Patent Description:
When charging a rechargeable battery cell, the chemical reactions within the battery cell may cause an increase in temperature. Some types of battery cells, such as those of lithium-ion (Li-ion) batteries, may be susceptible to thermal runaway, in which the temperature increase caused by the charge cycle causes a further increase in temperature. Thermal runaway can compromise or destroy the battery cell, but also cause damage to the charger and the housing and/or device in which the battery cell is located.

As technology continues to evolve, there is a need to provide improved power sources, particularly battery cells and battery modules, for such systems that may be powered by or store their energy using battery technologies. For example, certain types of battery modules may undergo overcharge testing to determine boundaries and/or limits of the battery module and its individual battery cells. Additionally, in certain instances, for example due to changing environmental conditions or other operating conditions, battery cells may be subject to overcharging. Overcharge tests and overcharging may lead to thermal runaway. Therefore, it is recognized that a need exists for devices that may prevent or block thermal runaway.

The document <CIT> relates to a rechargeable battery that includes an electrode assembly including a first electrode, a second electrode, and a separator disposed between the first and second electrodes. The battery further includes a case housing the electrode assembly, and a cap assembly connected to the case. The cap assembly includes a first short-circuit tab electrically connected to the first electrode, a second short-circuit tab electrically connected to the second electrode, a deformable plate electrically connecting the first short circuit tab to the second short circuit tab by being transformed upon the pressure increase, and a connection member formed between the short-circuit tab and the deformable plate or formed between the short-circuit tab and the electrode assembly.

The present invention relates to an overcharge protection device cover assembly according to independent claims <NUM> and <NUM>, wherein further developments of the invention are provided in the sub-claims, respectively.

The present disclosure relates to an overcharge protection device cover assembly for use with a battery cell housing, the battery cell housing having a first terminal and a second terminal, the overcharge protection device cover assembly comprising: a first terminal pad having a first length, the first terminal pad being contactable with the first terminal of the battery cell housing; a second terminal pad having a second length that is greater than the first length, the second terminal pad being contactable with the second terminal of the battery cell housing; a reversal device that is deflectable toward the first and second terminal pads; and a conductive element between the reversal device and the first and second terminal pads.

The present disclosure also relates to an overcharge protection device cover assembly, the overcharge protection device cover assembly having a base plate including a reversal device, the reversal device being transitionable between a first configuration and a second configuration; a first terminal pad having a first length; a second terminal pad having a second length that is greater than the first length; a conductive element between the reversal device and the first and second terminal pads; and a spacer plate between the base plate and the first terminal pad. The first terminal pad is a first distance from the base plate when the reversal device is in the first configuration and the second terminal pad is a second distance from the base plate when the reversal device is in the first configuration, the first distance being greater than the second distance.

The present disclosure also relates to a battery cell having a battery cell housing, the battery cell housing including first terminal and a second terminal; and an overcharge protection device cover assembly affixable to the battery cell housing. The overcharge protection device cover assembly includes a base plate coupled to the battery cell housing between the first and second terminals, the base plate having a reversal device that is transitionable between a first configuration and a second configuration; a first terminal pad having a first end portion, a second end portion opposite the first end portion, and a first length, the first end portion of the first terminal pad being in contact with the first terminal; a second terminal pad having a first end portion, a second end portion opposite the first end portion, and a second length that is greater than the first length, the first end portion of the second terminal pad being in contact with the second terminal. The battery cell also includes a conductive element between the reversal device and the first and second terminal pads; and a spacer plate between the base plate and the first terminal pad, the first terminal pad being a first distance from the base plate when the reversal device is in the first configuration and the second terminal pad being a second distance from the base plate when the reversal device is in the first configuration, the first distance being greater than the second distance.

Referring now to the drawings, an overcharge protection device cover assembly <NUM> constructed in accordance with the principles of the present disclosure is shown in <FIG>. The overcharge protection device cover assembly <NUM> is shown coupled to a battery cell housing <NUM> in <FIG>. The overcharge protection device cover assembly <NUM> and the battery cell housing <NUM> are collectively referred to herein as a battery cell <NUM>. In one embodiment, the overcharge protection device cover assembly <NUM> includes a base plate <NUM> configured to be in contact with, adjacent, or coupled to the battery cell housing <NUM>, a first (or negative) terminal pad <NUM> in contact with a first (or negative) terminal <NUM>, a second (or positive) terminal pad <NUM> in contact with a second (or positive) terminal <NUM>, a reversal device <NUM> (reversal device <NUM> is not visible in <FIG>), and a conductive element <NUM> between the reversal device <NUM> and the first <NUM> and second <NUM> terminal pads. In some embodiments the conductive element <NUM> is in the shape of disk, but other shapes can be used depending in design requirements, e.g., rectangle, square, etc. In some embodiments, the reversal device <NUM> is shaped in the form of a disk, but other shapes can be implemented depending on design requirements. In some embodiments, the reversal device is formed of a metal or polymer that allows the inner portion of the deflection device <NUM> to deflect from a first position to a second position, the second position allowing activation of the overcharging protection by electrically short-circuiting the battery terminals. In one embodiment, the overcharge protection device cover assembly <NUM> is configured to be coupled to a surface of the battery cell housing <NUM> between the first <NUM> and second <NUM> terminals. In one embodiment, the reversal device <NUM> is integrated with, defined by, or coupled to the base plate <NUM>, and at least a portion of the reversal device <NUM> is deflectable. Further, the reversal device <NUM> may be composed of a more flexible material or may be thinner than the base plate <NUM>, such that internal pressure within the battery cell housing <NUM> is able to deflect the reversal device <NUM> but not the base plate <NUM>. The conductive element <NUM> is movable, at least in a linear direction that is orthogonal to, or at least substantially orthogonal to, the base plate <NUM>. However, it will be understood that the first terminal pad <NUM> and first terminal <NUM> may instead be a positive terminal pad and positive terminal, and the second terminal pad <NUM> and second terminal <NUM> may instead be a negative terminal pad and negative terminal. In some embodiments, the overcharge protection device cover assembly <NUM> also includes a vent aperture <NUM> configured to be aligned with a vent (not shown) in the battery cell housing <NUM> when the overcharge protection device cover assembly <NUM> is coupled to the battery cell housing <NUM>. In some embodiments, the overcharge protection device cover assembly <NUM> also includes an electrolyte aperture <NUM> to enable the addition of electrolyte to battery cell within the battery cell housing <NUM>.

The overcharge protection device cover assembly <NUM> includes asymmetric first <NUM> and second <NUM> terminal pads. In one embodiment, the second terminal pad <NUM> has a length LSP that is less than a length LFP of the first terminal pad <NUM> (for example, as shown in <FIG>). Alternatively, the first terminal pad <NUM> may have a length LFP that is less than the length LSP of the second terminal pad <NUM>. Further, the first <NUM> and second <NUM> terminal pads are in contact with or coupled to the first <NUM> and second <NUM> terminals, respectively. In one embodiment, the first terminal pad <NUM> includes a first end portion <NUM> that is in contact with or coupled to the first terminal <NUM> and a second end portion <NUM> opposite the first end portion <NUM>. The second end portion <NUM> is not coupled to any other component of the overcharge protection device cover assembly <NUM>, and is freely movable relative to the base plate <NUM> in a linear direction that is crosswise (e.g., orthogonal) to the base plate <NUM>. Thus, the first end portion <NUM> of the first terminal pad <NUM> includes a pivot point <NUM> at the first terminal <NUM> about which the first terminal pad <NUM> may move. Likewise, the second terminal pad <NUM> includes a first end portion <NUM> that is in contact with or coupled to the second terminal <NUM> and a second end portion <NUM> opposite the first end portion <NUM>. The second end portion <NUM> is not coupled to any other component of the overcharge protection device cover assembly <NUM>, and is freely movable relative to the base plate <NUM> in a linear direction that is orthogonal to, or at least substantially orthogonal to, the base plate <NUM>. Thus, the first end portion <NUM> of the second terminal pad <NUM> includes a pivot point <NUM> at the second terminal <NUM> about which the second terminal pad <NUM> may move. As such, the overcharge protection device cover assembly <NUM> is transitionable from a first configuration (for example, as in a normal operating condition, as shown in <FIG> and <FIG>) to a second configuration (for example, as in an electrical short circuit condition, as shown in <FIG> and <FIG>). Although the second end portions <NUM>, <NUM> are disclosed herein as being movable in a linear direction relative to the base plate <NUM>, it will be understood that the second end portions <NUM>, <NUM> will move about their corresponding pivot points in an arc, albeit a small arc.

Referring now to <FIG>, a first embodiment of an overcharge protection device cover assembly <NUM> is shown. The reversal device <NUM> is deflectable or transitionable between a first (inverted) configuration and a second (everted) configuration, and transition of the reversal device <NUM> between the first and second configurations causes the overcharge protection device cover assembly <NUM> as a whole to transition between the first and second configurations. In a normal operating condition (e.g., before the reversal device <NUM> is deflected from an increase in internal pressure within the battery cell), as shown in <FIG>, the first <NUM> and second <NUM> terminal pads are uneven in height, although they each lie in a plane that is parallel to, or at least substantially parallel to, the plane in which the base plate <NUM> lies. The first terminal pad <NUM> includes a first (or upper) surface <NUM> and a second (or lower) surface <NUM> opposite the first surface <NUM>. Likewise, the second terminal pad <NUM> includes a first (or upper) surface <NUM> and a second (or lower) surface <NUM> opposite the first surface <NUM>. When the overcharge protection device cover assembly <NUM> is in a normal operating condition (for example, as shown in <FIG>), the first surface <NUM> of the first terminal pad <NUM> and the first surface <NUM> of the second terminal pad <NUM> are located at different distances from the base plate <NUM>, the reversal device <NUM>, and the conductive element <NUM>. The second surface <NUM> of the first terminal pad <NUM> and the second surface <NUM> of the second terminal pad <NUM> are also located at different distances from the base plate <NUM>, the reversal device <NUM>, and the conductive element <NUM>. For example, the second surface <NUM> of the first terminal pad <NUM> is located a first distance DFP from the base plate <NUM> and the second surface <NUM> of the second terminal pad <NUM> is located a second distance DSP from the base plate <NUM>. To accomplish this, the overcharge protection device cover assembly <NUM> also includes a spacer plate <NUM> between the base plate <NUM> and the first terminal pad <NUM>, thereby positioning the first terminal pad <NUM> at a greater distance from the base plate <NUM>, the reversal device <NUM>, and the conductive element <NUM>. In one embodiment, the spacer plate <NUM> lies in a plane that is parallel to, or at least substantially parallel to, the base plate <NUM>. The cross-sectional view of <FIG> shows that the first terminal pad <NUM> and the second terminal pad <NUM> are not coplanar when the overcharge protection device cover assembly <NUM> is in the normal operating condition.

Further, each terminal pad <NUM>, <NUM> has a working thickness T. The working thickness T is the thickness of at least the second end portion <NUM>, <NUM> of each terminal pad <NUM>, <NUM> proximate the conductive element <NUM>, at the location with which the conductive element <NUM> comes into contact with each terminal pad <NUM>, <NUM> when the overcharge protection device cover assembly <NUM> is in the short condition. In the embodiment shown in <FIG>, the working thickness T of each terminal pad <NUM>, <NUM> is the same.

In an electrical short circuit condition (that is, after the reversal device <NUM> is deflected from an increase in internal pressure within the battery cell), as shown in <FIG>, deflection of the reversal device <NUM> exerts a force against the conductive element <NUM>, moving the conductive element <NUM> toward and into contact with the second surface <NUM> of the first terminal pad <NUM> and then the second surface <NUM> of the second terminal pad <NUM>. As the second terminal pad <NUM> is located closer to the base plate <NUM>, the reversal device <NUM>, and the conductive element <NUM> (due to the lack of a spacer plate <NUM> between the base plate <NUM> and the second terminal pad <NUM>), deflection of the reversal device <NUM> will cause the conductive element <NUM> to come into contact with the second surface <NUM> of the second terminal pad <NUM> before the second surface <NUM> of the first terminal pad <NUM>. Additionally, as the second terminal pad <NUM> has a greater length LSP than the length LFP of the first terminal pad <NUM>, the second terminal pad <NUM> is more easily pivoted at its pivot point <NUM> and moved linearly until at least a portion of the second end portion <NUM> of the second terminal pad <NUM> is at the same distance from the base plate <NUM> as at least a portion of the second end portion <NUM> of the first terminal pad <NUM> (for example, as shown in <FIG>). In one embodiment, at least a portion of the second surface <NUM> of the first terminal pad <NUM> and at least a portion of the second surface <NUM> of the second terminal pad <NUM> are aligned, as they are both in contact with the conductive element <NUM> when the overcharge protection device cover assembly <NUM> is in the electrical short circuit condition. In the electrical short circuit condition, the conductive element <NUM> is in contact with both the first terminal pad <NUM> and the second terminal pad <NUM>, establishing a short circuit to prevent the battery cell from overcharging. When the conductive element <NUM> is in contact with both terminal pads <NUM>, <NUM>, the second terminal pad <NUM> may be pivoted about its pivot point <NUM>, thereby creating an angle between the plane in which the base plate <NUM> lies and the plane in which the second terminal pad <NUM> lies. This angle may be very small, such as approximately <NUM>° or less in some embodiments. Further, as the second end portion <NUM> of the first terminal pad <NUM> and second end portion <NUM> of the second terminal pad <NUM> are aligned when the overcharge protection device cover assembly <NUM> is in the electrical short circuit condition and reversal device <NUM> is fully deflected (everted), with the conductive element <NUM> is at the its furthest distance from the base plate <NUM>, rather than when the overcharge protection device cover assembly <NUM> is in the normal operating condition, much less precision is required during manufacture and assembly. Further, the configuration of the first <NUM> and second <NUM> terminal pads ensures the conductive element <NUM> will reliably contact both terminal pads <NUM>, <NUM> to establish a short circuit when overcharge protection is needed. It will be understood that although <FIG> shows that the terminal pads <NUM>, <NUM> are not coplanar when the overcharge protection device cover assembly <NUM> is in the normal operating condition, and that at least a portion of each of the first surfaces <NUM>, <NUM> of the terminal pads <NUM>, <NUM> are aligned when the overcharge protection device cover assembly <NUM> is in the electrical short circuit condition, the terminal pads <NUM>, <NUM> may be configured differently that that shown, provided the conductive element <NUM> contacts one of the terminal pads <NUM>, <NUM> before the other when the reversal device <NUM> deflects to move the conductive element <NUM> toward the terminal pads <NUM>, <NUM>.

Referring now to <FIG>, a second embodiment of an overcharge protection device cover assembly <NUM> is shown. The second embodiment of the overcharge protection device cover assembly <NUM> of <FIG> is similar to the first embodiment of the overcharge protection device cover assembly <NUM> of <FIG> and, therefore, the same references numbers are used. However, unlike the first embodiment of the overcharge protection device cover assembly <NUM>, the second embodiment of the overcharge protection device cover assembly <NUM> includes first <NUM> and second <NUM> terminal pads with different working thicknesses TFP and TSP at the second end portion <NUM> of the first terminal pad <NUM> proximate the conductive element <NUM> and at the second end portion <NUM> of the second terminal pad <NUM> proximate the conductive element <NUM>. In one embodiment, the second terminal pad <NUM> has a working thickness TSP that is greater than the working thickness TFP of the first terminal pad <NUM>.

When the overcharge protection device cover assembly <NUM> is in the normal operating condition, the first <NUM> and second <NUM> terminal pads are uneven in height. That is, the first surface <NUM> of the first terminal pad <NUM> and the first surface <NUM> of the second terminal pad <NUM> are located at different distances from the base plate <NUM>, the reversal device <NUM>, and the conductive element <NUM>. The second surface <NUM> of the first terminal pad <NUM> and the second surface <NUM> of the second terminal pad <NUM> are also located at different distances from the base plate <NUM>, the reversal device <NUM>, and the conductive element <NUM>. For example, the second surface <NUM> of the first terminal pad <NUM> is located a first distance DFP from the base plate <NUM> and the second surface <NUM> of the second terminal pad <NUM> is located a second distance DSP from the base plate <NUM>. To accomplish this, the overcharge protection device cover assembly <NUM> includes s spacer plate <NUM> between the base plate <NUM> and the first terminal pad <NUM>. The cross-sectional view of <FIG> shows that the first terminal pad <NUM> and the second terminal pad <NUM> are not coplanar when the overcharge protection device cover assembly <NUM> is in the normal operating condition.

In the electrical short circuit condition, as shown in <FIG>, deflection of the reversal device <NUM> exerts a force against the conductive element <NUM>, moving the conductive element <NUM> toward and into contact with the second surface <NUM> of the first terminal pad <NUM> and the second surface <NUM> of the second terminal pad <NUM>. As the second terminal pad <NUM> is located closer to the base plate <NUM>, the reversal device <NUM>, and the conductive element <NUM> (due to the lack of a spacer plate <NUM> between the base plate <NUM> and the second terminal pad <NUM>), deflection of the reversal device <NUM> will case the conductive element <NUM> to come into contact with the second surface <NUM> of the second terminal pad <NUM> before the second surface <NUM> of the first terminal pad <NUM>. Additionally, as the second terminal pad <NUM> has a greater length LSP than the length LFP of the first terminal pad <NUM>, the second terminal pad <NUM> is more easily pivoted at its pivot point <NUM> and moved linearly until at least a portion of the second end portion <NUM> of the second terminal pad <NUM> is at the same distance from the base plate <NUM> as at least a portion of the second end portion <NUM> of the first terminal pad <NUM> (for example, as shown in <FIG>). In one embodiment, at least a portion of the second surface <NUM> of the first terminal pad <NUM> and at least a portion of the second surface <NUM> of the second terminal pad <NUM> are aligned, as they are both in contact with the conductive element <NUM> when the overcharge protection device cover assembly <NUM> is in the electrical short circuit condition. In the electrical short circuit condition, the conductive element <NUM> is in contact with both the first terminal pad <NUM> and the second terminal pad <NUM>, establishing a short circuit to prevent the battery cell from overcharging. When the conductive element <NUM> is in contact with both terminal pads <NUM>, <NUM>, the second terminal pad <NUM> may be pivoted about its pivot point <NUM>. Further, as the second end portion <NUM> of the first terminal pad <NUM> and second end portion <NUM> of the second terminal pad <NUM> are aligned when the overcharge protection device cover assembly <NUM> is in the electrical short circuit condition and reversal device <NUM> is fully deflected (everted), with the conductive element <NUM> is at the its furthest distance from the base plate <NUM>, rather than when the overcharge protection device cover assembly <NUM> is in the normal operating condition, much less precision is required during manufacture and assembly. Further, the configuration of the first <NUM> and second <NUM> terminal pads ensures the conductive element <NUM> will reliably contact both terminal pads <NUM>, <NUM> to establish a short circuit when overcharge protection is needed. It will be understood that although <FIG> shows that the terminal pads <NUM>, <NUM> are not coplanar when the overcharge protection device cover assembly <NUM> is in the normal operating condition, and that at least a portion of each of the first surfaces <NUM>, <NUM> of the terminal pads <NUM>, <NUM> are aligned when the overcharge protection device cover assembly <NUM> is in the electrical short circuit condition, the terminal pads <NUM>, <NUM> may be configured differently that that shown, provided the conductive element <NUM> contacts one of the terminal pads <NUM>, <NUM> before the other when the reversal device <NUM> deflects to move the conductive element <NUM> toward the terminal pads <NUM>, <NUM>.

An overcharge protection device cover assembly constructed in accordance with the principles of the present disclosure provides certain benefits over currently known overcharge protection devices. For example, the overcharge protection device cover assemblies <NUM> disclosed herein each include terminal pads <NUM>, <NUM> of unequal heights from the base plate <NUM> and conductive element <NUM> when the overcharge protection device cover assembly <NUM> is in a normal operating condition. This reduces manufacturing cost and complexity, as the terminal pads <NUM>, <NUM> do not require precise alignment during assembly. Further, the terminal pads <NUM>, <NUM> also are of unequal lengths (that is, the second terminal pads <NUM> are longer than the first terminal pads <NUM>) to allow the longer terminal pad <NUM> to pivot more easily on its pivot point <NUM>. During an electrical short circuit condition, deflection of the reversal device <NUM> causes the conductive element <NUM> to contact the longer second terminal pad <NUM> before the shorter first terminal pad <NUM>. When the reversal device <NUM> is fully deflected and the conductive element <NUM> has been moved to its farthest position from the base plate <NUM>, the first <NUM> and second <NUM> terminal pads are aligned. This configuration ensures that the conductive element <NUM> will reliably contact both the first <NUM> and second <NUM> terminal pads to establish a short circuit when overcharge protection is needed. In contrast, prior art overcharge protection devices require precisely aligned terminal pads for reliable overcharge protection, which increases manufacturing cost and complexity.

In one embodiment, an overcharge protection device cover assembly <NUM> for use with a battery cell housing <NUM> having first terminal <NUM> and a second terminal <NUM> includes a first terminal pad <NUM> having a first length LFP, the first terminal pad <NUM> being contactable with the first terminal <NUM> of the battery cell housing <NUM>, and a second terminal pad <NUM> having a second length LSP that is greater than the first length LFP, the second terminal pad <NUM> being contactable with the second terminal <NUM> of the battery cell housing <NUM>. The overcharge protection device cover assembly <NUM> also includes a reversal device <NUM> that is deflectable toward the first <NUM> and second <NUM> terminal pads and a conductive element <NUM> between the reversal device <NUM> and the first <NUM> and second <NUM> terminal pads.

In one aspect of the embodiment, the first terminal pad <NUM> includes a first end portion <NUM> and a second end portion <NUM> opposite the first end portion <NUM> and the second terminal pad <NUM> includes a first end portion <NUM> and a second end portion <NUM> opposite the first end portion <NUM>, the first end portion <NUM> of the first terminal pad <NUM> being contactable with the first terminal <NUM> of the battery cell housing <NUM> and the first end portion <NUM> of the second terminal pad <NUM> being contactable with the second terminal <NUM> of the battery cell housing <NUM>. In one aspect of the embodiment, the first terminal pad <NUM> includes a first pivot point <NUM> about which the first terminal pad <NUM> is pivotable and the second terminal pad <NUM> includes a second pivot point <NUM> about which the second terminal pad <NUM> is pivotable. In one aspect of the embodiment, the overcharge protection device cover assembly <NUM> further includes a base plate <NUM>, the base plate <NUM> defining the reversal device <NUM>, and a spacer plate <NUM> between the base plate <NUM> and the first terminal pad <NUM>. In one aspect of the embodiment, the second end portion <NUM> of the first terminal pad <NUM> and the second end portion <NUM> of the second terminal pad <NUM> are each movable in a direction that is orthogonal to a plant of the base plate <NUM>.

In one aspect of the embodiment, the reversal device <NUM> is transitionable between a first configuration and a second configuration. In one aspect of the embodiment, the first terminal pad <NUM> is a first distance from the reversal device <NUM> when the reversal device <NUM> is in the first configuration and the second terminal pad <NUM> is a second distance from the reversal device <NUM> when the reversal device <NUM> is in the first configuration, the first distance being greater than the second distance.

In one aspect of the embodiment, each of the first and second terminal pads includes a working thickness T, the working thickness T of the first terminal pad and the working thickness T of the second terminal pad being the same.

In one aspect of the embodiment, the first terminal pad <NUM> includes a first working thickness TFP and the second terminal pad <NUM> includes a second working thickness TSP that is greater than the first working thickness TFP.

In one aspect of the embodiment, transition of the reversal device <NUM> from the first configuration to the second configuration causes the conductive element <NUM> to contact the second terminal pad <NUM> before the conductive element <NUM> contacts the first terminal pad <NUM>.

In one embodiment, an overcharge protection device cover assembly <NUM> includes a base plate <NUM> including a reversal device <NUM>, the reversal device <NUM> being transitionable between a first configuration and a second configuration, a first terminal pad <NUM> having a first length LFP, a second terminal pad <NUM> having a second length LSP that is greater than the first length LFP, a conductive element <NUM> between the reversal device <NUM> and the first <NUM> and second <NUM> terminal pads, and a spacer plate <NUM> between the base plate <NUM> and the first terminal pad <NUM>. The first terminal pad <NUM> is a first distance from the base plate <NUM> when the reversal device <NUM> is in the first configuration and the second terminal pad <NUM> is a second distance from the base plate <NUM> when the reversal device <NUM> is in the first configuration, the first distance being greater than the second distance.

In one embodiment, a battery cell <NUM> includes a battery cell housing <NUM>, the battery cell housing <NUM> including first terminal <NUM> and a second terminal <NUM>, and an overcharge protection device cover assembly <NUM> affixable to the battery cell housing <NUM>. The overcharge protection device cover assembly <NUM> includes: a base plate <NUM> coupled to the battery cell housing <NUM> between the first <NUM> and second <NUM> terminals, the base plate <NUM> having a reversal device <NUM> that is transitionable between a first configuration and a second configuration; a first terminal pad <NUM> having a first end portion <NUM>, a second end portion <NUM> opposite the first end portion <NUM>, and a first length LFP, the first end portion <NUM> of the first terminal pad <NUM> being in contact with the first terminal <NUM>; a second terminal pad <NUM> having a first end portion <NUM>, a second end portion <NUM> opposite the first end portion <NUM>, and a second length LSP that is greater than the second length LFP, the first end portion <NUM> of the second terminal pad <NUM> being in contact with the second terminal <NUM>; a conductive element <NUM> between the reversal device <NUM> and the first <NUM> and second <NUM> terminal pads; and a spacer plate <NUM> between the base plate <NUM> and the first terminal pad <NUM>. The first terminal pad <NUM> is a first distance from the base plate <NUM> when the reversal device <NUM> is in the first configuration and the second terminal pad <NUM> is a second distance from the base plate <NUM> when the reversal device <NUM> is in the first configuration, the first distance being greater than the second distance.

In one aspect of the embodiment, the second end portion of each of the first and second terminal pads includes a working thickness T, the working thickness T of the second end portion of each of the first terminal pad and the working thickness T of the second terminal pad being the same.

In one aspect of the embodiment, the second end portion of the first terminal pad <NUM> has a first working thickness TFP and the second end portion of the second terminal pad <NUM> has a second working thickness TSP that is greater than the first working thickness TFP.

In one aspect of the embodiment, the conductive element <NUM> is in contact with the first <NUM> and second <NUM> terminal pads when the conductive element <NUM> is in the second configuration. In one aspect of the embodiment, a short circuit is established in the battery cell <NUM> when the conductive element <NUM> is in the second configuration.

Claim 1:
An overcharge protection device cover assembly (<NUM>) for use with a battery cell housing, the battery cell housing (<NUM>) having a first terminal (<NUM>) and a second terminal (<NUM>), the overcharge protection device cover assembly (<NUM>) comprising:
- a first terminal pad (<NUM>) having a first length (LFP), the first terminal pad (<NUM>) being contactable with the first terminal (<NUM>) of the battery cell housing (<NUM>);
- a second terminal pad (<NUM>) having a second length (LSP) that is greater than the first length (LFP), the second terminal pad (<NUM>) being contactable with the second terminal (<NUM>) of the battery cell housing (<NUM>);
- a reversal device (<NUM>) that is deflectable toward the first and second terminal pads (<NUM>, <NUM>); and
- a conductive element (<NUM>) between the reversal device (<NUM>) and the first and second terminal pads (<NUM>, <NUM>),
wherein the reversal device (<NUM>) is configured to transition between a first configuration and a second configuration, wherein the first terminal pad (<NUM>) is a first distance (DFP) from the reversal device (<NUM>) when the reversal device (<NUM>) is in the first configuration and the second terminal pad (<NUM>) is a second distance (DSP) from the reversal device (<NUM>) when the reversal device (<NUM>) is in the first configuration, the first distance (DFP) being greater than the second distance (DSP),
wherein transition of the reversal device (<NUM>) from the first configuration to the second configuration causes the conductive element (<NUM>) to contact the second terminal pad (<NUM>) before the conductive element (<NUM>) contacts the first terminal pad (<NUM>).