BATTERY ASSEMBLIES WITH SUB-COOLED PHASE-CHANGE MATERIALS

Abstract

A PCM with a subcooling function can be used to release heat to warm a battery before fast charging by triggering a switch to the fixed phase within the PCM. A battery temperature management system can incorporate a PCM with a subcooling function within a temperature-modulating cell to supply heat to a battery before fast charging and absorb heat during fast charging. A vehicle can incorporate a battery and a PCM with a subcooling function within a temperature-modulating cell to supply heat to the battery before fast charging and absorb heat during fast charging.

Description

FIELD OF TECHNOLOGY

[0001] This disclosure generally concerns battery management systems. GENERAL STATE OF THE ART

[0002] In certain batteries, lower operating temperatures can affect lithium plating rates and charge acceptance. Therefore, warming a battery before fast charging can increase charge acceptance. SUMMARY

[0003] One method involves, in response to a request to charge a battery, initiating a first phase change in a supercooled phase change material (“PCM”) of a composition adjacent to the battery, causing the PCM to solidify in order to release latent stored heat to heat the battery and, during charging, absorbing heat through the PCM as it undergoes a second phase change, causing the PCM to liquefy in order to cool the battery.

[0004] A battery temperature management device includes a temperature modulating cell containing a battery-adjacent composition including a phase change material ("PCM") configured to be supercooled, an ultrasonic transducer, and a controller programmed to turn on the ultrasonic transducer upon receiving a request to charge the battery, wherein turning on the ultrasonic transducer causes a first phase change in the PCM, causing the PCM to solidify to release latent stored heat.

[0005] A vehicle includes a battery, a temperature-modulating cell containing a battery-adjacent composition that includes a phase-change material (“PCM”) configured to be submerged, a submerged disk, and a controller programmed to send an electrical signal upon receiving a request to charge the battery, in order to disrupt the disk so that it causes an initial phase change in the PCM, causing the PCM to solidify in order to release latent stored heat. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a method of using a PCM with subcooling capability to heat and, at another time, cool a battery cell. Fig. 2 shows a battery temperature management device. Fig. 3 shows an exemplary operation of the battery temperature management device from Fig. 2. Fig. Figure 4 shows a vehicle. Fig. 5 shows an example operation of the vehicle from Fig. 4. DETAILED DESCRIPTION

[0006] Embodiments are described herein. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various and alternative forms. The figures are not necessarily to scale. Some features may be exaggerated or reduced to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art.

[0007] Various features illustrated and described with respect to any of the figures may be combined with features illustrated in one or more other figures to produce embodiments not explicitly illustrated or described. The illustrated combinations of features provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of this disclosure may be desirable for particular applications or implementations.

[0008] Fast charging can cause a battery to degrade more quickly compared to other charging modes. This degradation is more likely at "low temperatures" below 30°C. The low temperature can cause a reduced ion transfer rate, limiting the ability of ions to reach the bottom of the electrode. This reduced ion transfer rate can result in slower charging. Charging at low temperatures can also cause lithium plating on the anode surface. Some lithium plating processes are irreversible, so this process can reduce the battery's lithium content, thus shortening its cycle life.

[0009] A "target temperature," such as a temperature between approximately 30°C and approximately 50°C, can accelerate ion transfer and reduce lithium plating during fast charging. By increasing ion conductivity and diffusion in the electrode, a target temperature can reduce polarization on the anode material surface, leading to faster charging and longer battery cycle life.

[0010] A "high temperature," such as a temperature above 60°C, can cause a side reaction that reduces battery life. Therefore, high temperatures should be avoided.

[0011] Known battery thermal management systems may involve the use of a phase-change material ("PCM") or a mixture of PCMs to passively absorb heat above a certain temperature. Example PCMs may include organic materials, inorganic materials, and salt eutectics. For example, a paraffin wax absorbs heat as the wax liquefies to assume a higher-energy phase. Because heat dissipation is a goal of these established processes, the teachings of many processes shift away from a PCM with a subcooling function (a supercooled PCM), which would retain heat until nucleation is induced to promote crystallization.

[0012] A PCM with subcooling capability can be included in a battery temperature management system to increase charge acceptance and extend cycle life by warming a battery cell before fast charging. Including a PCM with subcooling capability in a battery temperature management system enables battery cooling and also allows energy to be stored and released at a predetermined time and in a predetermined manner to warm the battery for fast charging.

[0013] The PCM with subcooling capability can be contained within a composition that is enclosed by a temperature-modulating cell. The volume of the composition can be smaller than the total volume of the temperature-modulating cell, allowing the composition to expand to fill a space defined by the temperature-modulating cell during phase transitions.

[0014] Certain earlier battery temperature management systems designed to heat a battery for fast charging do so by passing an electric current through a resistively heatable material, either inside or outside the battery. Passing this current requires a power source: either the battery itself or an additional source outside the battery. Earlier battery temperature management systems can impact battery performance, such as when the battery itself is supplying power to a resistively heatable material, or they can involve additional components that take up space or increase weight.

[0015] In a system that includes a PCM with a subcooling function, the energy used to preheat the battery for fast charging is energy stored in the PCM the last time the PCM was heated above its melting point, including possibly the last time the battery was fast-charged. Furthermore, the battery temperature management system that includes a PCM with a subcooling function may use external power to activate a trigger.

[0016] One PCM can have a different melting point or latent heat compared to another PCM. By including a mixture of two or more PCMs, determined through testing, simulation, etc., a composition can have a melting point, for example, between 35 °C and 60 °C, and a latent heat as required by the battery temperature management system. For example, a composition with a higher latent heat can heat a battery cell to a higher temperature than would be the case with a composition with a lower latent heat in an equivalent system and environment.

[0017] A composition including a PCM with a subcooling function may have a thermal conductivity lower than necessary to heat an adjacent battery cell to a target temperature. For example, a composition including a PCM and an additive with a higher thermal conductivity than the PCM may transfer heat to heat an adjacent battery cell to a higher temperature than would be the case with a composition including the PCM alone in an equivalent system and environment. Example additives may include graphite or a metal foam.

[0018] A relationship between the mass of a composition containing a PCM with subcooling capability and the mass of a battery cell can influence whether the composition heats the battery cell to a target temperature. The total heat contained in the mass of the composition, measured in joules (J), can be determined by multiplying the latent heat of the composition, measured in J / kg, by the mass of the composition, measured in kg. Similarly, a resulting temperature change of the battery cell, measured in °C, can be determined by dividing the specific heat of the battery, measured in J / (kg*°C), by the mass of the battery, measured in kg, into the heat transferred from the composition to the battery cell, measured in J.

[0019] Fig. 1 shows a method for using a subcooling PCM to heat a battery cell and, at another time, cool the battery cell. A legend 134 shows that an arrow plus sun rays indicates heat transfer. The figure shows a charge request 102 being transmitted 104 to trigger a phase change 106 in the subcooling PCM. This trigger 106, applied 108 to a subcooled liquid PCM 110, causes a transition to the solid phase 114. As the liquid PCM 110 undergoes a solid phase transition 114 to become a solid 112, heat is released 116, and this heats an adjacent battery cell 118. While a battery is being charged 120, heat is generated 122, and this causes a solid PCM 124 to transition to the liquid phase 128.When the solid PCM 124 undergoes a liquid phase change 128 to become a liquid 126, the phase change 128 removes heat 122 from the battery, resulting in cooling of a battery cell 132 130.

[0020] Fig. 2 shows a battery temperature management device. The battery temperature management device includes a battery cell 212 adjacent to a temperature-modulating cell 210. The temperature-modulating cell 210 includes a composition that includes a PCM with subcooling function 208. An ultrasonic transducer 206 is included in the composition 208, and the ultrasonic transducer 206 is connected 204 to a controller 202. In Fig. Figure 2 shows the ultrasonic transducer 206 submerged in the composition 208 and directly connected to the controller 202 (Figure 204). Some embodiments may involve the ultrasonic transducer 206 not being submerged as shown, but instead adjacent to the composition 208 or located outside the temperature-modulating cell 210. Some embodiments may replace the ultrasonic transducer 206 with another trigger to induce nucleation in the PCM with subcooling function, such as a submerged disk disturbed by an electrical signal. Some embodiments may connect the controller 202 and the ultrasonic transducer 206 indirectly via an intermediate component or wirelessly.

[0021] Fig. 3 shows an exemplary operation of the battery temperature management device from Fig. 2. The controller receives a charging request 302. The controller switches on the ultrasonic transducer 304, and the ultrasonic transducer releases the composition 306, which includes a PCM with a subcooling function, so that a change to the solid phase occurs. The phase change generates heat 308, which is conducted to an adjacent battery cell.

[0022] Fig. 4 shows a vehicle 402. The vehicle 402 includes a controller 404, and the vehicle 402 includes a battery cell 414 adjacent to a temperature-modulating cell 412. The temperature-modulating cell 412 includes a composition including a PCM with subcooling function 410. A submerged disk 408 is included in the composition 410, and the submerged disk 408 is connected 406 to the controller 404. In Fig. Figure 4 shows the submerged disk 408 directly connected to the controller 404. Some embodiments can connect the controller 402 and the submerged disk 408 indirectly via an intermediate component or wirelessly. Some embodiments can replace the submerged disk 408 with another trigger, such as an ultrasonic transducer, to induce nucleation in the PCM with subcooling function. Some embodiments can connect the controller 404 and the ultrasonic transducer 408 indirectly via an intermediate component or wirelessly. Some embodiments can include the submerged disk 408 containing a metallic substance.

[0023] Fig. 5 shows an example operation of the vehicle from Fig. 4. A charge request 502 is transmitted to the controller. The controller perturbs 504 the submerged disk, and the perturbation triggers 506 the composition, which includes a PCM with a subcooling function, to switch to the solid phase. The phase change generates heat 508, which is conducted to an adjacent battery cell. A predetermined mass of the composition is such that the battery cell is heated to 30°C to 50°C. The amount of mass required to achieve this heating can be determined through testing, simulation, etc. Fig. 5 illustrates that the charging request 502 originates outside the vehicle. Some embodiments may include a charging request 502 originating from inside the vehicle.

[0024] The algorithms, methods, or processes disclosed in this document may be executable by or implemented by a computer, controller, or processing device, which may include any dedicated electronic control unit or programmable electronic control unit. Furthermore, the algorithms, methods, or processes may be stored in many forms as computer- or controller-executable data and instructions, including, but not limited to, information permanently stored on non-writable storage media, such as read-only memory devices, and information modifiably stored on writable storage media, such as compact discs, random access memory devices, or other magnetic and optical media. The algorithms, methods, or processes may also be implemented in software-executable objects.Alternatively, the algorithms, methods, or processes may be implemented in whole or in part using suitable hardware components, such as application-specific integrated circuits, field-programmable gate arrays, state machines, or other hardware components or devices, or a combination of firmware, hardware, and software components.

[0025] Although exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms included in the claims. Other topologies and variations are naturally considered.

[0026] The terms used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosed subject matter. For example, the terms "controller" and "controllers" may be used interchangeably throughout this specification, since the functionality of a controller may be distributed across multiple controllers / modules, all of which may communicate using standard techniques.

[0027] As previously described, the features of different embodiments can be combined to form further embodiments of the invention, which may not be expressly described or illustrated. Although various embodiments may have been described in such a way that they offer advantages or are preferred over other embodiments or implementations according to the prior art with respect to one or more desired properties, the person skilled in the art understands that compromises may be made with respect to one or more features or properties in order to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, among others, strength, durability, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc.Thus, embodiments that are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.

[0028] According to the present invention, a method includes: in response to a request to charge a battery, initiating a first phase change in a supercooled phase change material ("PCM") of a composition adjacent to the battery, causing the PCM to solidify to release latent stored heat to heat the battery; and during charging, absorbing heat by the PCM as it undergoes a second phase change, causing the PCM to liquidize to cool the battery.

[0029] In one aspect of the invention, triggering involves switching on an ultrasonic transducer to cause the composition to solidify through nucleation.

[0030] In one aspect of the invention, triggering involves disturbing a submerged disc with an electrical signal to cause the composition to solidify through nucleation.

[0031] In one aspect of the invention, the composition includes a thermally conductive additive such that the thermal conductivity of the composition containing the additive is greater than the thermal conductivity of the PCM.

[0032] In one aspect of the invention, a predefined mass of the composition is used to heat the battery to 30 °C to 50 °C.

[0033] In one aspect of the invention, the composition includes a predefined mixture of PCMs, such that the melting point of the composition is between 35 °C and 60 °C.

[0034] According to the present invention, a battery temperature management device is provided, comprising: a temperature modulating cell containing a battery-adjacent composition including a phase change material ("PCM") configured to be supercooled; an ultrasonic transducer; and a controller programmed to turn on the ultrasonic transducer upon receiving a request to charge the battery, causing a first phase change in the PCM, thereby solidifying the PCM and releasing latent stored heat.

[0035] According to one embodiment, the temperature modulating cell contains a volume of the composition that is smaller than a total volume of the temperature modulating cell, such that the composition can expand to fill a space defined by the temperature modulating cell when the phase is changed.

[0036] According to one embodiment, the temperature modulating cell includes a predetermined mass of the composition to heat the battery to 30°C to 50°C.

[0037] According to one embodiment, the composition comprises a mixture of PCMs such that a melting point of the composition is between 35 °C and 60 °C.

[0038] According to one embodiment, the composition further includes a thermally conductive additive such that the thermal conductivity of the composition including the additive is greater than the thermal conductivity of the PCM.

[0039] According to one embodiment, the thermally conductive additive comprises a metal foam.

[0040] According to one embodiment, the thermally conductive additive includes graphite.

[0041] According to the present invention, a vehicle is provided including: a battery; a temperature modulating cell containing a composition adjacent to the battery including a phase change material ("PCM") configured to be supercooled; a submerged disk; and a controller programmed, upon receiving a request to charge the battery, to send an electrical signal to disturb the disk to cause a first phase change in the PCM, thereby solidifying the PCM to release latent stored heat.

[0042] According to one embodiment, the temperature modulating cell contains a volume of the composition that is smaller than a total volume of the temperature modulating cell, such that the composition can expand to fill a space defined by the temperature modulating cell when the phase is changed.

[0043] According to one embodiment, the temperature modulating cell includes a predetermined mass of the composition to heat the battery to 30°C to 50°C.

[0044] According to one embodiment, the composition includes a mixture of PCMs, such that the melting point of the composition is between 35 °C and 60 °C.

[0045] According to one embodiment, the composition further includes a thermally conductive additive such that the thermal conductivity of the composition including the additive is greater than the thermal conductivity of the PCM.

[0046] According to one embodiment, the heat-conducting additive is a metal foam.

[0047] According to one embodiment, the heat-conducting additive is graphite.

Claims

[1] Method comprising: in response to a request to charge a battery, initiating a first phase change in a supercooled phase change material (“PCM”) of a composition adjacent to the battery, causing the PCM to solidify to release latent stored heat to heat the battery; and During charging, the PCM absorbs heat as it undergoes a second phase change that causes the PCM to become liquid to cool the battery. [2] The method of claim 1, wherein said triggering includes turning on an ultrasonic transducer to cause the composition to solidify by nucleation. [3] The method of claim 1, wherein said triggering includes disturbing a submerged disk with an electrical signal to cause the composition to solidify by nucleation. [4] The method of claim 1, wherein the composition includes a thermally conductive additive such that the thermal conductivity of the composition including the additive is greater than the thermal conductivity of the PCM. [5] The method of claim 1, wherein a predefined mass of the composition is used to heat the battery to 30°C to 50°C. [6] The method of claim 1, wherein the composition comprises a predefined mixture of PCMs such that a melting point of the composition is between 35 °C and 60 °C. [7] Battery temperature management device, comprising: a temperature modulating cell including a battery-adjacent composition including a phase change material (“PCM”) configured to be supercooled; an ultrasonic transducer; and a controller programmed to turn on the ultrasonic transducer upon receiving a request to charge the battery, causing an initial phase change in the PCM, causing the PCM to solidify and release latent stored heat. [8] The battery temperature management device of claim 7, wherein the temperature modulating cell contains a volume of the composition that is less than a total volume of the temperature modulating cell such that the composition can expand to fill a space defined by the temperature modulating cell when the phase is changed. [9] The battery temperature management device of claim 7, wherein the temperature modulating cell includes a predetermined mass of the composition to heat the battery to 30°C to 50°C. [10] The battery temperature management device of claim 7, wherein the composition includes a mixture of PCMs such that a melting point of the composition is between 35°C and 60°C. [11] The battery temperature management device of claim 7, wherein the composition further includes a thermally conductive additive such that the thermal conductivity of the composition including the additive is greater than the thermal conductivity of the PCM. [12] The battery temperature management device of claim 11, wherein the thermally conductive additive includes a metal foam. [13] The battery temperature management device of claim 11, wherein the thermally conductive additive includes graphite. [14] Vehicle comprising: a battery; a temperature modulating cell including a battery-adjacent composition including a phase change material (“PCM”) configured to be supercooled; a submerged disc; and a controller programmed, upon receiving a request to charge the battery, to send an electrical signal to disturb the disk to initiate a first phase change in the PCM, causing the PCM to solidify to release latent stored heat. [15] The vehicle of claim 14, wherein the temperature modulating cell contains a volume of the composition that is less than a total volume of the temperature modulating cell such that the composition can expand to fill a space defined by the temperature modulating cell when the phase is changed.

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