Batteries with an integrated cooling system

Abstract

The invention relates to a novel cooling system integrated into lithium-ion (Li-ion) batteries. This system comprises two flexible liquid-cooling plates configured to dissipate heat generated by the cylindrical Li-ion batteries, in particular heat accumulated at the center thereof. These flexible plates incorporate a specific mixture of water and glycol, thereby optimizing their thermal conductivity while preventing corrosion and algal growth. The cooling process relies on liquid convection, thereby ensuring optimal battery operation and extending battery service life.

Description

[0001] Batteries with Integrated Cooling System

[0002] FIELD OF INVENTION

[0003] The present invention relates to an innovative cooling system integrated into lithium-ion (Li-ion) batteries. Composed of two flexible liquid cooling plates, this system is designed to dissipate the heat generated by cylindrical Li-ion batteries, particularly the heat accumulated at their center. These flexible plates incorporate a specific mixture of water and glycol, thus optimizing their thermal conductivity while preventing corrosion and algae growth. The cooling process relies on liquid convection, ensuring optimal battery operation and extending their lifespan.

[0004] EARLIER ART

[0005] Lithium-ion batteries play a crucial role in various fields, particularly in electric mobility. With the increasing prevalence of electric micromobility in our daily lives, these batteries have become ubiquitous. However, electric micromobility vehicles, often lacking dedicated cooling systems, expose their batteries to the risk of overheating. This can lead to rapid battery deterioration and, in the most serious cases, safety incidents such as explosions.

[0006] Li-ion battery overheating results from various factors, including improper charging and discharging conditions (excessive voltage or current, particularly during rapid charging or aggressive discharging), internal short circuits due to manufacturing defects or physical damage, as well as high ambient temperatures, exposure to external heat sources, or natural aging. This combination of factors can compromise battery stability and safety by leading to heat buildup.

[0007] Integrating battery cooling systems, commonly used in electric cars, into electric micromobility vehicles presents significant technical and economic challenges. These sophisticated systems are complex to adapt and can lead to a substantial increase in the production and maintenance costs of small electric vehicles. Furthermore, most of these vehicles are equipped with only a temperature sensor, which limits the optimal use of the battery module.

[0008] Temperature plays a fundamental role in the performance and durability of Li-ion batteries. At high temperatures, battery capacity and lifespan are reduced, while the risk of internal degradation increases. Conversely, excessively low temperatures also decrease capacity but can lead to increased internal resistance, affecting battery responsiveness and charging. These thermal variations impact the kinetics of electrochemical reactions, thus altering the structure of the electrodes and causing degradation, directly affecting the performance and longevity of Li-ion batteries.

[0009] According to Li, Shen, et al. in their study entitled "Optimal cell tab design and cooling strategy for cylindrical lithium-ion batteries" published in the Journal of Power Sources 492 (2021): 229594, high temperatures in Li-ion batteries significantly impact their state of health (SoH). Based on electrothermal simulations and experimental measurements by Jiang, Lei, et al. in their study entitled "Electrothermal modeling and experimental verification for 18650 Li-ion cell," published in the IEEE Vehicle Power and Propulsion Conference (2016), this heat accumulates at the center of the cylindrical Li-ion battery. This leads to temperature differences between the center and the ends of the battery, creating a thermal gradient that can alter the current density and cause various electrode failures, thus accelerating aging and inducing thermal runaway.

[0010] To address this issue, the addition of dual flexible liquid cooling plates (PFRLs) to the surface of the battery's outer metal casing is proposed. This approach aims to efficiently dissipate the heat accumulated in the battery's core towards the extremities, thereby lowering the temperature and achieving a uniform temperature profile, thus preserving optimal performance and durability.

[0011] BRIEF DESCRIPTION OF THE INVENTION

[0012] The present invention aims to improve the safety, performance, and durability of Li-ion batteries by using a double PFRL (Flexible Liquid Cooling Plate) deposited on the battery's outer metallic casing. This self-cooling battery can reduce the temperature buildup at the battery's core during aggressive charging and discharging, thus preserving the battery's health over a longer period. These batteries can be assembled into modules or packs, suitable for the electric mobility industry or any other market requiring electrical energy storage.

[0013] This invention relates to Li-ion batteries that can be integrated into portable devices or electric motor vehicles, such as laptops, electric scooters, or motorcycles. These self-cooling batteries are rechargeable and allow for the storage of electrical energy.

[0014] The self-cooling Li-ion energy storage system can be used as a single cell or in the form of battery packs or modules. BRIEF DESCRIPTION OF DRAWINGS

[0015] In all drawings, similar reference numbers designate the same object or action, unless the context indicates otherwise. The sizes and relative positions of objects in the drawings are not necessarily drawn to scale.

[0016] Figure 1: Top view of the PFRL according to an embodiment of the present invention.

[0017] Figure 2: Cross-sectional view of the PFRL.

[0018] Figure 3: Top view of two opposing PFRLs, deposited on an outer metallic casing before their assembly in a cylindrical Li-ion battery.

[0019] Figure 4: Three-dimensional view of the cylindrical self-cooling Li-ion battery based on liquid convection.

[0020] DETAILED DESCRIPTION OF THE INVENTION

[0021] In the following description, certain aspects are discussed in detail for a clear understanding of the disclosed invention. It should be noted that the well-known structures and methods of manufacturing Li-ion batteries and liquid cooling plates have not been addressed.

[0022] The disclosed self-cooling battery features a significant innovation for improving and maintaining consistent performance over numerous operating cycles. This improvement includes the use of two PFRLs deposited on the battery's outer metallic casing, as described in Figures 1-2-3-4. Each embodiment is detailed below.

[0023] Figure 1 illustrates the structure of the PFRL 100 according to the embodiment of this disclosure, which is based on liquid cooling technology. The operation of the PFRL is based on a heat transfer system between the evaporator 1 and the thermal diffusion plate 2.

[0024] During fast charging, a significant amount of energy is rapidly injected into the battery to recharge it in a short period of time. This process can lead to higher internal resistance within the battery, which generates heat. Furthermore, fast charging can increase the chemical reaction within the battery, causing a rise in temperature, particularly in the center of the battery.

[0025] Similarly, during a rapid discharge, the battery releases stored energy more quickly than during a normal discharge. This faster energy release can also increase the battery's internal resistance, leading to heat generation that accumulates in the center of the battery.

[0026] These rapid charging and discharging processes can exacerbate energy efficiency losses and increase heat loss within the battery. More intense electrochemical reactions, coupled with the rapid flow of lithium ions between the anode and cathode, contribute to this temperature increase.

[0027] Higher temperatures can affect battery performance, accelerate aging, and in some cases, cause long-term damage by altering electrode materials or degrading the electrolyte. Therefore, thermal management is crucial for maintaining an appropriate temperature during the rapid charging and discharging of Li-ion batteries.

[0028] Evaporator 1 comes into direct contact with the center of the battery, where heat accumulates. When heat reaches evaporator 1, the coolant inside absorbs this heat, causing partial evaporation of the liquid. This change of state, from liquid to gas (evaporation), allows for efficient heat absorption at the center of the battery.

[0029] Next, the gas thus formed moves towards the thermal diffusion plate 2. This plate is designed to diffuse heat over a larger surface area, allowing for more efficient dissipation to areas further from the hottest zone. The heat is dispersed within this plate, where it is distributed more evenly, facilitating its dissipation outwards and to the cell's extremities.

[0030] The liquid, meanwhile, returns to evaporator 1 after releasing heat, thus completing the cooling process. This circulation of the liquid between evaporator 1 and heat diffusion plate 2 allows for the continuous absorption and dissipation of heat, thereby maintaining more stable operating temperatures in the battery.

[0031] The internal structure of PFRL 200, as shown in Figure 2, can be fabricated on a graphite base layer 5. The detailed manufacturing process of PFRL 100 in this embodiment of the present disclosure can be described as follows:

[0032] 1. Precise Design: Define the detailed specifications, including the overall shape of the PFRL 100, the size, and the channel layout. Computer-aided design (CAD) software such as Ansys SpaceClaim can be used to model and plan the channel geometry according to the specific cooling requirements of the batteries.

[0033] 2. Specific Materials: Materials are selected based on their thermal and mechanical properties. Flexible polymers and thermally conductive materials such as graphite can be used. These materials are prepared as base layers for the fabrication of the PFRLs. 3. Channel Fabrication: Channels are created on the graphite base layer 5, prepared using precise manufacturing techniques. Laser cutting or molding methods can be employed to shape the cooling channels with high precision. In this design, three types of channels were adopted to maximize cooling efficiency by controlling liquid movement:

[0034] - The 6 thin channels are designed to maximize the contact area between the coolant and the hot surface. They allow a more concentrated flow of coolant into the heat-generating areas, thus ensuring efficient heat absorption.

[0035] - The wide channel 7 facilitates the movement of the coolant after it has absorbed heat. Once the liquid has absorbed the thermal energy from hot areas, this wider channel allows it to move more freely. This helps to distribute the heated liquid over a larger surface area, contributing to its dissipation and preventing localized overheating.

[0036] - Tesla's 8 micro-valves ensure one-way coolant flow from the 6 thin channels to the 7 wide channel, preventing heat from flowing in the opposite direction. This doubles the heat dissipation capacity of standard vapor chambers, allowing for a slimmer design.

[0037] 4. Coolant Injection: Once the channels are integrated, the specific coolant is carefully injected into them. This step requires meticulous handling to ensure complete and uniform filling of all channels.

[0038] 5. Sealing and Quality Testing: The channels are sealed with a graphite top layer 3 to ensure the system is leak-proof. Vias 4 can then be fabricated on the wide channel 7 to equalize pressure and facilitate gas movement within the system, thus preventing the formation of air pockets. These vias 4 are precisely designed and manufactured to prevent leaks, ensuring they are properly sealed and insulated to contain the liquid within the designated channels. These techniques involve the use of appropriate sealing materials and manufacturing processes that guarantee the integrity of the PFRL 100, preventing leaks despite the presence of numerous vias. Rigorous testing, such as pressure tests to verify seal integrity and performance tests to evaluate cooling efficiency, is conducted to ensure the quality of the PFRL 100.

[0039] 6. Integration into the battery: Once the quality tests are successful, the PFRLs are deposited on an outer metallic casing 9 to form a double opposed PFRLs casing 300, as illustrated in Figure 3. This casing then takes its tubular shape to accommodate the internal battery components, including the electrodes and electrolyte.

[0040] Figure 4 illustrates the three-dimensional view of the self-cooling battery.

[0041] 400, consisting of a cylindrical Li-ion battery 10, where its double-sided opposing PFRL casing 300 can be covered with polypropylene (PP) or polyethylene (PE). These plastics are often used to hold the internal components of the battery.

[0042] The disclosed 400 self-cooling battery is designed to minimize temperature during rapid charging and discharging, thereby extending its lifespan while maintaining consistent charging time and capacity performance. This battery can be used in various emerging applications such as micromobility, wearable electronics, and energy storage systems.

[0043] INDUSTRIAL APPLICATION

[0044] The industrial application of this invention, a self-cooling battery with dual PFRLs (flexible liquid cooling plates), is crucial for improving the thermal management of batteries used in electric micromobility vehicles, drones, and portable devices. By effectively regulating battery temperature, this technology increases battery lifespan, improves safety by preventing overheating, and optimizes energy performance. The integration of this flexible cooling plate addresses the growing need for more reliable and sustainable energy systems in various industrial sectors.

[0045] REFERENCES

[0046] Li, Shen, et al. “Optimal cell tab design and cooling strategy for cylindrical lithium-ion batteries.” Journal of Power Sources 492 (2021): 229594.

[0047] Jiang, Lei, et al. "Electro-thermal modeling and experimental verification for 18650 Li- ion cell." 2016 IEEE Vehicle Power and Propulsion Conference (VPPC). IEEE, 2016.

[0048] 5

[0049] 10

Claims

DEMANDS 1. Self-cooling battery (400), comprising: a cylindrical lithium-ion battery (10), which in turn comprises a casing with opposing double flexible liquid cooling plates (PFRLs) (300) 2. The battery, according to claim 1, wherein the two PFRLs (100) are deposited in a mirror manner, ensuring cooling of the Li-ion battery during rapid charging and discharging.

3. The battery, according to claims 1 and 2, wherein each PFRL (100) comprises: • a base layer (5) and a top layer (3) made of a flexible, inelastic material, such as graphite, having a high thermal conductivity of approximately 150 W / mK • Thin channels (6) to maximize the contact area between the coolant and the hot surface, allowing a more concentrated flow of coolant into heat-generating areas, thus ensuring efficient heat absorption. • an evaporator (1) in direct contact with the center of the battery (10), where heat accumulates, causing partial evaporation of the coolant inside, which allows for efficient heat absorption. • a thermal diffusion plate (2) designed to diffuse heat over a larger area, thus enabling more efficient dissipation to areas away from the hottest area and facilitating its uniform distribution and dissipation outwards and to the ends of the battery (10). • a wide channel (7) facilitating the movement of the coolant after heat absorption in the evaporator (1), allowing a more uniform distribution of the heated liquid over a larger area to promote its dissipation and avoid localized overheating.

4. The battery, according to claims 1 to 3, wherein the PFRL (100) is characterized in that the evaporator (1) comprises Tesla micro-valves (8) to prevent heat from moving in the reverse direction.

5. The battery, according to claims 1 to 4, where the PFRL (100), is characterized in that the wide channel (7) includes vias (4) to equalize pressure and facilitate the movement of gases in the system, thus avoiding the formation of air pockets.

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