lid. Casing  50  is similar to the casing  28  of  FIG. 2A  except that it is cylindrical instead of being of a prismatic shape. In this case, the mandrel used to wind the electrode assembly is of a cylindrically shaped rod. 
     Winding an anode/separator/cathode structure limits the geometric configuration of the resulting cell to cylindrical or generally rectangular shapes. In some applications, these shapes are inefficient because the internal casing volume is grossly under-utilized. For example, the curved ends  20 ,  22  of electrode assembly  10  fit well into the ends  34 ,  36  of the prismatic-shaped casing  10  ( FIG. 2A ) and the upper  26  and lower edges fairly match the shape of the lid  40  and bottom wall  38 , respectively. However, if the bottom wall of casing  10  is shaped other than relatively planar, that would not be true. Depending on the shape of the bottom wall  38 , there could be a large volume of unused space inside the casing. This is because it is difficult to provide wound electrode assemblies having other than planar upper and lower edges. 
     As such, a variety of multiplate electrode assemblies have been used to address this problem. Such multiplate electrode assembly solutions have been disclosed in U.S. Pat. No. 6,881,514 to Ahn et al., U.S. Pat. No. 6,328,770 to Gozdz, U.S. Pat. No. 6,136,471 to Yoshida et al., as well as U.S. patent application publications 2005/0260490 to Persi et al., and 2007/0100012 and 2009/0208832, both to Beard. These disclosures discuss embodiments utilizing various chemicals to aid in the binding of the electrodes to the separator layer. When laminated together, these chemicals typically block the pore structure of the separator, thereby reducing the performance of the cell. 
     Still other electrochemical cells have been designed with various mechanical joint methods to hold and stack the electrode and separator plates. Such embodiments have been disclosed in U.S. Pat. No. 4,996,128 to Aldecoa et al., U.S. Pat. No. 5,288,565 to Gruenstern, U.S. Pat. No. 6,627,347 to Fukuda et al., U.S. Pat. No. 7,179,562 to Zolotnik et al., as well as U.S. patent application publications 2001/0041288 to Onishi et al., and 2003/0171784 to Dodd et al. These disclosures provide electrochemical cells with various mechanical joining methods to hold the stacked electrode plates and separators together. These mechanical joining embodiments utilize joints that occupy space within the cell. This space, which could have been utilized by electrochemical materials, reduces the volumetric efficiency of the electrochemical cell. In addition, the mechanical joints of these prior art cells generally have alignment issues in which the electrode plates and separators are not properly aligned. Furthermore, over time, these mechanical joining methods could shift or change due to mechanical stresses and/or chemical reactions within the cell. As a result, the mechanical joining embodiments compromise the electrical performance of the cell. 
     Accordingly, a need exists for an electrochemical cell with an improved multiplate construction. That, among other things, improves electrode and separator alignment and eliminates separator pore structure blockage in an assembly that maximizes utilization of the cell&#39;s internal volume. The electrode assemblies of the present invention are suitably configured for housing in casings of other than the traditional prismatic shape ( FIG. 2A ) or cylindrical shape ( FIG. 2B ). Such “irregularly shaped” electrode assemblies and the casings that house them are particularly well suited for powering implantable medical devices, and the like. Medical devices are being implanted in increasingly disparate parts of the body. For this reason, they must be of varied shapes and sizes, which, in turn, drives the shape of the associated power source. Thus, a process is needed for manufacturing electrochemical cells having shapes that take advantage of as much of the internal volume in a casing, even one of an irregular shape, as possible. 
     SUMMARY OF THE INVENTION 
     The present invention describes an economical method for manufacturing an electrode assembly of virtually any shape to fit into a similarly shaped casing without compromising volumetric efficiency. This is accomplished by providing an electrode assembly of a multiplate design. The anode and the cathode plates are shaped to substantially match the internal shape of the casing. That way, no matter what shape the medical device dictates the electrode assembly assume, as little internal volume as possible inside the casing is left unoccupied by electrode active materials. 
     This is accomplished using an adhesive membrane positioned between adjacent anode and cathode electrode plates. The adhesive membrane is positioned between the electrodes such that it joins them therebetween without increasing the electrode assembly volume. In addition, the adhesive membrane provides consistent spacing and alignment between the electrode plates without adversely reacting with the electrolyte within the cell. 
     These features of the present invention will become increasingly more apparent to those skilled in the art by reference to the following detailed description of the preferred embodiments and the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a prior art wound electrode assembly. 
         FIG. 2A  is a perspective view of a prior art prismatic shaped electrochemical cell. 
         FIG. 2B  is a perspective view of a prior art cylindrically shaped electrochemical cell. 
         FIG. 3  illustrates a perspective view of an embodiment of an electrochemical cell of the present invention. 
         FIG. 3A  shows an enlarged cross-sectional view of as section of adhesive membrane according to the present invention. 
         FIG. 4  is a cross-sectional side view of an embodiment of a multiplate electrode assembly according to the present invention. 
         FIG. 4A  illustrates a top view of the multiplate electrode assembly of  FIG. 4 . 
         FIG. 5  is a cross-sectional side view of an alternate embodiment of a multiplate electrode assembly of the present invention. 
         FIG. 6  is a cross-sectional side view of an alternate embodiment of a multiplate electrode assembly of the present invention. 
         FIG. 7  is a cross-sectional side view of an additional embodiment of a multiplate electrode assembly of the present invention. 
         FIG. 8  is a cross-sectional side view of an alternate embodiment of a multiplate electrode assembly comprising electrode plates of uneven length. 
         FIG. 9A  shows a side profile view of an embodiment of an electrochemical cell of the present invention. 
         FIG. 9B  illustrates a side end view of the embodiment of the electrochemical cell shown in  FIG. 9A . 
         FIG. 9C  is a front-end view of the embodiment of the electrochemical cell shown in  FIG. 9A . 
         FIG. 10A  shows a side profile view of an embodiment of an electrochemical cell comprising an alternate geometric shape of the present invention. 
         FIG. 10B  illustrates a side end view of the embodiment of the electrochemical cell shown in  FIG. 10A . 
         FIG. 10C  is a front-end view of the embodiment of the electrochemical cell shown in  FIG. 10A . 
         FIG. 11A  shows a side profile view of an embodiment of an electrochemical cell comprising an alternate geometric shape of the present invention. 
         FIG. 11B  illustrates a side end view of the embodiment of the electrochemical cell shown in  FIG. 11A . 
         FIG. 11C  is a front-end view of the embodiment of the electrochemical cell shown in  FIG. 11A . 
         FIG. 12A  shows a side profile view of an embodiment of an electrochemical cell comprising an alternate geometric shape of the present invention. 
         FIG. 12B  illustrates a side end view of the embodiment of the electrochemical cell shown in  FIG. 12A . 
         FIG. 12C  is a front-end view of the embodiment of the electrochemical cell shown in  FIG. 12A . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The benefits of the present invention are best understood by first illustrating an irregularly shaped casing housing an electrochemical cell. Irregularly shaped casings are becoming increasingly more common, especially in implantable medical devices. These include cardiac defibrillators, cardiac pacemakers, neuro-stimulators, drug pumps, and the like. Such medical devices are designed to reside inside the body so that their shape is as unobtrusive as possible. This, in turn, dictates the shape of the associated power source. 
       FIG. 3  is a perspective view, partly broken away, of an electrochemical cell  60  comprising a multiplate electrode assembly  62  housed in an irregularly shaped casing  64  according to the present invention. The electrode assembly  62  comprises a plurality of anode or negatively charged electrode plates  66  in electrical association with a plurality of cathode or positively charged electrode plates  68  having a separator  70  disposed intermediate each anode and cathode plate to prevent direct physical contact between them. 
     An adhesive membrane  72  is preferably positioned intermediate each anode and cathode plate  66 ,  68 , about at least a portion of the perimeter of either plate, to bond each of them together. The adhesive membrane  72  comprises a polymeric layer upon which an adhesive material is affixed that facilitates bonding. The adhesive material may reside on either one or both sides of the front and back of the membrane. In a preferred embodiment, the adhesive membrane  72  is designed to hold the anode and cathode plates  66 ,  68  together within the electrode assembly stack. More specifically, the adhesive membrane  72  is preferably positioned about the perimeter of the electrode plates  66 ,  68  such that the electrochemical reaction, between the plates, is not, impeded. As will be discussed more in detail, the adhesive membrane  72  may be formed in a strip or single parallel layer formation which is positioned along at least a portion of the perimeter of either of the plates  66 ,  68 . Alternately, the adhesive membrane  72  may be formed in a. “ring like” shape in which the adhesive membrane  72  circumferentially surrounds the active material of either the anode  66  or cathode  68  plate. 
       FIG. 3A  illustrates an embodiment of the adhesive membrane  72 . The adhesive membrane is preferably composed of a material that does not react with the electrolyte within the cell. This is designed such that the adhesive membrane material does not adversely react within the cell, degrading the cell&#39;s electrical performance. More specifically, the adhesive membrane  72  is preferably composed of a silicone or acrylic material. In a preferred embodiment, the adhesive membrane  72  comprises a carrier layer  74  of polypropylene on which an adhesive layer  76  of Acryl resides on a carrier layer top surface  78  and/or a carrier layer bottom surface  80 . In a preferred embodiment, the thickness of the carrier layer  74  ranges from about 10 um to about 100 um and the thickness of the adhesive layer  76  ranges from about 1 um to about 10 um. The adhesive membrane  72  may be obtained from Tapex Inc. of Gyeonggi-do Korea. 
     The adhesive membrane  72  provides many benefits to the electrode stack assembly. First, the adhesive layer  76  of the membrane  72  minimizes movement of adjacent plates within the electrode stack assembly. Second, since the adhesive membrane  72  is positioned between the current collector plates  66 ,  68  about the perimeter of the plates, the membrane  72  does not occupy additional space within the assembly, thereby facilitating an efficient stack design within the casing  64  of the electrochemical cell  60 . Third, the position of the membrane  72  about the perimeter of the plates  66 ,  68  facilities improved electrode plate alignment and reduces uneven current densities. Fourth, the controlled thickness of the adhesive membrane  72  provides an even cathode-to-anode distance which also ensures a proper electrochemical reaction between adjacent plates  66 ,  68 . Fifth, since the adhesive membrane  72  is positioned about the perimeter of the plates  66 ,  68  the membrane  72  provides additional electrical insulation between the anode electrode  66  and cathode electrode  68  which minimizes the possibility of an undesirable electrical short circuit therebetween. 
     Proper alignment of the plates  66 ,  68  is an important parameter in cell design in that it improves the electrochemical reaction rate. A correct electrode plate alignment is particularly important in lithium ion exchange of secondary cells. Uneven current densities often occur in the coiled electrode design of the electrochemical cell  10  of the prior art ( FIG. 1 ). Many times the construction of these coiled electrode assemblies result in areas of uneven mechanical stresses within the coil. As the coil is wound, generally the inner layers of the coil are wound tighter than the outer coil layers. These uneven stresses within the coil often result in uneven current densities within the coil, which may adversely affect the chemical reactions within the cell. For example, the inner-coiled layers, that are wound tighter, generally have a greater current density than the outer layers. Therefore, these coiled electrode assembly designs are often prone to undesirable electrical performance issues. 
     If the cell is intended to be of a case-negative configuration, then the outwardly most plates are of the anode electrode, preferably in direct contact with the inside of a casing  64 . The casing may comprise materials such as stainless steel, mild steel, nickel-plated mild steel, titanium, tantalum or aluminum, but not limited thereto, so long as the metallic material is compatible for use with components of the cell. 
     As shown in  FIG. 3 , the casing  64  is of a deep drawn type having opposed front and back side walls  82  and  84  extending to a left planar end wall  86  and a right planar end wall  88 . As illustrated, the left end wall  86  is of a longer length than the right end wall  88 . The side walls  82 ,  84  and end walls  86 ,  88  each extend to and meet with a bottom wall  90  to form the casing comprising a unitary deep drawn can. Since the left end wall  86  is of a greater length than the right end wall  88 , the bottom wall  90  is of an irregular curved shape of a varied radii. This means that if a wound electrode assembly of the type shown in  FIG. 1  were housed inside casing  64 , there would be a considerable amount of internal volume left unoccupied by active components, especially adjacent to the bottom wall  90 . This detracts from volumetric efficiency. 
     A lid  92  secured to the upper edges of face walls  82 ,  84  and end walls  86 ,  88 , such as by welding, closes the casing  64 . The lid  92  supports an anode terminal lead  94  insulated from the lid and casing by a glass-to-metal seal  96 . In addition, in the case of a secondary chemistry, the lid  92  may support a cathode terminal lead  98  insulated from the lid and casing by a second glass-to-metal seal  100 . There may also be an electrolyte fill opening  102  in the lid closed by a closure means, such as a stainless steel ball, as is well known by those skilled in the art. The leads  94 ,  98  are connected to their respective electrodes, either the anode  66  or the cathode  68 . 
     Alternatively, the casing  64  and lid  92  may serve as the lead for either electrode, typically the anode. This describes a case-negative primary cell design. If a case-positive primary cell design is desired, lead  92  is connected to the anode plates  66  while the cathode plates  68  are electrically connected to the casing and the lid. 
       FIG. 4  illustrates a cross-sectional view of an embodiment of a bi-cell multiplate electrode assembly  104  of the present invention. The multiplate electrode assembly  104  comprises one anode or negative electrode plate  66  and one cathode or positive electrode plate  68 . This bi-cell electrode assembly  104  illustrates a basic example of the electrochemical cell  60  of the present invention. 
     As illustrated, the anode plate  66  comprises an anode right end wall  106  and an anode left end wall  108 , both extending from an anode upper wall  110  to an anode bottom wall  112  and being intermediate first and second major sides. An anode current collector  114  extends longitudinally through the anode plate  66  from the anode right end wall  106  to the anode left end wall  108 . 
     As shown, a first anode current collector lead portion  116  extends through the anode left end wall  108 . An anode or negative electrode active material  118  contacts both a top  120  and bottom  122  surface of the current collector  114  to form the anode  66 . However, the anode material  118  may be positioned such that it only contacts one surface, either the top or bottom surface  120 ,  122 , of the anode current collector  114 . 
     The cathode or positive electrode plate  68  resides immediately adjacent to the anode plate  66 . The cathode plate  68  comprises a cathode right end wall  124  and a cathode left end wall  126 , both extending from a cathode upper wall  128  to a cathode bottom wall  130  and being intermediate first and second major sides. A cathode current collector  132 , comprising a top surface  136  and a bottom surface  138  extends longitudinally through the cathode  68  from the left end wall  126  to the right end wall  124 . A cathode or positive electrode material  134  is positioned on the cathode current collector  132 . As shown, the cathode material  134  resides on both sides of the cathode current collector  132  to form the cathode  68 . However, the electrode assembly may be constructed such that the cathode material  134  only resides on one surface of the cathode current collector  132 . 
     A cathode separator membrane  140  is preferably positioned about the perimeter of the cathode plate  68 . As shown in the embodiment of  FIG. 4 , the cathode separator membrane  140  comprises a separator right end wall  142  and a cathode separator left end wall  144 , both extending from a cathode separator upper wall  146  to a cathode separator bottom wall  148  and being intermediate first and second major sides. The cathode current collector  132  preferably extends through one of the cathode separator&#39;s right or left end walls  142 ,  144  to facilitate electrical contact of the cathode current collector. The membrane  140  is preferably constructed of one layer. To maximize efficiency of space within the cell, however, the separator membrane  140  may be constructed of two or more sub-layers. 
     As illustrated in  FIGS. 4 and 4A , the adhesive membrane  72  is positioned about a perimeter  150  of the anode plate  66 . More specifically, the adhesive membrane  72  is positioned within a space extending from about 0.25 inches of an outer edge  153  of the anode plate  66 . Furthermore, the cathode plate  68  may be positioned within an inner perimeter  152  of the adhesive membrane  72  such that the adhesive membrane extends circumferentially around the cathode plate  68 . In addition, a portion of adhesive membrane  72  may be positioned immediately adjacent an exterior surface  154  of the cathode left end wall  126  and immediately adjacent an exterior surface  156  of the cathode right end wall  124 . 
     As shown in  FIG. 3A , the adhesive layer  72  has a thickness that extends from a top surface  158  to a bottom surface  160 , the top and bottom surfaces extending between right and left sidewalls  161 A and  161 B. The thickness of the adhesive membrane  72  is preferably selected such that the top adhesive surface  158  contacts the first lead portion  139  of the cathode plate  68  and a bottom surface  160  of the adhesive membrane  72  contacts the anode material  112 . On the opposite side of the stack, a portion of adhesive membrane  72  may be positioned immediately adjacent the right end wall  124  of the cathode plate  68 . The bottom surface  160  of the adhesive membrane  72  contacts the top surface of the anode material  112 . 
     As shown in  FIG. 4 , the adhesive membrane  72  may be positioned such that the right adhesive membrane sidewall  161 A is in contact with the cathode plate left wall  126 . Furthermore, the bottom surface  160  of the adhesive membrane is in contact with the upper anode wall  110  and the adhesive membrane top surface  158  is in contact with the first cathode lead portion  139 . 
       FIG. 4A  illustrates a top view of the electrode plate stack assembly  104  of  FIG. 4 . As illustrated, the adhesive membrane  72  is positioned such that it surrounds the perimeter of the cathode plate  68 . The adhesive membrane  72 , by surrounding the perimeter of cathode plate  68 , minimizes movement thereof and forms an additional insulation barrier. Alternatively, the adhesive membrane  72  may be positioned along a portion or portions of the perimeter  150  of the anode plate  66 . 
     The electrode plate assembly embodiments illustrated in  FIGS. 5, 6, and 8 , are most beneficial in the construction of a secondary electrochemical cell. As shown, the carbonaceous anode plate  66  extends beyond that of the cathode plate  68 . That way, there is always a portion of the anode  66  opposite the lithiated cathode active material  134  so that as the cell is being recharged, the lithium ions intercalate into the carbonaceous anode material and do not plate out as dendritic formations. Dendrites are undesirable as they can lead to cell shorting. 
       FIGS. 5-8  illustrate various non-limiting embodiments of multiplate electrode assemblies of the present invention.  FIG. 5  illustrates an embodiment of an electrode assembly  200  comprising seven anode plates  66  and six cathode plates  68  that are sandwiched together in an alternating orientation. As shown in  FIGS. 3 and 5 , the cathode current collector  132  extends through both the left and right end walls  144 ,  142  of the cathode plate  68 . In particular, the first lead portion  139  extends past the cathode plate left wall  126  while a second cathode current collector lead portion  162  extends past the cathode plate right wall  124 . 
     Similarly to the embodiment shown in  FIG. 4 , the adhesive membrane resides about the perimeter of the cathode plate  68 . However, in the embodiment illustrated in  FIG. 5 , two adhesive membranes  72  are positioned between opposed facing anode plates  66  and about the perimeter of the cathode plate  68 . As shown in  FIGS. 3 and 5 , a first adhesive membrane  72 A is supported on a top surface  162  of the anode plate  66  and a second adhesive membrane  72 B is supported on a bottom surface  164  of an adjacent anode plate  66 . The cathode plate  68  resides between the two adjacent anode plates  66 . 
       FIG. 6  illustrates a cross-sectional view of an alternate embodiment of an electrode assembly  250  of the present invention. Like the previous electrode assemblies, electrode assembly  250  comprises multiple anode and cathode plates  66 ,  68  positioned in an alternating fashion. Specifically, seven anode plates and six cathode plates are positioned in an alternating sequence in the stack assembly. However, unlike the previous assemblies, assembly  250  comprises an anode separator  155  that encloses the anode material  106  therewithin. The anode separator  155  comprises the same material as the cathode separator  146  as previously discussed. 
       FIG. 7  illustrates yet another embodiment of an electrode assembly  300  of the present invention. In this embodiment, the anode and cathode plates  66 ,  68  are of a similar length. Anode and cathode plates  66 ,  68  of a similar length are beneficial in the construction of primary, non-rechargeable cell cells. In addition, a series of adhesive membranes  72  have been positioned between adjacent left and right lead portions  139 ,  162  of the cathode plates  68  and the right and left lead portions  116 A,  116 B of the anode plates  66 . Alternatively, the adhesive membrane  72  may be positioned around the perimeters of both of the anode  66  and cathode  66  plates. 
     More specifically, the adhesive membrane  72 , may be positioned such that the adhesive membrane top surface  158  is in contact with either the first cathode lead portion  116 B or the second cathode lead portion  116 A. The adhesive membrane bottom surface  160  is in contact with either the first anode lead portion  139  or the second anode lead portion  162 . Furthermore, that adhesive membrane right sidewall  161 A or the adhesive membrane left sidewall  161 B is in contact with the anode separator  155  or the cathode separator  140 . 
       FIG. 8  illustrates an alternate embodiment of an electrode plate assembly  350  comprising electrode plates of decreasing length. As shown, starting from the first bottom electrode position, the length of the anode plates  66  decrease as the assembly progresses to the top and final electrode position. Likewise, the length of the corresponding cathode plates  68  also becomes progressively shorter. In this embodiment, it is preferred that the length of the cathode plate  68  is shorter than the length of the immediately adjacent anode plates  66 . This preferred plate orientation enables the first and second adhesive membranes  72 A and  728  to be positioned such that the cathode plate  68 , particularly, the cathode electrode material  134  resides therebetween. 
       FIGS. 9A-C ,  10 A-C,  11 A-C and  12 A-C illustrate non-limiting examples of which the geometry of the casing  64  of the electrochemical cell  60  of the present invention may comprise. These examples are for illustrative purposes and are not meant to be limiting. It is contemplated that the geometry of the casing  64  could be of a multitude of container shapes and forms. 
       FIGS. 9A, 98 and 9C  illustrates side, top, and front end views of a casing embodiment  500  comprising opposed front and backside walls  502  and  504  extending to a left end wall  506  and a right end wall  508 . The end walls  506  and  508  are planar, although that is not necessary. Left end wall  506  may be longer in length than right end wall  508 , and both extend to a bottom wall  510  of an irregularly curved shape. Lid  512  encloses casing  500 . 
       FIGS. 10A, 108, and 10C  illustrate side, top, and front end views of an alternative embodiment of casing  550  comprising opposed front and backside walls  552  and  554  extending to a left end wall  556  and a right end wall  558 . Like casing  500 , casing embodiment  550  comprises planar end walls  556  and  558 , although that is not necessary. As shown, both the right end wall  558  and the left end wall  556  curved towards each other to form end wall  560 . Lid  562  encloses the casing  552 . 
       FIGS. 11A, 11B, and 11C  illustrate side, top, and front end views of an alternative embodiment of casing  600  comprising opposed front and backside walls  602  and  604  extending to a left end wall  606  and a right end wall  608 . As illustrated, left end wall  606  has a curved surface that extends from edge  610  to the right end wall  608  at edge  612 . Right end wall  608  is planar, although not necessary. Lid  614  encloses casing embodiment  600 . 
       FIGS. 12A, 125, and 12C  illustrate side, top, and front end views of an alternative embodiment of casing  650  comprising opposed front and backside walls  652  and  654  extending to a curved left end wall  656  and a curved right end wall  658 . As illustrated, the front end wall  652  has a curved surface whose end points meet at the planar backside wall  654 . As illustrated, the front side wall  652  has a curved surface that extends from the planar bottom sidewall  654 . A lid  660  encloses the casing  650 . 
     The electrode assembly process begins with construction of the anode and cathode current collectors  114 ,  132 . First, each side of a substrate of conductive material (not shown) is coated with an electrode active material mixture (not shown) in selected areas. The electrode active mixture typically comprises an anode or cathode active material, a binder such as a fluoro-resin powder and a conductive diluent such as a powdered carbonaceous material. This mixture in slurry form is sprayed, brushed, rolled, spread or otherwise contacted to the substrate to coat areas from which electrodes will later be cut. Suitable materials for the substrate of the anode and cathode current collectors  114 ,  132  include stainless steel, titanium, tantalum, platinum, gold, aluminum, cobalt nickel alloys, highly alloyed ferritic stainless steel containing molybdenum and chromium, and nickel-, chromium-, and molybdenum-containing alloys. 
     The thusly-coated substrate is then moved through an oven (not shown) to drive off any volatile compounds in the slurry and to cure the electrode active mixture contacted to the substrate. Next, the electrode plates are cut from the conductive substrate in the precise shape dictated by the casing. Second, the electrode active material is coated to the coated substrate, cured and leaving the selectively coated substrate from which the electrode plates are subsequently cut. 
     Once the electrode plates  66 ,  68  have been formed, the separator material is positioned between the anode plate  66  and the cathode plate  68 . In an embodiment, the cathode separator  140  is positioned over the cathode plate  68  such that the cathode material  134  is enveloped within. More preferably, a bottom surface of the separator material  134  is positioned in contact with a first layer of the cathode material  140  and a second layer of separator material  140  is positioned in contact with the top surface of the cathode  68 . The first and second layers of separator material  140  are heat treated at their respective ends to seal the cathode material  134  therewithin. If desired, the anode separator  156  may be positioned around the anode plate  66 . In the same manner as the cathode separator  140 , a first layer of separator material is positioned in contact with the bottom surface of the anode material  106  and a second layer of separator material is positioned in contact with the top surface of the anode material  106 . The first and second layers of separator material are heated at their respective ends to seal the anode material  106  therewithin. 
     The electrodes  66 ,  68  are then positioned in the desired stacked orientation, which may include the electrode assembly embodiments illustrated in  FIGS. 4-11 . The adhesion membrane  72  is positioned between the electrode plates, more specifically between opposed facing plates  66 ,  68  along at least a portion of the perimeter of either the anode or cathode electrode plate  66 ,  68 . Once the stack of electrodes  66 ,  68  and adhesion membranes  72  are complete, the electrode assembly is then laminated together at a temperature ranging from about 100° C. to about 200° C. for about 5 minutes to about 30 minutes with a pressure of about 0.5 lb-f to about 5 lb-f. Alternatively, each pair of alternating electrodes  66 ,  68  may be laminated immediately after each pair is positioned within the assembly as the stack is built. 
     After construction of the multiplate electrode assembly is completed, the stack is inserted into the casing to substantially occupy the internal volume thereof, a conductive structure connects the connectors  116 ,  139  to their respective terminals. This may take the form of connecting the anode connector to an anode lead (not shown) welded to the interior of the casing  64  or to the lid  92  for a cell in a case-negative design with the cathode connector welded to the terminal pin  94  insulated from the lid  92  and casing  64  by the glass-to-metal seal  96 . Additionally, the anode lead may be pinched between the lid and the casing and subsequently fused as they are hermetically welded together. Methods of welding include, but are not limited to, resistance welding, plasma welding, ultrasonic welding and laser welding. Regardless of where the anode lead is welded to the casing  64 , the lid  92  is hermetically sealed thereto. 
     The electrode assembly is useful in an electrochemical cell of either a primary chemistry or a secondary, rechargeable chemistry. For both the primary and secondary types, the cell comprises an anode active metal selected from Groups IA, IIA and IIIB of the Periodic Table of the Elements, including lithium, sodium, potassium, etc., and their alloys and intermetallic compounds including, for example, Li—Si, Li—Al, Li—B, Li—Mg and Li—Si—B alloys and intermetallic compounds. The preferred metal comprises lithium. An alternate negative electrode comprises a lithium alloy, such as lithium-aluminum alloy. The greater the amount of aluminum present by weight in the alloy, however, the lower the energy density of the cell. 
     For a primary cell, the anode is a thin metal sheet or foil of the lithium material, pressed or rolled on a metallic anode current collector, i.e., preferably comprising nickel, to form the negative electrode. In the exemplary cell of the present invention, the negative electrode has an extended tab or lead of the same material as the current collector, i.e., preferably nickel, integrally formed therewith such as by welding and contacted by a weld to a cell case of conductive material in a case-negative electrical configuration. Alternatively, the negative electrode may be formed in some other geometry, such as a bobbin shape, cylinder or pellet to allow an alternate low surface cell design. 
     In secondary electrochemical systems, the anode or negative electrode comprises an anode material capable of intercalating and de-intercalating the anode active material, such as the preferred alkali metal lithium. A carbonaceous negative electrode comprising any of the various forms of carbon (e.g., coke, graphite, acetylene black, carbon black, glassy carbon, etc.) which are capable of reversibly retaining the lithium species, is preferred for the anode material. A “hairy carbon” material is particularly preferred due to its relatively high lithium-retention capacity. “Hairy carbon.” is a material described in U.S. Pat. No. 5,443,928 to Takeuchi et al., which is assigned to the assignee of the present invention and incorporated herein by reference. Graphite is another preferred material. Regardless of the form of the carbon, fibers of the carbonaceous material are particularly advantageous because they have excellent mechanical properties that permit them to be fabricated into rigid electrodes that are capable of withstanding degradation during repeated charge/discharge cycling. Moreover, the high surface area of carbon fibers allows for rapid charge/discharge rates. 
     A typical negative electrode for a secondary cell is fabricated by mixing about 90 to 97 weight percent “hairy carbon” or graphite with about 3 to 10 weight percent of a binder material, which is preferably a fluoro-resin powder such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylenetetrafluoroethylene (ETFE), polyamides, polyimides, and mixtures thereof. This negative electrode admixture is provided on a current collector such as of a nickel, stainless steel, or copper foil or screen by casting, pressing, rolling or otherwise contacting the admixture thereto. 
     In either the primary cell or the secondary cell, the reaction at the positive electrode involves conversion of ions that migrate from the negative electrode to the positive electrode into atomic or molecular forms. For a primary cell, the cathode active material comprises a carbonaceous chemistry or at least a first transition metal chalcogenide constituent which may be a metal, a metal oxide, or a mixed metal oxide comprising at least a first and a second metals or their oxides and possibly a third metal or metal oxide, or a mixture of a first and a second metals or their metal oxides incorporated in the matrix of a host metal oxide. The cathode active material may also comprise a metal sulfide. 
     Carbonaceous active materials are preferably prepared from carbon and fluorine, which includes graphitic and nongraphitic forms of carbon, such as coke, charcoal or activated carbon. Fluorinated carbon is represented by the formula (CF x ) n  wherein x varies between about 0.1 to 1.9 and preferably between about 0.5 and 1.2, and (C 2 F) n  wherein n refers to the number of monomer units which can vary widely. 
     The metal oxide or the mixed metal oxide is produced by the chemical addition, reaction, or otherwise intimate contact of various metal oxides, metal sulfides and/or metal elements, preferably during thermal treatment, sol-gel formation, chemical vapor deposition or hydrothermal synthesis in mixed states. The active materials thereby produced contain metals, oxides and sulfides of Groups IB, IIB, IIIB, IVB, VB, VIB, VIIB and VIII, which include the noble metals and/or other oxide and sulfide compounds. A preferred cathode active material is a reaction product of at least silver and vanadium. 
     One preferred mixed metal oxide is a transition metal oxide having the general formula SM x V 2 O y  where SM is a metal selected from Groups IB to VIIB and VIII of the Periodic Table of Elements, wherein x is about 0.30 to 2.0 and y is about 4.5 to 6.0 in the general formula. By way of illustration, and in no way intended to be limiting, one exemplary cathode active material comprises silver vanadium oxide having the general formula Ag x V 2 O y  in any one of its many phases, i.e., β-phase silver vanadium oxide having in the general formula x=0.35 and y=5.8, γ-phase silver vanadium oxide having in the general formula x=0.80 and y=5.40 and ξ-phase silver vanadium oxide having in the general formula x=1.0 and y=5.5, and combination and mixtures of phases thereof. For a more detailed description of such cathode active materials, reference is made to U.S. Pat. No. 4,310,609 to Liang et al., which is assigned to the assignee of the present invention and incorporated herein by reference. 
     Another preferred composite transition metal oxide cathode material includes V 2  O z  wherein z≦5 combined with Ag 2  O having silver in either the silver(II), silver(I) or silver(0) oxidation state and CuO with copper in either the copper(II), copper(I) or copper(0) oxidation state to provide the mixed metal oxide having the general formula Cu x Ag y V 2 O z , (CSVO). Thus, the composite cathode active material may be described as a metal oxide-metal oxide-metal oxide, a metal-metal oxide-metal oxide, or a metal-metal-metal oxide and the range of material compositions found for Cu x Ag y V 2 O z  is preferably about 0.01≦z≦6.5. Typical forms of CSVO are Cu 0.16 Ag 0.67 V 2 O z  with z being about 5.5 and Cu 0.5  Ag 0.5 V 2 O z  with z being about 5.75. The oxygen content is designated by z since the exact stoichiometric proportion of oxygen in CSVO can vary depending on whether the cathode material is prepared in an oxidizing atmosphere such as air or oxygen, or in an inert atmosphere such as argon, nitrogen and helium. For a more detailed description of this cathode active material, reference is made to U.S. Pat. No. 5,472,810 to Takeuchi et al. and U.S. Pat. No. 5,516,340 to Takeuchi et al., both of which are assigned to the assignee of the present invention and incorporated herein by reference. 
     In addition to the previously described fluorinated carbon, silver vanadium oxide and copper silver vanadium oxide, Ag 2 O, Ag 2  O 2 , CuF 2 , Ag 2 CrO 4 , MnO 2 , V 2 O 5 , MnO 2 , TiS 2 , Cu 2 S, FeS, FeS 2 , copper oxide, copper vanadium oxide, and mixtures thereof are contemplated as useful active materials. 
     In secondary cells, the positive electrode preferably comprises a lithiated material that is stable in air and readily handled. Examples of such air-stable lithiated cathode active materials include oxides, sulfides, selenides, and tellurides of such metals as vanadium, titanium, chromium, copper, molybdenum, niobium, iron, nickel, cobalt and manganese. The more preferred oxides include LiNiO 2 , LiMn 2 O 4 , LiCoO 2 , LiCu 0.92  Sn 0.08  O 2  and LiCo 1-x  Ni x O 2 . A preferred secondary couple is of a carbonaceous anode material and a lithium cobalt oxide cathode active material. 
     To charge such secondary cells, the lithium ion comprising the positive electrode is intercalated into the carbonaceous negative electrode by applying an externally generated electrical potential to the cell. The applied recharging electrical potential serves to draw lithium ions from the cathode active material, through the electrolyte and into the carbonaceous material of the negative electrode to saturate the carbon. The resulting Li x C 6  negative electrode can have an x ranging between 0.1 and 1.0. The cell is then provided with an electrical potential and is discharged in a normal manner. 
     An alternate secondary cell construction comprises intercalating the carbonaceous material with the active lithium material before the negative electrode is incorporated into the cell. In this case, the positive electrode body can be solid and comprise, but not be limited to, such active materials as manganese dioxide, silver vanadium oxide, titanium disulfide, copper oxide, copper sulfide, iron sulfide, iron disulfide and fluorinated carbon. However, this approach is compromised by problems associated with handling lithiated carbon outside of the cell. Lithiated carbon tends to react when contacted by air or water. 
     The above described cathode active materials, whether of a primary or a secondary chemistry, are incorporation into an electrochemical cell by mixing one or more of them with a binder material. Suitable binders are powdered fluoro-polymers; more preferably powdered polytetrafluoroethylene or powdered polyvinylidene fluoride present at about 1 to about 5 weight percent of the cathode mixture. Further, up to about 10 weight percent of a conductive diluent is preferably added to the cathode mixture to improve conductivity. Suitable materials for this purpose include acetylene black, carbon black and/or graphite or a metallic powder such as powdered nickel, aluminum, titanium and stainless steel. The preferred cathode active mixture thus includes a powdered fluoro-polymer binder present at about 1 to 5 weight percent, a conductive diluent present at about 1 to 5 weight percent and about 90 to 98 weight percent of the cathode active material. Cathode components are prepared by contacting the cathode active mixture in the form of a slurry onto one of the previously described conductive substrates serving as a current collector. The preferred cathode current collector material is titanium, and most preferably the titanium cathode current collector has a thin layer of graphite/carbon paint applied thereto. 
     In order to prevent internal short circuit conditions, the cathode is separated from the Group IA, IIA or IIIB anode by a suitable separator material. The separator is of electrically insulative material, and the separator material also is chemically unreactive with the anode and cathode active materials and both chemically unreactive with and insoluble in the electrolyte. In addition, the separator material has a degree of porosity sufficient to allow flow there through of the electrolyte during the electrochemical reaction of the cell. Illustrative separator materials include fabrics woven from fluoropolymeric fibers including polyvinylidine fluoride, polyethylenetetrafluoroethylene, and polyethylenechlorotrifluoroethylene used either alone or laminated with a fluoropolymeric microporous film, non-woven glass, polypropylene, polyethylene, glass fiber materials, ceramics, a polytetrafluoroethylene membrane commercially available under the designation ZITEX (Chemplast Inc.), a polypropylene membrane commercially available under the designation. CELGARD (Celanese Plastic Company, Inc.) and a membrane commercially available under the designation DEXIGLAS (C. H. Dexter, Div., Dexter Corp.). 
     The electrochemical cell of the present invention further includes a nonaqueous, ionically conductive electrolyte that serves as a medium for migration of ions between the anode and the cathode electrodes during the electrochemical reactions of the cell. The electrochemical reaction at the electrodes involves conversion of ions in atomic or molecular forms that migrate from the anode to the cathode. Thus, nonaqueous electrolytes suitable for the present invention are substantially inert to the anode and cathode materials, and they exhibit those physical properties necessary for ionic transport, namely, low viscosity, low surface tension and wettability. 
     A suitable electrolyte has an inorganic, ionically conductive salt dissolved in a nonaqueous solvent, and more preferably, the electrolyte includes an ionizable alkali metal salt dissolved in a mixture of aprotic organic solvents comprising a low viscosity solvent and a high permittivity solvent. The inorganic, ionically conductive salt serves as the vehicle for migration of the anode ions to intercalate or react with the cathode active materials. Preferably, the ion forming alkali metal salt is similar to the alkali metal comprising the anode. In the case of an anode comprising lithium, the electrolyte salt is a lithium-based salt selected from LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , LiClO 4 , LiO 2 , LiAlCl 4 , LiGaCl 4 , LiC(SO 2  CF 3 ) 3 , LiN(SO 2  CF 3 ) 2 , LiSCN, LiO 3  SCF 3 , LiC 6 F 5 SO 3 , LiO 2 CCF 3 , LiSO 6 F, LiB(C 6 H 5 ) 4 , LiCF 3 SO 3 , and mixtures thereof. 
     Low viscosity solvents useful with the present invention include esters, linear and cyclic ethers and dialkyl carbonates such as tetrahydrofuran (THF), methyl acetate (MA), diglyme, trigylme, tetragylme, dimethyl carbonate (DMC), 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1-ethoxy, 2-methoxyethane (EME), ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, diethyl carbonate (DEC), dipropyl carbonate, and mixtures thereof, and high permittivity solvents include cyclic carbonates, cyclic esters and cyclic amides such as propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate, acetonitrile, dimethyl sulfoxide, dimethyl formamide, dimethyl acetamide, γ-valerolactone, γ-butyrolactone (GBL), N-methyl-pyrrolidinone (NMP), and mixtures thereof. In the present invention, the preferred anode for a primary cell is lithium metal and the preferred electrolyte is 0.8M to 1.5M LiAsF 6  or LiPF 6  dissolved in a 50:50 mixture, by volume, of propylene carbonate as the preferred high permittivity solvent and 1,2-dimethoxyethane as the preferred low viscosity solvent. 
     A preferred electrolyte for a secondary cell of an exemplary carbon/LiCoO 2  couple comprises a solvent mixture of EC:DMC:EMC:DEC. Most preferred volume percent ranges for the various carbonate solvents include EC in the range of about 20% to about 50%; DMC in the range of about 12% to about 75%; EMC in the range of about 5% to about 45%; and DEC in the range of about 3% to about 45%. In a preferred form of the present invention, the electrolyte activating the cell is at equilibrium with respect to the mole ratio of DMC:EMC:DEC. This is important to maintain consistent and reliable cycling characteristics. It is known that due to the presence of low-potential (anode) materials in a charged cell, an un-equilibrated molar mixture of DMC:DEC in the presence of lithiated graphite (LiC 6 ≈0.01 V vs Li/Li + ) results in a substantial amount of EMC being formed. When the concentrations of DMC, DEC and EMC change, the cycling characteristics and temperature rating of the cell change. Such unpredictability is unacceptable. This phenomenon is described in detail in U.S. Pat. No. 6,746,804 to Can et al., which is assigned to the assignee of the present invention and incorporated herein by reference. Electrolytes containing the quaternary carbonate mixture of the present invention exhibit freezing points below −50° C., and lithium ion secondary cells activated with such mixtures have very good cycling behavior at room temperature as well as very good discharge and charge/discharge cycling behavior at temperatures below −40° C. 
     The glass used in the glass-to-metal seals is of a corrosion resistant type having up to about 50% by weight silicon such as CABAL 12, TA 23, FUSITE 425 or FUSITE 435. The positive terminal leads preferably comprise titanium although molybdenum, aluminum, nickel alloy, or stainless steel can also be used. The cell lids are typically of a material similar to that of the casing. 
     It is appreciated that various modifications to the present inventive concepts described herein may be apparent to those of ordinary skill in the art without departing from the spirit and scope of the present invention as defined by the herein appended claims.