Patent Description:
Battery cells are used to provide power to a wide variety of portable electronic devices, including laptop computers, tablet computers, mobile phones, personal digital assistants (PDAs), digital music players, watches, and wearable devices. A commonly used type of battery is a lithium battery, which can include a lithium-ion or a lithium-polymer battery.

Lithium batteries often include cells that are made of alternating layers of anode and cathode electrodes, with a separator disposed there-between. The layers may be packaged in an cylindrical enclosure. Anode electrodes of the cell may be electrically coupled to a wall of the enclosure where the enclosure is itself, made of a conductive material. The cathode electrodes, however, may require an electrical feedthrough to enable an electrical connection, through the enclosure, to the cathode electrodes. In addition, electrical feedthroughs must insulate the electrical connection to the cathode electrodes from the enclosure to prevent shorting of the battery cell. The enclosure enclosing the electrodes may be filled with electrolyte thereby requiring the electrical feedthrough to also provide a hermetically seal to prevent unwanted leakage or failure.

Conventional feedthroughs for cylindrical battery cells may utilize a crimping operation to attach the feedthrough to the enclosure. Such crimping operations, however, may require additional space on the enclosure to accommodate the crimp and to ensure a proper seal, thereby reducing packaging efficiency.

Relevant prior art is for example disclosed in documents <CIT> and <CIT>.

The disclosed embodiments provide for a battery cell that utilizes an overmolded glass feedthrough to prevent electrical contact or shorting of electrodes to the feedthrough. The battery cell includes a wound set of layers that include a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer. The set of layers are enclosed within a cylindrical enclosure having an opening for receiving a feedthrough. The feedthrough includes an annular channel having an outer sidewall, an inner sidewall, and a base; an insulator formed of glass; and a pin extending through the insulator. The insulator is bonded to the inner sidewall of the annular channel and a portion of the base of the annular channel. The insulator also includes an overmold portion that extends between the base of the annular channel and the set of layers. The overmold portion is configured to prevent electrical contact between the set of layers and the annular channel. The pin is electrically coupled to the set of layers to form an external battery terminal.

In some embodiments, a battery feedthrough includes an annular channel, an insulator, and a pin. The annular channel may include an outer sidewall, an inner sidewall, and a base. The insulator may be formed of glass, and bonded to the inner sidewall of the annular channel and a portion of the base of the annular channel. The insulator further includes an overmold portion that extends from the base of the annular channel. The pin is configured to form an external battery terminal.

In some embodiments, a method for manufacturing a battery cell is disclosed. The method includes inserting a set of layers within a cylindrical enclosure through an opening. The set of layers include a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer. The method also includes welding a tab extending from the set of layers to a pin, the pin electrically coupled to the set of layers to form an external battery terminal. The method further includes folding the tab within the cylindrical enclosure and disposing a feedthrough within the opening of the cylindrical enclosure. The feedthrough includes an annular channel having an outer sidewall, an inner sidewall, and a base. The feedthrough also includes an insulator formed of glass that is bonded to the inner sidewall of the annular channel and a portion of the base of the annular channel. The insulator includes an overmold portion that extends from the base of the annular channel. The overmold portion is configured to prevent electrical contact between the set of layers and the annular channel. The feedthrough also includes the pin extending through the insulator.

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.

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.

Rechargeable batteries for portable electronic devices often include cells that are made of alternating layers of anode and cathode electrodes, with a separator disposed there-between. The layers may be packaged in an enclosure and may utilize an electrical feedthrough to make an electrical connection to cathode electrodes through the enclosure. The enclosure enclosing the electrodes may be filled with electrolyte thereby requiring the feedthrough to hermetically seal the enclosure to prevent unwanted leakage or failure. In addition, electrical feedthroughs must insulate the electrical connection from the enclosure to prevent shorting of the battery cell.

Conventional feedthroughs for cylindrical battery cells may utilize a crimping operation to attach the feedthrough to the enclosure. Such crimping operations, however, require additional space on the enclosure to accommodate the crimp and to ensure a proper seal, thereby reducing packaging efficiency. Accordingly, there is a need for certain embodiments of a compact and robust feedthrough for use in small or thin cylindrical battery cells that improves packaging efficiency and increases energy capacity.

The disclosed technology addresses the foregoing limitations of conventional feedthroughs for cylindrical battery cells by utilizing a glass feedthrough that utilizes an overmold to insulate the feedthrough from the electrodes, thereby improving packaging efficiency and increasing energy capacity by eliminating the need for a crimping operation and associated components.

<FIG> illustrate views of a conventional cylindrical battery cell <NUM>. The conventional cylindrical battery cell <NUM> utilizes a crimping operation to create a crimp <NUM> at a feedthrough. The crimp <NUM> requires use of an insert <NUM> that creates a mechanical stop for the crimping operation, and when crimped, creates a seal between an enclosure of the battery cell <NUM> and the feedthrough. As shown in <FIG>, the insert <NUM> and other components associated with a successful crimping operation results in a distance H1 between a set of layers or jelly roll, and an end of the battery cell <NUM>. Specifically, in order to adequately crimp sidewalls of the enclosure to the insert <NUM>, there must be sufficient area surrounding the crimp <NUM> to allow a crimping operation to be performed.

<FIG> illustrates a cross-section view of a cylindrical battery cell <NUM> with an overmolded glass feedthrough, in accordance with various aspects of the subject technology. The battery cell <NUM> comprises a cylindrical enclosure <NUM> having a first opening <NUM>, a wound set of layers <NUM> enclosed within the cylindrical enclosure <NUM>, and a feedthrough <NUM>. The enclosure <NUM> may be formed of a rigid material, such as a metal alloy which may, for example, include stainless steel, aluminum, aluminum alloy, or other sufficiently rigid materials as would be known by a person of ordinary skill in the art. The enclosure <NUM> may have a non-corrosive coating line the interior of the enclosure <NUM> and is configured to enclose and protect one or more sets of electrodes or layers disposed within the enclosure. The enclosure <NUM> may have a cylindrical, cuboid, prism, conical, or pyramid shape. In one aspect, the enclosure <NUM> may be drawn from tube stock to form a cylinder having the first opening <NUM> and a second opening <NUM>. In other aspects, the enclosure <NUM> may have a closed end opposite the first opening <NUM>. The first opening <NUM> and/or the second opening <NUM> may each be configured to receive the feedthrough <NUM>.

The wound set of layers <NUM> may comprise at least one cathode layer with an active coating, a separator, and at least one anode layer with an active coating, as discussed below with reference to <FIG>. A tab (as shown in <FIG>) may extend from the anode and/or cathode layers, as discussed further below.

The feedthrough <NUM> may comprise an annular channel <NUM>, an insulator <NUM>, and a pin <NUM>. The feedthrough <NUM> is configured to seal the set of layers <NUM> within the enclosure <NUM> and to provide an electrical connection to the anode or cathode layer of the set of layers <NUM> via the pin <NUM>. The feedthrough <NUM> may be disposed within the first opening <NUM> and bonded, glued, welded, or coupled, to the enclosure <NUM>. As shown in <FIG>, the feedthrough <NUM> eliminates the need for a crimping operation by utilizing a bonding, gluing, welding, or coupling operation, and utilizes an overmolded insulator <NUM> to prevent inadvertent electrical contact between the annular channel <NUM> and the set of layers <NUM>. As a result, a distance H2 between the set of layers <NUM> (e.g., jelly roll) and an end of the battery cell <NUM> is reduced when compared to the conventional battery cell <NUM> of <FIG>, thereby improving packaging efficiency and increasing energy capacity by eliminating the need for a crimping operation and associated components.

<FIG> illustrates a detailed cross-section view of the cylindrical battery cell <NUM> with the overmolded glass feedthrough <NUM>, in accordance with various aspects of the subject technology. The annular channel <NUM> of the feedthrough <NUM> comprises an outer sidewall, an inner sidewall, and a base. The outer sidewall of the annular channel <NUM> contacts a corresponding sidewall of the enclosure <NUM>, and after a bonding, gluing, welding, or coupling operation, creates a hermetic seal between the feedthrough <NUM> and the enclosure <NUM>. For example, the annular channel <NUM> may be welded to the opening <NUM> of the enclosure <NUM> along a periphery by welding the outer sidewall of the annular channel <NUM> to the sidewall of the enclosure <NUM>. The annular channel <NUM> may be made of a rigid material, and may further be made of a material that is adequate for welding to the enclosure <NUM>. For example, if the enclosure <NUM> is formed of a stainless steel material, the annular channel <NUM> may also be formed of a stainless steel material to enable welding of the annular channel <NUM> and enclosure <NUM>.

The insulator <NUM> is formed of an electrically insulating material, such as glass, and includes an overmold portion <NUM> to prevent electrical contact between the cathode <NUM> or anode <NUM> of the set of layers, and the annular channel <NUM>. The insulator <NUM> may be bonded to the inner sidewall of the annular channel <NUM> and a portion of the base of the annular channel <NUM>. The insulator <NUM> is also bonded to the pin <NUM> and surrounds the pin <NUM>. The overmold portion <NUM> of the insulator <NUM> extends between the base of the annular channel <NUM> and the separator <NUM> of the set of layers. As discussed above, the overmold portion <NUM> prevents electrical contact between the set of layers and the annular channel <NUM>.

The pin <NUM> extends through the insulator <NUM> and is electrically coupled to the cathode <NUM> or anode <NUM> of the set of layers to form an external battery terminal. The pin may comprise a metal or alloy, or material that is capable of conducting electricity, such as molybdenum. In one aspect, the pin <NUM> may be spot welded to a tab <NUM> extending from the cathode <NUM> or anode <NUM> of the set of layers. The tab <NUM> may extend from the opening <NUM> to facilitate a spot welding operation to the pin <NUM>. When coupled to the tab <NUM> extending from the set of layers, electrical energy from the cathode <NUM> or anode <NUM>, for example, passes through the tab <NUM> and to the pin <NUM>, to thereby provide an external terminal for the battery cell <NUM>. After welding, the tab <NUM> may be configured to be stowed or folded within the enclosure <NUM>, proximal to the feedthrough <NUM>, and more specifically, proximal to the annular channel <NUM>. The overmold portion <NUM> of the insulator <NUM> is further configured to prevent electrical contact between the fold of the tab <NUM> and the annular channel <NUM>. For example, by extending a diameter of the overmold portion <NUM> to extend radially beyond the fold of the tab <NUM>, electrical contact between the fold of the tab <NUM> and the annular channel <NUM> is prevented.

In some aspects, the battery cell <NUM> may further comprise a second feedthrough disposed at the second opening <NUM> (as shown in <FIG>). The second opening <NUM> may be disposed opposite the first opening <NUM>. The second feedthrough may comprise the same components as the feedthrough <NUM>, which may include a second annular channel (similar to annular channel <NUM>), a second insulator (similar to insulator <NUM>), and a second pin (similar to pin <NUM>). The second feedthrough is configured to electrically couple the cathode <NUM> or anode <NUM> of the set of layers to form a second external battery terminal.

<FIG> illustrates a cross-section view of an assembled battery <NUM>, in accordance with various aspects of the subject technology. The assembled battery <NUM> includes the battery cell <NUM>, enclosure <NUM>, feedthrough <NUM>, a battery management unit <NUM>, and battery terminals <NUM>. The battery management unit <NUM> is configured to manage recharging of the battery cell <NUM>. The terminals <NUM> are configured to engage with corresponding connectors on a portable electronic device to provide power to components of the portable electronic device.

The battery cell <NUM> includes a plurality of layers <NUM> comprising a cathode with an active coating <NUM>, a separator <NUM>, and an anode with an active coating <NUM>. For example, the cathode <NUM> may be an aluminum foil coated with a lithium compound (e.g., LiCoO<NUM>, LiNCoMn, LiCoAl or LiMn<NUM>O<NUM>) and the anode <NUM> may be a copper foil coated with carbon or graphite. The separator <NUM> may include polyethylene (PE), polypropylene (PP), and/or a combination of PE and PP, such as PE/PP or PP/PE/PP. The separator <NUM> comprises a microporous membrane that also provides a "thermal shut down" mechanism. If the battery cell reaches the melting point of these materials, the pores shut down which prevents ion flow through the membrane.

The plurality of layers <NUM> may be wound to form a jelly roll structure or can be stacked to form a stacked-cell structure. The plurality of layers <NUM> are enclosed within enclosure <NUM> and immersed in an electrolyte <NUM>, 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 anode layers <NUM> of the plurality of layers <NUM> may be coupled to the enclosure <NUM> or may be coupled to a second feedthrough via a second tab (not shown) extending from the anode layers <NUM>. The cathode layers <NUM> of the plurality of layers <NUM> may be coupled to a first tab <NUM>, which may include intermediate tabs <NUM> extending from each cathode layer <NUM>. The first tab <NUM> and the second tab extend from the plurality of layers <NUM> for electrical connection to other battery cells, the battery management unit <NUM>, or other components as desired.

<FIG> illustrates a portable electronic device <NUM>, in accordance with various aspects of the subject technology. The above-described rechargeable battery <NUM> can generally be used in any type of electronic device. For example, <FIG> illustrates a portable electronic device <NUM> which includes a processor <NUM>, a memory <NUM> and a display <NUM>, which are all powered by the battery <NUM>. Portable electronic device <NUM> 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 <NUM> may correspond to a battery pack that includes one or more battery cells. Each battery cell may include a set of layers sealed in an enclosure, including a cathode with an active coating, a separator, an anode with an active coating, and utilize an electrical feedthrough that maximizes packaging efficiency and increases reliability by preventing accidental or inadvertent electrical shortage through implementation of a feedthrough <NUM> having an overmolded insulator <NUM>, as described above.

<FIG> illustrates an example method <NUM> for manufacturing a battery cell, 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 <NUM>, a set of layers are inserted within a cylindrical enclosure through an opening in the enclosure. The set of layers comprise a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer. At operation <NUM>, a tab extending from the set of layers is welded to a pin of a feedthrough. The pin is electrically coupled to the set of layers to form an external battery terminal. At operation <NUM>, the tab is folded within the cylindrical enclosure. At operation <NUM>, a feedthrough is disposed within the opening of the cylindrical enclosure. As described above, the feedthrough comprises an annular channel having an outer sidewall, an inner sidewall, and a base. The feedthrough also comprises an insulator formed of glass, the insulator bonded to the inner sidewall of the annular channel and a portion of the base of the annular channel. The insulator further comprises an overmold portion that extends from the base of the annular channel to prevent electrical contact between the set of layers and the annular channel, as well as prevent electrical contact between the tab and the annular channel. The feedthrough also comprises the pin, where the pin extends through the insulator.

At operation <NUM>, the feedthrough is welded to the cylindrical enclosure by welding the outer sidewall of the annular channel to the cylindrical enclosure along a periphery of the opening. At operation <NUM>, the cylindrical enclosure is filled with electrolyte.

The method <NUM> may further include disposing a second feedthrough within a second opening of the cylindrical enclosure. The second feedthrough may include a second annular channel comprising an outer sidewall, an inner sidewall, and a base. The second feedthrough may also comprise a second insulator formed of glass, the second insulator bonded to the inner sidewall of the second annular channel and a portion of the base of the second annular channel. The second insulator also comprises an overmold portion that extends from the base of the second annular channel to prevent electrical contact between the set of layers and the second annular channel, as well as prevent electrical contact between a second tab extending from the set of layers and the second annular channel. The second feedthrough also comprises a second pin extending through the second insulator, the second pin electrically coupled to the set of layers to form a second external battery terminal. In one aspect, the second pin may be coupled to the second tab via a welding operation, as discussed above with respect to operation <NUM>.

The method <NUM> may further include welding the outer sidewall of the second annular channel to the cylindrical enclosure along a periphery of the second opening to thereby create a hermetic seal at the second opening of the cylindrical enclosure.

Claim 1:
A method for manufacturing a battery cell, the method comprising:
inserting a set of layers within a cylindrical enclosure through a first opening, the set of layers comprising a cathode layer, an anode layer, and a separator layer disposed between the cathode layer and the anode layer;
welding a tab extending from the set of layers to a pin, the pin electrically coupled to the set of layers to form an external battery terminal;
folding the tab within the cylindrical enclosure;
disposing a feedthrough within the first opening of the cylindrical enclosure, the feedthrough comprising:
an annular channel comprising an outer sidewall, an inner sidewall, and a base;
an insulator formed of glass, the insulator bonded to the inner sidewall of the annular channel and a portion of the base of the annular channel, the insulator further comprising an overmold portion that extends from the base of the annular channel, the overmold portion configured to prevent electrical contact between the set of layers and the annular channel; and
the pin, the pin extending through the insulator; and
welding the outer sidewall of the annular channel to the cylindrical enclosure along a periphery of the first opening.