Patent Publication Number: US-2022223973-A1

Title: Battery cell and electronic apparatus having such battery cell

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Bypass Continuation application of International Application No. PCT/CN2020/082119, filed on Mar. 3, 2020 and entitled “BATTERY CELL AND ELECTRONIC APPARATUS HAVING SUCH BATTERY CELL”, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     This application relates to the battery field, and in particular, to a battery cell and an electronic apparatus having such battery cell. 
     BACKGROUND 
     Currently, most electronic apparatuses on the market have built-in batteries to power them, and battery cells used by the market now all use a packaging bag to accommodate an electrode assembly. As the voltage and energy density of battery cells gradually increase, thermal stability of the battery cells gradually declines, with failures found in safety tests, indicating possible safety issues with the battery cells during use of electronic apparatuses by consumers, causing certain hazards. 
     SUMMARY 
     In view of the foregoing situation, it is necessary to provide a battery cell and an electronic apparatus having such battery cell, in order to mitigate safety issues with battery cells. 
     Embodiments of this application provide a battery cell, including an electrode assembly and a packaging bag configured to accommodate the electrode assembly, where the electrode assembly includes a tab; a sealing zone is formed on a periphery of the packaging bag, one end of the tab is electrically connected to a body of the electrode assembly, and an other end of the tab protrudes out of the sealing zone; the sealing zone is provided with a weak zone, and in a predetermined temperature range, a packaging tension between the weak zone and the packaging bag reduces to release gas inside the battery cell to the outside of the battery cell. 
     According to some embodiments of this application, the packaging tension is defined as F (measured in N/6 mm) and temperature as T, and F and T in the weak zone satisfy the following relation: F=(0.5−f)×T/20+6.5×f−2.75. Parameters in this relation are calculated numerically, where 110° C.≤T≤130° C. and 4.5N/6 mm≤f≤5.5N/6 mm. 
     According to some embodiments of this application, the battery cell further includes a first sealing adhesive and a second sealing adhesive provided between the tab and the packaging bag, where the tab is provided between the first sealing adhesive and the second sealing adhesive, the weak zone is formed through thermal fusion of the second sealing adhesive and the packaging bag, and a thickness of the first sealing adhesive or the second sealing adhesive is greater than 25 μm. 
     According to some embodiments of this application, the first sealing adhesive includes a first adhesive layer and a second adhesive layer, where the first adhesive layer is provided between the second adhesive layer and the packaging bag, the second adhesive layer is provided between the first adhesive layer and the tab, and in a predetermined temperature range, a packaging tension between the first adhesive layer and the packaging bag or the second adhesive layer is less than packaging tension between the second adhesive layer and the tab. 
     According to some embodiments of this application, the first sealing adhesive includes a first adhesive layer and a second adhesive layer, where the first adhesive layer is provided between the second adhesive layer and the tab, the second adhesive layer is provided between the first adhesive layer and the packaging bag, and in a predetermined temperature range, a packaging tension between the first adhesive layer and the tab or the second adhesive layer is less than a packaging tension between the second adhesive layer and the packaging bag. 
     According to some embodiments of this application, a total thickness of the first adhesive layer and the second adhesive layer is greater than or equal to 25 μm, and less than or equal to 100 μm, and a thickness of the first adhesive layer or the second adhesive layer is greater than 10 μm. 
     According to some embodiments of this application, the first sealing adhesive includes a first adhesive layer, a second adhesive layer, and a third adhesive layer that are arranged in order, where the first adhesive layer is provided between the second adhesive layer and the packaging bag, the third adhesive layer is provided between the second adhesive layer and the tab, and in a predetermined temperature range, a packaging tension between the first adhesive layer and the packaging bag is less than a packaging tension between the second adhesive layer and the first adhesive layer or the third adhesive layer, and a packaging tension between the third adhesive layer and the tab is less than a packaging tension between the second adhesive layer and the first adhesive layer or the third adhesive layer. 
     According to some embodiments of this application, a total thickness of the first adhesive layer, the second adhesive layer, and the third adhesive layer is greater than or equal to 25 μm and less than or equal to 100 μm, and a thickness of the first adhesive layer, the second adhesive layer, or the third adhesive layer is greater than 10 μm. 
     According to some embodiments of this application, the weak zone is provided in the sealing zone in a location other than where the tab protrudes out. 
     Embodiments of this application further provide an electronic apparatus, including a battery, where the battery includes a battery cell and a housing accommodating the battery cell, and the battery cell includes the foregoing battery cell. 
     In the foregoing battery cell and the electronic apparatus having such battery cell, a sealing zone of a packaging bag is provided with a weak zone, and a packaging tension of the weak zone in the packaging bag reduces in a predetermined temperature range, so as to release heated gas generated inside the battery cell to the outside of the battery cell through the weak zone, reduce heat accumulated inside the battery cell, and alleviate deformation of the battery cell, thereby greatly improving safety performance of the battery cell. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view of a battery cell in a first embodiment of this application. 
         FIG. 2  is a sectional view of a tab portion of the battery cell in  FIG. 1 . 
         FIG. 3  is a sectional view of a tab of a battery cell in a second embodiment of this application. 
         FIG. 4  is a sectional view of a tab of a battery cell in a third embodiment of this application. 
         FIG. 5  is a sectional view of a tab of a battery cell in a fourth embodiment of this application. 
         FIG. 6  is a sectional view of a battery cell in a fifth embodiment of this application. 
         FIG. 7  is a sectional view of a weak zone in the battery cell in  FIG. 6 . 
     
    
    
     REFERENCE SIGNS OF MAIN COMPONENTS 
       
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Battery cell 
                 100 
               
               
                   
                 Electrode assembly 
                 10 
               
               
                   
                 Electrode assembly body 
                 11 
               
               
                   
                 Tab 
                 12 
               
               
                   
                 Positive tab 
                 121 
               
               
                   
                 Negative tab 
                 122 
               
               
                   
                 Packaging bag 
                 20 
               
               
                   
                 Sealing zone 
                 30 
               
               
                   
                 Packaging zone 
                 31 
               
               
                   
                 Weak zone 
                 32 
               
               
                   
                 First sealing adhesive 
                 321 
               
               
                   
                 First adhesive layer 
                 3211 
               
               
                   
                 Second adhesive layer 
                 3212 
               
               
                   
                 Third adhesive layer 
                 3213 
               
               
                   
                 Second sealing adhesive 
                 322 
               
               
                   
                   
               
            
           
         
       
     
     DETAILED DESCRIPTION 
     The following clearly describes the technical solutions in the implementations of this application with reference to the accompanying drawings in the implementations of this application. Apparently, the described implementations are some but not all of the implementations of this application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of this application without creative efforts shall fall within the protection scope of this application. 
     It should be noted that when an element is referred to as being “fastened” to another element, it may be directly fastened to the another element or an intermediate element may be present. When an element is considered to be “connected” to another element, it may be directly connected to the another element or an intermediate element may be present. When an element is considered to be “provided” at another element, it may be directly disposed at the another element or an intermediate element may be present. The terms “vertical”, “horizontal”, “left”, “right”, and similar expressions used herein are merely for description purposes. 
     Unless otherwise defined, all technical and scientific terms used herein shall have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are merely intended to describe specific embodiments but not intended to constitute any limitation on this application. The term “and/or” used herein includes any and all combinations of one or more relevant listed items. 
     This application provides a battery cell, where the battery cell includes an electrode assembly and a packaging bag configured to accommodate the electrode assembly, where the electrode assembly includes a tab, a sealing zone is formed on a periphery of the packaging bag, one end of the tab is electrically connected to a body of the electrode assembly, and an other end of the tab protrudes out of the sealing zone. The sealing zone is provided with a weak zone, and in a predetermined temperature range, a packaging tension of the weak zone in the packaging bag reduces to release gas inside the battery cell to the outside of the battery cell. 
     Referring to  FIG. 1  and  FIG. 2 , a first embodiment of this application provides a battery cell  100 . The battery cell  100  includes an electrode assembly  10  and a packaging bag  20 . The packaging bag  20  wraps the electrode assembly  10 . The packaging bag  20  seals and accommodates the electrode assembly  10  through a sealing zone  30  on a periphery of the packaging bag  20 . 
     Specifically, the electrode assembly  10  includes an electrode assembly body  11  and a tab  12  electrically connected to the electrode assembly body  11 . The tab  12  is provided in one end surface of the electrode assembly body  11 . 
     The packaging bag  20  is configured to accommodate the electrode assembly body  11 , where one end of the tab  12  connected to the electrode assembly body  11  is wrapped by the sealing zone  30 , and an other end of the tab  12  is left protruding out of the sealing zone  30  to expose the packaging bag  20 . 
     The sealing zone  30  includes a weak zone  32 . One end of the tab  12  protrudes out of the weak zone  32 . When temperature rises to within a particular range, a packaging tension of the weak zone  32  drops rapidly, so that under this temperature range, gas generated by the electrode assembly body  11  is released outside the packaging bag through the weak zone  32 . Thus, temperature of the electrode assembly body  11  and deformation of the battery cell can be reduced to avoid safety issues such as short circuit and even fire. In some embodiments, the temperature ranges from 110° C. to 130° C. and may be adjusted depending on actual needs. 
     According to some embodiments of this application, the packaging tension in the weak zone  32  is defined as F (measured in N/6 mm) which has the following relation with temperature T: F=(0.5−f)×T/20+6.5×f−2.75, where 110° C.≤T≤130° C. and 4.5N/6 mm≤f≤5.5N/6 mm Parameters in this relation are calculated numerically. When the temperature is lower than 110° C., a packaging tension of the weak zone  32  is roughly the same as a packaging tension of other parts of the packaging zone, so gas cannot be released to the outside through the weak zone  32 . When the temperature rises to or above 130° C., a packaging tension of the weak zone  32  drops rapidly to nearly disappear while a packaging tension of other parts of the packaging zone remains roughly unchanged, so that the weak zone  32  is forced to open by gas inside the battery cell to ensure safety performance of the battery cell. 
     Specifically, the battery cell  100  includes a first sealing adhesive  321  and a second adhesive  322 . Two sides of the tab  12  are bonded by the first sealing adhesive  321  and the second sealing adhesive  322  respectively, and the bonded combination are hot pressed with part of the packaging bag  20  to form the weak zone  32 . 
     In some embodiments, the first sealing adhesive  321  and the second sealing adhesive  322  each consist of one adhesive layer. When a temperature of the adhesive layer rises to 110° C. to 130° C., a packaging tension between the first sealing adhesive  321  or the second sealing adhesive  322  and the packaging bag  20  and the tab  12  that are on two sides of the adhesive layer drops rapidly. 
     In some embodiments, the first sealing adhesive  321  and the second sealing adhesive  322  both have a thickness greater than 25 μm. Preferably, a thickness of the first sealing adhesive  321  and the second sealing adhesive  322  are both 30 μm. 
     Also referring to  FIG. 3 , which shows the tab  12  of the battery cell  100  in a second embodiment of this application. Different from the first embodiment, the first sealing adhesive  321  and the sealing adhesive  322  each includes two adhesive layers. 
     Specifically, the first sealing adhesive  321  includes a first adhesive layer  3211  and a second adhesive layer  3212 . The first adhesive layer  3211  is provided between the second adhesive layer  3212  and the packaging bag  20 , and the second adhesive layer  3212  is provided between the first adhesive layer  3211  and the tab  12 . A packaging tension of the first adhesive layer  3211  satisfies a foregoing relation between a packaging tension and temperature in the weak zone  32 . A packaging tension change of the second adhesive layer  3212  is roughly the same as packaging tension change in other parts of the packaging zone. 
     Therefore, when temperature rises to 110° C. to 130° C., a packaging tension between the first adhesive layer  3211  and the packaging bag  20  or the second adhesive layer  3212  rapidly drops, while a packaging tension between the second adhesive layer  3212  and the tab  12  remains unchanged, so that a packaging tension weak zone  32  exists between the first adhesive layer  3211  and the packaging bag  20  or the second adhesive layer  3212 , allowing heated gas generated by the electrode assembly body  11  to release. 
     In some embodiments, the second sealing adhesive  322  and the third sealing adhesive  321  may have a same structure. 
     In some embodiments, a total thickness of the first adhesive layer  3211  and the second adhesive layer  3212  ranges from 25 μm to 100 μm, and the first adhesive layer  3211  and the second adhesive layer  3212  both have a thickness greater than 10 μm. Preferably, the first adhesive layer  3211  and the second adhesive layer  3212  are both 15 μm thick. 
     It can be understood that the second sealing adhesive  322  may alternatively be the same as the second sealing adhesive  322  in the first embodiment. On the contrary, the first sealing adhesive  321  may be the same as the first sealing adhesive  321  in the first embodiment, and the second sealing adhesive  322  may consist of two adhesive layers. 
     Also referring to  FIG. 4 , which shows the tab  12  of the battery cell  100  in a third embodiment of this application. Different from the first embodiment, the first sealing adhesive  321  and the sealing adhesive  322  each consist of two adhesive layers. Different from the second embodiment, the two adhesive layers are arranged in reverse order. 
     Specifically, the first sealing adhesive  321  includes a first adhesive layer  3211  and a second adhesive layer  3212 . The first adhesive layer  3211  is provided between the second adhesive layer  3212  and the tab  12 , and the second adhesive layer  3212  is provided between the first adhesive layer  3211  and the packaging bag  20 . A packaging tension of the first adhesive layer  3211  satisfies the foregoing relation between a packaging tension and temperature in the weak zone  32 . Tension change of the second adhesive layer  3212  is roughly the same as tension change in other parts of the packaging zone. 
     Therefore, when temperature rises to 110° C. to 130° C., a packaging tension between the first adhesive layer  3211  and the tab  12  or the second adhesive layer  3212  rapidly drops, while a packaging tension between the second adhesive layer  3212  and the packaging bag  20  remains unchanged, so that a packaging tension weak zone  32  exists between the first adhesive layer  3211  and the tab  12  or the second adhesive layer  3212 , allowing heated gas generated by the electrode assembly body  11  to release. 
     In some embodiments, the first sealing adhesive  322  and the second sealing adhesive  321  may have a same structure. 
     In some embodiments, a total thickness of the first adhesive layer  3211  and the second adhesive layer  3212  ranges from 25 μm to 100 μm, and the first adhesive layer  3211  and the second adhesive layer  3212  both have a thickness greater than 10 μm. Preferably, a thickness of the first adhesive layer  3211  and the second adhesive layer  3212  are both 15 μm. 
     It can be understood that the second sealing adhesive  322  may alternatively be the same as the second sealing adhesive  322  in the first embodiment or the second embodiment. On the contrary, the first sealing adhesive  321  may be the same as the first sealing adhesive  321  in the first embodiment or the second embodiment, and the second sealing adhesive  322  may include two adhesive layers. 
     Also referring to  FIG. 5 , which shows the tab  12  of the battery cell  100  in a fourth embodiment of this application. Different from the first embodiment, the first sealing adhesive  321  and the second sealing adhesive  322  each include three adhesive layers. 
     Specifically, the first sealing adhesive  321  includes a first adhesive layer  3211 , a second adhesive layer  3212 , and a third adhesive layer  3213 . The first adhesive layer  3211  is provided between the second adhesive layer  3212  and the packaging bag  20 , and the second adhesive layer  3212  is provided between the first adhesive layer  3211  and the third adhesive layer  3213 . The third adhesive layer  3213  is provided between the second adhesive layer  3212  and the tab  12 . A packaging tension of the first adhesive layer  3211  and the third adhesive layer  3213  satisfies the foregoing relation between a packaging tension and temperature in the weak zone  32 . Tension change of the second adhesive layer  3212  is roughly the same as tension change in other parts of the packaging zone. 
     Therefore, when temperature rises to 110° C. to 130° C., a packaging tension between the first adhesive layer  3211  and the packaging bag  20  rapidly drops, and a packaging tension between the third adhesive layer  3213  and the tab  12  rapidly drops, while a packaging tension between the second adhesive layer  3212  and the first adhesive layer  3211  and that between the second adhesive layer  3212  and the third adhesive layer  3213  remain unchanged or slightly reduces, so a packaging tension weak zone  32  exists between the first adhesive layer  3211  and the packaging bag  20  or between the third adhesive layer  3213  and the tab  12 , allowing heated gas generated by electrode assembly body  11  to release. 
     In some embodiments, the first sealing adhesive  322  and the second sealing adhesive  321  may have a same structure. 
     In some embodiments, a total thickness of the first adhesive layer  3211 , the second adhesive layer  3212  and the third adhesive layer  3213  ranges from 25 μm to 100 μm, and the first adhesive layer  3211 , the second adhesive layer  3212  and the third adhesive layer  3213  all have a thickness greater than 10 μm. Preferably, the first adhesive layer  3211 , a thickness of the second adhesive layer  3212  and the third adhesive layer  3213  are all 13 μm. 
     It may be understood that the second sealing adhesive  322  may alternatively be the same as the second sealing adhesive  322  in the first, second or third embodiment. On the contrary, the first sealing adhesive  321  may be the same as the first sealing adhesive  321  in the first, second or third embodiment, and the second sealing adhesive  322  may consist of three adhesive layers. 
     It may be understood that a packaging tension of the second adhesive layer  3212  may further satisfy the foregoing relation between a packaging tension and temperature in the weak zone  32 , and correspondingly, tension change of the first adhesive layer  3211  and the third adhesive layer  3213  is roughly the same as tension change in other parts of the packaging zone. 
     Referring to  FIG. 6  and  FIG. 7 , which show the battery cell  100  in a fifth embodiment of this application. Different from the first embodiment, the tab  12  is packaged by a packaging zone  31  of the sealing zone  30 . Other parts of the sealing zone  30  of the packaging bag  20  include a weak zone  32 . 
     Specifically, the weak zone  32  bonds to two sides of the packaging bag  20 . When temperature rises to 110° C. to 130° C., a packaging tension between the weak zone  32  and the packaging bag  20  on two sides of the weak zone  32  rapidly drops, so that package of the packaging bag  20  fails to function, thus allowing heated gas generated by the electrode assembly body  11  to release through the weak zone  32 . 
     In some embodiments, the tab  12  includes a positive tab  121  and a negative tab  122 , where the positive tab  121  may be made of aluminum, and the negative electrode tab  122  may be made of nickel. The positive tab  121  and the negative tab  122  are provided opposite each other on an end surface of the electrode assembly body  11 . 
     The first sealing adhesive  321  and the second sealing adhesive  322  in the first embodiment, the first adhesive layer  3211  in the second and the third embodiments, the first adhesive layer  3211  and the third adhesive layer  3213  in the fourth embodiment and the weak zone  32  in the fifth embodiment may all be made by adjusting a ratio of polypropylene (PP) adhesive and polyethylene (PE) adhesive, for example, by mixing PP adhesive and PE adhesive in a ratio of 1:1. Alternatively, they may be made by mixing PP adhesive and a material with an expansion coefficient significantly different from that of PP adhesive when the temperature is higher than 110° C. 
     A packaging tension test was performed on an adhesive mixture of PP adhesive and PE adhesive in a ratio of 1:1 and a conventional packaging adhesive. 
     Example: a battery cell with a tab packaged by an adhesive mixture of PP adhesive and PE adhesive in a ratio of 1:1. 
     Comparative Example: a battery cell with a tab package by a conventional adhesive. 
     The packaged batteries in the example and the comparative example were clamped on a tensile machine, and kept at different temperatures for 5 minutes before start of the tension test. Results of the test were: a packaging tension of the battery in the example dropped rapidly at the temperature from 110° C. to 130° C.; while a packaging tension of the battery in the comparative example did not drop until the temperature was above 150° C. (conventional packaging adhesives all cease to function at 150° C.). 
     The embodiments of this application further provide an electronic apparatus, including a battery, where the battery includes a battery cell  100  and a housing accommodating the battery cell  100 , and the battery cell includes any one of the foregoing battery cells in the foregoing embodiments. 
     In the foregoing battery cell  100  and the electronic apparatus having such battery cell  100 , a sealing zone  32  of a packaging bag  20  is provided with a weak zone  32 , and a packaging tension of the weak zone  32  in the packaging bag  20  reduces in a predetermined temperature range, so as to release heated gas generated inside the battery cell  100  to the outside of the battery cell  100  through the weak zone  32  when heat accumulates inside the battery cell  100 , thereby reducing heat accumulated inside the battery cell  100  and alleviating deformation of the battery cell, which greatly improves safety performance of the battery cell and avoids safety issues such as short circuit and even fire. 
     The foregoing embodiments are merely intended to describe the technical solutions of this application, but not intended to constitute any limitation. Although this application is described in detail with reference to exemplary embodiments, persons of ordinary skill in the art should understand that modifications or equivalent replacements can be made to the technical solutions of this application, without departing from the spirit and essence of the technical solutions of this application.