Thermoelectric sensor for lithium ion battery

Abstract

A thermoelectric temperature sensor (100) integrated into a lithium ion battery. The sensor comprises a first sensor electrode (110) and a second sensor electrode (120), both in ionic contact with the electrolyte of the cell. The first sensor electrode (110) and the second sensor electrode (120) have different thermoelectric coefficients such that they can generate a potential difference as a function of temperature. A protective ionically conductive coating (130) is applied on the sensor electrode to protect it while maintaining ionic conductivity between it and the electrolyte. According to the structure, the accurate real-time temperature monitoring in the battery can be realized, the thermal management is improved, and the operation safety is improved.

Description

Technical Field

[0001] This invention relates to the field of temperature sensors. More specifically, it relates to a thermoelectric temperature sensor for lithium-ion batteries. Background Technology

[0002] Battery Management Systems (BMS) in electric vehicles typically acquire only limited information about the internal state of battery cells due to the lack of advanced cell-integrated sensors. Specifically, BMSs usually use a small number of temperature sensors attached to the outside of each battery cell in each battery pack. Therefore, only the average external temperature of the cell is known, while the internal temperature of the cell may differ significantly from the external temperature. Furthermore, sudden changes in internal cell temperature take time to be transmitted to the outside, causing a delay in the detection of such changes and consequently delaying the execution of relevant safety protocols. Integrated temperature sensors, on the other hand, can detect hazardous conditions more quickly and accurately.

[0003] Existing research has attempted to address these issues by integrating various sensors within the battery cell. For example, thermistors, thermocouples, and resistive temperature detectors (RTDs) have been considered potential internal temperature sensors. However, these methods typically introduce significant size and complexity into the battery structure, impacting battery functionality and capacity. Furthermore, because these sensors react chemically with the electrolyte, their performance degrades over time, reducing their reliability in long-term applications such as electric vehicles.

[0004] Therefore, there is an urgent need for a sensor that can reliably monitor the internal temperature of a lithium-ion battery throughout its entire lifespan, with minimal impact on the battery's size and performance.

[0005] Finally, it is widely recognized in the art that it is necessary to incorporate a reference electrode within the battery cell to measure the potential of the battery electrodes. By measuring the potential of the battery electrodes, the reference electrode can provide information such as the state of charge or health of the electrodes. However, in existing research on integrated reference electrodes, such devices also suffer from problems of large size and susceptibility to degradation. Summary of the Invention

[0006] The purpose of this invention is to provide a sensor for lithium-ion batteries capable of monitoring the internal temperature of the battery cell. Another purpose of this invention is to provide a battery incorporating the sensor, and a method for monitoring the internal temperature of a lithium-ion battery.

[0007] The above objectives are achieved by the apparatus and method of the present invention.

[0008] In a first aspect, embodiments of the present invention relate to a thermoelectric temperature sensor integrated into a lithium-ion battery. The sensor includes:

[0009] - First sensor electrode and second sensor electrode, wherein both sensor electrodes are in ion contact with the electrolyte of the lithium-ion battery;

[0010] - wherein the first sensor electrode and the second sensor electrode have different thermoelectric coefficients;

[0011] -And the sensor electrode is provided with a protective ion-conductive coating.

[0012] The advantage of this invention is that the potential difference between the sensor electrodes is temperature-dependent, thereby enabling the sensor to measure the internal temperature of the battery.

[0013] Another advantage of this embodiment of the invention is that the sensor electrode can be used as a reference electrode to monitor the potential of the battery electrode. This dual functionality allows the sensor to perform multiple functions simultaneously (temperature sensing and potential monitoring) without requiring a separate sensor or additional components for each function.

[0014] Another advantage of this invention is that the coating stabilizes the interface between the sensor electrode and the battery electrolyte, preventing side reactions and avoiding sensor degradation over time. This coating prevents unwanted side reactions between the sensor electrode and the battery electrolyte, which could otherwise lead to sensor performance degradation or cause measurement results to drift over time.

[0015] In some embodiments of the present invention, the first sensor electrode is a lithium-ion electrode.

[0016] In some embodiments of the present invention, the second sensor electrode comprises lithium metal.

[0017] In some embodiments of the present invention, the second sensor electrode is a lithium-ion electrode.

[0018] In some embodiments of the present invention, the protective ion-conducting coating comprises a solid electrolyte (ceramic or other type). The ion-conducting coating may be an ion-transparent thin film (e.g., an alumina or titanium oxide film) prepared by atomic layer deposition. In some embodiments of the present invention, the protective ion-conducting coating comprises lithium oxynitride or lithium lanthanum titanate.

[0019] In some embodiments of the present invention, the first sensor electrode and / or the second sensor electrode and / or the ion-conducting coating are thin films.

[0020] In some embodiments of the invention, the sensor is configured to be used simultaneously as a temperature sensor and a potential sensor (i.e., a reference electrode) for a lithium-ion battery.

[0021] In a second aspect, embodiments of the present invention relate to a lithium-ion battery, the battery comprising:

[0022] - An electronic casing that houses the positive electrode, negative electrode, and electrolyte of the battery;

[0023] - and a thermoelectric temperature sensor according to any embodiment of the present invention. The sensor is integrated inside the battery and forms ion contact with the battery's electrolyte.

[0024] The advantage of this invention lies in its ability to perform accurate real-time temperature measurement of the interior of a lithium-ion battery. Traditional temperature sensors (such as those mounted externally to the battery) can only measure external or surface temperatures, which may differ significantly from the actual internal temperature. Furthermore, the conduction of internal thermal events to the outside takes time, resulting in a noticeable detection delay for external sensors. Therefore, internal sensors can provide temperature information much faster, which is particularly important in scenarios requiring a response to sudden temperature changes (such as adjusting cooling settings or emergency shutdown).

[0025] Another advantage of this invention is that the design ensures that the sensor occupies very little space inside the battery, and therefore, unlike larger internal sensors, it does not significantly affect the battery's energy density or functionality.

[0026] Another advantage of this invention is that, by monitoring the potential of the battery electrodes, the sensor electrode of the temperature sensor can also be used as a reference electrode to monitor the state of charge of the battery electrodes. This dual-function characteristic significantly improves the efficiency and practical value of the sensor by enabling it to perform multiple roles simultaneously (temperature sensing and potential monitoring) without the need for additional sensors or components. This dual function is achieved through the contact between the sensor electrode and the battery electrolyte: if the sensor has its own internal electrolyte but no chemical contact with the battery electrolyte, it cannot be used simultaneously as a reference electrode for monitoring the battery electrode potential.

[0027] In some embodiments of the present invention, the electrolyte is a liquid electrolyte.

[0028] In some embodiments of the present invention, the electrolyte is a solid electrolyte.

[0029] In some embodiments of the present invention, a thermoelectric temperature sensor is disposed near the positive electrode of the battery to monitor temperature changes in the vicinity of the positive electrode. In some embodiments of the present invention, a thermoelectric temperature sensor is disposed near the negative electrode of the battery to monitor temperature changes in the vicinity of the negative electrode.

[0030] In a third aspect, embodiments of the present invention relate to a method for monitoring the internal temperature of a lithium-ion battery. The method includes:

[0031] - Integrate the thermoelectric temperature sensor according to the present invention into the battery, wherein the electrolyte of the battery is used as the electrolyte of the thermoelectric temperature sensor;

[0032] - Measure the potential difference between the first sensor electrode and the second sensor electrode as a function of temperature;

[0033] - Determine the internal temperature of the battery based on the measured potential difference.

[0034] In some embodiments of the present invention, the method includes the step of recalibrating the sensor by applying a current to the sensor electrodes to compensate for changes in the state of charge of the sensor electrodes.

[0035] The advantage of this invention is that calibration can be completed by applying only a very small current to the thin-film sensor electrode.

[0036] In some embodiments of the present invention, the method includes measuring the potential difference between one of the sensor electrodes of the thermoelectric temperature sensor and the positive electrode of the lithium-ion battery, or measuring the potential difference between one of the sensor electrodes and the negative electrode of the battery.

[0037] An advantage of this embodiment of the invention is that the thermoelectric temperature sensor can be used as a reference electrode. Another advantage is that, since the sensor can simultaneously measure temperature, temperature effect correction can be applied to the measurement results.

[0038] Specific and preferred aspects of the invention are set forth in the appended independent and dependent claims. Features of the dependent claims may be suitably combined with features of the independent and other dependent claims, not merely those expressly set forth in the claims.

[0039] These and other aspects of the invention will be apparent from the embodiments described below, and will be illustrated with reference to the embodiments described below. Attached Figure Description

[0040] Figure 1 A schematic diagram of a thermoelectric temperature sensor (without a protective coating) according to an embodiment of the present invention is shown.

[0041] Figure 2 A thermoelectric temperature sensor according to an embodiment of the present invention is shown, wherein the protective coating of the sensor covers only the sensor electrodes and leads.

[0042] Figure 3 A thermoelectric temperature sensor according to an embodiment of the present invention is shown, wherein the protective coating of the sensor is applied only to the sensor electrodes.

[0043] Figure 4A cross-sectional schematic diagram of a thermoelectric temperature sensor according to an embodiment of the present invention is shown.

[0044] Figure 5 A schematic diagram of a lithium-ion battery according to an embodiment of the present invention is shown, wherein a thermoelectric temperature sensor is integrated in the battery and the sensor is in contact with the electrolyte.

[0045] Figure 6 A layered structure of a battery stack including a thermoelectric temperature sensor is shown according to an embodiment of the present invention.

[0046] Figure 7 This paper explains the principle of generating a potential difference that changes with temperature using two sensor electrodes with different thermoelectric properties, according to an embodiment of the present invention.

[0047] Figure 8 A curve showing the potential difference of a thermoelectric temperature sensor according to an embodiment of the present invention as a function of temperature is shown. The sensor includes a lithium metal sensor electrode and a partially lithium-ion sensor electrode with a LiPON coating.

[0048] Figure 9 An exemplary flowchart of a method for monitoring the internal temperature of a lithium-ion battery according to an embodiment of the present invention is shown.

[0049] Any reference numerals in the claims should not be construed as limiting the scope.

[0050] In different accompanying drawings, the same reference numerals refer to the same or similar elements. Detailed Implementation

[0051] The invention will be described with reference to specific embodiments and certain accompanying drawings, but is not limited thereto; rather, it is defined solely by the claims. The described drawings are merely illustrative and not restrictive. In the drawings, some elements may be enlarged and not drawn to scale for illustrative purposes. Dimensions and relative dimensions do not correspond to an actual reduction in scale for the practice of the invention.

[0052] The terms "first," "second," etc., used in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a temporal, spatial, hierarchical, or any other order. It should be understood that the terms thus used are interchangeable where appropriate, and the embodiments of the invention described herein can operate in an order different from that described or illustrated herein.

[0053] Furthermore, the terms "top," "below," etc., used in the specification and claims are for descriptive purposes and are not necessarily used to describe relative positions. It should be understood that such terms are interchangeable where appropriate, and that embodiments of the invention described herein can operate in orientations different from those described or illustrated herein.

[0054] It should be noted that the term "comprising" as used in the claims should not be construed as limiting itself to the means listed thereafter; it does not exclude other elements or steps. Therefore, the term should be interpreted as specifying the presence of the features, integers, steps, or components stated as mentioned, but does not exclude the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Thus, the scope of the expression "device comprising means A and B" should not be limited to a device consisting solely of components A and B. It means that for the present invention, the only relevant components of the device are A and B.

[0055] Throughout this specification, the reference to "an embodiment" or "an embodiment" means that a specific feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. Therefore, the phrase "in an embodiment" or "in an embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, but may refer to different embodiments. Furthermore, in one or more embodiments, specific features, structures, or characteristics may be combined in any suitable manner, as will be apparent to those skilled in the art from this disclosure.

[0056] Similarly, it should be understood that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, drawing, or description for the purpose of simplification and to aid in understanding one or more of the various inventive aspects. However, this approach to the disclosure should not be construed as reflecting an intention to claim more features than are expressly recited in each claim. Rather, as reflected in the appended claims, inventive aspects lie in fewer features than all the features of a single foregoing disclosed embodiment. Thus, the claims appended to the Detailed Description are thereby explicitly incorporated into this Detailed Description, wherein each claim itself represents a separate embodiment of the invention.

[0057] Furthermore, while some embodiments described herein include features that are included in other embodiments but not others, it will be understood by those skilled in the art that combinations of features from different embodiments are intended to fall within the scope of the invention and form different embodiments. For example, any embodiment of the claimed embodiments in the appended claims may be used in any combination.

[0058] Numerous specific details are set forth in the description provided herein. However, it should be understood that embodiments of the invention can be practiced without these specific details. In other instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0059] In this embodiment of the invention, when describing the sensor electrode forming an ionic contact with the electrolyte of a lithium-ion battery, it means that electrochemical ion exchange can occur between the sensor electrode and the electrolyte. Therefore, the coating disposed on the sensor electrode has ionic conductivity.

[0060] In a first aspect, embodiments of the present invention relate to a thermoelectric temperature sensor (100) integrated into a lithium-ion battery. The sensor (100) includes a first sensor electrode (110) and a second sensor electrode (120), both of which form ion contacts with the electrolyte (240) of the battery. The first sensor electrode (110) and the second sensor electrode (120) have different thermoelectric coefficients, and the sensor electrodes are provided with a protective ion-conducting coating (130). In some embodiments of the invention, a first electronic lead (140) is connected to the first sensor electrode (110), and a second electronic lead (150) is connected to the second sensor electrode (120). An example schematic diagram of such a temperature sensor is shown below. Figures 1 to 4 As shown.

[0061] Figure 1 The sensor structure without a protective coating is shown, wherein a first electronic lead (140) is connected to a first sensor electrode (110), a second electronic lead (150) is connected to a second sensor electrode (120), and all components are disposed on a sensor substrate (105).

[0062] There are several options for coating application. A single coating can cover the entire sensor, or a coating can be applied only to the sensor electrodes and leads, or only to the sensor electrodes. The coatings on different sensor electrodes and / or leads can use the same material, or different materials can be used for each sensor electrode and / or lead.

[0063] Figure 2 The sensor structure is shown with a coating applied only to the sensor electrodes and leads.

[0064] Figure 3 The sensor structure with a coating only on the sensor electrodes is shown.

[0065] In some embodiments of the present invention, both sensor electrodes (110, 120) are capable of lithium-ion exchange with the battery electrolyte (240). Because each sensor electrode material responds differently to temperature changes, the potential difference dU between the two sensor electrodes...total The relationship between temperature and the change is as follows:

[0066]

[0067] Wherein, α1 is the thermoelectric coefficient of the first sensor electrode (110), and α2 is the thermoelectric coefficient of the second sensor electrode (120).

[0068] This makes potentiometric temperature measurement possible. The principle involves using two sensor electrodes with different thermoelectric properties to generate a potential difference that changes with temperature, as follows: Figure 7 As shown in the figure, the voltage (V110) of the first sensor electrode and the voltage (V120) of the second sensor electrode vary with temperature.

[0069] The thermoelectric temperature sensor (100) described in various embodiments of the present invention can be fabricated as follows: A thin, electrically and chemically insulating foil substrate (105) can be provided. Such a substrate (105) in... Figure 4 As shown in the diagram. Next, micropatterned electron leads (140, 150) can be fabricated by photolithography. Then, thin films of two different lithium-ion electrode materials (110, 120) can be deposited at the locations in contact with the electron leads, for example, by electrochemical deposition. Finally, an ion-conductive protective coating (130) can be deposited to maintain a stable chemical interface and enable smooth migration of lithium ions.

[0070] In a second aspect, embodiments of the present invention relate to a lithium-ion battery (200) comprising a battery casing (210) housing a positive electrode (220), a negative electrode (230), and an electrolyte (240). The battery also includes a thermoelectric temperature sensor (100) according to an embodiment of the present invention. The sensor is integrated inside the battery and contacts the electrolyte (240). In embodiments of the present invention, the lithium-ion battery (200) further includes a separator (250) located between the positive electrode (220) and the negative electrode (230). A schematic diagram of such a battery is shown in... Figure 5 The diagram illustrates a qualitative concept, not the actual geometry or integration of a battery. Typically, a battery consists of a stack of electrode layers and an electrolyte / separator layer, with the electrode layers occupying the majority of the volume. The combination of the positive electrode (cathode), negative electrode (anode), electrolyte, and separator constitutes the battery cell. A battery can consist of multiple cells connected in series, parallel, or a series-parallel combination to achieve the desired voltage and capacity.

[0071] The electronic leads (140, 150) of the sensor (100) extend out of the battery through a hole in the battery housing (210). In various embodiments of the invention, the sensor volume is small relative to the electrolyte volume: its thickness is maintained on the order of 500 nm to 10 μm, and its lateral dimensions are maintained on the order of 10 μm to 1 mm.

[0072] Figure 6 A layered stack of a battery 200 according to various embodiments of the present invention is shown. The stacked assembly includes the following components:

[0073] 1. Battery housing (210): An external structure that provides housing and protection for the stacked internal components. The housing (210) ensures the stability and integrity of the stacked components and maintains the correct position of all other components.

[0074] 2. Positive battery electrode (220): Located inside the housing (210), this battery electrode serves as the positive terminal of the battery stack.

[0075] 3. Negative battery electrode (230): Located inside the housing (210), this battery electrode serves as the negative terminal of the battery stack.

[0076] 4. Electrolyte (240): Filled in the space between the positive electrode (220) and the negative electrode (230), the electrolyte (240) provides a medium for ion conduction, allowing ions to move freely within the stack. The electrolyte (240) is crucial to the operation and performance of the stack.

[0077] 5. Thermoelectric temperature sensor (100): Integrated within the stacked structure, the thermoelectric temperature sensor (100) according to various embodiments of the present invention is in contact with the electrolyte (240) and is designed to monitor the temperature of the battery. The sensor (100) includes sensor electrodes with different thermoelectric coefficients, enabling accurate temperature measurement inside the battery.

[0078] 6. Separator (250): Physically separates the anode and cathode, preventing them from contacting and short-circuiting. The separator is porous, allowing lithium ions to pass through it via the electrolyte. The pores of the separator are filled with electrolyte, which surrounds the separator.

[0079] 7. Battery housing (210): The second mention of housing (210) emphasizes its encapsulating function, providing mechanical support and environmental isolation for the internal battery electrodes and sensors.

[0080] The lithium-ion battery (200) according to various embodiments of the present invention may include multiple such stacks.

[0081] In various embodiments of the invention, the first sensor electrode (110) is a lithium-ion electrode, and / or the second sensor electrode (120) is a lithium-ion electrode (i.e., an electrode capable of exchanging lithium ions with the electrolyte). These materials are chosen because they have the ability to exchange lithium ions with the electrolyte. Such electrodes can be used to generate voltages that vary with temperature.

[0082] Preferably, the sensor electrodes exhibit thermal and chemical stability within the expected operating temperature range. For electric vehicle applications, this temperature range is approximately -20°C to +80°C.

[0083] Preferably, the material of the sensor electrode is selected based on its electrochemical potential stability. The electrochemical potential of the sensor electrode should remain stable and unaffected by temperature fluctuations.

[0084] Preferably, the two sensor electrodes exhibit significantly different thermoelectric coefficients to maximize the thermal sensitivity of the sensor voltage, thereby providing a high thermal conductivity. In various embodiments of the invention, the sensor sensitivity value is between 0.1 mV / K and 10 mV / K.

[0085] In various embodiments of the present invention, the sensor electrode undergoes a lithium exchange reaction, and its electrochemical potential falls within the electrochemical window of the electrolyte. For typical liquid electrolytes such as carbonates, this electrochemical window is generally between 1 volt and 4 volts relative to lithium / lithium ion (Li / Li+), although technological advancements may extend this window to 0 volts to 5 volts.

[0086] In various embodiments of the invention, the selection of materials ensures the feasibility of the electrode deposition process, which also improves manufacturability. For example, materials that can be molded and processed at low temperatures, such as materials that can be deposited by printing, can be selected.

[0087] Suitable electrode materials include:

[0088] -Based on embedded electrodes: such as certain transition metal oxides and phosphates.

[0089] -Metal alloyed electrode: composed of lithium-transition metal alloy (Li n It is composed of M, where M is a transition metal.

[0090] - Conversion electrode: Involved in chemical conversion reactions.

[0091] - Prussian blue analogues: specifically transition metal hexacyanoferrates, which exhibit excellent thermal stability, tunable thermoelectric behavior, compatibility with an electrochemical potential of approximately 3V and electrolyte window, and ease of deposition.

[0092] In embodiments of the present invention, the first sensor electrode and / or the second sensor electrode comprise at least partially lithiated lithium intercalation material. This lithium intercalation material may be selected, for example, from lithium titanate (Li4Ti5O4). 12 It is a group consisting of α and β (Si).

[0093] In some embodiments of the invention, the second sensor electrode (120) comprises lithium metal. Such a lithium metal electrode is particularly suitable for use as a reference electrode.

[0094] The protective ion-conducting coating applied to these sensor electrodes must allow lithium ions to pass freely between the sensor electrodes and the electrolyte. This coating is an electronic insulator to prevent side reactions between the sensor electrodes and the electrolyte. The interface between the coating and the electrolyte must be chemically stable to avoid side reactions during sensor operation.

[0095] Suitable coating materials include ion-conducting solid electrolytes, such as lithium oxyphosphide (LPO). Ceramic solid electrolytes (such as LPO or lithium lanthanum titanate (LLTO)), atomic layer deposition (ALD) coatings (e.g., conformal coatings of alumina or titanium dioxide), and molecular layer deposition (MLD) coatings can also be used. Combining different coatings allows for further optimization of performance by leveraging their complementary properties.

[0096] In embodiments of the invention, the first sensor electrode (110), the second sensor electrode (120), and / or the ion-conducting coating (130) are implemented in thin film form. Using thin film for these components offers several advantages, including precise thickness control, improved surface area to volume ratio, and enhanced integration in compact devices. Thin films allow for efficient layering and can be deposited with high uniformity, which benefits both device performance and manufacturability. Furthermore, thin films optimize ion conductivity and facilitate controlled interactions with the electrolyte, thereby improving the overall functionality and reliability of the system. In various embodiments of the invention, the thickness of the protective ion-conducting coating may, for example, be between 1 nm and 10 μm. In various embodiments of the invention, the thickness of the sensor electrode may, for example, be between 10 nm and 1 μm.

[0097] For an exemplary thermoelectric temperature sensor according to an embodiment of the present invention, which has a lithium metal sensor electrode coated with lithium oxyphosphide (LiPON) and a partially lithium silicon sensor electrode, the potential difference (U) between the two electrodes was measured at different temperatures (T). Figure 8 As shown, this potential difference responds to changes in electrode temperature with a signal strength of 0.25 mV / K. This signal strength is higher than that provided by established thermocouples or resistance-based sensors (under actual current detection).

[0098] In embodiments of the invention, the sensor is designed to function simultaneously as a temperature sensor and a reference electrode within the lithium-ion battery (200). A first sensor electrode (110) or a second sensor electrode (120) can be used as a reference electrode to electrochemically determine the potential of the battery electrodes. This reference electrode measures the electrochemical potential of the electrolyte relative to the positive (220) or negative (230) electrode of the lithium-ion battery. This measurement provides a stable reference point upon which the voltage of the positive (220) or negative (230) electrode can be independently measured, thereby enabling precise monitoring of the potential of each battery electrode during charge-discharge cycles.

[0099] In embodiments of the present invention, a voltage sensing circuit may be provided for measuring the voltage across the electrodes (e.g., measuring the voltage between sensor electrodes when measuring a voltage indicating temperature; or measuring the voltage between sensor electrodes and battery electrodes when the sensor is used as a reference electrode).

[0100] This dual functionality enables the sensor to continuously monitor the battery's internal temperature, providing real-time thermal data, which is crucial for managing battery performance and preventing overheating. Simultaneously, the sensor also serves as a stable reference electrode, accurately measuring the battery's electrochemical potential. This dual-purpose design integrates two important monitoring functions into a single component, simplifying system architecture, reducing the need for additional electrodes, and minimizing internal space footprint within the battery. By combining temperature sensing with potential reference, this approach improves the accuracy, reliability, and efficiency of the battery management system.

[0101] One advantage of this invention is that by using the battery's electrolyte for sensor operation, the sensor design becomes simpler and its size can be reduced. Compared to conventional sensors that require a dedicated sensor electrolyte, this design allows for a thinner profile and smaller lateral dimensions, significantly reducing the sensor's volume and structural complexity. The sensor thickness can, for example, be less than 10 μm. Furthermore, due to contact with the electrolyte, the sensor electrodes can also serve as reference electrodes, combining both functions into a single device. This again improves the ratio between the amount of information acquired and the volume required to achieve that information acquisition.

[0102] Furthermore, another advantage of this invention is that, due to the reversible interaction between the sensor electrodes and the electrolyte, the long-term stability of the sensor signal is easier to maintain. The interface can be effectively stabilized by using an ion-conductive coating. Moreover, since the thin-film sensor electrodes store very little charge, any changes in the state of charge of the sensor electrodes (which could affect the signal) can be recalibrated with minimal current.

[0103] In embodiments of the invention, the electrolyte of the battery is a liquid electrolyte. Suitable liquid electrolytes may comprise lithium salts (such as lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), or lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)) dissolved in a liquid organic solvent (such as propylene carbonate or ethylene carbonate), consistent with common practices in commercial lithium-ion batteries. The selection of these electrolyte compositions may be based on their compatibility with the requirements of lithium-ion batteries, such as ionic conductivity, chemical stability, and safety.

[0104] Regarding sensor integration, there are no particularly stringent electrolyte requirements for sensor operation. Instead, the electrolyte should primarily be optimized to meet the battery's performance and efficiency needs, including factors such as stability at high voltages, ion mobility, and thermal performance. However, for seamless sensor integration, it is advantageous if the electrolyte's electrochemical window can accommodate the potential range of the sensor electrodes.

[0105] Alternatively, in embodiments of the invention, different types of solid-state electrolytes can be used as battery electrolytes, providing a variety of options for tailoring battery performance to specific application requirements. Examples of suitable solid-state electrolytes include ceramics (such as lithium oxyphosphine nitride LiPON), garnet-type structures (such as lithium lanthanum zirconate LLZO), lithium nitride-based materials, and perovskite structures (such as lithium lanthanum titanate LLTO). Each type of solid-state electrolyte possesses unique properties: ceramic and garnet-type electrolytes typically exhibit high ionic conductivity and stability, while perovskite-type and lithium nitrite-based electrolytes may offer higher mechanical strength or better compatibility with lithium metal anodes.

[0106] Similar to liquid electrolytes, there are no specific requirements imposed on solid-state electrolytes for sensor integration. Instead, the selection of a solid-state electrolyte should primarily be based on the battery's performance requirements, such as maximizing ionic conductivity, improving stability at high voltages, and providing thermal stability. However, it is simpler to integrate the sensor into a battery using a solid-state electrolyte when the electrochemical window of the solid-state electrolyte can accommodate the potential range of the sensor electrodes. Most solid-state electrolytes on the market today typically meet this compatibility standard.

[0107] In embodiments of the invention, a temperature sensor (100) is positioned near the positive electrode (220) to monitor temperature changes in the vicinity of the positive electrode; or it is positioned near the negative electrode (230) to monitor temperature changes in the vicinity of the negative electrode. The ability to position the sensor near either electrode provides design flexibility, enabling targeted temperature monitoring based on the specific needs of the battery application. By tracking temperature changes at these critical locations, the system can adjust operating parameters to improve battery safety, optimize performance, and mitigate degradation over time.

[0108] In a third aspect, the present invention provides a method (300) for monitoring the internal temperature of a lithium-ion battery (200) using an integrated thermoelectric temperature sensor (100), such as Figure 9 As shown in the diagram, this exemplary flowchart details the key steps (310, 320, and 330) involved in obtaining accurate temperature measurements inside the battery to optimize performance and safety.

[0109] - Step 310: In the first step, the thermoelectric temperature sensor (100) according to an embodiment of the present invention is directly integrated into the battery. This integration process includes positioning the sensor to utilize the same electrolyte present in the battery, thereby establishing a direct connection between the sensor electrode and the electrolyte. This step is most easily performed during the manufacturing process of the battery cell, but integration can also be performed after the battery manufacturing is completed.

[0110] Step 320: After integration, the sensor measures the potential difference between the first sensor electrode (110) and the second sensor electrode (120). This potential difference is temperature-dependent due to the thermoelectric properties of the electrodes in contact with the electrolyte. As the internal temperature of the battery changes, this potential difference reflects these changes, thus providing a direct and accurate indication of the internal thermal condition. This method utilizes the thermoelectric effect—the property of potential difference changing with temperature—to enable the sensor to operate efficiently within the electrochemical environment of the battery.

[0111] Step 330: In this final step, the system determines the internal temperature of the battery (200) based on the measured potential difference. This can be achieved using a calibration curve or by using the known thermoelectric coefficient of the material. The processing device converts the potential difference into an accurate temperature reading. The battery management system can then use this information to adjust operating parameters as needed, such as modifying the charge / discharge rate of individual cells or modules, or activating thermal management mechanisms. This provides an effective, real-time method for tracking the internal temperature of the battery. This helps prevent overheating and improves battery life and performance.

[0112] pass Figure 9The steps outlined in the method (300) enable precise monitoring of the internal temperature of the battery using a thermoelectric temperature sensor. This integration improves temperature management, enabling lithium-ion batteries to operate more safely and efficiently.

[0113] The method (300) according to an embodiment of the present invention may further include the additional step of measuring the potential difference between one of the electrodes (110, 120) of the thermoelectric temperature sensor (100) and the positive electrode (220) or negative electrode (230) of the lithium-ion battery (200). In this case, the thermoelectric temperature sensor is used as a reference electrode. Furthermore, since the sensor also measures temperature, the obtained potential difference can be corrected for temperature effects.

[0114] In an embodiment of the invention, the method (300) includes an additional step of recalibrating the sensor by applying a current to the electrodes of the thermoelectric temperature sensor (100). This recalibration step is designed to compensate for any variations in sensor performance that may occur due to changes in the state of charge (SoC) of the sensor electrodes over time. Specifically, a change in the SoC of the first or second sensor electrode may cause a change in the potential difference measured by the sensor, thereby distorting the signal. By periodically applying small, carefully selected currents to each sensor electrode, the SoC can be kept constant, thereby eliminating noise associated with changes in SoC. Due to the small size of the sensor, this does not cause significant changes in the electrolyte salt concentration.

Claims

1. A thermoelectric temperature sensor (100) integrated into a lithium-ion battery, the sensor comprising: - A first sensor electrode (110) and a second sensor electrode (120), wherein both sensor electrodes (110, 120) are in ion contact with the electrolyte (240) of the lithium-ion battery; -The first sensor electrode (110) and the second sensor electrode (120) have different thermoelectric coefficients; - and the sensor electrode is provided with a protective ion-conducting coating (130).

2. The thermoelectric temperature sensor (100) as described in claim 1, characterized in that, The first sensor electrode (110) is a lithium-ion electrode.

3. The thermoelectric temperature sensor (100) as described in any one of the preceding claims, characterized in that, The second sensor electrode (120) contains lithium metal.

4. The thermoelectric temperature sensor (100) as described in any one of claims 1 or 2, characterized in that, The second sensor electrode (120) is a lithium-ion electrode.

5. The thermoelectric temperature sensor (100) as described in any one of the preceding claims, characterized in that, The protective ion-conductive coating (130) contains a solid electrolyte.

6. The thermoelectric temperature sensor (100) as claimed in any of the preceding claims, characterized in that, The first sensor electrode (110) and / or the second sensor electrode (120) and / or the ion-conducting coating (130) are thin films.

7. The thermoelectric temperature sensor (100) as described in any of the preceding claims, characterized in that, The sensor is configured to be used simultaneously as a temperature sensor and a potential sensor for the lithium-ion battery (200).

8. A lithium-ion battery (200), comprising: - A battery casing (210) that houses the positive electrode (220), the negative electrode (230), and the electrolyte; - and a thermoelectric temperature sensor (100) as described in any of the preceding claims, wherein the sensor (100) is integrated into the battery (200) and forms ion contact with the electrolyte (240) of the battery.

9. The lithium-ion battery (200) as described in claim 8, characterized in that, The electrolyte is a liquid electrolyte.

10. The lithium-ion battery (200) as described in claim 8, characterized in that, The electrolyte is a solid electrolyte.

11. The lithium-ion battery (200) according to any one of claims 8 to 10, characterized in that, The thermoelectric temperature sensor (100) is positioned near the positive electrode (220) to monitor temperature changes near the positive electrode, or is positioned near the negative electrode (230) to monitor temperature changes near the negative electrode.

12. A method (300) for monitoring the internal temperature of a lithium-ion battery (200), comprising: - Integrating (310) the thermoelectric temperature sensor (100) as described in any one of claims 1 to 7 into the battery, wherein the electrolyte of the battery is used as the electrolyte of the thermoelectric temperature sensor (100); -Measure (320) the potential difference between the first sensor electrode (110) and the second sensor electrode (120) as a function of temperature; - The internal temperature of the battery (200) is determined based on the measured potential difference (330).

13. The method (300) as claimed in claim 12, characterized in that, The method further includes the step of recalibrating the sensor by applying a current to the sensor electrodes to compensate for changes in the state of charge of the sensor electrodes.

14. The method (300) as described in any one of claims 12 and 13, characterized in that, Further, it includes measuring the potential difference between one of the sensor electrodes (110, 120) of the thermoelectric temperature sensor (100) and the positive battery electrode (220), or measuring the potential difference between one of the sensor electrodes (110, 120) and the negative battery electrode (230).

Images