Patent Publication Number: US-2023148155-A1

Title: Alluminum battery

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwanese application no. 110141782, filed on Nov. 10, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND 
     Technical Field 
     The disclosure relates to a battery. Particularly, the disclosure relates to an aluminum battery. 
     Description of Related Art 
     Generally speaking, for a pole lug and a pole tab of a battery, melt soldering is typically selected to provide high temperature by friction, instantaneous high heat release, or the like to melt metal for joining. However, when such joining is applied to an aluminum battery, it is likely that the strength at the soldering position is reduced by the increase in temperature at the soldering position, and pseudo-soldering or unstable soldering thus occurs. As a result, it is likely to adverse affect the overall performance of the aluminum battery. Therefore, how to improve the overall performance of the aluminum battery is a challenge. 
     SUMMARY 
     The disclosure provides an aluminum battery of which the overall performance may be improved. 
     An aluminum battery of the disclosure includes a shell, an electric core, a pole tab, and a joint. The shell has an internal space. The electric core is disposed in the internal space. The electric core includes a pole sheet group. The pole sheet group has a pole lug. The pole tab is partially exposed from the shell. The joint penetrates the pole lug and the pole tab to join and electrically connect the pole lug and the pole tab. 
     In an embodiment of the disclosure, the joint includes a rivet, a screw, or a combination thereof. 
     In an embodiment of the disclosure, the pole lug and the pole tab respectively have holes, and joining performed by the joint includes riveting, fixing, or a combination thereof. 
     In an embodiment of the disclosure, a thickness of the electric core is at least greater than 1 cm. 
     In an embodiment of the disclosure, the thickness of the electric core is between 1 cm and 3 cm. 
     In an embodiment of the disclosure, a material of the joint includes metal, and an electrical conductivity of the metal is at least greater than 3.78 ∗ 10 7  S/m. 
     In an embodiment of the disclosure, the metal includes gold, copper, silver, aluminum, or a combination thereof. 
     In an embodiment of the disclosure, the pole sheet group includes a plurality of positive pole sheets and a plurality of negative pole sheets, the negative pole sheets are aluminum pole sheets, and the positive pole sheets are nickel pole sheets. 
     In an embodiment of the disclosure, the number of the joints penetrating the pole lug and the pole tab is greater than or equal to one. 
     In an embodiment of the disclosure, the joint is not in direct contact with the shell. 
     Based on the foregoing, in the disclosure, the joining between the pole lug and the pole tab of the electric core of the aluminum battery (disposed in the internal space of the shell) is improved. In other words, in the aluminum battery, the joint penetrating the pole lug and the pole tab is employed to join and electrically connect the pole lug and the pole tab, preventing pseudo-soldering or unstable soldering by physical joining (mechanical joining). As a result, favorable joining result and strength between the pole lug and the pole tab are presented, and the overall performance can be thus improved. 
     To make the aforementioned more comprehensible, several embodiments accompanied with drawings are described in detail as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. 
         FIG.  1 A  is a schematic partial top view of an aluminum battery according to an embodiment of the disclosure. 
         FIG.  1 B  is a schematic partial cross-sectional view of an aluminum battery according to an embodiment of the disclosure. 
         FIG.  2    is a schematic view of the result of numbers of joints versus discharge capacities of aluminum batteries according to different embodiments of the disclosure. 
         FIG.  3    is a schematic view of the result of numbers of joints versus coulombic efficiencies of aluminum batteries according to different embodiments of the disclosure. 
         FIG.  4    is a schematic view of the comparison result between negative electrode resistance values of Example and Comparative Examples. 
         FIG.  5    is a schematic view of the comparison result between positive electrode resistance values of Example and Comparative Examples. 
         FIG.  6    is a schematic view of the comparison result between discharge capacities of Example and Comparative Example. 
         FIG.  7    is a schematic view of the comparison result between coulombic efficiencies of Example and Comparative Example. 
         FIG.  8    is a schematic view of the comparison result between self-discharge rates of Example and Comparative Example. 
     
    
    
     It should be noted that illustration of shell is omitted from  FIG.  1 A  to clearly present other members. 
     DESCRIPTION OF THE EMBODIMENTS 
     To make the content of the disclosure more comprehensible, embodiments are provided below as examples according to which the disclosure can be carried out. For clarity in description, many practical details will be explained in the following description. Nonetheless, it should be understood that these practical details are not intended to limit the disclosure. In other words, these practical details are not essential in part of the embodiments of the disclosure. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the related fields to which the disclosure belongs. 
       FIG.  1 A  is a schematic partial top view of an aluminum battery according to an embodiment of the disclosure.  FIG.  1 B  is a schematic partial cross-sectional view of an aluminum battery according to an embodiment of the disclosure.  FIG.  2    is a schematic view of the result of numbers of joints versus discharge capacities of aluminum batteries according to different embodiments of the disclosure.  FIG.  3    is a schematic view of the result of numbers of joints versus coulombic efficiencies of aluminum batteries according to different embodiments of the disclosure.  FIG.  4    is a schematic view of the comparison result between negative electrode resistance values of Example and Comparative Examples.  FIG.  5    is a schematic view of the comparison result between positive electrode resistance values of Example and Comparative Examples.  FIG.  6    is a schematic view of the comparison result between discharge capacities of Example and Comparative Example.  FIG.  7    is a schematic view of the comparison result between coulombic efficiencies of Example and Comparative Example.  FIG.  8    is a schematic view of the comparison result between self-discharge rates of Example and Comparative Example. 
     With reference to  FIG.  1 A  to  FIG.  8   , an aluminum battery  100  of this embodiment includes a shell  110 , an electric core  120 , a pole tab  130 , and a joint  140 . The shell  110  has an internal space  112 . The electric core  120  is disposed in the internal space  112 . The pole tab  130  is partially exposed from the shell  110  (the pole tab  130  extends from the internal space  112  to the outside of the shell  110  as shown in  FIG.  1 B ). In addition, the electric core  120  includes a pole sheet group  122  having a pole lug  124 . The joint  140  penetrates the pole lug  124  and the pole tab  130  to join and electrically connect the pole lug  124  and the pole tab  130 . Accordingly, in this embodiment, the joining between the pole lug  124  and the pole tab  130  of the electric core  122  of the aluminum battery  100  is improved. In other words, in the aluminum battery  100 , the joint  140  penetrating the pole lug  124  and the pole tab  130  is employed, preventing pseudo-soldering or unstable soldering by physical joining (mechanical joining). As a result, favorable joining result and strength between the pole lug  124  and the pole tab  130  are presented, and the overall performance can be thus improved. 
     Further, in the aluminum battery of this embodiment, the joint  140  is employed to directly join the pole lug  124  of the pole sheet group  122  to the current collecting position of the pole tab  130  in the internal space  112  to provide stable mechanical strength and high current collection (low resistance) by the physical joining (mechanical joining) mode by the joint  140 . Therefore, even in the case with a relatively high charge and discharge rate (C-rate) and a relatively high current, the discharge capacity and the coulombic efficiency of the aluminum battery  100  of this embodiment may still be improved. In addition, in the aluminum battery  100  of this embodiment, since a physical joining (mechanical joining) mode is employed, that is, high-temperature soldering is not required, pseudo-soldering or unstable soldering may be unlikely to occur. Accordingly, the pole lug  124  and the pole tab  130  of the pole sheet group  122  may be smoothly fitted, thus reducing the electrical loss of the external circuit. As a result, the performance in the self-discharge rate of the aluminum battery  100  may also be improved. Nonetheless, the disclosure is not limited thereto. 
     In some embodiments, the joint  140  includes a rivet, a screw, or a combination thereof. In addition, the pole lug  124  and the pole tab  130  may respectively have holes. Therefore, joining performed by the joint  140  may include riveting, fixing, or a combination thereof. For example, when the joint  140  is a rivet, the joining performed by the joint  140  may be riveting, and when the joint  140  is a screw, the joining performed by the joint  140  may be fixing. Nonetheless, the disclosure is not limited thereto. The joint  140  may be any suitable elements that may penetrate the pole lug and the pole tab  130 , and the joining may be correspondingly selected depending on the elements. 
     In some embodiments, when soldering is employed, the probability of pseudo-soldering or unstable soldering increases as a thickness of the electric core  120  increases. For example, when the thickness of the electric core  120  is at least greater than 1 centimeter (cm), for example, between 1 cm and 3 cm, the overall performance of the aluminum battery  100  can be improved more obviously by the use of the physical joining (mechanical joining) of this embodiment compared to soldering. Nonetheless, the disclosure is not limited thereto. When the physical joining (mechanical joining) of this embodiment is applied to a case where the thickness of the electric core  120  is less than 1 cm, the overall performance of the aluminum battery  100  can also be improved compared to soldering. 
     In some embodiments, a material of the joint  140  includes metal. An electrical conductivity of the metal is at least greater than 3.78∗10 7  S/m (highly thermally conductive metal). For example, the metal may include gold, copper, silver, aluminum, or a combination thereof. Nonetheless, the disclosure is not limited thereto. 
     In some embodiments, a thermal conductivity of the joint  140  may be greater than 237 W/m∗K, but the disclosure is not limited thereto. 
     In some embodiments, the pole sheet group  122  includes a plurality of positive pole sheets and a plurality of negative pole sheets. The pole tab  130  includes two pole tabs to be electrically connected respectively with the positive/negative pole lug  124  of the pole sheet group  122 . The negative pole sheets may be aluminum (Al) pole sheets, and the positive pole sheets may be nickel (Ni) pole sheets. Nonetheless, the disclosure is not limited thereto. 
     In some embodiments, the joint  140  is not in direct contact with the shell  110 . In other words, the joint  140  is not employed for the fixed connection between the shell  110  and other elements. Nonetheless, the disclosure is not limited thereto. 
     In some embodiments, the pole sheets of the pole sheet group  122  further include a separator  150 . In other words, the separator  150  is disposed between two adjacent pole sheets to prevent short circuits between the two poles. The separator  150  is, for example, glass fiber or a polymer film. Nonetheless, the disclosure is not limited thereto. 
     In some embodiments, the number of the joint  140  penetrating the pole lug  124  and the pole tab  130  is greater than or equal to one. For example, as shown in  FIG.  2    and  FIG.  3   , when the number of the joint  140  penetrating the pole lug  124  and the pole tab  130  is one or more (two), approximately the same performance (in the discharge capacity and the coulombic efficiency) can be presented in both cases. Here,  FIG.  2    and  FIG.  3    are respectively a discharge capacity test and a coulombic efficiency test performed with a test instrument of Chen Tech BT 2000-5V/50A under conditions that the positive electrode was an aluminum foil, the separator was glass fiber, and the negative electrode was a carbon-coated nickel foil, being charged and discharged at 4C (fully charged/discharged within 15 minutes), in a voltage interval of 1.0 Volt (V) to 2.4 V and at a current value of 2.4 amperes (A). Here, 4C refers to charging and discharging completed within ¼ hour (individually within ¼ hour). 
     The efficacy of the disclosure will be to describe more specifically below with reference to Example 1, Comparative Example 1, and Comparative Example 2. In addition, although Example 1 is described below, the details of the materials and processes used may be appropriately changed without going beyond the scope of the disclosure. Therefore, the disclosure should not be interpreted restrictively by Example 1 described below. 
     Example 1 
     In the pole sheet group of the aluminum battery of Example 1, the positive pole sheets were nickel pole sheets, the negative pole sheets were aluminum pole sheets, and the pole lug and the pole tab were joined by riveting, so that a rivet penetrated the pole lug and the pole tab. 
     Comparative Example 1 
     In the pole sheet group of the aluminum battery of Comparative Example 1, the positive pole sheets were nickel pole sheets, the negative pole sheets were aluminum pole sheets, and the pole lug and the pole tab were joined by capacitive-mode soldering. 
     Comparative Example 2 
     In the pole sheet group of the aluminum battery of Comparative Example 2, the positive pole sheets were nickel pole sheets, the negative pole sheets were aluminum pole sheets, and the pole lug and the pole tab were joined by ultrasonic waves. 
     Here, other undescribed compositions and specifications of the aluminum battery may be obtained by those of ordinary skill in the related fields to which the disclosure belongs according to any content covered and included within the spirit and scope of the appended claims. In addition, the capacitive-mode soldering and ultrasonic waves may be any technique familiar to those of ordinary skill in the related fields, and will not be repeatedly described here. 
       FIG.  4    and  FIG.  5    are respectively resistance tests performed with a test instrument of Fluke BT508 digital AC meter under conditions that the pole tab was a nickel pole tab (2 cm∗6 cm∗0.2 cm), 20 pieces of nickel foils (2 cm∗6 cm∗0.03 cm), and 20 pieces of aluminum foil (2 cm ∗ 6 cm ∗ 0.05 cm). The results of  FIG.  4    and  FIG.  5    show an obvious drop in the vertical resistance of the negative electrode ( FIG.  4   ) and the positive electrode ( FIG.  5   ) of Example 1 compared to Comparative Example 1 and Comparative Example 2 (the bars in the box plots are more concentrated at the lower part, and Comparative Example 2 has outliers at the higher part), thus reducing the impedance of electrons entering and leaving the electric core. Therefore, in the discharge capacity, the coulombic efficiency, and the self-discharge rate, the performance of an aluminum battery with the use of physical joining (mechanical joining) is improved. 
       FIG.  6    and  FIG.  7    are respectively a discharge capacity test and a coulombic efficiency test performed with a test instrument of Chen Tech BT 2000-5V/50A under conditions that the positive electrode was an aluminum foil, the separator was glass fiber, and the negative electrode was a carbon-coated nickel foil, being charged and discharged at 4C (fully charged/discharged within 15 minutes), in a voltage interval of 1.0 V to 2.4 V and at a current value of 2.4 A. The results of  FIG.  6    and  FIG.  7    show an obvious increase in the discharge capacity and the coulombic efficiency of Example 1 (the bars in the box plots are more concentrated at the higher part) when a large current at a charge and discharge rate of 4C is used compared to Comparative Example 1. Further, when physical joining (mechanical joining) is employed in place of the conventional capacitive-mode soldering, since the joining strength is higher with physical joining (mechanical joining) under the operating environment of the aluminum battery, it is possible to greatly reduce the resistance at the soldering position and prevent the occurrence of pseudo-soldering or unstable soldering. Accordingly, if an adjustment is subsequently made toward a higher charging and discharging current for the aluminum battery system due to the particularity of the system, more advantages and higher economical values are possible with the use of physical joining (mechanical joining). 
       FIG.  8    is a self-discharge rate test performed with a test instrument of Chen Tech BT 2000-5V/50A under conditions that the positive electrode was an aluminum foil, the separator was glass fiber, and the negative electrode was a carbon-coated nickel foil, being charged and discharged at 4C (fully charged/discharged within 15 minutes), in a voltage interval of 1.0 V to 2.4 V and at a current value of 2.4 A for a self-discharge time of 1 day. In the battery field, the self-discharge rate may also be one of the key indicators. The self-discharge rate is related to the amount of electricity that may actually be used and the amount of electricity that is naturally discharged and wasted after the battery is charged. The joining is a factor that affects the self-discharge rate. The joining is related to the loss of the external circuit, and the degree of joining between different current collectors and current conductors directly affects the current loss of the external circuit, thus affecting the result of self-discharge. Therefore, the results of  FIG.  8    show an obvious drop in the self-discharge rate of Example 1 is (the bars in the box plot are more concentrated in the lower part) after one day of self-discharge compared to Comparative Example 1. 
     In summary of the foregoing, in the disclosure, the joining between the pole lug and the pole tab of the electric core of the aluminum battery (disposed in the internal space of the shell) is improved. In other words, in the aluminum battery, the joint penetrating the pole lug and the pole tab is employed to join and electrically connect the pole lug and the pole tab, preventing pseudo-soldering or unstable soldering by physical joining (mechanical joining). As a result, favorable joining result and strength between the pole lug and the pole tab are presented, and the overall performance can be thus improved. In addition, when the thickness of the electric core is at least greater than 1 cm, the overall performance of the aluminum battery can be improved more obviously by the use of the physical joining (mechanical joining) of the disclosure compared to soldering. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.