PATENT DOCUMENT

Publication Number: US-11742512-B2
Application Number: US-202016739488-A
Country: US
Kind Code: B2

Title: Asymmetric battery pack utilizing C-Rate balancing

Abstract:
Battery packs having jelly roll battery cells of different capacities may have an imbalance in the charging and/or discharging current supplied to and provided by each jelly roll due to differences in capacity specific impedance between the battery cells of the battery pack. A C-rate (i.e., current relative to rated capacity) of a lower capacity first battery cell and a higher capacity second battery cell connected in parallel may be balanced by repositioning and/or increasing the number of cathode tabs and anode tabs of the second jelly roll battery cell to reduce an impedance of the second battery cell.

Claims:
What is claimed is: 
     
       1. An asymmetric battery pack, comprising:
 a first battery cell, the first battery cell comprising a wound set of layers comprising a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer, the cathode layer having a first end, a second end, and a first length defined by a distance between the first end and the second end of the cathode layer, and the anode layer having a first end, a second end, and a length defined by a distance between the first end and the second end of the anode layer, wherein the first battery cell has a first capacity; 
 a second battery cell connected in parallel with the first battery cell, the second battery cell comprising a wound set of layers comprising a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer, the cathode layer having a first end, a second end, and a second length defined by a distance between the first end and the second end of the cathode layer, and the anode layer having a first end, a second end, and a length defined by a distance between the first end and the second end of the anode layer, wherein the second length of the cathode layer in the second battery cell is greater than the first length of the cathode layer in the first battery cell and the second battery cell has a second capacity that is greater than the first capacity of the first battery cell;
 wherein the first battery cell further comprises a cathode tab extending from the cathode layer of the first battery cell, and an anode tab extending from the anode layer of the first battery cell; 
 wherein the cathode tab is disposed at or near the first end of the cathode layer of the first battery cell and the anode tab is disposed at or near the first end of the anode layer of the first battery cell; 
 wherein the second battery cell further comprises a first cathode tab extending from the cathode layer of the second battery cell, and a first anode tab extending from the anode layer of the second battery cell; and 
 wherein the first cathode tab is disposed away from the first end of the cathode layer of the second battery cell to reduce an impedance of the second battery cell and balance a C-rate of the second battery cell with a C-rate of the first battery cell. 
 
 
     
     
       2. The asymmetric battery pack of  claim 1 , wherein the first anode tab of the second battery cell is disposed away from the first end of the anode layer of the second battery cell. 
     
     
       3. The asymmetric battery pack of  claim 1 , wherein the first cathode tab of the second battery cell is disposed proximate to a midpoint of the second length of the cathode layer of the second battery cell. 
     
     
       4. The asymmetric battery pack of  claim 3 , wherein the first anode tab of the second battery cell is disposed proximate to a midpoint of the length of the anode layer of the second battery cell. 
     
     
       5. The asymmetric battery pack of  claim 1 , further comprising a second cathode tab extending from the cathode layer of the second battery cell, wherein the first cathode tab of the second battery cell is disposed at a distal end of the cathode layer of the second battery cell and the second cathode tab of the second battery cell is disposed at the proximal end of the cathode layer of the second battery cell. 
     
     
       6. The asymmetric battery pack of  claim 5 , further comprising a second anode tab extending from the anode layer of the second battery cell, wherein the first anode tab of the second battery cell is disposed at a distal end of the anode layer of the second battery cell and the second anode tab of the second battery cell is disposed at a proximal end of the anode layer of the second battery cell. 
     
     
       7. The asymmetric battery pack of  claim 1 , further comprising a second cathode tab and a third cathode tab extending from the cathode layer of the second battery cell, wherein the first cathode tab, the second cathode tab, and the third cathode tab of the second battery cell are spaced apart at increasing intervals with respect to a length of the cathode layer of the second battery cell. 
     
     
       8. The asymmetric battery pack of  claim 7 , further comprising a second anode tab and a third anode tab extending from the anode layer of the second battery cell, wherein the first anode tab, the second anode tab, and the third anode tab of the second battery cell are spaced apart at increasing intervals with respect to a length of the anode layer of the second battery cell. 
     
     
       9. The asymmetric battery pack of  claim 1 , wherein at least one of the first cathode tab of the second battery cell and the first anode tab of the second battery cell extends toward a centerline of the cathode layer or anode layer of the second battery cell. 
     
     
       10. The asymmetric battery pack of  claim 1 , wherein at least one of the first cathode tab of the second battery cell and the first anode tab of the second battery cell extends along an entire width of the cathode layer or anode layer of the second battery cell. 
     
     
       11. The asymmetric battery pack of  claim 1 , wherein the first cathode tab of the second battery cell extends from a first edge of the cathode layer of the second battery cell; and wherein the first anode tab of the second battery cell extends from a second edge, opposite the first edge, of the anode layer of the second battery cell.

Description:
PRIORITY 
     This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 62/826,037, entitled “ASYMMETRIC BATTERY PACK UTILIZING C-RATE BALANCING,” filed on Mar. 29, 2019, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to battery cells, and more particularly, to asymmetric battery cells in a battery pack that utilize C-Rate balancing. 
     BACKGROUND 
     A jelly roll battery cell includes wound layers of a cathode and an anode, with tabs extending from each to enable electrical connection to the cathode and anode layers. Conventionally, tabs are located near an end of a cathode and anode layer. Jelly rolls having higher capacities typically require longer and/or wider cathode and anode layers compared to jelly rolls with lower capacities. Connecting two or more jelly rolls in parallel where the jelly rolls have differing capacities, may result in an imbalance in the charging and/or discharging current supplied to and provided by each jelly roll. In addition, jelly rolls connected in parallel that each have a differing battery cell design (e.g., differing electrode shape among two or more jelly rolls) but substantially equal capacities, may nonetheless have an imbalance in the charging and/or discharging current supplied to and provided by each jelly roll due to differences in their impedance. 
     SUMMARY 
     The disclosed embodiments provide for a battery pack that utilizes C-Rate balancing by reducing an impedance of a higher capacity battery cell to balance a C-Rate of the battery pack. The battery pack includes a first battery cell having a wound set of layers comprising a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer. The first battery cell has a first capacity. The battery pack also includes a second battery cell connected in parallel with the first battery cell. The second battery cell includes a wound set of layers comprising a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer. The second battery cell has a second capacity that is greater than the first capacity of the first battery cell, includes a first cathode tab extending from the cathode layer of the second battery cell, and a first anode tab extending from the anode layer of the second battery cell. The first cathode tab is disposed away from a proximal end of the cathode layer of the second battery cell to reduce an impedance of the second battery cell and balance a C-rate of the second battery cell with a C-rate of the first battery cell. 
     The disclosed embodiments provide for a battery pack that utilizes C-Rate balancing by reducing an impedance of a higher capacity battery cell to balance a C-Rate of the battery pack. The battery pack includes a first battery cell having a wound set of layers comprising a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer. The first battery cell has a first capacity. The battery pack also includes a second battery cell connected in parallel with the first battery cell. The second battery cell includes a wound set of layers comprising a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer. The second battery cell has a second capacity that is greater than the first capacity of the first battery cell, includes a first cathode tab extending from the cathode layer of the second battery cell, and a first anode tab extending from the anode layer of the second battery cell. The first anode tab is disposed away from a proximal end of the anode layer of the second battery cell to reduce an impedance of the second battery cell and balance a C-rate of the second battery cell with a C-rate of the first battery cell. 
     In some embodiments, a method for balancing a C-rate of battery jelly rolls of different capacities is disclosed. The method includes packaging a first jelly roll having a first capacity and a second jelly roll having a second capacity that is greater than the first capacity into a battery pack. The method further includes balancing a C-rate of the second jelly roll with a C-rate of the first jelly roll by positioning a first cathode tab and a first anode tab of the second jelly roll away from a proximal end of a cathode layer and an anode layer, respectively, to reduce an impedance of the second jelly roll. The method also includes connecting the first jelly roll and the second jelly roll in parallel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments herein may be better understood by referring to the following description in conjunction with the accompanying drawings in which like reference numerals indicate identical or functionally similar elements. Understanding that these drawings depict only exemplary embodiments of the disclosure and are not therefore to be considered to be limiting of its scope, the principles herein are described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG.  1 A  illustrates a perspective view of a conventional battery pack; 
         FIG.  1 B  illustrates a perspective view of a conventional battery pack; 
         FIG.  2 A  illustrates a perspective view of a battery pack, in accordance with various aspects of the subject technology; 
         FIG.  2 B  illustrates a perspective view of a battery pack, in accordance with various aspects of the subject technology; 
         FIG.  3 A  illustrates a cross-section view of a battery cell, in accordance with various aspects of the subject technology; 
         FIG.  3 B  illustrates a cross-section view of a battery cell, in accordance with various aspects of the subject technology; 
         FIG.  4 A  illustrates an unwound battery cell, in accordance with various aspects of the subject technology; 
         FIG.  4 B  illustrates an unwound battery cell, in accordance with various aspects of the subject technology; 
         FIG.  4 C  illustrates an unwound battery cell, in accordance with various aspects of the subject technology; 
         FIG.  5 A  illustrates a cross-section view of a battery cell, in accordance with various aspects of the subject technology; 
         FIG.  5 B  illustrates a cross-section view of a battery cell, in accordance with various aspects of the subject technology; 
         FIG.  6 A  illustrates an unwound battery cell, in accordance with various aspects of the subject technology; 
         FIG.  6 B  illustrates an unwound battery cell, in accordance with various aspects of the subject technology; 
         FIG.  7 A  illustrates a detail view of a tab extending from an electrode, in accordance with various aspects of the subject technology; 
         FIG.  7 B  illustrates a detail view of a tab extending from an electrode, in accordance with various aspects of the subject technology; 
         FIG.  7 C  illustrates a detail view of a tab extending from an electrode, in accordance with various aspects of the subject technology; 
         FIG.  8    illustrates a detail view of tabs extending from electrodes, in accordance with various aspects of the subject technology; 
         FIG.  9    illustrates a portable electronic device, in accordance with various aspects of the subject technology; and 
         FIG.  10    illustrates an example method for balancing a C-rate of battery jelly rolls of different capacities, in accordance with various aspects of the subject technology. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the disclosure. 
     A jelly roll battery cell includes wound layers of a cathode and an anode, with tabs extending from each to enable electrical connection to the cathode and anode layers. Conventionally, tabs are located near an end of a cathode and anode layer. Jelly rolls having higher capacities typically require longer and/or wider cathode and anode layers compared to jelly rolls with lower capacities. Connecting two or more jelly rolls in parallel with each jelly roll having a different capacity, may result in the higher capacity jelly roll having an increased impedance compared to the lower capacity jelly roll due to the increased length and/or width of an active layer disposed on the electrodes of the higher capacity jelly roll. Further, jelly rolls connected in parallel that each have a differing battery cell design (e.g., differing electrode shape among two or more jelly rolls) but substantially equal capacities, may nonetheless have an imbalance in the charging and/or discharging current supplied to and provided by each jelly roll due to differences in their impedance. Generally, the longer the electrode length, or wider the electrode width, the higher the current collector substrate resistance. Jelly rolls having a significant difference in capacity and/or impedance that are connected in parallel, may result in an imbalance in the charging and/or discharging current supplied to and provided by each jelly roll. An imbalance may lead to a lower capacity jelly roll consuming a larger proportion of a charging current. Accordingly, there is a need for certain embodiments of a battery pack having jelly rolls of different capacities, shapes, and/or designs that have the same C-Rate to enable the jelly rolls to split the charging and discharging current in proportion to their respective capacities. 
     The disclosed technology addresses the foregoing limitations of conventional asymmetric battery packs by balancing a C-Rate of a higher capacity jelly roll with a C-Rate of a lower capacity jelly roll by repositioning and/or increasing the number of cathode and anode tabs of the higher capacity jelly roll to reduce an impedance of the higher capacity jelly roll to thereby balance a C-Rate of the jelly rolls. The disclosed technology further addresses the foregoing limitations of conventional asymmetric battery packs that comprise battery cells connected in parallel that each have a differing battery cell design (e.g., differing electrode shape among two or more battery cells) but substantially equal capacities, by reducing an impedance of a higher impedance battery cell by repositioning and/or increasing the number of cathode and anode tabs of the higher impedance battery cell to thereby balance a C-Rate of the battery cells. C-Rate balancing allows battery cells connected in parallel to be charged and discharged at the same C-Rate. In other words, the charging and discharging current is split in proportion to the respective capacity of each connected battery cell. Specifically, because jelly rolls connected in parallel share the same charge and discharge voltage, a voltage drop of each jelly roll should be made equal, i.e., ΔV=I i  Z i =I j  Z j , where “I” is the load or current in amperes and “Z” is impedance. With C-Rate balancing, the capacity specific impedance (“QSI”) of each jelly roll should be made equal, i.e., QSI=Q i  Z i =Q j  Z j , where “Q” is the capacity and “Z” is impedance. The QSI for a particular jelly roll is a function of electrode length or width because the longer or wider an electrode, the higher the substrate resistance. 
       FIGS.  1 A and  1 B  illustrate perspective views of a conventional battery pack  100 . The conventional battery pack  100  includes a first conventional jelly roll  120  and a second conventional jelly roll  130  connected in parallel, enclosed in an enclosure  110 . The first conventional jelly roll  120  may have a lower capacity compared to the second conventional jelly roll  130 . As a result, the first conventional jelly roll  120  may be formed of electrodes (e.g., a cathode and an anode layer) that have a length that is less than a length of electrodes of the second conventional jelly roll  130 . The first conventional jelly roll  120  may therefore have a smaller width and/or thickness “t” compared to a width and/or thickness “T” of the second conventional jelly roll  130  based on the number of windings in each of the first and second conventional jelly rolls,  120  and  130  respectively. Each of the first and second conventional jelly rolls,  120  and  130  respectively, may have tabs extending from their respective electrodes disposed at an end of the electrodes of each of the first and second conventional jelly rolls,  120  and  130  respectively. Because the first and second conventional jelly rolls,  120  and  130  respectively, have different capacities and tabs placed at ends of the electrodes, an impedance of the second conventional jelly roll  130  is higher than an impedance of the first conventional jelly roll  120 . As a result, a disproportionate amount of charging current may be directed to the first conventional jelly roll  120  having a lower impedance and a lower capacity which may lead to poor battery pack  100  performance with respect to charging and/or discharging. 
     As shown in  FIG.  1 A , the first and second conventional jelly rolls,  120  and  130  respectively, may be arranged in a side-by-side configuration. Tabs extend from ends of the electrodes of the first and second conventional jelly rolls,  120  and  130  respectively. When wound, the tabs are positioned at the center of each of the first and second conventional jelly rolls,  120  and  130  respectively. Referring to  FIG.  1 B , the first and second conventional jelly rolls,  120  and  130  respectively, may be arranged in a stacked configuration. 
       FIGS.  2 A and  2 B  illustrate perspective views of a battery pack  200 , in accordance with various aspects of the subject technology. The battery pack  200  may comprise a first battery cell  220  and a second battery cell  230  connected in parallel, and enclosed in an enclosure  210 . The first battery cell  220  may have a first capacity and the second battery cell  230  may have a second capacity that is greater than the first capacity of the first battery cell  220 . As shown in  FIG.  2 A , the first and second battery cells,  220  and  230  respectively, may be arranged in a side-by-side configuration. As shown in  FIG.  2 B , the first and second battery cells,  220  and  230  respectively, may be arranged in a stacked configuration. Other arrangements and battery pack  200  configurations are contemplated without departing from the scope of the subject technology. 
     It is also understood that the battery pack  200  may comprise a first battery cell  220  and a second battery cell  230  connected in parallel, each having the same capacity. The second battery cell  230 , however, may have a higher impedance than the first battery cell  220  based on a different battery cell design for the second battery cell  230 . For example, the second battery cell  230  may have a length that is 2× longer than a length of the first battery cell  220 , and the second battery cell  230  may have a width that is ½ narrower than a width of the first battery cell  220 . Each of the first and second battery cells,  220  and  230  respectively, may therefore, have a substantially equal surface area (A=L*W) and thus, have a substantially equal capacity, but with an impedance imbalance. In this example, because the second battery cell  230  has a length that substantially greater than the length of the first battery cell  220 , the impedance of the second battery cell  230  is greater than the impedance of the first battery cell  220 . 
       FIG.  3 A  illustrates a cross-section view of the first battery cell  220 , in accordance with various aspects of the subject technology. The first battery cell  220  may comprise a wound set of layers comprising a cathode layer  310 A, an anode layer  320 A, a first separator layer  330 A disposed between the cathode layer  310 A and the anode layer  320 A, and a second separator layer  340 A disposed between the anode layer  320 A and the cathode layer  310 A. Proximate to or at a first end  350 A of the cathode layer  310 A and the anode layer  320 A of the first battery cell  220 , a first cathode tab  315 A may extend from the cathode layer  310 A, and a first anode tab  325 A may extend from the anode layer  320 A. 
       FIG.  3 B  illustrates a cross-section view of the second battery cell  230 , in accordance with various aspects of the subject technology. The second battery cell  230  may comprise a wound set of layers comprising a cathode layer  310 B, an anode layer  320 B, a first separator layer  330 B disposed between the cathode layer  310 B and the anode layer  320 B, and a second separator layer  340 B disposed between the anode layer  320 B and the cathode layer  310 B. 
     The cathode layer  310 A,B may be an aluminum foil coated with a lithium compound (e.g., LiCoO 2 ) and the anode layer  320 A,B may be a copper foil coated with carbon or graphite. The separator  330 A,B and  340 A,B may include polyethylene (PE), polypropylene (PP), and/or a combination of PE and PP, such as PE/PP or PP/PE/PP. The wound set of layers are enclosed within enclosure  210  and immersed in an electrolyte, which for example, can be a LiPF6-based electrolyte that can include Ethylene Carbonate (EC), Polypropylene Carbonate (PC), Ethyl Methyl Carbonate (EMC) or DiMethyl Carbonate (DMC). The electrolyte can also include additives such as Vinyl carbonate (VC) or Polyethylene Soltone (PS). The electrolyte can additionally be in the form of a solution or a gel. 
     The second battery cell  230  further comprises a first cathode tab  315 B extending from the cathode layer  310 B, and a first anode tab  325 B extending from the anode layer  320 B. In one aspect, the first cathode tab  315 B is disposed away from a first end  350 B of the cathode layer  310 B of the second battery cell  230  to reduce an impedance of the second battery cell  230  and balance a C-rate of the second battery cell  230  with a C-rate of the first battery cell  220 . In another aspect, the first anode tab  325 B is disposed away from the first end  350 B of the anode layer  320 B of the second battery cell  230  to reduce the impedance of the second battery cell  230  and balance the C-rate of the second battery cell  230  with the C-rate of the first battery cell  220 . 
       FIG.  4 A  illustrates an unwound first battery cell  220 , in accordance with various aspects of the subject technology. The unwound first battery cell  220  comprises the cathode layer  310 A and the anode layer  320 A. The cathode layer  310 A has a first length  405  defined by a distance between the first end  350 A and a second end  360 A of the cathode layer  310 A. The anode layer  320 A has a length defined by a distance between the first end  350 A and the second end  360 A of the anode layer  320 A that may be about the first length  405 . 
     The cathode tab  315 A extending from the cathode layer  310 A may be disposed a distance  415  from the first end  350 A of the cathode layer  310 A. The anode tab  325 A may be disposed a distance  425  from the first end  350 A of the anode layer  320 A. In one aspect, the cathode tab  315 A and the anode tab  325 A are disposed at or near the first end  350 A. 
       FIG.  4 B  illustrates an unwound second battery cell  230 , in accordance with various aspects of the subject technology. The unwound second battery cell  230  comprises the cathode layer  310 B and the anode layer  320 B. The cathode layer  310 B has a second length  455  defined by a distance between the first end  350 B and a second end  360 B of the cathode layer  310 B that is greater than the first length  405  of the first battery cell  220 . The anode layer  320 B has a length defined by a distance between the first end  350 B and the second end  360 B of the anode layer  320 B that may be about the second length  455 . 
     In one aspect, because the length  405  of the electrodes (e.g., cathode layer  310 A and anode layer  320 A) of the first battery cell  220  is less than the length  455  of the electrodes (e.g., cathode layer  310 B and anode layer  320 B) of the second battery cell  230 , the capacity of the first battery cell  220  is less than the capacity of the second battery cell  230 . In another aspect, because the length  455  of the second battery cell  230  is greater than the length  405  of the first battery cell  220 , placement of the cathode tab  315 B extending from the cathode layer  310 B and/or placement of the anode tab  325 B extending from the anode layer  320 B may be disposed away from the first end  350 B of the cathode layer  310 B and anode layer  320 B, respectively, to reduce an impedance of the second battery cell  230  and to balance the C-rate of the second battery cell  230  with the C-rate of the first battery cell  220 . 
     For example, as shown in  FIG.  4 B , the cathode tab  315 B may be disposed proximate to a midpoint of the length  455  of the cathode layer  310 B at a distance  465 . The anode tab  325 B may be similarly disposed proximate to the midpoint of the length  455  of the anode layer  320 B at a distance  475 . Alternatively, the cathode tab  315 B and/or the anode tab  325 B may be disposed proximate to one-third or two-thirds of the length  455  of the cathode layer  310 B and/or the anode layer  320 B, respectively. By positioning the cathode tab  315 B and/or the anode tab  325 B at or near the midpoint, one-third, or two-thirds of the length of the electrodes, the impedance of the second battery cell  230  may be reduced, thereby splitting a charging or discharging current in proportion to the respective capacities of the first battery cell  220  and the second battery cell  230 . For example, the first battery cell  220  may have a capacity of 1,000 mAh and an impedance of 200 milli-ohms, and the second battery cell  230  may have a capacity of 2,000 mAh and an impedance of 100 milli-ohms, despite having a length  455  that is much larger than a length  405  of the first battery cell  220 . By positioning the cathode tab  315 B and the anode tab  325 B at or near the midpoint, one-third, or two-thirds of the length of the electrodes (e.g., cathode layer  310 B and anode layer  320 B) of the second battery cell  230 , the impedance of the second battery cell  230  may be reduced compared to an impedance of conventional battery cells (e.g., conventional jelly rolls  120 ,  130 ) having tabs disposed at or near an end of the electrodes. 
       FIG.  4 C  illustrates an alternative embodiment of the unwound battery cell  230 , in accordance with various aspects of the subject technology. In one aspect, the cathode layer  310 B may have more than one cathode tab  315 B extending therefrom, and the anode layer  320 B may have more than one anode tab  325 B extending therefrom. Specifically, because the length  455  of the second battery cell  230  is greater than the length  405  of the first battery cell  220 , increasing the number of cathode tabs  315 B and/or increasing the number of anode tabs  325 B may reduce an impedance of the second battery cell  230  to balance the C-rate of the second battery cell  230  with the C-rate of the first battery cell  220 . 
     For example, as shown in  FIG.  4 C , a first cathode tab  315 B may be disposed proximate to the first end  350 B of the cathode layer  310 B and a second cathode tab  315 B may be disposed proximate to the second end  360 B. A first anode tab  325 B may be similarly disposed proximate to the first end  350 B of the anode layer  320 B and a second anode tab  325 B may be disposed proximate to the second end  360 B. By increasing the number of cathode tabs  315 B and/or the anode tabs  325 B, the impedance of the second battery cell  230  may be reduced (compared to an impedance of conventional jelly rolls  120 ,  130 ), thereby splitting a charging or discharging current in proportion to the respective capacities of the first battery cell  220  and the second battery cell  230   
       FIG.  5 A  illustrates a cross-section view of the first battery cell  220 , in accordance with various aspects of the subject technology. As described above, the first battery cell  220  may comprise the wound set of layers comprising the cathode layer  310 A, the anode layer  320 A, the first separator layer  330 A disposed between the cathode layer  310 A and the anode layer  320 A, and the second separator layer  340 A disposed between the anode layer  320 A and the cathode layer  310 A. Proximate to or at the first end  350 A of the cathode layer  310 A and the anode layer  320 A of the first battery cell  220 , the first cathode tab  315 A may extend from the cathode layer  310 A, and the first anode tab  325 A may extend from the anode layer  320 A. 
       FIG.  5 B  illustrates a cross-section view of an alternative second battery cell  230 , in accordance with various aspects of the subject technology. The second battery cell  230  may comprise the wound set of layers comprising the cathode layer  310 B, the anode layer  320 B, the first separator layer  330 B disposed between the cathode layer  310 B and the anode layer  320 B, and the second separator layer  340 B disposed between the anode layer  320 B and the cathode layer  310 B. The second battery cell  230  further comprise a plurality of cathode tabs  515 A-N extending from the cathode layer  310 B, and a plurality of anode tabs  525 A-N extending from the anode layer  320 B. In one aspect, the plurality of cathode tabs  515 A-N may be equally spaced apart along a length of the cathode layer  310 B of the second battery cell  230 , may be positioned on every wrap, every second wrap, every third wrap, or every fourth wrap; to reduce an impedance of the second battery cell  230  and balance a C-rate of the second battery cell  230  with a C-rate of the first battery cell  220 . In another aspect, the plurality of anode tabs  525 A-N may be equally spaced apart along a length of the anode layer  320 B, may be positioned on every wrap, every second wrap, every third wrap, or every fourth wrap; to reduce the impedance of the second battery cell  230  and balance the C-rate of the second battery cell  230  with the C-rate of the first battery cell  220 . 
       FIG.  6 A  illustrates an unwound first battery cell  220 , in accordance with various aspects of the subject technology. As described above, the unwound first battery cell  220  comprises the cathode layer  310 A and the anode layer  320 A. The cathode layer  310 A has the first length  405  and the anode layer  320 A has a length that may be about the first length  405 . The cathode tab  315 A extending from the cathode layer  310 A may be disposed the distance  415  from the first end  350 A of the cathode layer  310 A. The anode tab  325 A may be disposed the distance  425  from the first end  350 A of the anode layer  320 A. In one aspect, the cathode tab  315 A and the anode tab  325 A are disposed at or near the first end  350 A. 
       FIG.  6 B  illustrates an alternative unwound second battery cell  230 , in accordance with various aspects of the subject technology. The unwound second battery cell  230  comprises the cathode layer  310 B and the anode layer  320 B. The cathode layer  310 B has a third length  505  defined by a distance between the first end  350 B and a second end  360 B of the cathode layer  310 B that is greater than the first length  405  of the first battery cell  220 . The anode layer  320 B has a length defined by a distance between the first end  350 B and the second end  360 B of the anode layer  320 B that may be about the third length  505 . 
     In one aspect, because the length  405  of the electrodes (e.g., cathode layer  310 A and anode layer  320 A) of the first battery cell  220  is less than the length  505  of the electrodes (e.g., cathode layer  310 B and anode layer  320 B) of the second battery cell  230 , the capacity of the first battery cell  220  is less than the capacity of the second battery cell  230 . In another aspect, because the length  505  of the second battery cell  230  is greater than the length  405  of the first battery cell  220 , utilizing the plurality of cathode tabs  315 B that each extend from the cathode layer  310 B and/or the plurality of anode tabs  325 B that each extend from the anode layer  320 B reduces an impedance of the second battery cell  230  and balances the C-rate of the second battery cell  230  with the C-rate of the first battery cell  220 . 
     For example, as shown in  FIG.  6 B , the cathode layer  310 B may comprise a plurality of cathode tabs  515 A-D that are spaced apart at increasing intervals with respect to the length  505  of the cathode layer  310 B of the second battery cell  230 . For example, a first cathode tab  515 A and a second cathode tab  515 B may be spaced apart by a distance  535 . The second cathode tab  515 B and a third cathode tab  515 C may be spaced apart by a distance  545 , that is more than the distance  535 . The third cathode tab  515 C and a fourth cathode tab  515 D may be spaced apart by a distance  555 , that is more than the distance  545 . 
     The anode layer  320 B may comprise a plurality of anode tabs  525 A-D that are spaced apart at increasing intervals with respect to the length  505  of the anode layer  320 B of the second battery cell  230 . For example, a first anode tab  525 A and a second anode tab  525 B may be spaced apart by a distance  565 . The second anode tab  525 B and a third anode tab  525 C may be spaced apart by a distance  575 , that is more than the distance  565 . The third anode tab  525 C and a fourth anode tab  525 D may be spaced apart by a distance  585 , that is more than the distance  575 . 
     By utilizing the plurality of cathode tabs  515 A-N and/or the plurality of anode tabs  525 A-N, the impedance of the second battery cell  230  may be reduced, thereby splitting a charging or discharging current in proportion to the respective capacities of the first battery cell  220  and the second battery cell  230 . For example, the first battery cell  220  may have a capacity of 1,000 mAh and an impedance of 200 milli-ohms, and the second battery cell  230  may have a capacity of 2,000 mAh and an impedance of 100 milli-ohms despite having a length  505  that is much larger than a length  405  of the first battery cell  220 . By utilizing the plurality of cathode tabs  515 A-N and/or the plurality of anode tabs  525 A-N, the impedance of the second battery cell  230  may be reduced compared to an impedance of conventional battery cells (e.g., conventional jelly rolls  120 ,  130 ) having a single tab disposed at or near an end of the electrodes. 
     It is also understood that while the plurality of cathode tabs  515 A-N and the plurality of anode tabs  525 A-N are discussed herein with reference to the second battery cell  230 , the first battery cell  220  may also utilize the tab positioning described herein to reduce an impedance of the first battery cell  220 , if desired. The battery pack  200 , may therefore utilize battery cells  220 ,  230  that each implement an impedance reduction scheme, as described above. 
       FIGS.  7 A- 7 C  illustrate detail views of a tab  315 B,  325 B extending from an electrode, in accordance with various aspects of the subject technology. The tab  315 B may extend from the cathode layer  310 B and/or the tab  325 B may extend from the anode layer  320 B. As shown in  FIG.  7 A , the tab  315 B,  325 B may extend from an outer edge of the cathode layer  310 B and anode layer  320 B, respectively. Referring to  FIG.  7 B , the tab  315 B,  325 B may extend toward a centerline of the cathode layer  310 B and anode layer  320 B, respectively. In some aspects, by extending the tab  315 B,  325 B toward the centerline of the cathode layer  310 B and/or anode layer  320 B, a surface area of the tab  315 B,  325 B in contact with the cathode layer  310 B and/or anode layer  320 B is increased to further reduce an impedance of the second battery cell  230 . Referring to  FIG.  7 C , the tab  315 B,  325 B may extend along an entire width of the cathode layer  310 B and anode layer  320 B, respectively. In some aspects, by extending along the entire width of the cathode layer  310 B and/or anode layer  320 B, a surface area of the tab  315 B,  325 B in contact with the cathode layer  310 B and/or anode layer  320 B is further increased to further reduce an impedance of the second battery cell  230 . 
       FIG.  8    illustrates a detail view of tabs  315 B,  325 B extending from electrodes, in accordance with various aspects of the subject technology. In one aspect, the cathode tab  315 B of the second battery cell  230  may extend from a first edge of the cathode layer  310 B. The anode tab  325 B of the second battery cell  230  may extend from a second edge, opposite the first edge, of the anode layer  320 B. 
       FIG.  9    illustrates a portable electronic device  900 , in accordance with various aspects of the subject technology. The above-described rechargeable battery pack  200  can generally be used in any type of electronic device. For example,  FIG.  9    illustrates a portable electronic device  900  which includes a processor  902 , a memory  904  and a display  906 , which are all powered by the battery pack  200 . Portable electronic device  900  may correspond to a laptop computer, tablet computer, mobile phone, personal digital assistant (PDA), digital music player, watch, and wearable device, and/or other type of battery-powered electronic device. Battery pack  200  may correspond to a battery pack that includes one or more battery cells  220 ,  230 . Each battery cell  220 ,  230  may include a set of layers, including a cathode with an active coating, a separator, an anode with an active coating, with the battery pack  200  utilizing C-Rate balancing as described above. 
       FIG.  10    illustrates an example method  1000  for balancing a C-rate of battery jelly rolls of different capacities, in accordance with various aspects of the subject technology. It should be understood that, for any process discussed herein, there can be additional, fewer, or alternative steps performed in similar or alternative orders, or in parallel, within the scope of the various embodiments unless otherwise stated. 
     At operation  1010 , a first jelly roll having a first capacity and a second jelly roll having a second capacity that is greater than the first capacity are packaged into a battery pack. The first and second jelly rolls each comprise a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer. At operation  1020 , a C-rate of the second jelly roll is balanced with a C-rate of the first jelly roll by positioning a first cathode tab and a first anode tab of the second jelly roll away from a proximal end of a cathode layer and an anode layer, respectively, to reduce an impedance of the second jelly roll. At operation  1030 , the first jelly roll and the second jelly roll are connected in parallel. 
     In another aspect, an example method for balancing a C-rate of jelly rolls of different impedances may include packaging a first jelly roll having a first impedance and a second jelly roll having a second impedance that is greater than the first impedance into a battery pack. The first and second jelly rolls each comprise a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer. A C-rate of the second jelly roll is balanced with a C-rate of the first jelly roll by positioning a first cathode tab and a first anode tab of the second jelly roll away from a proximal end of a cathode layer and an anode layer, respectively, to reduce an impedance of the second jelly roll. 
     Although a variety of examples and other information was used to explain aspects within the scope of the appended claims, no limitation of the claims should be implied based on particular features or arrangements in such examples, as one of ordinary skill would be able to use these examples to derive a wide variety of implementations. Further and although some subject matter may have been described in language specific to examples of structural features and/or method steps, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to these described features or acts. For example, such functionality can be distributed differently or performed in components other than those identified herein. Rather, the described features and steps are disclosed as examples of components of systems and methods within the scope of the appended claims.

Metadata:
Filing Date: 20200110
Publication Date: 20230829
Grant Date: 20230829
Priority Date: 20190329
Inventors: ROY, LOREN L.
GUO, QINGZHI
RAMADASS, PREMANAND
YOON, HYUNGOOK
SHI, JINJUN
Assignee: APPLE INC
CPC Classifications: [{"code": "H01M10/0431", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01M10/0587", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/209", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/247", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/531", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M2010/4292", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M10/0431", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01M10/0431", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01M10/0587", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M2010/4292", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M2220/30", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M10/0525", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M10/441", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02E60/10", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M50/531", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02P70/50", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M50/209", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/247", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M2010/4292", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01M10/0587", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M10/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/531", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/247", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01M50/209", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 72603708