Abstract:
An apparatus and method for fabricating continuous cathode collecters for use in lithium/thionyl chloride and lithium/sulfuryl chloride cells is described. The preferred electrically conductive material is acetylene black mixed with a polytetrafluroethylene (PTFE) binder in a dry, powderized form. The collector substrate is a nickel or stainless steel foil that has been expanded into a mesh or otherwise provided with perforations. A centering adjustment of the collector substrate controls loading of the electrically conductive mixture onto each side thereof. The dry, powdered electrically conductive mixture is then continuously fed into the calender and formed into a collector structure by locking to itself through the collector substrate perforations before being cut to size.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from provisional application Ser. No. 60/752,867, filed Dec. 22, 2005. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to the art of electrochemical cells and, more particularly, to a lithium-containing cell with an electrically conductive counter-collector fabricated by a new continuous feed apparatus. In general, it has been discovered that electrically conductive materials, such as of a carbonaceous chemistry, can readily be compressed onto the opposed major sides of a perforated conductive collector substrate without sloughing off or delaminating. This makes the resulting carbonaceous laminate particularly useful as a cathode collector in lithium/oxyhalide cells. 
     2. Prior Art 
     Primary lithium oxyhalide cells are used extensively in applications requiring high gravimetric and volumetric energy density. Among the many sizes and chemistries available, cells can be developed for low rate or high rate applications and to operate from temperatures as low as −70° C. to as high as 200° C. The anode material usually consists of lithium or lithium alloyed with various elements such as aluminum, magnesium or boron and the cathode collector usually consists of some form of carbon held together using a suitable binder. The electrolyte generally consists of a solvent system of thionyl chloride, phosphoryl chloride or sulfuryl chloride. Often, additional compounds or interhalogen compounds such as sulfur dioxide, chlorine, bromine, bromine chloride and others may be dissolved therein to modify the cell for a particular purpose, such as extending the operating rate or temperature of the cell. Electrolyte salts are also added to the solvent system to assist in ionic transfer during cell discharge. Such salts may include lithium chloride in combination with aluminum trichloride or gallium trichloride. Lithium tetrachloroaluminate salt (LAC) or lithium tetrachlorogallate salt (LGC) is then formed in-situ. Typically used catholytes include chlorinated sulfuryl chloride (CSC) having either LAC or LGC dissolved therein. These systems are commonly referred to as LAC/CSC and LGC/CSC. 
     The liquid oxyhalides of the elements of Group V or Group VI of the Periodic Table are liquid active reducible cathode materials (depolarizer). As used herein and as disclosed in an article titled “Electrochemical Reactions in Batteries” by Akiya Kozawa and R. A. Powers, in the Journal of Chemical Education—Vol. 49, pages 587 to 591, September, 1972 edition, a cathode depolarizer is the cathode reactant and, therefore, is the material electrochemically reduced at the cathode collector. The cathode collector is not an active reducible material and functions as a current collector plus electronic conductor to the cathode terminal of the cell. In other words, the cathode collector is a situs for the electrochemical reduction reaction of the active cathode material and the electronic conductor to the cathode terminal. 
     A liquid active reducible cathode material (depolarizer) can either be employed by itself in an electrochemical device (i.e. galvanic cell), mixed with a conductive solute, which is a non-reactive material but is added to improve conductivity of the liquid active reducible cathode materials, or mixed with both a conductive solute and a reactive or non-reactive co-solvent. A reactive co-solvent material is one that is electrochemically active and, therefore, functions as an active cathode material while a non-reactive co-solvent is one that is electrochemically inactive and, therefore, cannot function as an active cathode material. 
     Any compatible solid which is substantially electronically conductive is useful as the cathode collector. However, it is desirable to have as much surface contact as possible between the cathode-electrolyte and the collector, and a pressed carbonaceous powder collector that provides a high surface area interface with the liquid cathode electrolyte is preferred. This means that the manufacturing process needs to produce collectors having uniform carbonaceous basis weights, which is defined as the gram amount of the carbonaceous material per unit volume, with little thickness variability across the collector sheet. Cells exhibiting consistent discharge performance from one cell to the next result when strict tolerances for these parameters are maintained. 
     SUMMARY OF THE INVENTION 
     Thus, the present invention is particularly directed to an apparatus and method for fabricating continuous cathode collectors for use in lithium/thionyl chloride and lithium/sulfuryl chloride cells. The preferred electrically conductive material is acetylene black mixed with a polytetrafluoroethylene (PTFE) binder in a dry, powderized form. The collector substrate is a nickel or stainless steel foil that has been expanded into a mesh or otherwise provided with perforations. The powdered electrically conductive mixture is then continuously fed into a calender and formed into a collector structure by locking to itself through the collector substrate perforations before being cut to size. 
     The key to this process is a feed hopper assembly and calender. The calender is directly below the feed hopper. The feed hopper includes two-chambered hoppers, one on each side of the collector substrate, a set of centering guide plates and a vibratory feeding system. Adjustments for the hopper assembly include centering the collector substrate with respect to the calender gap, regulating the distance from the end of the guide plates to the gap, and the vibratory feed speed. The centering adjustment controls loading of the electrically conductive mixture on each side of the collector substrate, although the process is fairly tolerant to this because the substrate is self-centering. The feed rate of the electrically conductive mixture delivered to the collector substrate is controlled by the distance from the end of the guide plates to the calender gap. The feed hoppers may also include high and low fill sensors that regulate the vibratory system to control the weight of the electrically conductive mixture in the hoppers. An agitator may be included so that the electrically conductive mixture is consistently “fluffed” and devoid of clumps that can lead to an uneven coating. 
     These and other objects and advantages of the present invention will become increasingly more apparent by a reading of the following description in conjunction with the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a perspective view of an apparatus  10  for fabricating a cathode current collector sheet according to the present invention. 
         FIG. 2  is a perspective view of the apparatus  10  illustrated in  FIG. 1 , but partly broken away to show the carbonaceous material  12  being calendared to a metallic current collector  14 . 
         FIG. 3  is a front elevational view of the apparatus  10 . 
         FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a plan view of the apparatus  10 . 
         FIG. 6  is an enlarged view of the indicated area shown in  FIG. 4 . 
         FIG. 7  is an enlarged view of the indicated area shown in  FIG. 1 . 
         FIG. 8  is a detailed perspective view of the calender hopper  28  and its various adjustment mechanisms. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present apparatus is particularly useful for manufacturing cathode collector structures such as pressed carbonaceous powder collectors for lithium/oxyhalide electrochemical cells. More particularly, however, the present apparatus is useful for manufacturing “electrode” structures for cells of both a primary and a secondary chemistry. The primary chemistry configuration can include a positive electrode of either a liquid catholyte system having an electrically conductive or electroactive material supported on a collector substrate or a solid cathode active material supported on a current collector. 
     Regardless the cell configuration, such cells preferably comprise an anode active material of a metal selected from Groups IA, IIA or IIIB of the Periodic Table of the Elements, including the alkali metals lithium, sodium, potassium, etc., and their alloys and intermetallic compounds including, for example, Li—Mg, Li—Si, Li—Al, Li—B, Li—Al—Mg and Li—Si—B alloys and intermetallic compounds. The preferred anode active material is lithium. A lithium alloy such as a lithium-aluminum alloy is also useful; however, the greater the amounts of aluminum present by weight in the alloy, the lower the energy density of the cell. 
     In a primary cell of either an oxyhalide chemistry or a solid positive electrode, the form of the anode may vary. Preferably the anode is a thin metal sheet or foil of lithium pressed or rolled on a metallic anode current collector, i.e., preferably comprising nickel. The anode current collector has an extended tab or lead contacted by a weld to a cell case of conductive metal in a case-negative electrical configuration. Alternatively, the anode may be formed in some other geometry, such as a bobbin shape, cylinder or pellet to allow an alternate low surface cell design. 
     In the case of oxyhalide chemistry, the cell comprises a cathode collector of electrically conductive material supported on a collector substrate. An oxyhalide cell operates in the following manner. When the ionically conductive catholyte solution becomes operatively associated with the anode and the cathode collector, an electrical potential difference develops between terminals operatively connected to the anode and to the cathode collector. The electrochemical reaction at the anode includes oxidation to form metal ions during cell discharge. The electrochemical reaction at the cathode collector involves conversion into atomic or molecular forms of those ions that migrate from the anode to the cathode collector. In addition, the halogen and/or interhalogen of the catholyte is believed to undergo a reaction or reactions with the nonaqueous solvent thereof resulting in the formation of a compound or complex which exhibits the observed open circuit voltage of the cell. Exemplary electrically conductive materials for the cathode collector include acetylene black, graphite, coke, carbon black, and carbon monofluoride contacted to a metal screen. A preferred electrically conductive material is acetylene black due to its relatively high lithium-retention capacity and because acetylene black carbonaceous particles have excellent mechanical properties that permit them to be fabricated into cathode collector structures. 
     A typical cathode collector is fabricated by dry mixing about 80 to 95 weight percent of at least one of the above listed electrically conductive materials, preferably acetylene black, with about 1 to 10 weight percent of a powdered conductive diluent and about 1 to 10 weight percent of a binder material, preferably a thermoplastic polymeric binder material. The term “dry” means that the electrically conductive mixture of the electrically conductive material and the conductive diluent is substantially free from liquids, especially water. 
     The term thermoplastic polymeric binder material is used in its broad sense and any polymeric material, preferably in a powdered form, which is inert in the cell and which passes through a thermoplastic state, whether or not it finally sets or cures, is included within the meaning of the term “thermoplastic polymer”. Representative materials include polyethylene, polypropylene and fluoropolymers such as fluorinated ethylene and propylene, polyvinylidene fluoride (PVDF), polyethylenetetrafluroethylene (ETFE), and polytetrafluoroethylene (PTFE), the latter material being most preferred. Natural rubbers are also useful as the binder material with the present invention. 
     Suitable conductive diluents include carbon black and/or graphite. A preferred carbonaceous diluent is KETJENBLACK® carbon. Metals such as nickel, aluminum, titanium and stainless steel in powder form are also useful as conductive diluents when mixed with the above listed conductive materials. This mixture is then contacted to at least one major side, and preferably both major sides, of a perforated conductive substrate selected from the group consisting of nickel, copper, titanium, cobalt, tantalum, aluminum, stainless steel, and alloys thereof as a foil or screen. The conductive substrate preferably has a thickness of from about 0.001 inches to about 0.02 inches. 
     Referring now to the drawings,  FIGS. 1 to 8  illustrate an apparatus  10  for calendaring an electrically conductive mixture  12  to a collector substrate  14 . The thusly calendared electrically conductive structures are useful as cathode collectors for lithium/oxyhalide cells and as carbonaceous anodes for lithium ion cells, and the like. The apparatus  10  comprises a pair of side-by-side right and left material feed hoppers  16  and  18  leading to respective primary chutes  20  and  22  which, in turn, lead to respective secondary chutes  24  and  26 . The secondary chutes  24 ,  26  deliver the electrically conductive mixture  12  to a calendar hopper  28  that is compartmentalized by an adjustable gate  30 . The calender hopper  28  in conjunction with the gate  30  delivers the electrically conductive mixture  12  to a pair of side-by-side rollers  32  and  34  that calender the electrically conductive mixture onto opposite sides of the collector substrate  14  moving through the gate and the rollers  32 ,  34 . The collector substrate movement is by the counter rotating action of the calendar rollers  32 ,  34 . 
     The present apparatus  10  will first be more specifically described with respect to the right feed hopper  16 , which is a mirror structure of the left feed hopper  18 . The right feed hopper  16  comprises an upper vertical sidewall  36  supported on a downwardly and inwardly tapered sidewall  38  except for a vertical front wall  40 . The vertical sidewall  36  and front wall  40  surround an open end  42  through which the electrically conductive mixture  12  is loaded into the hopper  16 . The tapered sidewall  38  funnels to a hopper channel portion  44  extending to an outlet  46  in the front wall  40  through which the electrically conductive mixture  12  moves by gravity feed to the downwardly inclined primary chute  20 . Preferably, a high and low fill sensor regulates a vibratory mechanism (not shown for hopper  16 ) mounted on the outside of the tapered sidewall  38  opposite the chute outlet  46  to control the weight of the electrically conductive mixture in the hopper. 
     Similarly, the left feed hopper  18  comprises an upper vertical sidewall  48  supported on a downwardly and inwardly tapered sidewall  50  except for a vertical front wall  52 . The vertical sidewall  48  and front wall  52  surround an open end  54  through which the electrically conductive mixture  12  is loaded into the hopper  18 . The tapered sidewall  50  funnels to a hopper channel portion  56  extending to an outlet  58  in the front wall  52  through which the electrically conductive mixture  12  moves by gravity feed to the downwardly inclined primary chute  22 . Preferably, a high and low fill sensor regulates a vibratory mechanism  60  ( FIG. 3 ) mounted on the outside of the tapered sidewall  50  opposite the chute outlet  58  to control the weight of the electrically conductive mixture in the hopper  18 . 
     The primary chute  20  for the right hopper  16  is an elongated channel-shaped member extending from a proximal end located directly under the hopper outlet  46  to a distal end. An outlet  61  is provided in the primary chute  20  at its distal end. That way, the electrically conductive mixture  12  travels along the length of the primary chute  20  and falls through its outlet  61  to the secondary chute  24 . The secondary chute  24  comprises opposed sidewalls  62  and  64  extending upwardly from a bottom wall  66 . The secondary chute sidewall  62  extends forwardly beyond the terminus of the opposing chute sidewall  64 . This provides the secondary chute bottom wall  66  with an angled edge  68  tapering inwardly from sidewall  62  to sidewall  64 . 
     The primary chute  22  for the left hopper  18  is an elongated channel-shaped member extending from a proximal end located directly under the hopper outlet  58  to a distal end. An outlet  70  is provided in the primary chute  72  at its distal end. The secondary chute  26  also comprises an elongate channel-shaped member extending from a proximal end located directly under the primary chute opening  70  to a distal end. The secondary chute  22  comprises sidewalls  72  and  74  extending upwardly from a bottom wall  76 . The secondary chute sidewall  74  extends forwardly beyond the terminus of the opposing chute sidewall  72 . This provides the secondary chute bottom wall  76  with an angled edge  78  tapering inwardly from sidewall  74  to sidewall  72 . 
     As particularly shown in  FIGS. 1 to 5  and  8 , the side-by-side secondary chutes  24 ,  26  deliver the electrically conductive mixture  12  to the calender hopper  28 . The calender hopper  28  is supported above a platform  80  and comprises a generally rectangular-shaped upper sidewall  82  extending to an opening  84  through which the electrically conductive mixture  12  leaving the secondary chutes  24 ,  26  drops. The calender hopper upper surrounding sidewall  82  confines the electrically conductive mixture as it moves downwardly into a funnel-shaped portion  86 . The funnel-shaped portion  86  comprises angled sidewalls  88  and  90  extending to and meeting with front and back sidewalls  92  and  94 . The angled sidewalls  88 ,  90  extend downwardly and inwardly to a closely-spaced relationship with the side-by-side rollers  32 ,  34  ( FIGS. 4 and 6 ). The adjustable gate  30  bifurcates the calender hopper  28  into a right portion receiving the electrically conductive mixture from the right secondary chute  24  and a left portion receiving the electrically conductive mixture  12  from the left secondary chute  26 . Preferably, agitators  91  are provided in the right and left calender hopper portions so that the electrically conductive mixture  12  is consistently “fluffed” and devoid of clumps that can lead to an uneven coating. 
     As more clearly shown in  FIGS. 4 and 6 , the gate  30  comprises a right plate  96  and a left plate  98  that are disposed in a vertical side-by-side orientation with a fixed gap there between. The current collector  14  unfurls from a spool  100  and moves in a downwardly direction to enter the gate  30  at its proximal end  30 A to move through the fixed gap between the gate plates  96 ,  98  to the distal gate end  308  and then downwardly through and between the rollers  32 ,  34 . Simultaneously, the electrically conductive mixture  12  is deposited in the calender hopper  28  evenly distributed from the front wall  92  to the back wall  94  thereof. This is because of the inwardly tapered edges  68 ,  78  of the respective secondary chutes  24 ,  26 . As this happens, roller  32  rotates in a counter clockwise direction while roller  34  rotates in a clockwise direction. The plates  96 ,  98  are provided with respective beveled edges  96 A and  98 A angling upwardly and outwardly at the distal gate end  308 . That way, calender gaps  97 A and  97 B are formed between the beveled edges  96 A,  98 A and the respective curved surfaces of the rollers  32 ,  34 . The bevel gaps  97 A,  97 B regulate the thickness of the dry electrically conductive mixture  12  calendered on the opposed major sides of the collector substrate  14 . Even though the electrically conductive mixture is compressed to a thickness less than the width of the calender gaps  97 A,  97 B, the coated thickness is directly related to these widths. 
     Thus, the rotating action of the rollers  32 ,  34  pulls the collector substrate  14  through the gate plates  96 ,  98  along with a regulated amount of the electrically conductive mixture  12  that is subsequently pressed in a smooth coating having a desired thickness onto the opposed major sides of the collector substrate  14 . The resulting electrically conductive structure  102  comprising a regulated thickness of electrically conductive mixture laminated or otherwise coated onto the opposite sides of the collector substrate  14  is shown in  FIGS. 4 ,  6  and  7 . 
     In order to maintain the electrically conductive mixture coated at a regulated thickness onto each side of the collector substrate  14 , apparatus  10  has several adjustable features. As particularly shown in  FIG. 8 , a first adjustable mechanism  104  provides for moving the gate  30  in an upwardly and downwardly vertical direction. A second adjustable mechanism  106  provides for moving the gate  30  back and forth in a sideways direction. Finally, a third adjustable mechanism  108  provides for moving at least one of the rollers  32 ,  34  to increase and decrease the gap between them. While the various adjustable mechanisms  104 ,  106  and  108  are shown as threaded members engaged with mating sliding blocks that is by way of representation only. The adjustable mechanism  104 ,  106  and  108  can also be hydraulic, pneumatic, or electrical actuated motors to accomplish the same functions. 
     More particularly, adjustable mechanism  104  comprises a horizontal bar  110  fixed to the right side of the calender hopper  28 . A slidable block  112  is secured to the gate plates  96 ,  98  at the calender hopper sidewall  92 . This block  112  has a threaded opening that receives a threaded member  114 . Relative rotational movement between the threaded member  114  and the block  112  moves the block vertically along a slide  116  in the hopper sidewall  92  to either raise or lower the block  112 . In turn, this causes the gate plates  96 ,  98  to move either in an upwardly or downwardly direction with respect to a horizontal axis  118  ( FIG. 6 ) through the center of the rollers  32 ,  34 . As the gate  30  moves in an upwardly direction, the calender gaps  97 A,  97 B between the beveled edges  96 A,  98 A of the plates  96 ,  98  and the respective rollers  32 ,  34  increases to thereby increase the loading of the electrically conductive mixture  12  coated onto the opposed collector substrate sides. Conversely, the calender gaps  97 A,  97 B between the beveled edges  96 A,  98 A and the rollers decrease as the gate  30  moves in a downwardly direction. This consequently decreases the electrically conductive mixture loaded onto the opposed collector substrate major sides. A hand crank  120  helps effect relative movement of the threaded member  114  and the block  112 . A distance read-out  122  helps an operator make precise adjustments with the crank  120 . As shown in  FIGS. 1 to 5 , adjustable mechanism  104  has a similar structure adjacent to calendar hopper sidewall  94 . 
     Adjustable mechanism  106  comprises a vertical bar  124  fixed to the right sides of the gate plates  96 ,  98  at the calender hopper sidewall  92 . A block  126  is secured to the calender hopper sidewall  92 . This block  126  has a threaded opening that receives a threaded member  128 . That way, relative rotational movement between the threaded member  128  and the block  126  moves the bar  124  along a horizontal slide  130 . In turn, this movement causes the gate  30  including both plates  96 ,  98  to move laterally in a back and forth direction with respect to the rollers  32 ,  34 . As the gate  30  moves toward angled sidewall  88  of the calender hopper  28 , the calender gap  97 A between the beveled edge  96 A of gate plate  96  and the roller  32  decreases and the calender gap  97 B between the beveled edge  98 A of gate plate  98  and roller  34  increases. Conversely, as the gate  30  moves toward angled sidewall  90  of the calender hopper  28 , the calender gap  97 A between the beveled edge  96 A of gate plate  96  and the roller  32  increases and the calender gap  97 B between the beveled edge  98 A of gate plate  98  and roller  34  decreases. A hand crank  132  helps effect relative movement of the threaded member  128  and the block  124 . A distance read-out  134  helps an operator make precise adjustments with the crank  132 . As shown in  FIGS. 1 to 5 , adjustable mechanism  106  has a similar structure adjacent to calender hopper sidewall  94 . 
     Adjustable mechanism  108  comprises a stationary bar  136  fixed to the calender hopper sidewalls  88  and  92  by a plate  138 . An axel  140  supports roller  32  for fixed rotational movement. A second plate  142  is fixedly connected to the calender hopper sidewalls  90  and  92 . A laterally adjustable block  144  supports an axel  146  that provided for rotational movement of the other roller  34 . Spaced apart pins  148  and  150  connect between the block  136  and plate  142 . These pins  148 ,  150  allow the adjustable block  144  to ride back and forth there along. This actuating movement is brought about by a threaded member  152  having one end rotationally secured to the adjustable block  144  and the other end received in a threaded opening in the fixed second plate  142 . That way, as the threaded member  152  is rotated in either a clockwise or counter clockwise direction, the adjustable block  144  including its axel  146  and supported roller  34  moves back and forth towards and away from the other roller  32  to decrease and increase the relative nip gap between them. Additionally, the adjustment mechanism  108  regulates the roller speed and, therefore, through-put. While not shown in the drawings, an adjustment crank along with a read-out helps an operator make these fine adjustments. A similar adjustable mechanism  108  resides on the opposite side of the calendar hopper  28  to adjust the opposite end of axel  146  in a uniform manner across the width of the collector substrate  14  moving through the gate  30 . 
     The resulting electrically conductive structure  102  leaving the calender hopper  28  is a laminate of the electrically conductive mixture  12  compressed onto the opposed major sides of the perforated collector substrate  14  and is deposited onto the platform  80 . The laminate may have a uniform basis weight on each side of the conductor substrate or the opposed sides may support uneven basis weights. Also, an operator can load different electrically conductive materials or mixtures of active materials onto opposed sides of the conductive substrate using the dual feed hoppers  16 ,  18  and the adjustable mechanisms  104 ,  106  and  108 . As previously discussed, suitable electrically conductive active materials for a lithium/oxyhalide cell include acetylene black, graphite, coke, carbon black, and carbon monofluoride. So, in an exemplary lithium/oxyhalide cell, different ones of these materials can be contacted to the opposed substrate sides, or mixtures thereof with different constituent loadings. 
     In any event, the electrically conductive structure  102  maintains its structural integrity because the electrically conductive mixture  12  locks to itself through the perforations of the collector substrate  14 . Also, the various adjustments  104 ,  106  and  108  ensure that the distance of the calender gaps  97 A,  97 B between the beveled edges  96 A,  98 A of the gate plates  96 ,  98  and the rollers  32 ,  34  are maintained as desired so that the electrically conductive mixture  12  is coated on the opposite collector substrate  14  sides in even and regulated thicknesses ranging from about 0.020 inches to about 0.25 inches and with desired basis weights. This is important for electrochemical cells to have consistent discharge characteristics from cell to cell in a build run and also from one build run to the next. Then, the electrically conductive structure  102  can either be rolled up onto a spool (not shown) for later processing or cut into lengths suitable for an electrochemical cell in the process of being built. If desire, the electrically conductive structure  102  can also be heated to up to about 300° C. in a post processing sintering step. This helps to cure or set the thermoplastic binder to ensure structural integrity. 
     Other electrically conductive materials useful for constructing an electrode of either a primary or a secondary electrochemical cell are selected from fluorinated carbon, a metal, a metal oxide, a metal sulfide or a mixed metal oxide. Such electrode active materials include silver vanadium oxide, copper silver vanadium oxide, manganese dioxide, titanium disulfide, copper oxide, copper sulfide, iron sulfide, iron disulfide, cobalt oxide, nickel oxide, copper vanadium oxide, and other materials typically used in alkali metal electrochemical cells. 
     Suitable fluorinated carbons are 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  and wherein the n refers to the number of monomer units, which can vary widely. These electrode active materials are composed of carbon and fluorine, and include graphitic and nongraphitic forms of carbon, such as coke, charcoal or activated carbon. 
     In secondary or lithium-ion cells, the positive electrode preferably comprises a lithiated material that is stable in air and readily handled. Examples of such air-stable lithiated cathode 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 , LiCo 0.92 Sn 0.08 O 2  and LiCo 1-x Ni x O 2 . 
     To discharge such secondary cells, the lithium ions comprising the positive electrode intercalated into a carbonaceous negative electrode or anode by applying an externally generated electrical potential to recharge the cell. The applied recharging electrical potential serves to draw the lithium ions from the cathode material, through the electrolyte and into the carbonaceous anode to saturate the carbon comprising the anode. 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 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 positive electrode for a primary or a secondary cell is prepared in a similar manner as previously described with respect to fabrication of a cathode collector for an oxyhalide cell. In that respect, the positive electrode is prepared by mixing about 80 to 99 weight percent of an already prepared electrically conductive material in a finely divided form with about 1 to 10 weight percent of a powdered conductive diluent and about 1 to 10 weight percent of a binder material. Suitable conductive diluents and binder materials have already been described. 
     Similarly, if the active material is a carbonaceous counter electrode in a secondary cell, the electrode material preferably includes a conductive diluent and a binder material in a similar manner as the previously described primary, solid cathode electrochemical cell. 
     Electrodes prepared as described above are flexible and may be in the form of one or more plates operatively associated with at least one or more plates of a counter electrode material, or in the form of a strip wound with a corresponding strip of counter electrode material in a structure similar to a “jellyroll”. 
     For oxyhalide chemistries, the cell further comprises a nonaqueous, ionically conductive catholyte operatively associated with the anode and the cathode collector. In a cell chemistry having a solid positive electrode, the anode and cathode electrodes are activated with an ionically conductive electrolyte. In either case, the catholyte and the electrolyte serve as a medium for migration of ions between the anode and the cathode collector in the case of the oxyhalide chemistry and between the anode and the cathode electrodes in the solid positive electrode chemistry during the cell&#39;s electrochemical reactions. 
     For an oxyhalide cell, suitable nonaqueous solvent depolarizers exhibit those physical properties necessary for ionic transport, namely, low viscosity, low surface tension and wettability. In the case of a catholyte, suitable nonaqueous depolarizers are comprised of an inorganic salt dissolved in a nonaqueous codepolarizer system and, more preferably, a lithium metal salt dissolved in a catholyte solution comprising a halogen and/or interhalogen dissolved in a nonaqueous solvent. The halogen and/or interhalogen serve as a soluble depolarizer. They also can serve as a cosolvent in the electrochemical cell. The halogen is selected from the group of iodine, bromine, chlorine or fluorine while the interhalogen is selected from the group of ClF, ClF 3 , ICl, ICl 3 , IBr, IF 3 , IF 5 , BrCl, BrF, BrF 3 , BrF 5 , and mixtures thereof. The mole ratio of any one of the above-referenced halogens and/or interhalogens dissolved in any one of the above-referenced nonaqueous organic or inorganic solvents is from about 1:6 to about 1:1. 
     The nonaqueous solvent depolarizer may be one of the organic solvents which is substantially inert to the anode and electrically conductive collector materials such as tetrahydrofuran, propylene carbonate, acetonitrile, dimethyl sulfoxide, dimethyl foramide, dimethyl acetamide and in particular halogenated organic solvents such as 1,1,1,2,3,3,3-heptachloropropane or 1,4-difluorooctachlorobutane. The nonaqueous solvent depolarizer also may be one or a mixture of more than one of the inorganic solvents which can serve as both a solvent and a depolarizer such as thionyl chloride, sulfuryl chloride, selenium oxychloride, chromyl chloride, phosphoryl chloride, phosphorous sulfur trichloride and others. The ionic conductivity of the nonaqueous catholyte solution is preferably facilitated by dissolving a lithium salt in the nonaqueous depolarizer. Examples of lithium salts are lithium halides such as LiCl and LiBr and lithium salts of the LiMX n  type, such as LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , LiClO 4 , LiAlCl 4 , LiGaCl 4 , LiC(SO 2 CF 3 ) 3 , LiN(SO 2 CF 3 ) 2 , LiSCN, LiO 3 SCF 2 CF 3 , LiC 6 F 5 SO 3 , LiO 2 , LiO 2 CCF 3 , LiSO 3 F, LiB(C 6 H 5 ) 4 , LiCF 3 SO 3 , and mixtures thereof. Suitable salt concentrations typically range between about 0.25 to about 1.5 molar. Thus, the solution of halogen and/or interhalogens, the nonaqueous solvent depolarizer and, optionally, the ionic salt, serve as the codepolarizer and catholyte of the oxyhalide cell. 
     In electrochemical systems of either a primary or a secondary chemistry having a solid cathode or solid positive electrode, the nonaqueous solvent system comprises low viscosity solvents including tetrahydrofuran (THF), methyl acetate (MA), diglyme, trigylme, tetragylme, dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), 1,2-dimethoxyethane (DME), diisopropylether, 1,2-diethoxyethane, 1-ethoxy, 2-methoxyethane, dipropyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, diethyl carbonate, and mixtures thereof. While not necessary, the electrolyte also preferably includes a high permittivity solvent selected from 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-butyrolactone (GBL), γ-valerolactone, N-methyl-pyrrolidinone (NMP), and mixtures thereof. The nonaqueous solvent system also includes at least one of the previously described lithium salts in a concentration of about 0.8 to about 1.5 molar. For a solid cathode primary or secondary cell having lithium as the anode active material, such as of the Li/SVO couple, the preferred electrolyte is LiAsF 6  in 50:50, by volume, mixture of PC/DME. For a Li/CF x  cell, the preferred electrolyte is 1.0M to 1.4M LiBF 4  in γ-butyrolactone (GBL). 
     When the mechanical structure or configuration of the cell requires, a separator is employed to provide physical separation between the anode and the cathode collector for the oxyhalide cell and between the anode and the cathode in a solid positive electrode chemistry. The separator is of electrically insulative material, and the separator material also is chemically unreactive with the counter electrode materials and both chemically unreactive with and insoluble in the catholyte or the electrolyte, as the case may be. In addition, the separator material has a degree of porosity sufficient to allow flow therethrough of the catholyte or the electrolyte during the electrochemical reaction of the cell. 
     Illustrative separator materials include woven and non-woven fabrics of polyolefinic fibers or fluoropolymeric fibers including polyethylenetetrafluoroethylene, polyvinylidene fluoride, and polyethylenechlorotrifluoroethylene laminated or superposed with a polyolefinic or a fluoropolymeric microporous film. Suitable microporous films include 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 separator may also be composed of non-woven glass, glass fiber materials and ceramic materials. 
     The form of the separator typically is a sheet which is placed between the anode and the cathode collector or between the negative and the positive electrodes, and in a manner preventing physical contact there between. Such is the case when the anode is folded in a serpentine-like structure with a plurality of cathode current collector plates or positive electrode plates disposed intermediate the anode folds and received in a cell casing or when the electrode combination is rolled or otherwise formed into a cylindrical “jellyroll” configuration. 
     The assembly of the cell described herein is preferably in the form of a wound element cell. That is, the fabricated cathode collector or positive electrode, the anode or negative electrode and the separator are wound together in a “jellyroll” type configuration or “wound element cell stack” such that the anode or negative electrode is on the outside of the roll to make electrical contact with the cell case in a case-negative configuration. Using suitable top and bottom insulators, the wound cell stack is inserted into a metallic case of a suitable size dimension. The metallic case 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. 
     The cell header comprises a metallic disc-shaped body with a first hole to accommodate a glass-to-metal seal/terminal pin feedthrough and a second hole for electrolyte filling. The glass used 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 cathode collector or positive terminal pin feedthrough preferably comprises titanium although molybdenum, aluminum, nickel alloy, or stainless steel can also be used. The cell header comprises elements having compatibility with the other components of the electrochemical cell and is resistant to corrosion. The cathode collector or positive electrode lead is welded to the positive terminal pin in the glass-to-metal seal and the header is welded to the case containing the electrode stack. The cell is thereafter filled with the catholyte or electrolyte solution described hereinabove and hermetically sealed such as by close-welding a stainless steel ball over the fill hole, but not limited thereto. 
     The above assembly describes a case-negative cell, which is the preferred construction of the exemplary cell chemistries of the present invention. As is well known to those skilled in the art, the exemplary electrochemical systems can also be constructed in case-positive configurations. 
     It is apppreciates that various modifications to the invention concepts described herein may be apparent to those of ordinary skills in the art without departing from the scope of the present invention as defined by the appended claims.