Patent Application
20240405351
The present disclosure relates to a battery cell with a reversible, multiple-use vent valve for mitigation of internal cell pressure.
Electro-chemical battery cells may be broadly classified into primary and secondary batteries. Primary batteries, also referred to as disposable batteries, are intended to be used until depleted, after which they are simply replaced with new batteries. Secondary batteries, more commonly referred to as rechargeable batteries, employ specific chemistries permitting such batteries to be repeatedly recharged and reused, therefore offering economic, environmental and ease-of-use benefits compared to disposable batteries. Electro-chemical batteries may be used to power such diverse items as toys, consumer electronics, and motor vehicles.
An electro-chemical battery includes an anode, i.e., an electrode through which conventional electrical current enters the polarized battery, and a cathode, i.e., an electrode through which electrical current leaves the polarized battery. The anode and cathode electrodes are typically configured as wires or plates, where the anode is the electrode having excess positive charge. Generally, current flow is from cathode to anode via an electrical path external to the battery (with electrons moving in the opposite direction), regardless of the cell type and its operating mode. In secondary cells, cathode polarity with respect to the anode may be positive or negative depending on how the battery is being operated. The electrodes of an electro-chemical battery are typically immersed in an electrolyte that conducts ions as the battery charges or discharges and then sealed in a cell container.
Electro-chemical battery cell containers come in various sizes and shapes depending on energy and power requirements, as well as compartments in which the cell will be housed. Cylindrical, prismatic, and pouch cells containers are widely used, although cylindrical cells are more common. Cylindrical and prismatic battery cells include integrated gas vents to mitigate internal pressures and uncontrolled release of cell electrolyte. Higher cell pressures may result from overcharging due to a faulty charger, external or internal cell shorting, exposure to excessive heat, aging, etc. Generally, the vent is designed to rupture when the internal pressure reaches a critical value. In conventional battery cell designs, the vent is integrated into a battery cell cap plate creating a single-use assembly.
A battery cell includes a cathode element, an anode element, and an electrolyte disposed in contact with each of the cathode and anode elements. The battery cell also includes a battery cell case constructed from a rigid material and defining an internal chamber configured to house each of the cathode element, the anode element, and the electrolyte. The battery cell case defines at least one aperture configured to provide a gas path between the internal chamber and an external environment. The battery cell additionally includes a reversible, multiple-use valve assembly mounted to the battery cell case and configured to selectively open a fluid flow through the at least one aperture to relieve a gas pressure within the internal chamber exceeding a predetermined pressure threshold.
The battery cell case may be either cylindrical or prismatic.
The valve assembly may include at least one cantilever arm pivotably mounted to the case.
Each cantilever arm may be an elastic element constructed from a rigid material.
The rigid material may be one of spring steel, aluminum, engineered plastic, and ceramic.
The valve assembly may additionally include a valve tip connected to each cantilever arm and configured to selectively open and close the respective aperture.
Each valve tip may include at least a portion thereof constructed from a material configured to withstand temperatures up to 200 degrees Celsius and be chemically resistant to the electrolyte.
The material of at least a portion of each valve tip may be an elastomer.
The valve assembly may include multiple cantilever arms connected at a common attachment point on the battery cell case.
Each cantilever arm may include an adjustable pivot point configured to select the pressure threshold at which the valve assembly opens the corresponding aperture.
Each valve assembly may be additionally configured to open the respective aperture to fill or refill the battery cell case with electrolyte.
The valve assembly may be a wafer check valve spring-loaded against the battery cell case.
The above features and advantages, and other features and advantages of the present disclosure, will be readily apparent from the following detailed description of the embodiment(s) and best mode(s) for carrying out the described disclosure when taken in connection with the accompanying drawings and appended claims.
Those having ordinary skill in the art will recognize that terms such as “above”, “below”, “upward”, “downward”, “top”, “bottom”, “left”, “right”, etc., are used descriptively for the figures, and do not represent limitations on the scope of the disclosure, as defined by the appended claims. Furthermore, the teachings may be described herein in terms of functional and/or logical block components and/or various processing steps. It should be realized that such block components may be comprised of a number of hardware, software, and/or firmware components configured to perform the specified functions.
Referring to the figures, two exemplary embodiments of a battery cell are depicted. Specifically,
The cylindrical battery cell 10A and the prismatic battery cell 10B generally have similar internal components. As shown schematically in a cut-away state in
A rectangular prismatic battery cell 10B is also shown schematically in a cut-away state in
Generally, cylindrical and prismatic battery cells are designed and assembled to maintain physical integrity and reliable performance under a variety of external and internal stresses, such as due to vibration and temperature fluctuations. However, during specific situations resulting, for example, from overcharging, external or internal cell shorting, exposure to excessive heat, battery cells may generate excess gases leading to build-up of internal pressure. To prevent an uncontrolled rupture of the respective cell case, cylindrical and prismatic battery cells typically employ non-reversible, i.e., one-time use, vent(s) providing a controlled release of excess pressure. Such non-reversible vents are generally configured as integrated, e.g., preformed and/or welded, non-active covers. The non-reversible vents are designed to break or fracture under excess internal pressure along predetermined boundaries and thereby generate an opening in the respective cell case to exhaust the generated gases into a battery module/pack enclosure or to the ambient. Once such a non-reversible vent is fractured, thereby creating an opening in the battery case to relieve the gas pressure, the battery cell is typically beyond repair and is discarded.
As shown in
Specifically, the valve assembly 28 is designed and constructed to relieve gas pressure within the internal chamber 18 exceeding a predetermined pressure threshold Pt. The pressure threshold Pt may be approximately 0.1-10,000 Pa. In such capacity, the valve assembly 28 is configured to operate as a gas pressure release device. Following the release of excess pressure from the internal chamber 18, the valve assembly 28 is configured to return to its initial position where it seals the aperture(s) 22 in the battery cell case 16. Accordingly, the valve assembly 28 operating with the aperture 22 is intended to facilitate non-destructive venting of the battery cell 10A. 10B, permitting the corresponding cell case 16 and the vale assembly to be reused following a gas discharge event.
With continued reference to
As shown in
Alternatively, each valve assembly 28 may be configured as a wafer check valve generally shown in
Each valve assembly 28 may be additionally employed to open the respective aperture 22 to fill the battery cell case 16 with the electrolyte 12-3, such as during initial assembly of the cylindrical cell 10A or the prismatic battery cell 10B or refill the battery cell case following some of the electrolyte having escaped with the vented gases. Accordingly, in such capacity, the valve assembly 28 is configured to operate as a fluid fill and/or refill device. Following each instance the aperture(s) 22 in the battery cell case 16 is opened by the valve assembly 28, the valve assembly returns to its default closed position. The valve assembly 28 may therefore be a reversible, dual-purpose, multiple-use device facilitating convenient electrolyte fill of the battery cell, as well as permitting the battery cell case 16 to be reused, rather than discarded or recycled, following a gas venting event.
The detailed description and the drawings or figures are supportive and descriptive of the disclosure, but the scope of the disclosure is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claimed disclosure have been described in detail, various alternative designs and embodiments exist for practicing the disclosure defined in the appended claims. Furthermore, the embodiments shown in the drawings or the characteristics of various embodiments mentioned in the present description are not necessarily to be understood as embodiments independent of each other. Rather, it is possible that each of the characteristics described in one of the examples of an embodiment may be combined with one or a plurality of other desired characteristics from other embodiments, resulting in other embodiments not described in words or by reference to the drawings. Accordingly, such other embodiments fall within the framework of the scope of the appended claims.
