The present invention relates to leak detection, and more particularly, to wireless battery leak detection.
Wireless leak detection uses on-battery cell chips to report leaks in individual cells to the battery management unit (BMU) to prevent catastrophic short circuits and fires.
However, batteries do not have the capability to detect dangerous leaks in cells without cumbersome and unreliable chemical vapor detection systems that cannot pinpoint the leak location for remediation, isolation, or cleanup. This technology is needed as flammable and corrosive electrolytes that leak out of battery cells can create an atmosphere that can ignite with a spark or pose a personnel hazard, in addition to damaging the powered device. These leaks can cause a catastrophic fires in applications such as electric vehicles, personal electronics, and medical devices. In addition, the electrolyte can react with water to form corrosive or toxic conditions which can otherwise harm human technicians or users.
Existing leak detection systems rely on an analysis of electrolyte gasses or optical changes in materials, or even direct measurement impedance at the location of the suspected leak, in order to detect the leak. For example, leaks have traditionally been detected through mass changes in individual batteries, an approach that requires removal of cells from a battery, and vapor detection systems collecting from all over a battery but cannot pinpoint a location on a leaking cell and cannot identify which cell is leaking. These approaches typically have poor sensitivity, with optical or electrical measurements only able to detect large leaks without localization.
Detection of leaks in batteries may prevent serious safety issues from battery leaks in many human centered battery applications such as electric vehicles, personal electronics, aircraft, and medical devices. Accordingly, an improved wireless battery leak detection system and method is needed.
Certain embodiments of the present invention may provide solutions to the problems and needs in the art that have not yet been fully identified, appreciated, or solved by current battery leak detection technologies. For example, some embodiments of the present invention pertain to a leak detection system and/or method using wireless and remote detection and communication. A wireless leak detection system uses wireless communication to replace bulky harness wires and sensor wires in batteries, and can be localized at critical points in the cells as to where leaks can occur. A system employing the wireless leak detection has cell leads, measurement circuits, and communication capability built onto the cell wrapper or location, and includes a small measurement and control chip. In wireless leak detection, electrical leads are made utilizing sensor leads encompassing, adjacent to, or on locations where leaks may occur allowing for localized leak detection. A control chip at or adjacent to the location of the sensor may monitor the cell sensor for leaking electrolytes, and may wirelessly report a leaking cell back to the BMU. The BMU may then mitigate the leak through isolating the battery module, and/or alert the user to replace the cell or other remediation processes.
In one embodiment, an apparatus for detecting leaks in a battery includes a plurality of cells, each which include a pair of conductive leads bracketing a polymer seal, and a wireless measurement and communication chip (“chip”) configured to perform capacitive measurement, showing a change in capacitance when bridged by ionically conductive species or when a wick is suffused with an electrolyte.
In another embodiment, a method for determining a leak detection threshold in a battery includes generating, by a measurement chip or battery management unit (BMU), a capacitance detection limit CL, wherein the capacitance detection limit CL is based on a prior calibration of a sensor on a battery cell. The method also includes updating, by the BMU, a test schedule and/or frequency schedule received by the chip on the cell. The method further includes waking, or changing a state of, the chip from a “sleep mode” to a “awaken mode” to perform measurements on the battery cell, returning or changing the state of the chip from the “awaken mode” to the “sleep mode” after performing the measurement on the battery cell.
In order that the advantages of certain embodiments of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. While it should be understood that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:
Some embodiments pertain to detecting leaks in batteries using highly localized detection sensors, wireless communication, and signal filtering algorithms. For example, battery cells typically have one or more seals that may leak electrolytes during its life or other locations where leaks are likely to occur based on the application. In some embodiments, the system and/or method measures the capacitance across the seal by a sensor comprising of two or more conductive leads that are bridged by a material that may be wetted by the ionically conductive electrolyte. The measurement in the absence of a leak is the baseline capacitance between the leads, but in the presence of a leak, the measured signal demonstrates characteristic changes indicative of a leak. This can be seen in
For this detection, a pair of circular conductive leads-negative conductive lead 110 and positive conductive lead 112—are configured to bracket crimp seal 108. For purposes explanation, negative conductive lead 110 and positive conductive lead 112 will be now referred to as leads 110 and 112, respectively. Leads 110 and 112 are connected to a wireless measurement and communication chip (“chip”) 104, and are contained in or on a selected polymer 106, or other material. Other material may be defined as natural fibers such as felt or paper, polymer meshes, metals, oxides, natural materials or resins.
In some embodiments, polymer 106 may be wet by the cell electrolyte or can wick the electrolyte between leads 110 and 112. Polymer 106 may be wetted by the electrolyte, and may be porous or permeable, allowing electrolyte connection of the electrolyte to leads 110 and 112. It should be appreciated that polymer 106 is chosen for its ability to be wet by the electrolyte and not by water or another interfering agent. Other interfering agents, for purposes of this application, may include alcohols, ketones, alkanes, or other environmentally present chemicals.
Depending on the embodiment, polymer (or polymer wick) 106 is a porous or nonporous hydrophobic (water hating) polymer as opposed to a hydrophilic polymer that would be wet by water. Since the flammable electrolytes of cells 102 are typically able to wet hydrophobic surfaces, polymer 106 creates an ionic bridge to form between leads 110 and 112 without water sources being able to do the same. Further, polymer (or wick material) 106 may be tailored to be wet by the electrolyte and not wet by any expected chemicals.
Chip 104 may perform capacitive or other electronic measurements between leads 110 and 112. For purposes of explanation, a capacitive measurement is a type of electrical measurement such as a voltage measurement or current measurement. The capacitance measurement may show a change in capacitance when bridged by an ionically conductive species, such as the electrolyte, or when polymer (or wick) 106 is suffused with the electrolyte. Ionically conductive species include both materials that conduct electricity through electrons (e.g., conductive materials such as metals) or species that have mobile charged particles (e.g., ions moving in a liquid or gel). This change in capacitance indicates that leads 110 and 112 are bridged by ionic substance that can wet or permeate a polymer coating around and between leads 110 and 112. This is indicative of an electrolyte leak, as the electrolyte should be the only chemical present that can carry ions and still wet wick (or polymer) 106. This measurement may occur as soon as any amount of electrolyte exits crimp seal (i.e. leaked) 108 and breaches bridged leads 110 and 112.
Chip 104 may transmit the leak measurements back to the BMU for cell management to mitigate the consequence of a leak. This communication is sent through wireless means, such as an antenna, on or adjacent to the chip in communication with the BMU. For example,
Returning back to
In some embodiments, pair of leads 210 and 212 running along a seal 204 or 206 of pouch cell 200 may identify leaks in pouch cell 200 through change in capacitance. In particular, this may be accomplished through leads 210 and 212 along the edge of cell 200 at pouch seal 204 or 206. These leads 210 and 212 may extend along one or more of the battery pouch seals for localization of the leak detection.
Since the capacitance for a set of sensors is dependent on the material of the sensors, surrounding materials and their geometry, this capacitance detection limit CL value is determined for each induvial sensor, or a value for capacitance detection limit CL is determined by the use of a fractional value of a baseline capacitance Cn0 for the sensor. This value may then be determined from testing of the sensors with leaks or electrolyte volumes as in the above paragraphs, or may be set as a fixed deviation from the initial capacitance, for example, 1/10 of the initial capacitance.
At 504, the BMU updates a test schedule and/or frequency schedule, which is received by the chip. The test schedule is a measurement procedure for leak detection based on a schedule, which is determined either as a time frequency (e.g., every 1 second) or as a schedule with varying time periods between testing based on conditions (e.g., periods of high stress for the cells, times of high danger from a leaking cell, or other times when a higher or lower frequency of testing may be required). The frequency may also be repeated or periodic measurement of the sensor for which the measurement of the sensor may be averaged or otherwise weighted as indicated by the BMU.
At 506, the chip is woken up (or the state of chip is changed) from a “sleep mode” to a “awake mode” and method 600 of
At 606, the chip compares the capacitance measurement Cn with the initial baseline capacitance measurement Cn0. When the compared capacitance measurement Cn is less than the capacitance detection limit CL (i.e., Cn<CL), a positive detection signal—leak—for the selected sensor is sent to the BMU. If the measured value is greater than the capacitance detection limit CL, then the chip records—no leak—and sends this information to the BMU.
The measurement of the sensor can be other measurements other than capacitance, including measurement of resistance, conductance, impedance, voltage, inductance, current, or other measurements. These measurements will also have leak detection limit values as determined by the user, and if the measurement of the sensor exceeds this limit value a leak can be reported to the BMU.
Returning to
It should be noted that some of the system features described in this specification have been presented as modules, in order to more particularly emphasize their implementation independence. For example, a module may be implemented as a hardware circuit comprising custom very large scale integration (VLSI) circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, graphics processing units, or the like.
A module may also be at least partially implemented in software for execution by various types of processors. An identified unit of executable code may, for instance, include one or more physical or logical blocks of computer instructions that may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may include disparate instructions stored in different locations that, when joined logically together, comprise the module and achieve the stated purpose for the module. Further, modules may be stored on a computer-readable medium, which may be, for instance, a hard disk drive, flash device, RAM, tape, and/or any other such non-transitory computer-readable medium used to store data without deviating from the scope of the invention.
Indeed, a module of executable code could be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network.
It will be readily understood that the components of various embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the detailed description of the embodiments of the present invention, as represented in the attached figures, is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention.
The features, structures, or characteristics of the invention described throughout this specification may be combined in any suitable manner in one or more embodiments. For example, reference throughout this specification to “certain embodiments,” “some embodiments,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in certain embodiments,” “in some embodiment,” “in other embodiments,” or similar language throughout this specification do not necessarily all refer to the same group of embodiments and the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
It should be noted that reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment.
Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention.
One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.
This application is a divisional application of, and claims the benefit of, U.S. patent application Ser. No. 17/713,142, filed on Apr. 4, 2022. The entirety of the earlier filed application is incorporated herein by reference.
Number | Date | Country | |
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Parent | 17713142 | Apr 2022 | US |
Child | 18733698 | US |