PATENT DOCUMENT

Publication Number: US-9343720-B2
Application Number: US-201414452362-A
Country: US
Kind Code: B2

Title: Pre-treating separator to enable separator for pick and place operation

Abstract:
The described embodiments relate to methods and apparatus for improving pick and place operations. Pick and place operations involving the movement of flexible substrates can be improved by cooling a flexible substrate below a threshold temperature at which the flexible substrate transitions from a flexible state to a rigid state. Once in the rigid state, the flexible substrate can be handled and maneuvered by pick and place operations for a period of time with a limited risk of the flexible substrate wrinkling and tearing. In some embodiments, the flexible substrate is a thin polymeric substrate used to separate oppositely charged battery cells within a battery assembly.

Claims:
What is claimed is: 
     
       1. A method of assembling a battery, the method comprising:
 cooling a thermoplastic film below a temperature at which a stiffness of the thermoplastic film inhibits a first portion of the thermoplastic film from deforming with respect to a second portion of the thermoplastic film for a predetermined period of time; 
 cutting the thermoplastic film to a set of dimensions for forming a separator which corresponds to a set of dimensions of the battery; and 
 translating the thermoplastic film, via a pick and place operation, from a first position to a second position, 
 wherein the cutting, and translating of the thermoplastic film are completed during the predetermined period of time. 
 
     
     
       2. The method as recited in  claim 1 , wherein the first portion is a central portion of the thermoplastic film and the second portion is a peripheral portion of the thermoplastic film. 
     
     
       3. The method as recited in  claim 1 , wherein cooling the thermoplastic film below the temperature comprises cooling the thermoplastic film such that a first group of monomers of the thermoplastic film is inhibited from shifting past a second group of monomers of the thermoplastic film. 
     
     
       4. The method as recited in  claim 1 , wherein translating the thermoplastic film comprises coupling the thermoplastic film to a computer actuated arm. 
     
     
       5. The method as recited in  claim 1 , wherein translating the thermoplastic film comprises translating the thermoplastic film from the first position to a location above a battery cell corresponding to the second position; and
 placing the thermoplastic film atop the battery cell, wherein the cutting, translating, and placing are completed during the predetermined period of time. 
 
     
     
       6. The method as recited in  claim 5 , wherein cutting the thermoplastic film to the set of dimensions comprises cutting the thermoplastic film to have a shape and size in accordance with a top surface of the battery cell. 
     
     
       7. The method as recited in  claim 5 , wherein translating the thermoplastic film atop the battery cell comprises aligning an edge of the thermoplastic film with a corresponding edge of the battery cell. 
     
     
       8. The method as recited in  claim 1 , wherein cooling the thermoplastic film comprises cooling the thermoplastic film using a cooling bath or a cooling spray. 
     
     
       9. The method as recited in  claim 8 , wherein cooling the thermoplastic film comprises directing the cooling bath or the cooling spray at a top surface and bottom surface of the thermoplastic film. 
     
     
       10. The method as recited in  claim 8 , wherein the cooling spray comprises a plurality of spray patterns. 
     
     
       11. The method as recited in  claim 5 , wherein the thermoplastic film comprises a ceramic layer that increases dimensional stability of the thermoplastic film during operation of the battery cell. 
     
     
       12. The method as recited in  claim 11 , wherein the ceramic layer increases the thermoresistance of the thermoplastic film by inhibiting a tendency of the thermoplastic film to deform. 
     
     
       13. The method as recited in  claim 1 , further comprising flattening the thermoplastic film using a series of rollers. 
     
     
       14. The method as recited in  claim 13 , wherein the series of rollers rotate at a uniform coordinated speed to maintain uniform tension in the thermoplastic film. 
     
     
       15. The method as recited in  claim 13 , wherein the series of rollers include non-planar geometry for fashioning the thermoplastic film into a non-planar shape. 
     
     
       16. The method as recited in  claim 1 , wherein cutting the thermoplastic film comprises cutting the thermoplastic film to an initial set of dimensions which are smaller than a final set of dimensions of the thermoplastic film. 
     
     
       17. The method as recited in  claim 16 , wherein the initial set of dimensions accounts for a coefficient of thermal expansion of the thermoplastic film, such that the thermoplastic film achieves the final set of dimensions upon returning to a flexible state. 
     
     
       18. The method as recited in  claim 1 , further comprising optically tracking the dimensional accuracy of the separator after the step of cutting and before the step of translating the thermoplastic film. 
     
     
       19. The method as recited in  claim 1 , wherein cooling the thermoplastic film comprises submerging the thermoplastic film in a cooling bath until the thermoplastic film is cooled below a threshold temperature. 
     
     
       20. The method as recited in  claim 19 , wherein the threshold temperature is a temperature that is below a transition temperature that results in the thermoplastic film remaining below the transition temperature.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/US14/49768 with an international filing date of Aug. 5, 2014, entitled “PRE-TREATING SEPARATOR TO ENABLE SEPARATOR FOR PICK AND PLACE OPERATION,” which is incorporated herein by reference in its entirety for all purposes. 
    
    
     FIELD 
     The described embodiments relate generally to methods for improving pick and place operations in which a flexible substrate is moved. More particularly, the present embodiments relate to methods and apparatus for stiffening a thin polymeric substrate by cooling it below a threshold temperature at which the thin polymeric substrate becomes rigid enough to be moved by a pick and place machine. 
     BACKGROUND 
     As the demand for portable electronic devices increases, so does the demand for batteries. In order to meet the growing demand for batteries, more efficient methods for manufacturing batteries are desired. Assembly operations often utilize pick and place machines for assembly of various components. Unfortunately, when battery assembly operations include movement of components that have a tendency to bend and flex at room temperature, the bending and flexing of the components can prevent a pick and place machine from accurately transporting those components. For example, pick and place machines have a tendency to substantially wrinkle and/or bend components formed from flexible substrates that are often incorporated into a battery. Consequently, manufacturers of batteries are restricted to less efficient means of manipulating these types of battery components. 
     SUMMARY 
     This paper describes various embodiments that relate to cooling a thin polymeric substrate and assembling a battery. 
     A method for assembling a battery is disclosed. The method includes at least the following steps: cooling a thin polymeric substrate below a threshold temperature so that the thin polymeric substrate transitions from a flexible state to a rigid state during the cooling and maintains the rigid state for at least a first period of time; cutting the thin polymeric substrate to a set of desired dimensions; translating the thin polymeric substrate to a location above a first battery cell using a pick and place machine; and placing the thin polymeric substrate atop the first battery cell using the pick and place machine. The cutting, translation, and placing are all completed during the first period of time. 
     A method is disclosed. The method includes at least the following steps: cooling a substrate below a transition temperature at which the substrate transitions from a flexible state to a rigid state, and translating the substrate from a first position to a second position using a computer actuated arm. By cooling the substrate below the transition temperature the substrate maintains the rigid state during the translation, thereby preventing inadvertent flexing and bending of the substrate during the translation. 
     A method of assembling a battery is disclosed. The method includes at least the following steps: cooling a thermoplastic film below a temperature at which a stiffness of the thermoplastic film inhibits a first portion of the film from deforming with respect to a second portion of the thermoplastic film for a first period of time, such that the second portion of the film is prevented from inadvertently flexing and bending with respect to the first portion during subsequent operations; cutting the thermoplastic film to a set of dimensions; and translating the thermoplastic film from a first position to a second position. The cutting and translating of the thermoplastic film are both completed during the first period of time. 
     Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  shows how a pick and place operation can be utilized to assemble a battery; 
         FIGS. 2A-2E  show various cooling apparatuses that can be utilized to cool separator material below a threshold temperature; 
         FIGS. 3A-3B  show how a cutting apparatus can be utilized to cut separator material into a number of separators having a desired shape; 
         FIGS. 4A-4C  show how a pick and place operation can be utilized to translate and align the separators with a battery cell of a battery; 
         FIGS. 5A-5C  show how a number of pick and place operations can be concurrently utilized to fabricate a battery; 
         FIG. 6A  shows an isometric cross-sectional view of a number of battery cells arranged in a stack; 
         FIG. 6B  shows a close up cross-sectional view of how a fixturing device can be utilized to maintain a position of a separator subsequent to the pick and place operation; 
         FIGS. 7A-7B  show an isometric and a cross-sectional view of the separator including a thin polymeric substrate and ceramic layer; 
         FIG. 8  is a block diagram of an automated machine suitable for use with the described embodiments; and 
         FIG. 9  shows a flow chart representing a method for building a battery utilizing a pick and place machine to translate and align cooled separators within the battery. 
     
    
    
     DETAILED DESCRIPTION 
     Representative applications of methods and apparatus according to the present application are described in this section. These examples are being provided solely to add context and aid in the understanding of the described embodiments. It will thus be apparent to one skilled in the art that the described embodiments may be practiced without some or all of these specific details. In other instances, well known process steps have not been described in detail in order to avoid unnecessarily obscuring the described embodiments. Other applications are possible, such that the following examples should not be taken as limiting. 
     In the following detailed description, references are made to the accompanying drawings, which form a part of the description and in which are shown, by way of illustration, specific embodiments in accordance with the described embodiments. Although these embodiments are described in sufficient detail to enable one skilled in the art to practice the described embodiments, it is understood that these examples are not limiting; such that other embodiments may be used, and changes may be made without departing from the spirit and scope of the described embodiments. 
     Pick and place machines utilize robotic arms to carry out specific programmed steps or procedures which can be repeated with high accuracy and precision. Typically, the pre-programmed steps are based on a coordinate system which allows for a highly repeatable process to be performed. In addition, pick and place machines are used extensively to place electrical components on circuit boards because the pick and place machine allows for a continuous, highly reliable operation without the need of human intervention. Moreover, pick and place machines can be customized to suit a wide range of tasks. For example, a pick and place machine can be configured with a customized suction head, optimized for handling particularly sized rigid objects coming off a production line. 
     Unfortunately, a pick and place machine suffers from substantial limitations when handling a flexible object such as a thin polymeric substrate. One limitation is that the translational speed of the pick and place machine may need to be reduced to prevent flexing, bending or wrinkling of the thin polymeric substrate during a pick and place operation. Flexing, bending and wrinkling of the thin polymeric substrate are each adverse to precision pick and place operations because the coordinates associated with a position of the thin polymeric substrate become uncertain or even unknowable. This prevents the pick and place machine from being able to place the thin polymeric substrate in a precise manner. 
     Other limitations associated with conventional pick and place operations include the tendency of a central portion of the thin polymeric substrate to be drawn within one or more of the suction heads, thereby wrinkling and/or bending the thin polymeric substrate. This deformation caused by the aforementioned wrinkling or bending becomes problematic when thin polymeric substrates are incorporated into a stack because a deformed layer of a flexible material can prevent alignment of the stack, and in some cases prevent other layers of the stack from lying flat. These limitations may be remedied by customizing the tooling of the pick and place machine to avoid or mitigate these problems; however, customizing a pick and place machine for handling a thin polymeric substrate can become costly for a manufacturing operation. In addition to costs associated with customizing the tooling, the flexible nature of the thin polymeric substrate can still substantially slow movement of the thin polymeric substrate resulting in manufacturing delays, and increased cycle time necessary to account for slower pick and place operations. These factors can make such an endeavor undesirable. 
     One solution to the aforementioned problems is to cool the thin polymeric substrate prior to conducting a pick and place operation. By cooling the thin polymeric substrate, the thin polymeric substrate can be transitioned from a flexible state to a rigid state. The thin polymeric substrate becomes rigid during the cooling because relative motion between groups of nearby monomer chains within the thin polymeric substrate is reduced. Consequently, the inability of nearby monomer chains to move within the thin polymeric substrate substantially reduces the tendency of the thin polymeric substrate to deform. Once a transition temperature is reached, sometimes referred to as a glass transition temperature, the thin polymeric substrate can achieve a level of rigidity where little if any wrinkling, bending or flexing occurs. By cooling the thin polymeric substrate to a temperature far enough below the transition temperature, referred to in this application as a threshold temperature, the thin polymeric substrate can maintain a temperature below the transition temperature for a period of time. In this way, subsequent operations can be performed upon the thin polymeric substrate during the period of time without having to customize an operation that would ordinarily result in wrinkling, bending or flexible of the thin polymeric substrate. Consequently, a pick and place machine can be utilized to quickly lift or transport the thin polymeric substrate with limited risk of wrinkling, bending or flexing. 
     Cooling the thin polymeric substrate can have additional benefits. A cutting process is more likely to yield a straight line cut at a point of contact when monomer chains within the thin polymeric substrate are unable to move or deform. For example, when a blade comes into contact with the thin polymeric substrate, stretching and deforming of an individual monomer is inhibited so that the thin polymeric substrate fractures at the point of contact. In this way, the increased accuracy of the cutting process yields a higher dimensional accuracy of a final part. It should be noted that a crystalline structure within the thin polymeric substrate remains unaffected during a cooling process because there is not sufficient molecular mobility to allow the monomer chains to rearrange into a close packaging configuration. Consequently, a thin polymeric substrate chosen for a particular application based on its particular crystalline structure will not be adversely affected by the cooling process. 
     In one specific embodiment, the aforementioned processes can be utilized during a battery assembly operation. A battery can contain a number of positively and negatively charged battery cells separated by a number of interspersed thin polymeric substrates, known as separators. The purpose of the separators is to limit ionic flow to a single flow direction between the oppositely charged battery cells. The aforementioned process can be utilized to intersperse separators between battery cells. This process begins at a first step where a separator can be flattened using a series of rollers or other flattening processes. Second, a cooling process is used to set a desired geometry and rigidity of the separator by cooling the separator below a threshold temperature. In some embodiments, the separator can be cooled by conveying the separator through a cooling apparatus, such as a liquid nitrogen bath or spray. Next, the cooled separator can be cut to a desired dimension to fit within the battery. Subsequently, a pick and place machine can be utilized to transfer the cooled separator to the battery. In some embodiments, a fixturing device or mechanical guides can be utilized to facilitate proper placement of the separator in accordance with at least one edge of the battery and to maintain a position of the separator after the separator returns to a flexible state. Proper alignment of the separator between the oppositely charged battery cells prevents the ionic flow from bypassing the separator and flowing opposite the desired flow direction. The aforementioned process should be completed prior to the separator returning to the flexible state. It should be noted that the aforementioned process can be incorporated into a production line operation. 
     In addition, the separator can take many forms. For instance, the separator can be a thin polymeric substrate coated with a ceramic to increase thermal resistance and dimensional stability of the separator. Increasing thermal resistance and dimensional stability of the separator helps the separator maintain the same size and shape during high temperature operations of the battery cell so that the separator can maintain its function of limiting ionic flow to the desired flow direction. 
     These and other embodiments are discussed below with reference to  FIGS. 1-9 ; however, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  shows an overview of battery assembly operation  100  during which a number of separators  112  are fabricated and then subsequently interspersed between battery cells of battery  116 . As shown, battery assembly operation  100  involves a number of steps. First, spooling apparatus  102  unwinds to release an amount of separator material  104 . In some embodiments, separator material  104  can be a thermoplastic film such as a polyethylene film or a polypropylene film. In some embodiments, a width of separator material  104  can be substantially the same as a desired final dimension of separator  112 . Alternatively, in some embodiments separator material  104  may be oversized relative to the desired final dimensions of separator  112 . 
     As separator material  104  is unwound from spooling apparatus  102  rollers  106  can be utilized to convey, and in some embodiments maintain a uniform tension on separator material  104  during an initial portion of battery assembly operation  100 . Moreover, puller apparatus  109  can work in tandem with rollers  106  to help convey separator material  104  during the initial portion of battery assembly operation  100 . In addition, rollers  106  reduce the ability of separator material  104  to wrinkle or deform during conveyance in the initial portion of battery assembly operation  100 . This is accomplished by coordinating a rotational speed of rollers  106  to maintain the uniform tension on separator material  104 . In this way, a planar shape of separator material  104  can be maintained during the initial portion of battery assembly operation  100 . In some embodiments, separator material  104  can be flattened while it is being conveyed to the cooling apparatus. For example, separator material  104  can be flattened by conveying it between flattening rollers  107 . When two flattening rollers  107  are positioned parallel to and adjacent one another, flattening rollers  107  can be separated by a short distance that corresponds to the thickness of separator material  104 . When the distance is about the same as or less than the thickness of separator material  104 , conveying separator material  104  between the adjacent flattening rollers  107  can facilitate the removal of any minor wrinkles or bends in separator material  104 . In some embodiments, the gap between flattening rollers  107  can be substantially smaller than a thickness of separator material  104  so that as separator material  104  is flattened, separator material  104  is also thinned to achieve a desired thickness. In some embodiments, rollers  106  can have a non-planar geometry that fashions separator material  104  into a non-planar shape. The non-planar geometry of rollers  106  can impart a specific geometry to separator material  104  prior to separator material  104  undergoing a cooling operation. 
     As shown, rollers  106  convey separator material  104  through cooling apparatus  108 . Cooling apparatus  108  cools separator material  104  below a transition temperature causing separator material  104  to transition from a flexible state to a rigid state. The transition temperature for a thermoplastic corresponds to a temperature at which the thermoplastic undergoes a thermal transition resulting in relative motion between nearby monomers being inhibited; this thermal transition temperature is known as the glass transition temperature of the thermoplastic. Accordingly, cooling separator material  104  below the glass transition temperature transitions separator material  104  from a leathery flexible state into a glassy rigid state, thereby reducing the risk of separator material  104  wrinkling or bending. Consequently, cooling separator material  104  below the glass transition temperature increases the ability of a pick and place machine to handle and accurately place separator material  104  within battery  116 , such that separator material  104  is inhibited from wrinkling and bending. 
     An amount of time required to cool separator material  104  below the transition temperature can depend on at least the following factors: material characteristics of separator material  104 , and properties of a cooling agent utilized in cooling apparatus  108 . It should be noted that while bringing separator material  104  below the transition temperature does change the rigidity of separator material  104  in the desired manner, separator material  104  should generally be cooled far enough below the transition temperature to prevent separator material  104  from returning to a temperature above the transition temperature before a handling operation is completed. For this reason, the temperature of separator material  104  should be brought below a threshold temperature (substantially lower than the transition temperature) that allows separator material  104  to maintain the rigid state for at least a period of time necessary to complete subsequent operations. This period of time will generally be referred to as a fabrication time. The subsequent operations can include cutting separator material  104  into individual separators  112 , and translating and aligning separators  112  within battery  116  using a pick and place machine. In some embodiments, cooling separator material  104  below the threshold temperature causes separator material  104  to maintain the rigid state for at least thirty seconds. 
     As shown, rollers  106  convey separator material  104  to cutting apparatus  110 . Cutting apparatus  110  can be utilized to cut separator material  104  into a number of discrete separators  112 . Depending on a shape of battery  116 , a number of cutting apparatus  110  can be utilized to cut separator material  104  to substantially correspond to the dimensions of battery  116 . For example, a single blade cutter can be utilized to cut separator material  104 . Moreover, a cutting operation should be carried out during the fabrication time such that separator material  104  is more likely to yield a straight line cut when monomer chains within separator material  104  are unable to move or deform. In this way, separator  112  can achieve substantially greater dimensional accuracy resulting from the inability of separator material  104  to stretch or deform during the cutting operation. Consequently, by cutting separator material  104  during the fabrication time a cutting operation is more likely to yield separator  112  with a desired set of dimensions. 
     As shown, subsequent to cutting operation, a pick and place machine can be utilized to perform pick and place operation  114 . Pick and place operation  114  can be utilized to intersperse separator  112  within battery  116 . For example, the pick and place machine can place and align separator  112  on a top surface of a first battery cell. It should be noted that pick and place operation  114  should be carried out during the fabrication time to prevent separator  112  returning to a flexible state prior to completing the alignment of separator  112  within battery  116 . In some embodiments, pick and place operation  114  utilizes a suction head to grip separator  112 . Because separator  112  is maintained in a rigid state, the suction head can accurately and repeatedly place separator  112  within battery  116 , while limiting a risk of separator  112  wrinkling or tearing. In this way, a quality and accuracy of battery  116  can be improved and maintained during battery assembly operation  100 . 
       FIG. 2A  shows a specific configuration for cooling apparatus  108  that includes cooling bath  202 . Cooling bath  202  can be utilized to cool separator material  104  below a transition temperature causing separator material  104  to transition from a flexible state to a rigid state. Moreover, cooling bath  202  can utilize cooling agent  204  that is capable of cooling separator material  104  below a threshold temperature. In some embodiments, this is accomplished by submerging separator material  104  in cooling agent  204 . For example, cooling agent  204  taking the form of liquid nitrogen can utilize the aforementioned technique to cool separator material  104  below the threshold temperature. In some embodiments, cooling agent  204  can take the form of dry ice. In some embodiments, cooling apparatus  108  can utilize a processor to regulate a temperature of cooling agent  204 . For example, the processor can be utilized to control cooling apparatus  108  in accordance with inputs or parameters supplied to the processor. Some inputs can include a temperature of separator material  104  and separator  112  during various stages of battery assembly operation  100 . Other inputs can include a current temperature of cooling agent  204 . Still other inputs can include an amount of time a particular assembly line is taking to position separator  112  within battery  116 . In some embodiments, the processor can be configured to vary a rate at which separator material  104  is conveyed through cooling apparatus  108 . In these ways, cooling apparatus  108  can manipulate the temperature of separator material  104  as separator material  104  leaves cooling apparatus  108  to suit any number of potential operational or environmental changes. Moreover, cooling separator material  104  below the threshold temperature enables a pick and place machine to handle separator  112  with a limited risk of separator  112  wrinkling or tearing. It should be noted that although a pick and place machine can be utilized to handle separator  112 ; other techniques and apparatus can be utilized to handle separator  112  during the fabrication time. In some embodiments, the pick and place machine can take the form of a computer actuated arm that can perform the same functions described above. For example, the computer actuated arm can be utilized to handle separator  112 . 
     Rollers  106  and cooling apparatus rollers  206  can coordinate to maintain a uniform amount of tension on separator material  104  as separator material  104  passes through cooling apparatus  108 . In some embodiments, a control system can be utilized to coordinate a rotational speed of rollers  106  and cooling apparatus rollers  206 , thereby maintaining the uniform tension during an initial portion of battery assembly operation  100 . In some embodiments, cooling apparatus rollers  206  can be designed to shape separator material  104  to a desired geometry prior to entering cooling bath  202 . This shaping operation can be particularly useful when battery  116  has a non-planar geometry. In some embodiments, cooling roller  209  can be positioned after cooling apparatus  108  to mitigate warming of separator material  104  during a remaining portion of battery assembly operation  100 . 
       FIG. 2B  shows a specific configuration for cooling apparatus  108  that includes cooling sprayer  208 . In some embodiments, cooling sprayer  208  can utilize liquid nitrogen as coolant  210  to cool separator material  104  below the threshold temperature. In addition, cooling sprayer  208  can utilize rollers  106  to maintain a uniform tension on separator material  104  as discussed above. As shown in  FIG. 2B , cooling sprayer  208  is oriented so that coolant  210  is directed downward onto a top surface of separator material  104 , while an additional series of nozzles is oriented to spray coolant  210  upward onto a bottom side of separator material  104 . In this way, substantially all surfaces of separator material  104  can be contacted by coolant  210 , thereby increasing an efficiency at which separator material  104  is cooled. Furthermore, in some embodiments, cooling sprayer  208  can include a nozzle or nozzles having various spraying configurations that facilitate uniform cooling of separator material  104  below the threshold temperature during conveyance through cooling sprayer  208 . In some embodiments, cooling sprayer  208  can utilize a number of staggered nozzles positioned throughout the length of cooling sprayer  208  to substantially cover separator material  104  with coolant  210 . In this way, an arrangement and/or configuration of the nozzles can reduce the risk of a specific region of separator material  104  failing to be cooled below the threshold temperature during conveyance through cooling sprayer  208 . 
       FIGS. 2C-2E  show how cooling sprayer  208  can configure spray nozzles  212  to account for a width and thickness of separator material  104 . For example, the width of separator material  104  can vary in accordance with a final desired size of separator  112 . As shown in  FIG. 2C , spray nozzles  212  can be adjusted to emit first spray pattern  214  that substantially covers an entire surface of separator material  104   a  with coolant  210 . In this way, separator material  104   a  undergoes uniform cooling as it passes through first spray pattern  214 . A flow rate associated with first spray pattern  214  can also be adjusted to lower the temperature of separator material  104  to the threshold temperature.  FIG. 2D  depicts how cooling sprayer  208  can account for separator material  104   b  having an increased thickness. Cooling sprayer  208  can increase a flow rate of coolant  210  to account for the greater volume of separator material  104   b , as the greater volume associated with the increased thickness allows separator material  104   b  to store more internal energy when compared to a thinner material. In this way, the increased flow rate of coolant  210  sprayed onto separator material  104   b  can be utilized to account for the additional stored internal energy of separator material  104   b . In this way, cooling sprayer  208  can be adjusted to cool separator material  104   b  effectively below the threshold temperature. 
       FIG. 2E  shows how cooling sprayer  208  can accommodate a smaller surface area of separator material  104   c  by adjusting first spray pattern  214  to second spray pattern  216 . Second spray pattern  216  can be substantially more concentrated relative to first spray pattern  214 . The more concentrated spray pattern increases an amount of coolant  210  delivered to a particular area of separator material  104  without adjusting an overall flow rate of coolant  210  from spray nozzles  212 . As a result of the narrowed spray pattern, a flow rate of coolant  210  can be reduced as there is less material overall to account for relative to an amount of coolant  210  required to cool the wider separator material  104   a . It should be noted that spray nozzles  212  can emit an increased flow rate of coolant  210  to account for other characteristics of separator material  104 , such as a material type. For example, separator material  104  made from a polyethylene film may require an increased flow rate of coolant  210  sprayed onto a surface of separator material  104  to effectively cool the polyethylene film below its glass transition temperature. Conversely, the flow rate of coolant  210  can be reduced when separator material  104  is made from a polypropylene film, as polypropylene has a relatively higher glass transition temperature. 
       FIGS. 3A-3B  show how cutting apparatus  110  can be utilized to cut separator material  104  to a desired shape. As shown in  FIG. 3A , separator material  104  can be conveyed to cutting apparatus  110  using rollers  106  and subsequently away from cutting apparatus  110  using a material conveyance apparatus along the lines of conveyor belt  306 . Cutting apparatus  110  can utilize various cutting mechanisms; for example, cutting apparatus  110  can utilize single edge cutter  302  to cut separator  112  into a substantially rectangular shape using straight line cut  304 . In this way, the shape of separator  112  can substantially correspond to battery  116  having a rectangular shape. In some embodiments, optical sensor  316  can be utilized to track a dimensional accuracy of separator  112  after separator  112  is cut by cutting apparatus  110 . In this way, if separator  112  is cut to an improper dimension it can be discarded from battery assembly operation  100 . 
       FIG. 3B  shows how cutting apparatus  110  can utilize stamping apparatus  308  to cut separator material  104  at desired cut locations  310 . Stamping apparatus  308  can utilize multiple cutting edges to cut separator material  104  to a desired final shape. In this way, stamping apparatus  308  can cut separator material  104  into separator  312  that is non-rectangular in shape. Furthermore, separator  312  having a non-rectangular shape can be interspersed in battery  116  atop a first battery cell with a corresponding non-rectangular shape. Consequently, battery  116  can be utilized in final products where battery  116  is required to be a non-rectangular shape. For example, a lithium ion battery may be a non-rectangular shape in order to fit around internal components, such as in an electronic device. Moreover, stamping apparatus  308  can create secondary separator  314  that can be utilized in another battery  116  having a corresponding geometry. In this way, stamping apparatus  308  can be utilized to fabricate at least two distinct separators during each stamping cycle. In some embodiments, secondary separator  314  can be discarded or recycled. 
       FIGS. 4A-4C  depict pick and place operation  114  in which pick and place machine  402  is used to translate and align separator  112  within battery  116 .  FIG. 4A  shows how conveyor belt  306  can position separator  112  at pick-up position  404 . Subsequently, pick and place machine  402  can utilize pick and place head  406  to grip separator  112  at pick-up position  404  during each cycle of pick and place machine  402 . In this way, pick and place machine  402  can grip each subsequent separator  112  in the same precise location as a previous separator  112 . Consequently, pick and place machine  402  can place each subsequent separator  112  in the same precise location within battery  116  as a previous separator  112 .  FIG. 4B  shows pick and place machine  402  translating separator  112  away from pick-up position  404  and aligning separator  112  with a location above battery  116 . Subsequently,  FIG. 4C  shows separator  112  placed atop battery cell  408  within battery  116 . In some embodiments, pick and place machine  402  can align each edge of separator  112  with a corresponding edge of battery cell  408  when placing separator atop battery cell  408 . It should be noted that although pick and place head  406  can utilize a suction head, pick and place head  406  can utilize other coupling mechanisms. For example, pick and place head  406  can utilize a magnet to couple with separator  112  coated in a ferrous metal. In some embodiments, pick and place head  406  can utilize thermal sensor  410  to track a temperature of separator  112  during pick and place operation  114 . Moreover, thermal sensor  410  can signal pick and place machine  402  to discard separator  112  if separator  112  is above a transition temperature. 
     It should be noted that conveyor belt  306  can be utilized to continuously convey a number of separators  112  during pick and place operation  114 . Accordingly, a pick and place cycle rate can correspond to a conveyance rate of conveyor belt  306 . The pick and place cycle rate equates to a time it takes for pick and place machine  402  to translate separator  112  from pick-up position  404 , subsequently place separator  112  within battery  116 , and return to pick-up position  404 . In this way, separator  112  can be located at pick-up position  404  each time pick and place machine  402  returns to pick-up position  404 , thereby creating a continuous process. In some embodiments, multiple pick and place machines  402  can be utilized to assemble a number of batteries  116 . For example, multiple pick and place machines  402  can be positioned parallel to conveyor belt  306  with each individual pick and place machine  402  having a corresponding pick-up position  404  on conveyor belt  306 . In this way, multiple pick and place operations  114  can be performed concurrently resulting in a substantially greater number of batteries  116  being assembled compared to using a single pick and place machine  402 . Moreover, having a number of pick and place machines  402  performing at substantially the same time reduces a time period between cooling separators  112 , and assembling separators  112  into a battery, thereby reducing a risk of pick and place operation  114  failing to be carried out before separator  112  returns to a flexible state. 
       FIGS. 5A-5C  show one embodiment in which two pick and place machines  402  can be utilized to conduct pick and place operation  114 .  FIG. 5A  shows how multiple pick and places machines  402  can be configured to each translate one particular type of battery component. For example, in some embodiments, pick and place machine  402   a  can be utilized to move only separators  112 , while pick and place machine  402   b  can be utilized to move only battery cells  502  and  504 .  FIGS. 5B and 5C  show how pick and place machines  402   a  and  402   b  can sequentially assembly battery  116  by distributing separators  112  between battery cells  502  and  504 . As depicted in  FIG. 5B , pick and place machine  402   b  first positions battery cell  502  within battery  116 .  FIG. 5C  shows how separator  112  can be subsequently placed atop battery cell  502 .  FIGS. 5A-5C  show how separators  112  and battery cells  502  and  504  can be continuously supplied to pick and place machines  402   a  and  402   b  by at least two conveyor belts such that first conveyor belt  306   a  conveys only separators  112  to first pick-up position  404   a , and second conveyor belt  306   b  conveys only battery cells  502  and  504  to second pick-up position  404   b . Furthermore, battery cells  502  and  504  can be arranged on second conveyor belt  306   b  in an alternative order, as depicted. In some embodiments, a third conveyor belt can work in parallel with conveyor belt  306   b . In this way, conveyor belt  306   b  can convey only positively charged battery cells  504  and the third conveyor belt can supply only negatively charged battery cells  502 . In some embodiments, conveyor belts  306   a  and  306   b  can be arranged substantially parallel to each other and positioned equidistant from a single pick and place machine  402 . In this way, pick and place machine  402  can alternate between translating and placing each component of battery  116 . For example, separator  112  can be first placed atop negatively charged battery cell  502 , and subsequently positively charged battery cell  504  can be placed atop separator  112  using the single pick and place machine  402 . Accordingly, a quality and accuracy of battery  116  can be improved and maintained during battery assembly operation  100  by utilizing pick and place machine  402 . 
       FIG. 6A  shows an isometric cross-sectional view of battery  116  along with a desired ion flow direction during discharge. As shown, battery  116  utilizes negatively charged battery cell  502 , separator  112 , and positively charged battery cell  504 . In some embodiments, a number of battery components can be connected and arranged in a stack to form battery  116 . As shown, fixturing device  602  can be utilized to align each individual component placed within battery  116 . In some embodiments, this is accomplished by placing at least one vertical support within battery  116 . In this way, each individual component can be oriented substantially the same as the previous individual component. For example, separator  112  can be placed atop negatively charged battery cell  502 . Fixturing device  602  can then be utilized to align each corresponding edge of separator  112  and negatively charged battery cell  502 . By aligning the edges of separator  112  with the edges of the battery components, separator  112  can prevent ionic transfer from bypassing separator  112 . Because the ionic flow is forced to pass through separator  112 , separator  112  can effectively limit ionic flow through battery  116  to a desired flow direction. Furthermore, in some embodiments, fixturing device  602  can be removed prior to placing battery  116  in the final battery module. In other embodiments, fixturing device  602  can be incorporated into the final battery module. 
       FIG. 6B  shows a close up cross-sectional view of how fixturing device  602  can utilize clamps  604  to hold each individual component in place once aligned. In this way, each corresponding edge each individual component can be inhibited from shifting during subsequent assembly of battery  116 . For example, a polyolefin separator  112  can substantially contract in a linear dimension when cooled below a transition temperature. Consequently, the polyolefin separator  112  can substantially expand in the linear dimension upon returning to a flexible state. In this particular embodiment, clamp  604  can be utilized to fix a portion of the polyolefin separator  112  in the desired location during the temperature change of the polyolefin separator  112 . In another embodiment, depending on a material of separator  112 , cutting apparatus  110  can undersize separator  112  to account for an amount of thermal contraction/expansion of separator  112 , known as a coefficient of thermal expansion. In this way, clamps  604  can be utilized to fix a central portion of separator  112 , or the use of clamps  604  can be avoided altogether, and separator  112  can freely enlarge in a linear dimension upon returning to a flexible state, thereby substantially corresponding to a linear dimension of a first battery cell. 
       FIGS. 7A-7B  show an isometric and a cross-sectional view of separator  700  formed from thin polymeric substrate  702  and ceramic layer  704 . Separator  700  can utilize ceramic layer  704  to increase thermal resistance and dimensional stability of thin polymeric substrate  702  during a high temperature battery operation. During operation of battery  116 , ceramic layer  704  absorbs substantial amounts of thermal energy, thereby reducing the amount of thermal energy absorbed by monomer chains of thin polymeric substrate  702 . Additionally, ceramic layer  704  buttresses thin polymeric substrate  702  by inhibiting material migration and increasing dimensional stability of thin polymeric substrate  702 . In this way, battery  116  is less likely to short circuit due to separator  700  shrinking or deforming during high temperature operation of battery  116 . For example, a lithium ion battery can operate at a temperature above a melt temperature of a thermoplastic film used as thin polymeric substrate  702  within the lithium ion battery. Ceramic layer  704  can be utilized to increase the thermal resistance of the thermoplastic film, thereby reducing deformation and the ability of lithium ion battery to short-circuit. In some embodiments, a coating apparatus can be incorporated into battery assembly operation  100  to cover thin polymeric substrate  702  with ceramic layer  704 . 
       FIG. 8  illustrates a detailed view of automated machine  800  that can be used to implement the various components described herein, according to some embodiments. In particular, the detailed view illustrates various components that can be included in battery assembly operation  100  illustrated in  FIG. 1 . As shown in  FIG. 8 , automated machine  800  can include processor  802  that represents a microprocessor or controller for controlling the overall operation of automated machine  800 . Automated machine  800  can also include user input device  808  that allows a user of automated machine  800  to interact with automated machine  800 . For example, user input device  808  can take a variety of forms, such as a button, keypad, dial, touch screen, audio input interface, visual/image capture input interface, input in the form of sensor data, etc. Still further, automated machine  800  can include display  810  (screen display) that can be controlled by processor  802  to display information to the user. Data bus  816  can facilitate data transfer between at least storage device  840 , processor  802 , and controller  813 . Controller  813  can be used to interface with and control different equipment through and equipment control bus  814 . Automated machine  800  can also include network/bus interface  811  that couples to data link  812 . In the case of a wireless connection, network/bus interface  811  can include a wireless transceiver. 
     Automated machine  800  also includes a storage device  840 , which can comprise a single disk or a plurality of disks (e.g., hard drives), and includes a storage management module that manages one or more partitions within the storage device  840 . In some embodiments, storage device  840  can include flash memory, semiconductor (solid state) memory or the like. Automated machine  800  can also include a Random Access Memory (RAM)  820  and a Read-Only Memory (ROM)  822 . The ROM  822  can store programs, utilities or processes to be executed in a non-volatile manner. The RAM  820  can provide volatile data storage, and stores instructions related to the operation of battery assembly operation  100 . 
       FIG. 9  is a flow chart showing process steps involved in a battery assembly operation. At  902 , separator material is spooled towards rollers. A first length of the separator material can be fed through the rollers towards a cooling apparatus. Moreover, the rollers can enable a conveyance of the separator material by utilizing a frictional force between the surface of each roller and the surface of the separator material. Additionally, if the frictional force between rollers and the separator material is less than adequate to effectively convey the separator material, and further unwind the spool of separator material, a puller apparatus can be utilized to facilitate the conveyance of the separator material. In this way, a thermoplastic film with a low coefficient of friction on the rollers can still be incorporated into a battery assembly operation by utilizing the puller apparatus. Furthermore, multiple spools of separator material can be configured to simultaneously convey the separator material into the rollers. For example, the spools of separator material spools can be positioned to allow each individual spool of separator material to convey the separator material into the rollers. Consequently, the battery can incorporate multiple types of separators within the battery, such that each separator incorporated has distinct material properties. For example, a first spool can convey a polyethylene film while a second spool can convey a polypropylene film. 
     At  904 , rollers are utilized to flatten and/or shape the separator material into a desired geometry as the separator material is conveyed towards the cooling apparatus. For example, the rollers can be configured to remove any wrinkles or bends in the separator material and then flatten out the separator material during an initial portion of battery assembly operation. Furthermore, the rollers can be configured to maintain a uniform tension on the separator material during an initial portion of battery assembly operation. In this way, the separator material can remain taut, thereby reducing the tendency of the separator material to wrinkle and deform. Moreover, in some embodiments, at least one of the rollers can include a surface texture than can be used to impart a texture onto a surface of the separator material during conveyance of the separator material. In some embodiments, two rollers can be positioned parallel and adjacent to another, such that the two rollers are separated by a gap, the gap being a distance that is substantially smaller than a thickness of the separator material. In this way, the thickness of the separator material will be reduced when fed through the gap during conveyance through the two rollers. Consequently, a separator material having an initial thickness that is greater than a desired thickness can still be incorporated into the battery using the aforementioned thinning process. 
     At  906 , a cooling apparatus is utilized to stiffen the separator material by cooling the separator material below a transition temperature. The transition temperature is a temperature at which the separator material transitions from a flexible state to a rigid state. In some embodiments, the separator material transitions to the rigid state as a result of the cooling process because of an inability of a first group of monomers to shift past a second group of monomers within the separator material. Consequently, a first portion and a second portion of the separator can remain substantially within the same plane while the separator is being handled. Moreover, the cooling apparatus can utilize a cooling agent that is capable of cooling the separator material below a threshold temperature. The threshold temperature is substantially lower than the transition temperature so that the separator material can undergo a substantial temperature increase without exceeding the transition temperature and returning to a flexible state. In this way, the separator material can remain below the transition temperature for a period of time, known as the fabrication time. The fabrication time should be greater than an amount of time required for operations which depend upon the increased rigidity of the separator material to be successfully carried out. The cooling apparatus can take many forms, such as a cooling bath filled with dry ice or a cooling spray utilizing liquid nitrogen. Moreover, a cooling period (the amount of time it takes to cool the separator material below the threshold temperature) of the separator material within the cooling apparatus may be reduced by utilizing various cooling apparatus configuration. For example, when a cooling bath is filled with a cooling agent that takes the form of liquid nitrogen, the separator material can be cooled below the threshold temperature upon or shortly after contacting the liquid nitrogen. In this way, the cooling bath filled with liquid nitrogen facilitates a shorter cooling period, and consequently a substantially faster feed rate of the separator material through the cooling apparatus. In contrast, when the cooling agent takes the form of dry ice a substantially longer cooling period can be required. Consequently, dry ice may require a substantially slower feed rate, which may adversely affect the ability of subsequent operations to carry out a given operation before the fabrication time period expires. 
     In some embodiments, a cooling roller can be positioned after the cooling apparatus to help maintain a temperature of the separator material below the transition temperature for a longer period of time. In this way, a length of time spent by the separator material in the cooling apparatus can be reduced. Alternatively, the cooling roller can effectively increase the fabrication time. A conveyor belt can also utilize a cooled section to mitigate warming of a separator during the remainder of the battery assembly operation. In this way, a pick and place machine can have a substantially higher probability of carrying out the pick and place operation while the separator is in a rigid state. 
     At step  908 , the separator material is cut to a desired dimension to substantially correspond to the dimensions of the battery utilizing a cutting apparatus. The cutting apparatus can take many forms, for example, the cutting apparatus can utilize a single edge cutter. In other embodiments, the cutting apparatus can utilize a blade cutter that translates from a first location to a second location across the width of the separator material resulting in a straight line cut. In some embodiments, the cutting apparatus can utilize a stamping apparatus that can be utilized to cut the separator into non-rectangular geometries. Moreover, the stamping apparatus can be utilized to cut the separator material into multiple separators during each cutting cycle. In some embodiments, the multiple separators that result can be different in size and shape, and consequently each individual separator can be used in different battery assemblies. Furthermore, an optical sensor can be positioned following the cutting apparatus and can be utilized to track the dimensional accuracy of a separator cut by the cutting apparatus. In this way, the separator which is cut to an incorrect dimension can be removed from the battery assembly operation. The optical sensor can also be utilized to communicate a position of the separator to a computer actuated arm prior to translating the separator. 
     At  910 , a pick and place machine is utilized to first translate and subsequently align a separator atop a battery cell. In some embodiments, the pick and place machine can translate and align the separator atop the battery cell using a coupling mechanism such as a suction head as discussed above. In addition, the pick and place machine can utilize a thermal sensor located on the suction head. In this way, the thermal sensor can measure a temperature of the separator and consequently determine whether separator  112  remains below the transition temperature. Moreover, if the thermal sensor measures a separator above the transition temperature, the pick and place machine can discard the separator or send the separator back for additional cooling or reincorporation into a roll of separator material. Accordingly, a quality and accuracy of a battery can be improved and maintained during a pick and place operation by utilizing the thermal sensor attached to a pick and place head. 
     The various aspects, embodiments, implementations or features of the described embodiments can be used separately or in any combination. Various aspects of the described embodiments can be implemented by software, hardware or a combination of hardware and software. The described embodiments can also be embodied as computer readable code on a computer readable medium for controlling manufacturing operations or as computer readable code on a computer readable medium for controlling a manufacturing line. The computer readable medium is any data storage device that can store data which can thereafter be read by a computer system. Examples of the computer readable medium include read-only memory, random-access memory, CD-ROMs, HDDs, DVDs, magnetic tape, and optical data storage devices. The computer readable medium can also be distributed over network-coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of specific embodiments are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the described embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20140805
Publication Date: 20160517
Grant Date: 20160517
Priority Date: 20140805
Inventors: ZENG QINGCHENG
HAO SHOUWEI
SHIU BRIAN
Assignee: APPLE INC
CPC Classifications: [{"code": "H01M10/0404", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01M50/406", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/403", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M2220/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M2/145", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01M50/406", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/403", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02P70/50", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M10/0585", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M10/0436", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/049", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/0585", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M10/049", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M2220/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M10/0436", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/0404", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y02E60/10", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 55264239