Patent Publication Number: US-2022238858-A1

Title: Intermittently coated dry electrode for energy storage device and method of manufacturing the same

Description:
RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 16/675,012, filed on Nov. 5, 2019, which claims priority to and the benefit of Provisional Application No. 62/757,609 filed on Nov. 8, 2018 in the U.S Patent and Trademark Office, the entire contents of each of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Field 
     The described technology generally relates to energy storage devices, and specifically to methods for manufacturing intermittently coated dry electrodes for energy storage devices and energy storage devices including the intermittently coated dry electrodes. 
     Description of the Related Technology 
     Electrical energy storage cells are widely used to provide power to electronic, electromechanical, electrochemical, and other useful devices, for example, hybrid vehicles, plug-in hybrid vehicles and pure electric vehicles. Such cells include batteries such as primary chemical cells and secondary (rechargeable) cells, fuel cells, and various species of capacitors, including ultracapacitors. Increasing the operating power and energy of energy storage devices, including capacitors and batteries, would be desirable for enhancing energy storage, increasing power capability, and broadening real-world use cases. 
     SUMMARY 
     For purposes of summarizing the described technology, certain objects and advantages of the described technology are described herein. Not all such objects or advantages may be achieved in any particular embodiment of the described technology. Thus, for example, those skilled in the art will recognize that the described technology may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. 
     One inventive aspect is an intermittently coated dry electrode for an energy storage device. 
     Another aspect is a method of manufacturing an intermittently coated dry electrode for an energy storage device. 
     Another aspect is an energy storage device including intermittently coated dry electrodes. 
     Another aspect is a method of manufacturing a dry electrode for an energy storage device, comprising: providing a metal layer; providing an electrochemically active free-standing film formed of a dry active material; combining the electrochemically active free-standing film and the metal layer to form a combined layer; and removing a portion of the electrochemically active free-standing film from the combined layer so that the electrochemically active free-standing film is intermittently formed on the metal layer in a longitudinal direction of the metal layer. 
     Another aspect is a dry electrode for an energy storage device, comprising: a metal layer; and an electrochemically active free-standing film formed of a dry active material, wherein the electrochemically active free-standing film comprises a plurality of film portions intermittently formed on the metal layer in a longitudinal direction of the metal layer to expose a portion of the metal layer. 
     Another aspect is an energy storage device, comprising: a first electrode; a second electrode; and a separator interposed between he first and second electrodes, wherein each of the first and second electrodes comprises; a metal layer; and an electrochemically active free-standing film formed of a dry active material, wherein the electrochemically active free-standing film comprises a plurality of film portions intermittently formed on the metal layer in a longitudinal direction of the metal layer to expose a portion of the metal layer. 
     Another aspect is a method of manufacturing a dry electrode for an energy storage device, comprising: providing a metal layer; providing a first electrochemically active free-standing film formed of a dry active material; providing a second electrochemically active free-standing film formed of a dry active material; combining the first and second electrochemically active free-standing films with the metal layer to form a combined layer such that the metal layer is interposed between the first and second electrochemically active free-standing films; and removing a first portion of the first electrochemically active free-standing film and a second portion of the second electrochemically active free-standing film from the combined layer so that each of the first and second electrochemically active free-standing films is intermittently formed on the metal layer in a longitudinal direction of the metal layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating a process for manufacturing a dry electrode for an energy storage device. 
         FIG. 2  illustrates an electrochemically active free-standing film placed over a continuously adhesive coated metal foil before heat and/pressure is applied thereto. 
         FIG. 3  illustrates the electrochemically active free-standing film laminated onto the continuously adhesive coated metal foil after heat and pressure is applied thereto. 
         FIG. 4  illustrates an example continuously coated dry electrode. 
         FIG. 5  illustrates an electrochemically active free-standing film placed over an intermittently adhesive coated metal foil before heat and pressure is applied thereto. 
         FIG. 6  illustrates the electrochemically active free-standing film laminated onto the intermittently adhesive coated metal foil after heat and pressure is applied thereto. 
         FIG. 7  illustrates an example intermittently coated dry electrode according to an embodiment. 
         FIG. 8  illustrates an electrochemically active free-active film according to an embodiment. 
         FIG. 9  illustrates an example metal foil that includes metal foil portions that are intermittently coated with adhesive and uncoated metal foil portions according to an embodiment. 
         FIG. 10  illustrates an intermittently coated dry electrode according to another embodiment. 
         FIG. 11  illustrates an electrochemically active free-active film placed over an example uncoated metal foil according to another embodiment. 
         FIG. 12  illustrates a laminator roll assembly according to an embodiment that produces intermittently coated electrode laminates. 
         FIG. 13  illustrates an intermittently coated dry electrode produced by the laminator roll assembly of  FIG. 12 , according to an embodiment. 
         FIG. 14  illustrates an electrochemically active free-active film placed over an example uncoated metal foil according to another embodiment. 
         FIG. 15  illustrates a laminator roll assembly according to another embodiment. 
         FIG. 16  illustrates an intermittently coated dry electrode produced by the laminator roll assembly of  FIG. 15 , according to another embodiment. 
         FIG. 17  illustrates a laminator roll assembly that produces an asymmetric intermittent double-side coated dry laminate shown in  FIG. 18  according to an embodiment. 
         FIG. 18  illustrates a cross-sectional view of the asymmetric intermittent double-side coated dry laminate produced by the laminator roll assembly shown in  FIG. 17  according to an embodiment. 
         FIG. 19  illustrates a laminator roll assembly that produces an asymmetric intermittent double-side coated dry laminate shown in  FIG. 20  according to another embodiment. 
         FIG. 20  illustrates a cross-sectional view of the asymmetric intermittent double-side coated dry laminate produced by the laminator roll assembly shown in  FIG. 19  according to another embodiment. 
         FIG. 21  illustrates an intermittently coated dry electrode to be connected to an electrode tab according to an embodiment. 
         FIG. 22  illustrates an energy storage device according to an embodiment. 
         FIG. 23  illustrates a method of manufacturing a dry electrode for an energy storage device according to an embodiment. 
         FIG. 24  illustrates a method of manufacturing a dry electrode for an energy storage device according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Provided herein are various embodiments of a dry electrode for use in energy storage devices. In particular, in certain embodiments, energy storage devices disclosed herein include an intermittently coated dry electrode. For example, the described technology can provide dry electrode coating capability to include intermittent patterns for use in cylindrically wound cells with current collection designed across the width of the electrode. Also provided are methods for manufacturing such intermittently coated dry electrodes. The disclosed embodiments can provide a simplified and cost-effective electrode coating procedure for energy storage devices. 
     Energy storage devices such as lithium ion batteries have been relied on as a power source in numerous commercial and industrial uses, for example, in consumer devices, productivity devices, and in battery powered vehicles. However, demands placed on energy storage devices are continuously—and rapidly—growing. For example, the automotive industry is developing vehicles that rely on compact and efficient energy storage, such as plug-in hybrid vehicles and pure electric vehicles. Lithium ion batteries are well suited to meet future demands. 
     Key components of the storage potential of an energy storage device are electrodes. The electrochemical capabilities of electrodes, for example, the capacity and efficiency of battery electrodes, are governed by various factors. For example, distribution of active material, binder and additive(s); the physical properties of materials therein, such as particle size and surface area of active material; the surface properties of the active materials; and the physical characteristics of the electrode film, such as density, porosity, cohesiveness, and adhesiveness to a conductive element. Dry processing methods traditionally used a high shear and/or high pressure processing step to break up and commingle electrode film materials, which may contribute to structural advantages over electrode films produced using a wet process. 
       FIG. 1  is a block diagram illustrating a process  10  for making a dry electrode for an energy storage device. As used herein, the term “dry” implies non-use of liquid-phase solvents and additives in mixing and coating process of electrode during process steps described herein, other than during a final impregnating electrolyte step. The process  10  shown in  FIG. 1  begins by dry blending  18  dry active material particles  12 , dry conductive particles  14  and dry binder particles  16  to form a dry mixture. Furthermore, dry conductive particles  21  and dry binder particles  23  are also dry blended  19  to form a dry mixture which can be provided to an optional dry fibrillizing step  26  or  29 . The dry mixture is fibrillized in a dry fibrillizing step  20  using, for example, a jet-mill (not shown). During the dry fibrillizing step  20 , high shear forces are applied to the dry mixture in order to physically stretch it and form a network of thin web-like fibers. In a dry feed step  22  or  29 , the respective separate mixtures of dry particles formed in steps  19  and  20  are provided to respective containers (not shown) to form a dry film. The dry film is subsequently dry compacted and calendared by a roll-mill or calendar  24  to provide an embedded/intermixed dry film or a self-supporting electrode film (or electrochemically active free-standing film). The embedded/intermixed dry film is attached or bonded to a current collector (e.g., metal foil)  28 . A more detailed process of making an embedded/intermixed dry film including types of materials forming the dry films and materials forming the current collector is disclosed in U.S. Pat. No. 7,352,558, which is incorporated by reference herein in its entirety. 
     A self-supporting dry electrode film manufactured above may provide improved characteristics relative to a typical electrode film that is manufactured using a wet process. For example, a dry electrode film as provided herein may provide one or more of improved film strength, improved cohesiveness, improved adhesiveness, improved electrical performance, or reduced incidence of defects. The defects may include holes, cracks, surface pits in the electrode film. The adhesiveness may be adhesiveness to a current collector. The electrical performance may be specific capacity. The film strength may be tensile strength. 
     The materials and methods provided herein can be implemented in various energy storage devices. As provided herein, an energy storage device can be a capacitor, a lithium ion capacitor (LIC), an ultracapacitor, a battery such as a lithium ion battery, or a hybrid energy storage device combining aspects of two or more of the foregoing. 
       FIGS. 2-4  illustrate a process of making an example dry electrode. The example dry electrode may be an anode or a cathode. Referring to  FIG. 2 , an electrochemically active free-standing film  34  is placed over a metal foil  30 . The electrochemically active free-standing film  34  may be formed of an electrochemically active material. The electrochemically active material can be an anode active material or a cathode active material. The anode active material may include, for example, graphite, silicon, tin, lithium titanate, lithium metal, lithium alloy compound or composites derived from these compositions. The cathode active material may include, for example, nickel manganese cobalt oxide (NMC), nickel cobalt aluminum oxide (NCA), lithium cobalt oxide (LCO), lithium iron phosphate (LFP), activated carbon, lithium manganese oxide (LMO), lithium nickel manganese oxide (LNMO), iron sulfide, sulfur or composites derived from these compositions. The metal foil  30  may be formed of, for example, copper, aluminum, titanium, stainless steel or a combination thereof. The description of this paragraph applies to the remaining embodiments. 
     The metal foil  30  includes a continuously adhesive coated metal foil portion  32  and an uncoated metal foil portion  36 . The continuously adhesive coated metal foil portion  32  is continuously coated with an adhesive in a longitudinal direction of the metal foil  30 . The electrochemically active free-standing film  34  may be placed over a majority of the adhesive coated metal foil portion  32 . The active free-standing film  34  may also be placed over a portion of the uncoated metal foil portion  36  as shown in  FIG. 2 . In some embodiments, the active free-standing film  34  may not be placed over any portion of the uncoated metal foil  36  (not shown). After heat and/or pressure is applied to the active free-standing film  34  and the adhesive coated metal foil portion  32 , the active free-standing film  34  is laminated onto the adhesive coated metal foil portion  32  ( FIG. 3 ). The laminated film of  FIG. 3  includes an area of an unattached electrochemically active free-standing film  42  and an area of a film laminated to a coated metal foil  44 . The portion of the adhesive coated metal foil  32  that is not directly attached to the active free-standing film  34  may be removed by, for example, peeling or slitting. A continuously adhesive coated dry electrode  46  is subsequently formed ( FIG. 4 ). The dry electrode  46  of  FIG. 4  includes an uncoated metal foil portion  48  that can be used for electrically connecting the dry electrode  46  to other electrical components such as an electrode tab, positioned inside the final electrical device. The size or dimension of the uncoated foil portion  48  generally constitutes a significant portion of the final dry electrode  46 . Thus, the dimension of the continuously adhesive coated dry electrode  46  can be limited by the dimension of the uncoated portion  48 . 
       FIGS. 5-7  illustrate a process of making an example intermittingly coated dry electrode according to an embodiment. Referring to  FIG. 5 , an electrochemically active free-standing film  56  is placed over a metal foil  58 . The metal coil  58  is discontinuously or intermittently coated with an adhesive or an adhesive layer (not shown) in a longitudinal direction thereof. The adhesive layer may be formed from one or more of glue or thermoplastic such as polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), acrylics, fluoropolymers, polyesters, polyimides, polyamides, polyurethanes, polycarbonates, carbon or a combination thereof. The adhesive layer may be conductive (e.g., carbon adhesive layer). The coating weight for the conductive adhesive layer may be in the range of about 1 gram per square meter per side to about 5 grams per square meter per side with a dry coating density of about 0.2 grams per square centimeter per side to about 1.1 grams per square centimeter per side. The above coating weight and density can provide an optimum balance between a mechanically robust attachment of free-standing active films and lower costs. For example, the conductive adhesive layer can be thin (lowest loading weight) and as low in density as possible (minimal carbon adhesive material usage). These weight and density numbers are merely examples and other weight and density values are also possible. This applies to the remaining embodiments. The metal coil  58  includes coated portions  52  (or intermittently adhesive coated metal foil portions) and an uncoated portion  54  (or uncoated metal foil portion). The uncoated portion  54  is interposed between the adhesive coated portions  52 . The uncoated portion  54  may be placed around the middle of the metal foil  58  in the longitudinal direction of the metal foil  58 , however, the position of the uncoated portion  54  is not limited thereto. The discontinuously coated metal foil  58  may be produced via, for example, as gravure roll coating or slot die coating or screen printing or laser jet printing. 
     After heat and/or pressure is applied to the stacked layers ( 58 ,  56 ), the active free-standing film  56  is laminated onto the adhesive coated metal foil portions  52  ( FIG. 6 ). The laminated film of  FIG. 6  includes an area of an unattached electrochemically active free-standing film  62  and an area of a film laminated onto a coated metal foil  64 . The area of the unattached electrochemically active free-standing film  62  includes an upper portion and a middle portion (see two arrows shown in the upper region of  FIG. 6 ) of the active free-standing film  56  as shown in  FIG. 6 . The area of the film laminated to the coated metal foil  64  includes left and right portions (see two arrows shown in the lower region of  FIG. 6 ) of the active free-standing film  56  that vertically overlap the adhesive coated metal foil portions  52 . 
     After the portion of the active free-standing film  56  that vertically overlaps the uncoated metal foil portion  54  is removed, a discontinuously or intermittently coated dry electrode  72  is formed ( FIG. 7 ). The peeling/trimming or removal of the overlapping portion of the unattached free-standing film  62  can be carried out using, for example, an air knife and/or vacuum. Since the uncoated metal foil portion  54  is not coated with an adhesive and thus is not adhered to the corresponding portion of the active free-standing film  56 , the overlapping free-standing film portion can be more easily removed compared to the continuously adhesive coated electrode shown in  FIGS. 2-4 . The dry electrode  72  includes two active free-standing film portions  64   a  and  64   b  that are discontinuously or intermittently formed with respect to each other. The dry electrode  72  includes an uncoated foil portion  54  that is used for electrically connecting the electrode  72  to other elements such as an electrode tab. The dimension of the uncoated portion  54  may be substantially smaller than the uncoated portion  48  of the continuously coated dry electrode  46  in  FIG. 4 . For example, the width of the uncoated foil portion  54  may be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 millimeters, or any width in a range between any two of these values. In other embodiments, the width of the uncoated foil portion  54  may be 5-10, 10-20, 20-30, 30-40, or 40-50 millimeters or more in width. Thus, the embodiment shown in  FIGS. 5-7  can provide a simplified and cost-effective dry electrode making procedure for energy storage devices. 
       FIGS. 8-10  illustrate a process of making an example dry electrode according to another embodiment. In  FIG. 8 , an electrochemically active free-standing film  80  is shown. The active free-standing film  80  may be longer than the active free-standing film  34  shown in  FIG. 2  and the active free-standing film  56  shown in  FIG. 5 .  FIG. 9  shows a metal foil  90 . The metal foil  90  is discontinuously or intermittently coated with an adhesive in a longitudinal direction thereof as shown in  FIG. 9 . The active free-standing film  80  may be similar in dimension to the metal foil  90 . The metal coil  90  includes coated portions  92  (or intermittently adhesive coated metal foil portions) and uncoated portions  94  (or uncoated metal foil portions). The coated portions  92  and the uncoated portions  94  are alternately formed with respect to each other as shown in  FIG. 9 . The discontinuously coated metal foil portions  92  may be formed by intermittently coating an adhesive (described above) on the metal foil  90  via, for example, gravure roll coating, slot die coating, screen printing or laser jet printing. 
     In  FIGS. 9 and 10 , x represents the width of each of the uncoated metal foil portions  94  measured in the longitudinal direction of the metal foil  90 , and y represents the width of each of the coated metal foil portions  92 / 102  measured in the longitudinal direction. Although only three sets of the coated portions  92  and the uncoated portions  94  are shown in  FIG. 9 , more pairs of coated portions and uncoated portions can be formed (not shown). Those more pairs can be alternately formed with respect to each other. It should be realized that the ration of x/y may be any value where y is typically greater than x such that the width of the coated portion is greater than the value of the uncoated portion. In one embodiment, as discussed more fully below, the width y relates to the circumference of the final electrode winding such that each uncoated section  94  aligns with each other when the laminate film is wound into a rolled electrode format. 
     Similarly to  FIGS. 5 and 6 , after the active free-standing film  80  is placed over the intermittently adhesive coated metal foil portions  92  and the uncoated metal foil portions  94  of the metal foil  90 , heat and/or pressure may be applied to the stacked layers ( 80 ,  90 ) so that the active free-standing film  80  is laminated onto the adhesive coated metal foil portions  92 . Again, the active free-standing film  80  may not be adhered or very weakly attached to the uncoated metal foil portions  94  on which no adhesive is formed. Since there are three uncoated metal foil portions  94  provided in  FIG. 9 , the laminated film  100  in  FIG. 10  would initially include three portions (not shown) of the active free-standing film  80  that respectively vertically overlap the three uncoated metal foil portions  94  (before the three portions are removed). After the overlapping portions of the active free-standing film  80  are removed, a discontinuously or intermittently coated dry electrode  100  is formed ( FIG. 10 ). The peeling or removal of the overlapping portions of the active free-standing film  80  can be done in the same way discussed above with respect to the embodiments of  FIGS. 5-7 . 
     The electrode  100  includes intermittently coated portions  102  and uncoated foil portions  94 . At least one of the uncoated foil portions  94  can be used for electrically connecting the electrode  100  to other elements such as an electrode tab. The dimension of each of the uncoated portions  94  may be substantially smaller than the uncoated portion  48  of the continuously coated dry electrode  46  in  FIG. 4 . Thus, the embodiment shown in  FIGS. 8-10  can also provide a simplified and cost-effective dry electrode making procedure for energy storage devices. 
       FIGS. 11-13  illustrate a process of making an example dry electrode according to another embodiment. In  FIG. 11 , an electrochemically active free-standing film  110  and a metal foil  120  uncoated with an adhesive are shown. The active free-standing film  110  may have the same dimension as that of the active free-standing film  80  shown in  FIG. 8 . The active free-standing film  110  is placed over and aligned with the uncoated metal foil  120  before a laminator roll procedure in  FIG. 12  is performed. For the purpose of illustrating both the active free-standing film  110  and the uncoated metal foil  120 ,  FIG. 11  shows that the two elements  110  and  120  are slightly misaligned with each other, however, the elements  110  and  120  would be aligned before the laminator roll procedure. 
     Referring to  FIG. 12 , the active free-standing film  110  and the uncoated metal foil  120  are inserted into and laminated by a laminator roll assembly  130 . The laminator roll assembly  130  includes a pair of rollers  132  and  134 . The rollers  132  and  134  may have substantially the same diameter. The rollers  132  and  134  may be formed of the same material or different materials having the same or similar level of hardness so that a substantially uniform pressure is applied to the stacked layers ( 110 ,  120 ) by both of the rollers  132  and  134 . The rollers  132  and  134  respectively have openings  136  and  138 . The openings  136  and  138  may have the same dimension. In one embodiment, the openings  136  and  138  may have the same width or circumferential length (x) and same depths. In another embodiment, the openings  136  and  138  may have the same width (x), but may have different depths. Each of the openings  136  and  138  has a width (x) which is the same as that of each of uncoated metal foil portions  144  shown in  FIG. 13 . The length (y) of the remaining portion of each of the rollers  132  and  134  is the same as the width of each of intermittently coated portions  142  shown in  FIG. 13 . 
     A skilled person would appreciate that each of the laminate rollers  132  and  134  may have different dimensions of x and y, depending on the required dimensions of the intermittently coated portions  142  and the uncoated metal foil portions  144 . For example, when the width (x) of each uncoated metal foil portion becomes greater, circumferential lengths of the openings also become greater. In contrast, when the width (x) of each uncoated metal foil portion becomes smaller, circumferential lengths of the openings also become smaller. Once the dimension of x is defined, the dimension of the remaining portion (y) may be automatically defined. 
     During the laminating procedure in  FIG. 12 , the rollers  132  and  134  are positioned adjacent to each other such that the openings  136  and  138  are aligned with each other as shown in  FIG. 12 . When the stacked layers ( 110 ,  120 ) are inserted between the rollers  132  and  134 , the two layers ( 110 ,  120 ) are laminated into each other except for the portions that pass through the openings  136  and  138 , as the stacked layers ( 110 ,  120 ) are not pressed by the rollers  132 ,  134  in the openings  136  and  138 . The non-pressed portions of the active free-standing film  110  may be peeled off so that an intermittently coated dry electrode  140  is formed as shown in  FIG. 13 . The peeling procedure can be performed in the same way described above with respect the previous embodiments. 
     Although each of the rollers  132  and  134  of  FIG. 12  includes an opening, only one of the rollers  132  and  134  may have an opening. In this embodiment, only one of the two layers ( 110 ,  120 ) is directly contacted by the rollers  132  and  134  in the opening area, during the laminating roll procedure. 
     In another embodiment, each of the rollers  132  and  134  may include a plurality of openings (not shown). In this embodiment, each roller may have a dimension larger than the rollers  132  and  134  shown in  FIG. 12 . For example, two or more openings spaced apart from each other are formed in each of the rollers  132  and  134 . These rollers may have the same dimension and the same number of openings. Furthermore, the openings of each roller may be circumferentially aligned with each other during the laminating roll procedure so that the same portions of the active free-standing film  110  that form the x areas are not directly pressed by either of the rollers. The length of each of the openings may be the same as the width (x) of each of the uncoated metal foil portions  144 . The distance between adjacent openings may be the same as the width (y) of each of the intermittently coated portions  142 . In this embodiment, the laminating procedure and the peeling procedure can be more efficiently performed. 
     The above dry electrode making procedure can be applicable to a single-side coated electrode, a double-side coated electrode, and an offset coated electrode or asymmetric intermittent double-side coated dry laminate (double-side coated electrode with an intermittent pattern on one side differing from the other side to be described with respect to  FIGS. 17-20 ). In the double-side coated electrode, the intermittent pattern on one side can be symmetric to that on the other side. 
       FIGS. 14-16  illustrate a process of making an example dry electrode according to another embodiment. In  FIG. 14 , an electrochemically active free-standing film  150  and a metal foil  162  uncoated with an adhesive are shown. The active free-standing film  150  may have the same dimension as that of the active free-standing film  110  shown in  FIG. 11 . The active free-standing film  150  is placed over and aligned with the uncoated metal foil  162  before a laminator roll procedure in  FIG. 15  is performed. 
     Referring to  FIG. 15 , the active free-standing film  150  and the uncoated metal foil  162  are inserted into and laminated by a laminator roll assembly  170 . The laminator roll assembly  170  includes a pair of rollers  175  and  177 . The rollers  175  and  177  may have substantially the same diameter. The rollers  175  and  177  may be formed of the same material or different materials having the same level of hardness so that a substantially uniform pressure is applied to the stacked layers ( 150 ,  162 ) by both of the rollers  175  and  177 . 
     The relative position (e.g., vertical position) of the rollers  175  and  177  may be controlled such that a gap therebetween is periodically closed or opened while the rollers  175  and  177  are being rotated. In  FIG. 15 , reference numerals  172  and  176  represent a closed gap, and reference numeral  174  represents an open gap. In one embodiment, the intermittent periodicity of an intermittently coated dry electrode  180  shown in  FIG. 16  can be governed by the duration of applied pressure to the two layers  150  and  162  to produce a dimension x and a dimension y. In this embodiment, the dimension y, where the free-standing film  150  is attached to the metal foil  162 , is produced when the rollers  175  and  177  are closed (see  172  and  176  in  FIG. 15 ). The length (y) or the width of each of intermittently coated portions  184  shown in  FIG. 16  may be proportional to the duration of the rollers  175  and  177  being closed ( 172 ,  176 ). For example, the longer the duration of the rollers  175  and  177  being closed, the larger the length y is, and vice versa. Furthermore, the dimension x, where the free-standing film  150  is not attached to (but merely placed over) the metal foil  162 , is produced when the rollers  175  and  177  are opened (see  174  in  FIG. 15 ). The length (x) between adjacent intermittently coated portions  184  may be proportional to the duration of the rollers  175  and  177  being opened ( 174 ). For example, the longer the duration of the rollers  175  and  177  being opened ( 174 ), the larger the length x is, and vice versa. In one embodiment, both of the rollers  175  and  177  are moved to open or close the gaps therebetween. In another embodiment, only one of the rollers  175  and  177  is moved to open or close the gaps therebetween. 
     When the gaps of the rollers  175  and  177  are closed ( 172 ,  176 ), the stacked layers ( 150  and  162 ) are pressed by the rollers  175  and  177  and thus laminated into each other. When the gaps of the rollers  175  and  177  are opened ( 174 ), the stacked layers ( 150  and  162 ) are not pressed by the rollers  175  and  177  and thus not laminated into each other (i.e., merely placed over each other). The non-pressed portions of the active free-standing film  150  are removed so that the intermittently coated dry electrode  180  is formed as shown in  FIG. 16 . The removal procedure may be performed in the same way described above with respect to the previous embodiments. This way, the laminating procedure and the removal procedure can be more efficiently performed. 
     The above dry electrode making procedure can be applicable to a single-side coated electrode, a double-side coated electrode, and an offset coated electrode or asymmetric intermittent double-side coated dry laminate (double-side coated electrode with an intermittent pattern on one side differing from the other side to be described with respect to  FIGS. 17-20 ). 
       FIGS. 17 and 18  illustrate a process of making an asymmetric intermittent double-side coated dry laminate  300  with the use of a laminator roll assembly  320  according to one embodiment.  FIG. 17  illustrates a laminator roll assembly  320  that produces the asymmetric intermittent double-side coated dry laminate  300  shown in  FIG. 18  according to an embodiment.  FIG. 18  illustrates a cross-sectional view of the asymmetric intermittent double-side coated dry laminate  300  produced by the laminator roll assembly  320  shown in  FIG. 17  according to an embodiment. As briefly described above with respect to  FIGS. 14-16  and as shown in  FIG. 18 , the asymmetric intermittent double-side coated dry laminate  300  (or offset coated dry electrode) is a double-sided electrode with an intermittent pattern on one side that differs from the other side. 
     Referring to  FIG. 17 , the laminator roll assembly  320  includes upper and lower laminator rollers  307  and  309 . The roll assembly  320  receives a first film roll  304 , a second film roll  306  and a roll of an adhesive metal foil  305 . The first film roll  304  indicates a roll of an electrochemically active free-standing film for a first intermittent dry laminate  301  shown in  FIG. 18 . The second film roll  306  indicates a roll of an electrochemically active free-standing film for a second intermittent dry laminate  302  shown in  FIG. 18 . The adhesive metal foil roll  305  indicates a roll of an asymmetric intermittently coated adhesive metal foil  303  shown in  FIG. 18 . The adhesive metal foil roll  305  is interposed between the first and second film rolls  304  and  306  when being inserted into the roll assembly  320 . The first film roll  304 , the metal foil roll  305  and the second film roll  306  may be simultaneously unwound as the films and the metal layer are inserted between and pressed by the upper and lower rollers  307  and  309 . Similarly to the process shown in  FIG. 15 , the upper roller  307  is controlled to periodically press the first film roll  304  against the adhesive metal foil  305  to produce the first intermittent dry laminate  301 . For example, the first film roll  304  is pressed for a duration of the length “a” and not pressed for a duration of the length “b” shown in  FIG. 18 . Furthermore, the lower roller  309  is controlled to periodically press the first second film roll  306  against the adhesive metal foil  305  to produce the second intermittent dry laminate  302 . For example, the second film roll  306  is pressed for a duration of the length “c” and not pressed for a period of the length “d” shown in  FIG. 18 . The non-pressed areas may be removed from the laminated layer  308  in the same manner described above to produce the asymmetric intermittent double-side coated dry laminate  300  shown in  FIG. 18 . The removed portions may at least partially vertically overlap each other. The film portions of the first intermittent dry laminate  301  may at least partially vertically overlap the film portions of the second intermittent dry laminate  302  as shown in  FIG. 18 . 
     Referring to  FIG. 18 , the first intermittent dry laminate  301  and the second intermittent dry laminate  302  are asymmetric to each other. For example, the length a of each of the laminated portions of the first intermittent dry laminate  301  is different from the length c of each of the laminated portions of the second intermittent dry laminate  302 . Furthermore, the length b of the exposed portion of the upper surface of the metal foil  303  is also different from the length d of the exposed portion of the lower surface of the metal foil  303 . In some embodiments, the length b is less than the distance d as shown in  FIG. 18 . In other embodiments, the length b is greater than the length d (not shown). Furthermore, in some embodiments, the length c is less than the length a as shown in  FIG. 18 . In other embodiments, the length c is greater than the length a (not shown). 
     Although  FIGS. 17 and 18  show a process of making an asymmetric intermittent double-side coated dry laminate, a symmetric intermittent double-side coated dry laminate can also be made in the same way except that the pressing interval or duration would be the same for the upper and lower laminator rollers  307  and  309 . Furthermore,  FIGS. 17 and 18  show merely an example process of making an asymmetric intermittent double-side coated dry laminate, other roller assembly configurations and/or other arrangements of film rolls and metal foil roll may also be possible. 
       FIGS. 19 and 20  illustrate a process of making an asymmetric intermittent double-side coated dry laminate  310  with the use of a laminator roll assembly  340  according to another embodiment.  FIG. 19  illustrates the laminator roll assembly  340  that produces the asymmetric intermittent double-side coated dry laminate  310  shown in  FIG. 20  according to another embodiment.  FIG. 20  illustrates a cross-sectional view of the asymmetric intermittent double-side coated dry laminate  310  produced by the laminator roll assembly  340  shown in  FIG. 19  according to another embodiment. Referring to  FIG. 19 , the laminator roll assembly  340  includes a first laminator roll assembly  350  and a second laminator roll assembly  360 . The first laminator roll assembly  350  includes a first pair of laminator rollers  317  and  321 , and the second laminator roll assembly  360  includes a second pair of laminator rollers  323  and  318 . The roller  317  has an opening  352  with a width or circumferential length (b). The roller  318  has an opening  354  with a width or circumferential length (d) which is different from the circumferential length (b). 
     The first roll assembly  350  receives a first film roll  314  and an uncoated metal foil roll  315 . The first film roll  314  indicates a roll of an electrochemically active free-standing film for a first intermittent dry laminate  311  shown in  FIG. 20 . The second roll assembly  360  receives the first film roll  314 , the uncoated metal foil roll  315  and a second film roll  316 . The second film roll  316  indicates a roll of an electrochemically active free-standing film for a second intermittent dry laminate  312  shown in  FIG. 20 . The uncoated metal foil roll  315  indicates a roll of an asymmetric intermittently coated adhesive metal foil  313  shown in  FIG. 20 . The uncoated metal foil roll  315  is interposed between the first and second film rolls  314  and  316  when being inserted into the second roll assembly  360 . In other embodiments, the second film roll  316  and the uncoated metal foil roll  315  may be inserted into the first roll assembly  350  while the first film roll  314  (along with the second film roll  316  and the uncoated metal foil roll  315 ) is inserted into the second roll assembly  360 . In these embodiments, the roller  321  would have an opening with a circumferential length d and the roller  323  would have an opening with a circumferential length b. The first film roll  314  and the metal foil roll  315  may be unwounded before the second film roll  316  is unwound. 
     Similarly to the process shown in  FIG. 17 , when the first film roll  314  and the uncoated metal foil roll  315  are inserted into the rollers  317  and  321  to produce a first laminated layer  330  when exiting the first roll assembly  350 , and subsequently the first laminated layer  330  and the second film roll  316  are inserted into the rollers  323  and  318  to produce a second laminated layer  319  when exiting the second roll assembly  360 . The three layers  314 ,  315  and  316  are laminated into each other except for the portions of the layers  314  and  316  that pass through the openings  352  and  354 . The non-pressed portions may be removed from the second laminated layer  319  so that the asymmetric intermittent double-side coated dry laminate  310  is formed as shown in  FIG. 20 . 
     Although  FIGS. 19 and 20  show a process of making an asymmetric intermittent double-side coated dry laminate, a symmetric intermittent double-side coated dry laminate can be made in the same way except that the widths of the openings would be the same for the upper and lower laminator rollers  317  and  318 . Again,  FIGS. 19 and 20  show merely an example process of making an asymmetric intermittent double-side coated dry laminate, other roller assembly configurations and/or other arrangements of film rolls and metal foil roll may also be possible. 
       FIG. 21  illustrates an intermittently coated dry electrode  198  to be connected to an electrode tab according to an embodiment. The intermittently coated dry electrode  198  includes laminated portions  192  and  194  where an electrochemically active free-standing film is laminated onto a metal foil. The intermittently coated dry electrode  198  further includes an uncoated metal foil portion  196  described above. The uncoated metal foil portion  196  is used for connecting the dry electrode  198  to an electrode tab (see  FIG. 21 ) or other electrical component for connection with an external device (not shown). Although  FIG. 21  shows a single uncoated metal foil portion  196 , the electrode tab or other electrical component can be attached to one or more of a plurality of uncoated metal foil portions, for example, shown in  FIGS. 10, 13 and 16 . 
       FIG. 22  illustrates an energy storage device  200  according to an embodiment. The energy storage device  200  can be a battery, a capacitor or a hybrid type that combines the battery and the capacitor. The battery can include a liquid electrolyte battery or a polymer electrolyte battery or solid state battery. The polymer electrolyte may include a solid polymer electrolyte and plasticized gel polymer electrolyte. The liquid electrolyte battery may include a lithium ion battery. The polymer electrolyte battery may include a lithium polymer battery. The battery may have a cylindrical shape, a prismatic shape or a pouch shape. 
     The energy storage device  200  includes an electrode assembly  210 . The electrode assembly  210  includes a first electrode  220 , a second electrode  240 , and a separator  230  positioned between the first and second electrodes  220  and  240 . The separator  230  can be configured to electrically insulate the first and second electrodes  220  and  240  while permitting ionic communication between the two electrodes  220  and  240 . 
     The first electrode  220  can be an anode (a “negative electrode”) and the second electrode  240  can be a cathode (a “positive electrode”). Each of the anode and cathode electrodes  220  and  240  can be an intermittently coated dry electrode manufactured by one of the above described procedures of  FIGS. 5-19 . The first and second electrodes  220  and  240  respectively include non-coated metal foil portions  222  and  242  which are connected to respective electrode tabs  224  and  244  or other electrical components (not shown). 
     An energy storage device as provided herein can be of any suitable configuration, for example planar, spirally wound, button shaped, or pouch. An energy storage device as provided herein can be a component of a system, for example, a power generation system, an uninterruptible power source systems (UPS), a photo voltaic power generation system, an energy recovery system for use in, for example, industrial machinery and/or transportation. An energy storage device as provided herein may be used to power various electronic device and/or motor vehicles, including hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and/or electric vehicles (EV). 
       FIG. 23  illustrates a flowchart  2300  for a method of manufacturing a dry electrode for an energy storage device according to an embodiment. Although the process flow diagram  2300  is described herein with reference to a particular order, in various embodiments, states herein may be performed in a different order, or omitted, and additional states may be added. This may apply to the flowchart  2400  shown in  FIG. 24 . 
     In state  2310 , a metal layer is provided. For example, the metal layer can include a metal foil ( 58 ,  90 ,  120 ,  162 ) respectively shown in  FIGS. 5, 9, 11 and 14 . In state  2320 , an electrochemically active free-standing film formed of a dry active material is provided. For example, the electrochemically active free-standing film can be an electrochemically active dry film ( 56 ,  80 ,  110 ,  150 ) respectively shown in  FIGS. 5, 8, 11 and 14 . In state  2330 , the electrochemically active free-standing film and the metal layer are combined to form a combined layer. For example, the metal layer may be coated with an adhesive, the electrochemically active free-standing film may be placed over the metal layer and heat and/or pressure can be applied to the film and metal layer to combine the two elements as described with respect to  FIGS. 6 and 9 . As another example, the electrochemically active free-standing film may be placed over the metal layer, inserted between an opposing set of rollers and pressed by the rollers as described with respect to  FIGS. 12 and 15 . 
     In state  2340 , a portion of the electrochemically active free-standing film is removed from the combined layer. For example, as described with respect to  FIGS. 7, 10, 13 and 16 , portions of the electrochemically active free-standing film in which an adhesive is not attached or which are not pressed by the rollers can be removed from the metal layer portion of the combined layer via peeling or slitting. In state  2350 , the electrochemically active free-standing film is intermittently formed on the metal layer in a longitudinal direction of the metal layer, for example, as shown in  FIGS. 7, 10, 13 and 16 . As discussed above, the electrochemically active free-standing film can be formed on only one surface or opposing surfaces of the metal layer. 
       FIG. 24  illustrates a flowchart  2400  for a method of manufacturing a dry electrode for an energy storage device according to another embodiment. In state  2410 , a metal layer is provided. For example, the metal layer can include a roll of a metal foil ( 305 ,  315 ) shown in  FIGS. 17 and 19 . In state  2420 , a first electrochemically active free-standing film formed of a dry active material is provided. For example, the first electrochemically active free-standing film can include a roll of a first film ( 304 ,  314 ) shown in  FIGS. 17 and 19 . 
     In state  2430 , a second electrochemically active free-standing film formed of a dry active material is provided. For example, the second electrochemically active free-standing film can include a roll of a second film roll ( 306 ,  316 ) shown in  FIGS. 17 and 19 . In state  2440 , the first and second electrochemically active free-standing films are combined with the metal layer to form a combined layer such that the metal layer is interposed between the first and second electrochemically active free-standing films. For example, the rolls of the first and second electrochemically active free-standing films with the metal layer interposed therebetween are pressed by an opposing set of rollers (e.g., one pair of rollers or two pairs of rollers) as described with respect to  FIGS. 17 and 19 . 
     In state  2450 , a first portion of the first electrochemically active free-standing film and a second portion of the first electrochemically active free-standing film are removed from the combined layer as described with respect to  FIGS. 18 and 20 . In state  2460 , intermittent electrochemically active free-standing films are formed on opposing surfaces of the metal layer, for example, as shown in  FIGS. 18 and 20 . 
     As used herein, the terms “battery” and “capacitor” are to be given their ordinary and customary meanings to a person of ordinary skill in the art. The terms “battery” and “capacitor” are nonexclusive of each other. A capacitor or battery can refer to a single electrochemical cell that may be operated alone, or operated as a component of a multi-cell system. 
     Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. 
     Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination. 
     Moreover, while operations may be depicted in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and/or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added. Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products. For example, any of the components for an energy storage system described herein can be provided separately, or integrated together (e.g., packaged together, or attached together) to form an energy storage system. 
     For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
     Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment. 
     Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z. 
     Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. 
     The scope of the present disclosure is not intended to be limited by the specific disclosures of embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the systems and methods described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure. Accordingly, the scope of the present inventions is defined only by reference to the appended claims.