Patent Publication Number: US-2021175643-A1

Title: Conductive cell frame

Description:
REFERENCE TO RELATED APPLICATIONS 
     This non-provisional application claims priority claim under 35 U.S.C. § 119(a) on China Patent Application No. 201911230190.5 filed Dec. 4, 2019 the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a conductive cell frame for connecting battery cells, more particularly, to a conductive cell frame that prevents the battery cell from being damaged during connecting process. 
     BACKGROUND 
     Examples of secondary cells include nickel-metal hydride (NiMH) batteries, nickel-cadmium (NiCd) batteries, lithium-ion (Li-ion) batteries, and lithium-ion polymer (Li-Poly) batteries, wherein lithium-ion batteries have advantages like high energy density, high operation voltage, wide utility temperature range, no memory effect, long battery life, capable of being charged/discharged numerous times and so on. Lithium-ion batteries are widely used in portable electronics such as cellular phones, laptop computers, and digital cameras, and even expanded its usage to the automobile industry in recent years. 
     A battery cell is mainly composed of anode material, electrolyte, cathode material, separator and housing, wherein the separator separates the anode material and the cathode material to prevent short-circuit and the electrolyte is disposed in the porous separator for conducting ionic charge. The housing wraps the anode material, the separator, the electrolyte, and the cathode material inside, and is usually made of metal materials in general. 
     A conductive cell frame is often used for connecting a plurality of battery cells in series and/or in parallel to form a battery pack that is capable of outputting a voltage required by a product. Generally, the conductive cell frame and the battery cell are connected by electric welding, during which the temperatures of the conductive cell frame and the battery cell need to be raised and the conductive cell frame applies force or pressure onto the housing at the anode or cathode of the battery cell to complete the connection between the conductive cell frame and the battery cell. However, in the connecting process of the conductive cell frame and the battery cell as mentioned above, the housing of the battery cell is likely to be damaged due to over force or overheat, and in turn the battery cell is damaged. 
     SUMMARY 
     An object of the present disclosure is to provide a conductive cell frame that includes a first conductive portion and a plurality of second conductive portions, wherein the first conductive portion is connected to the second conductive portion through a eutectic portion. The first conductive portion and the second conductive portion are made of different metal materials, wherein a resistance of the second conductive portion is greater than a resistance of the first conductive portion. Through the implementation of the conductive cell frame of the present disclosure, energy consumption during electric welding process of the conductive cell frame and the battery cell is decreased and damages to the battery cell structure is reduced as well. Hence, the product yield and reliability are enhanced. 
     An object of the present disclosure is to provide a conductive cell frame that mainly includes a first conductive portion and a plurality of second conductive portions, wherein the second conductive portion is completely overlapped by the first conductive portion and formed a projection/bulge on the surface of the first conductive portion. The conductive cell frame is connected to the battery cell through the second conductive portion, wherein a gap is formed between the first conductive portion and the battery cell such that the electrolyte gas (gas of battery fluid) ejected from a bad battery cell can be expelled through the gap. Thus, the possibility of the electrolyte gas coming in contact with the conductive cell frame or other battery cells is reduced and so are the damages that may be caused therefrom. 
     An object of the present disclosure is to provide a conductive cell frame for connecting a plurality of battery cells in series and/or in parallel, wherein the battery cell includes an anode, a cathode and an insulation ring for isolating the cathode and the anode. The conductive cell frame is connected to the anode of the battery cell through a second conductive portion, wherein the cross-sectional area of the second conductive portion is smaller than the cross-sectional area of the anode or the encircled region formed by the insulation ring. 
     An object of the present disclosure is to provide a conductive cell frame that includes a first conductive portion, a plurality of eutectic portions, a plurality of conductive portions, and at least one protruding welding portion. The second conductive portion includes a first surface and a second surface, wherein the first surface of the second conductive portion is connected to the first conductive portion through the eutectic portion. The at least one protruding welding portion is disposed on the second surface of the second conductive portion and is used for connecting to a battery cell. The first conductive portion and the second conductive portion are of different materials, and the resistance of the second conductive portion is greater than the resistance of the first conductive portion. 
     Preferably, the second conductive portion includes at least one recess portion disposed on the first surface of the second conductive portion and the location of the recess portion corresponds to the location of the protruding welding portion. 
     Preferably, the second conductive portion and the first conductive portion are partially overlapped. 
     Preferably, the first conductive portion and the protruding welding portion on the second conductive portion are not overlapped. 
     Preferably, the second conductive portion is completely overlapped by the first conductive portion and formed a bulge on a surface of the first conductive portion to create a gap between the first conductive portion and the battery cell connected to the protruding welding portion. 
     Preferably, the battery cell includes an insulation ring for separating an anode and a cathode of the battery cell and the insulation ring has an encircled region in which the anode of the battery cell is located, and the cross-sectional area of the second conductive portion is smaller than or equal to the cross-sectional area of the anode or the encircled region of the insulation ring. 
     Preferably, the second conductive portion includes at least one recess portion disposed on the first surface of the second conductive portion and the location of the recess portion corresponds to the location of the protruding welding portion. The eutectic portion is connected to the first surface and the recess portion of the second conductive portion. 
     Preferably, the first conductive portion includes a plurality of branches respectively connected to the plurality of second conductive portions. 
     Preferably, the first conductive portion includes a plurality of branches, and each branch includes a plurality of sub-branches and is connected to one of the second conductive portions through the sub-branches. 
     Preferably, the thickness or the cross-sectional area of the second conductive portion is smaller than the thickness or the cross-sectional area of the first conductive portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The structure as well as preferred modes of use, further objects, and advantages of this present disclosure will be best understood by referring to the following detailed description of some illustrative embodiments in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a top view of a conductive cell frame according to an embodiment of the present disclosure. 
         FIG. 2  is a side view of a conductive cell frame and a battery cell according to an embodiment of the present disclosure. 
         FIG. 3  is a side view of a conductive cell frame connected with a battery cell according to an embodiment of the present disclosure. 
         FIG. 4  is a top view of a conductive cell frame according to another embodiment of the present disclosure. 
         FIG. 5  is a top view of a conductive cell frame according to yet another embodiment of the present disclosure. 
         FIG. 6  is a side view of a conductive cell frame and a battery cell according to yet another embodiment of the present disclosure. 
         FIG. 7  is a side view of a conductive cell frame connected with a battery cell according to yet another embodiment of the present disclosure. 
         FIG. 8  is a top view of a conductive cell frame according to yet another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1 and 2 , which are respectively a top view and a side view of a conductive cell frame according to an embodiment of the present disclosure, the conductive cell frame  10  includes a first conductive portion  11 , at least one second conductive portion  13  and at last one protruding welding portion  151 , wherein the first conductive portion  11  and the second conductive portion  13  are made of different materials and are connected through/joined by a eutectic portion  12 . In other words, there are a plurality of eutectic portions  12  as one eutectic portion  12  corresponds to one connection/joint between the first conductive portion  11  and the second conductive portion  13 . 
     The second conductive portion  13  includes a first surface  131  and a second surface  133 , which can be, for example, two opposite surfaces on the second conductive portion  13 , wherein parts of the first surface  131  of the second conductive portion  13  is connected to/joined with the first conductive portion  11  through the eutectic portion  12 , and thus the main structure of the conductive cell frame  10  is formed. The first conductive portion and the second conductive portion are connected or joined by processes like welding. 
     In one embodiment, at least one protruding welding portion  155  is disposed on the first surface  131  of the second conductive portion  13 , wherein the protruding welding portion  155  can be a bump or projection protruding from the first surface  131  of the second conductive portion  13 , and the second conductive portion  13  is connected/joined to the first conductive portion  11  through the protruding welding portion  155 . In practice, the first conductive portion  11  and the second conductive portion  13  are connected/joined by resistance welding process, where the protruding welding portion  155  on the first surface  131  of the second conductive portion  13  is placed/put in contact with the lower surface of the first conductive portion  11  and electric current is passed to the second conductive portion  13  through the first conductive portion  11 , thereby raising the temperature of the protruding welding portion  155  on the second conductive portion  13  and the temperature of the first conductive portion  11  in contact therewith, and forming the eutectic portion  12  between the first conductive portion  11  and the second conductive portion  13 . 
     Moreover, at least one protruding welding portion  151  is disposed on the second surface  133  of the second conductive portion  13 , wherein the protruding welding portion  151  is a bump/projection protruding from the second surface  133  of the second conductive portion  13 . Through the protruding welding portion  151 , the second conductive portion  13  is connected to a housing  171  of a battery cell  17 , and for example, connected to the anode or the cathode of the housing  171 . 
     In one embodiment, the protruding welding portions  155 / 151  are formed respectively on the first surface  131  and the second surface  135  of the second conductive portion  13  by stamping or pressing processes, and at least one recess portions  157 / 153  are respectively formed on the second surface  133  and the first surface  131  of the second conductive portion  13 , wherein the location of the recess portion  157 / 153  corresponds to the location of the protruding welding portion  155 / 151 . 
     It is to be noted that making the second conductive portion  13  by stamping/pressing process is merely an embodiment of the present disclosure, and the scope of the present disclosure is not limited thereby. Thus, the present disclosure is not limited to the first surface  131  and the second surface  133  of the second conductive portion  13  having at least one recess portion  153 / 157  thereon. In practice, the second conductive portion  13  can be made by other methods, such as casting, and so there won&#39;t be any recess portion  153 / 157  on the first surface  131  and the second surface  133  of the second conductive portion  13 . 
     In one embodiment, the second conductive portion  13  and the first conductive portion  11  are partially overlapped, wherein the first conductive portion  11  and the protruding welding portion  151  and/or the recess portion  153  on the second conductive portion  13  are not overlapped. Specifically, the protruding welding portion  151  and/or the recess portion  153  are disposed on the region of the second conductive portion  13  that is not overlapped with the first conductive portion  11 , so that the eutectic portion  12  that connects/joins the first conductive portion  11  and the second conductive portion  13  is not in contact with or does not touch the recess portion  153  of the second conductive portion  13 . 
     In practice, welding, which is a technique that joins different metals by using high heat or high pressure, is mainly used to connect/join the second conductive portion  13 , the protruding welding portion  151 , and the housing  171  of the battery cell  17 . 
     In one embodiment, the second conductive portion  13 , the protruding welding portion  151 , and the housing  171  of the battery cell  17  are connected/joined by resistance welding process. First, the protruding welding portion  151  on the second conductive portion  13  is placed/put in contact with the battery cell  17 , for example, in contact with the housing  171  at where the anode or the cathode of the battery cell  17  is, wherein the housing  171  is of a metal material. 
     Next, electric current is supplied to the second conductive portion  13 , the protruding welding portion  151  and the housing  171  of the battery cell  17 , all of which are made of metal materials and have electrical resistances, and therefore when the electric current passes through the second conductive portion  13 , the protruding welding portion  151  and the housing  171  of the battery cell  17 , there is an increase in the temperature of the protruding welding portion  151  and the temperature of the housing  171  of the battery cell  17  in contact therewith. 
     When the temperatures of the second conductive portion, the protruding welding portion  151  and the housing  171  of the battery cell  17  reach a specific value, a pool of molten material, or a weld pool, is formed. Force or pressure is then applied onto the housing  171  of the battery cell  17  through the second conductive portion  13  and the protruding welding portion  151  such that the protruding welding portion  151  on the second conductive portion  13  is pressed and sunk into the housing  171  of the battery cell  17 . After the temperatures of the second conductive portion  13 , the protruding welding portion  151  and the housing  171  of the battery cell  17  cooled down, the connection between the second conduction portion  13  and the battery cell  17  is complete. 
     In general, conductive cell frames are often made of materials with low resistance and high conductivity to reduce the energy loss from charging and discharging the battery cell through the conductive cell frame. When connecting a conductive cell frame having low resistance and the housing of the battery cell in contact by resistance welding, a greater electric current must be supplied to the conductive cell frame and the housing of the battery cell, and the energy consumption of welding the conductive cell frame and the battery cell is high. 
     Moreover, such conductive cell frame usually has a thicker thickness for increasing the cross-sectional area of the conductive cell frame so as to reduce the resistance of the conductive cell frame. But as the thickness of the conductive cell frame increases, the structural strength of the conductive cell frame is also enhanced, making the conductive cell frame harder to deform when connecting to the housing of the battery cell. Thus, when the conductive cell frame applies force or pressure onto the housing of the battery cell, the housing of the battery cell has a greater deformation. For example, the protruding welding portion on the conductive cell frame would make a deeper or wider cavity in the housing of the battery cell. 
     Hence, the housing structure of the battery cell could be damaged during the connecting process of the conductive cell frame and the battery cell and the reliability and durability of the battery cell is thus affected. The damage to the housing is, for example, formation of metal cracks on the housing of the battery cell. However, if a conductive cell frame with high resistance and low conductivity is selected in attempt to avoid the aforementioned issue occurred in welding the conductive cell frame to the battery cell, the energy loss from the charging and discharging of the battery cell through the conductive cell frame will increase. 
     To solve the aforementioned issue, the present disclosure provides the conductive cell structure  10  that is made by two different materials, wherein the first conductive portion  11  and the second conductive portion  13  are of different materials, and the resistance and/or the resistivity of the second conductive portion  13  is greater than that of the first conductive portion  11 . In other words, the conductivity of the first conductive portion  11  is higher than the conductivity of the second conductive portion  13 . The first conductive portion  11  is copper and the second conductive portion  13  is nickel, for example. 
     Since the second conductive portion  13  has a greater resistance, a small or lower current can be supplied to the second conductive portion  13  when connecting the second conductive portion  13  of the conductive cell frame  10  and the contacted housing  171  of the battery cell  17 . Therefore, resistance welding process can be used to connect/join the second conductive portion  13  and the housing  171  of the battery cell  17  so as to effectively reduce the energy consumed during the connecting/joining process of the conductive cell frame  10  and the battery cell  17 . 
     Furthermore, the thickness of the second conductive portion  13  is reduced to lessen the structural strength of the second conductive portion  13 . In one embodiment, the thickness or the cross-sectional area of the second conductive portion  13  is smaller than the thickness or the cross-sectional area of the first conductive portion  11 . When connecting/joining the second conductive portion  13  with the housing  171  of the battery cell  17  by resistance welding, both the second conductive portion  13  and the housing  17  of the battery cell  17  would deform so as to reduce the degree of deformation on the housing  171  of the battery cell  17 . As shown in  FIG. 3 , the protruding welding portion  151  on the second conductive portion  13  deforms during the resistance welding process and the thickness and/or area of a deformed portion  173  caused by the protruding welding portion  151  forcing/pressing on the housing  171  of the battery cell  17  is reduced. Hence, damages to the housing structure  171  of the battery cell  17 , like formation of metal cracks on the housing  171  of the battery cell  17 , can be avoided during the connecting/joining process of the conductive cell frame  10  and the battery cell  17 , and the durability and reliability of the battery cell  17  are enhanced. 
     In addition, since the first conductive portion  11  has a lower resistance value, there is no substantial increase in the resistance value of the conductive cell frame  10  with the addition of the second conductive portion  13 , and so the energy loss caused by the conductive cell frame  10  charging and discharging the battery cell  17  is reduced. 
     In the embodiment shown in  FIG. 1 , the first conductive portion  11  looks like a fishbone and has a plurality of branches  111 , wherein each of the branches  111  of the first conductive portion  11  is connected to one of the second conductive portions  13  through the eutectic portion  12 . For example, the first conductive portion  13  in  FIG. 1  includes six branches  111  and through the six branches  111  is connected to six second conductive portions  13 , wherein each of the six conductive portions  13  is connected to one battery cell  17 , and so the conductive cell frame  10  connects the six battery cells  17  in series and/or in parallel. 
     In another embodiment shown in  FIG. 4 , each branch  11  of the first conductive portion  11  has a plurality of sub-branches  113  disposed thereto, wherein each of the sub-branches  113  is connected to one of the second conductive portions  13 , such that each branch  111  of the first conductive portion  11  is connected to plurality of second conductive portions  13 . For example, the first conductive portion  11  in  FIG. 4  includes six branches  111 , wherein each branch  111  is connected to two sub-branches  113  and each sub-branch  113  is connected to one second conductive portion  13 , such that each branch  111  is connected to one battery cell  17  through two second conductive portions  13 . 
     It is to be noted that the present disclosure does not limit the number of the branches  111  and the sub-branches  113  of the first conductive portion  11  and the number of the second conductive portions  13  and the battery cells  17  connected to the first conductive portion  11 . 
     Referring to  FIGS. 5 and 6 , which are respectively a top view and a side view of a conductive cell frame according to another embodiment of the present disclosure, the conductive cell frame  20  includes, mainly, a first conductive portion  21 , at least one second conductive portion  13  and at least one protruding welding portion  251 , wherein the first conductive portion and the second conductive portion  23  are made of different materials and are connected through/joined by a eutectic portion  22 . In other words, there is at least one eutectic portion  22  as one eutectic portion  22  corresponds to one connection/joint between the first conductive portion  21  and the second conductive portion  23 . 
     Particularly, the second conductive portion  23  includes a first surface  231  and a second surface  233 , wherein the first surface  231  of the second conductive portion  23  is connected to/joined with the first conductive portion  21  through the eutectic portion  22  and thus the main structure of the conductive cell frame  20  is formed. 
     In one embodiment, at least one protruding welding portion  255  is disposed on the first surface  231  of the second conductive portion  23 , wherein the protruding welding portion  255  is a bump/projection that protrudes from the first surface  231  of the second conductive portion  23 , and the second conductive portion  23  is connected to/joined with the first conductive portion  21  through the protruding welding portion  255 . In practice, the first conductive portion  21  and the second conductive portion  23  are connected/joined by resistance welding, where the protruding welding portion  255  on the first surface  231  of the second conductive portion  23  is placed/put in contact with the lower surface of the first conductive portion  21 , and by supplying electric current to the second conductive portion  23  through the first conductive portion  21 , the temperatures of the protruding welding portion  255  and the contacted first conductive portion  21  are raised and the eutectic portion  22  is formed between the first conductive portion  21  and the second conductive portion  23 . 
     In one embodiment shown in  FIG. 6 , the cross-sectional area A 2  of the second conductive portion  23  is smaller than the cross-sectional area A 1  of the first conductive portion  21 , wherein the second conductive portion  23  is completely/fully overlapped by the first conductive portion  21 , like the entire first surface  231  and/or second surface  233  of the second conductive portion  23  is overlapped by the first conductive portion  21 , and formed a bulge on the surface of the first conductive portion  21 . After the second conductive portion  23  is connected to/joined with the first conductive portion through the eutectic portion  22 , the second conductive portion  23  forms a bulged conductive portion on the surface, such as the lower surface, of the first conductive portion  21 . 
     At least one protruding welding portion  251  is disposed on the second surface  233  of the second conductive portion  23 , wherein the protruding welding portion  251  is a bump/projection that protrudes from the second surface  233  of the second conductive portion  23 , and at least one recess portion  253  is disposed on the first surface  231  of the second conductive portion  23 , wherein the location of the recess portion  253  corresponds to the location of the protruding welding portion  251 . In other embodiments, there is no recess portion  253  disposed on the first surface  231  of the second conductive portion  23 . 
     Since the second conductive portion  23  is completely/fully overlapped by the first conductive portion  21 , the protruding welding portion  251  and/or the recess portion  253  on the second conductive portion  23  also overlaps with the first conductive portion  21 . When the first surface  231  of the second conductive portion  23  has the recess portion  253  thereon, the eutectic portion  22  connecting/joining the first conductive portion  21  and the second conductive portion  23  is only formed on the first surface  231  of the second conductive portion  23 , wherein there is no eutectic portion  22  in the recess portion  253 . In other embodiments, the eutectic portion  22  is formed both on the first surface  231  and in the recess portion  253  of the second conductive portion  23 ; in other words, the eutectic portion  22  is connected to the first surface  231  and the recess portion  253 . 
     In one embodiment, the second conductive portion  23 , the protruding welding portion  251  and the housing  271  of the battery cell  27  are connected/joined by resistance welding so as to complete the connection between the second conductive portion  23  and the battery cell  27 . The conductive cell frame  20  is made of two different materials, wherein the resistance and/or the resistivity of the second conductive portion  23  is greater than that of the first conductive portion  21 . In other words, the conductivity of the first conductive portion  21  is greater than that of the second conductive portion  23 . The first conductive portion  21  is copper and the second conductive portion  23  is nickel, for example. 
     Therefore, when connecting the conductive cell frame  20  and the contacted battery cell  27  by resistance welding, the electric current supplied from the first conductive portion  21  to the second conductive portion  23  and the housing  271  of the battery cell  27  can be lowered and so the energy consumption of connecting the conductive cell frame  20  and the battery cell is effectively reduced. 
     Moreover, the thickness of the second conductive portion  23  is decreased and the structural strength of the second conductive portion  23  is thereby lessened, such that the protruding welding portion  251  on the second conductive portion  23  also deforms during the resistance welding process. Therefore, the depth or area of the deformed portion  273  caused by the force or pressure applied by protruding welding portion  251  on the housing  271  of the battery cell  27  is reduced as shown in  FIG. 7  and the damages to the housing structure of the battery cell  27  during connecting process is avoided. 
     In the embodiment shown in  FIG. 5 , the first conductive portion  21  has a fishbone-like appearance that includes a plurality of branches  211 , and each branch  211  of the first conductive portion  21  is connected to one second conductive portion  23  through the eutectic portion  22 , wherein each second conductive portion  23  is completely overlapped by the branch  211  of the first conductive portion  21  which it connected to. 
     In another embodiment, as shown in  FIG. 8 , each branch  211  of the first conductive portion  21  is connected to a plurality of sub-branches  213 , wherein each of the sub-branches  213  is connected to one of the second conductive portions  23 , such that each branch  211  of the first conductive portion  21  is connected to plurality of second conductive portions  23  and is connected to a battery cell  27  through the plurality of second conductive portions  23 . 
     It is to be noted that the present disclosure does not limit the number of the branches  211  and the sub-branches on the first conductive portion  21  and the number of the second conductive portions  23  and the battery cells  27  connected to the first conductive portion  21 . 
     Since the second conductive portion  23  is completely overlapped by the first conductive portion  21  and protrudes from the surface, like the lower surface, of the first conductive portion  21 , a gap G as shown in  FIG. 7  is formed/created between the first conductive portion  21  and the connected battery cell  27  when the conductive cell frame  20  is connected to the housing  271  of the battery cell  27  through the second conductive portion  23 . If the battery cell  27  is damaged and ejects electrolyte gas (gas of battery fluid), the ejected electrolyte gas is expelled through the gap G between the first conductive portion  21  and the battery cell  27 , whereby the possibility or the length of time which the electrolyte gas comes in contact with the conductive cell frame  20  and/or other battery cells  27  is reduced and so the damages of other battery cells  27  is minimized. 
     In one embodiment, the battery cell  27  includes an anode  272 , a cathode  274  and an insulation ring for separating the anode  272  and the cathode  274 . More specifically, the insulation ring  275  forms an encircled region  24 , wherein the anode  272  of the battery cell  27  is located inside the encircled region  24  of the insulation ring  275 , and the area of the anode  272  is smaller than or equal to the area of the encircled region  24 . The cathode  274  is located outside of encircled region  24 , external of the insulation ring  275 . 
     In one embodiment, the cross-sectional area A 2  of the second conductive portion  23  is smaller than or equal to the cross-sectional area A 3  of the encircled region  24  inside the insulation ring  275 . In other words, the cross-sectional area A 2  of the second conductive portion  23  is smaller than or equal to the cross-sectional area A 3  of the anode  272  in the battery cell  27 . When the conductive cell frame  20  is connected to the anode of the battery cell  27 , only the second conductive portion  23  is in contact with the anode located in the insulation ring  275 . 
     Generally, when the battery cell  27  is damaged, the gas of battery fluid inside the battery cell  27  usually would eject out of the battery cell  27  from the insulation ring  275  which is the boarder between the anode  272  and the cathode  274 . In this embodiment, because the second conductive portion  23  only connects to the anode  272  inside the insulation ring  275  and there is the gap G between the first conductive portion  21 , the insulation ring  275  and the housing  271  of the battery cell  27 , the gas of battery fluid ejected from the battery cell  27  is expelled to the outside through the gap G. 
     The above disclosure is only the preferred embodiment of the present disclosure, and not used for limiting the scope of the present disclosure. All equivalent variations and modifications on the basis of shapes, structures, features and spirits described in claims of the present disclosure should be included in the claims of the present disclosure.