Immersion Cooling for EV Battery Temperature Control

1. Full Immersion Cooling Systems Using Dielectric Fluids

Immersion cooling represents a paradigm shift in thermal management for electric vehicle battery systems, offering direct thermal contact between cells and coolant. Unlike conventional air or indirect liquid cooling methods that struggle with thermal resistance and uneven heat distribution, full immersion systems provide comprehensive thermal coverage of battery cells.

One significant implementation submerges lithium-ion cells directly in glycol-based coolant within a sealed enclosure. This approach ensures consistent temperature regulation by eliminating the thermal bottlenecks associated with indirect cooling methods. The system incorporates a hermetic sealant at cell terminals, preventing coolant ingress while maintaining electrical isolation. This design not only enhances thermal performance during high-rate charging and discharging but also offers economic advantages by utilizing standard glycol-based fluids rather than specialized dielectric coolants.

For applications requiring enhanced heat transfer coefficients, the vortex generator-enhanced cooling block provides a sophisticated solution. This system addresses the fundamental limitations of traditional cooling approaches that rely on contact with base plates, which restrict thermal efficiency due to limited surface area engagement. By immersing batteries in insulating fluid and incorporating precisely engineered vortex generators along the cooling block's inner walls, the system creates controlled turbulence patterns that significantly increase local convective heat transfer. The design maintains a calculated minimum clearance between vortex structures and cells to optimize fluid dynamics while preventing excessive pressure drop. This configuration delivers superior thermal uniformity across various cell geometries and can be adapted to accommodate future high-energy-density battery formats.

A third approach focuses on mechanical integration through a modular battery pack architecture with compressible spacer plates. This design tackles the thermal gradient challenges inherent in densely packed battery arrays using cold plate systems. Battery cells are positioned between compressible plates within a sealed shell and submerged in non-conductive dielectric fluid. The compressible spacers serve dual functions: securing cells while enhancing mechanical compliance to accommodate thermal expansion and reduce vibration stress. Integrated fluid passages within the spacer assembly facilitate efficient coolant circulation throughout the battery array. This architecture supports high cell density while improving safety through electrical isolation, with the added benefit of simplified maintenance due to its modular configuration.

2. Partial Immersion and Hybrid Cooling Configurations

While full immersion cooling offers comprehensive thermal coverage, partial immersion and hybrid configurations provide targeted cooling solutions that balance thermal performance with practical constraints such as weight, cost, and integration complexity. These approaches strategically apply immersion cooling to critical thermal regions while using alternative methods elsewhere.

Traditional cooling methods typically access only the top and bottom surfaces of battery cells, which represent a small fraction of the total heat-generating area. This limitation becomes particularly problematic in high-density modules where the primary heat-generating side surfaces remain thermally isolated. The inner partition wall design addresses this fundamental limitation through a novel architectural approach. Battery cells are inserted through a specialized partition that divides each cell into upper and lower regions, allowing dielectric cooling liquid to contact the middle section of cells directly. This configuration targets cooling precisely where thermal management is most critical while maintaining structural simplicity and preserving energy density by eliminating bulky heat sinks.

The thermal performance of this partial immersion approach significantly outperforms conventional methods. By enabling direct coolant contact with the side surfaces of cells, heat extraction occurs at the primary thermal generation sites rather than relying on conduction through limited contact points. The partition wall, constructed from thermally stable, electrically insulating materials, provides both structural support and electrical isolation while facilitating the controlled flow of dielectric coolant.

Complementing this approach, metal-enclosed pouch-type battery units integrate immersion cooling with advanced thermal isolation and gas management systems. Individual cells are housed in metal cases featuring dedicated exhaust ports and thermal insulation layers, then fully submerged in dielectric fluid circulated through supply and return manifolds. This design addresses both thermal management and safety concerns simultaneously. During normal operation, the dielectric fluid provides efficient cooling; during failure events, hot gases vent through exhaust ports into a centralized manifold, effectively containing thermal runaway propagation. The additional insulating and partitioning elements between cells create multiple barriers against heat transfer and mechanical impact.

Both configurations demonstrate how partial immersion and hybrid approaches can be tailored to specific battery architectures. The partition wall design enables high-density packing with targeted thermal control, while the metal-enclosed system provides a comprehensive safety framework for high-voltage applications by combining immersion cooling with gas isolation and thermal compartmentalization. These hybrid strategies represent the evolution of battery thermal management toward systems that balance multiple performance parameters simultaneously.

3. Metal-Capped or Exhaust-Enabled Cell Designs for Thermal Runaway Mitigation

As energy density and power requirements increase in electric vehicle batteries, thermal runaway mitigation becomes increasingly critical. Advanced immersion cooling systems now incorporate specialized structural elements and exhaust mechanisms that not only manage normal operating temperatures but also actively contain thermal events.

The metal-capped pouch cells with exhaust-enabled enclosures represent a significant advancement in this domain. Unlike conventional battery enclosures that may trap heat and gases during failure events, these cells feature metallic shells with integrated exhaust ports and thermal insulation layers strategically positioned around vent regions. This design connects each cell's exhaust port to a dedicated manifold system that actively channels hot gases away from the battery enclosure during failure events. By preventing the accumulation of heat and flammable gases within the battery compartment, the system substantially reduces thermal runaway propagation risk. The structural partitioning between cells provides additional mechanical protection and thermal isolation, creating multiple barriers against cascading failures.

The thermal management capabilities of these systems are further enhanced through immersion cooling with extended coolant paths and turbulent flow optimization. This approach addresses the limitations of conventional cooling methods by fully submerging cells in dielectric coolant within a sealed enclosure. An internal baffle system divides the enclosure into distinct flow regions, forcing coolant to travel an extended path around the batteries. Strategically positioned flow spoilers induce controlled turbulence, significantly improving heat transfer coefficients. This configuration eliminates the thermal resistance typically introduced by intermediate materials such as cold plates or channel walls, resulting in more uniform temperature distribution and improved thermal response during both normal operation and thermal events.

System safety is further enhanced through the integration of deionization and ion monitoring mechanisms within the immersion-cooled battery pack. This system submerges both battery modules and high-voltage busbars in dielectric liquid while maintaining a controlled gap above the modules for optimized coolant flow. The design incorporates a flow-diverting upper cover and parallel channel network that minimize hydraulic resistance while maximizing coolant distribution. The distinguishing feature of this system is its deionization unit and conductive ion sensor, which continuously monitor and maintain the electrical insulation properties of the coolant. This ensures long-term dielectric integrity even under high-voltage conditions and provides rapid response capability if ion contamination occurs.

These integrated approaches to thermal safety represent a fundamental shift in battery system design philosophy. Rather than treating thermal management and safety as separate concerns, these technologies incorporate structural innovations, immersion cooling, and active monitoring systems into cohesive architectures that provide multiple layers of protection against thermal runaway while maintaining optimal operating temperatures during normal use.

4. Flow Path Optimization and Channel Design for Uniform Temperature Distribution

Achieving uniform temperature distribution across battery modules remains one of the most significant challenges in immersion cooling system design. The flow path architecture fundamentally determines cooling efficiency, thermal gradients, and system response to varying load conditions.

Traditional immersion cooling systems often introduce coolant through side plates, creating extended flow paths along the length or width of the battery core. This approach inevitably produces temperature gradients between upstream and downstream regions, resulting in uneven cooling and potential thermal stress. The multi-cavity top-down flow path architecture addresses this fundamental limitation by radically shortening coolant travel distance. This design utilizes an upper cover plate with precisely engineered strip-shaped through-holes and a diverter plate that distributes coolant vertically from the top of the battery stack. A complementary bottom plate facilitates efficient drainage, while integrated crossbeams with embedded water outlets and longitudinal beams with channel gaps ensure consistent coolant flow across all cells. This vertical distribution approach significantly reduces thermal gradients compared to horizontal flow configurations, enhancing temperature uniformity throughout the battery pack.

The thermal performance characteristics of this vertical flow system demonstrate several advantages over conventional approaches. By minimizing coolant travel distance, the system reduces the temperature differential between cells at different positions within the module. The uniform distribution of coolant from above ensures that all cells receive similar cooling capacity regardless of their position in the pack, eliminating the "first cell advantage" common in series-flow cooling systems. Additionally, the vertical flow pattern aligns with natural convection tendencies, enhancing passive thermal management during low-load conditions.

For applications where battery tabs create significant thermal hotspots due to high current density, the heat pipe-assisted dual-plate cooling architecture offers a specialized solution. This composite system addresses the challenge of localized heat accumulation at tabs without exposing these electrically sensitive components to direct coolant contact. Heat pipes extract thermal energy from tab regions and transfer it to an upper liquid cooling plate physically separated from the battery core. A lower cooling plate manages baseline thermal loads through direct contact with the battery. This decoupled approach provides targeted cooling for high-temperature zones while maintaining electrical safety by eliminating direct coolant exposure to sensitive components.

An alternative approach for managing complex thermal geometries around battery cells employs a solid-liquid two-phase immersion heat sink using polyurethane as the thermal medium. This innovative material transitions between solid and liquid phases in response to temperature changes, conforming to intricate cell surfaces during heating and providing consistent thermal contact. As the system cools, the medium resolidifies, effectively trapping heat while maintaining structural integrity. This phase-change mechanism ensures uniform thermal extraction from all cell surfaces, including traditionally difficult-to-cool regions, significantly reducing thermal hotspots and enhancing overall heat transfer efficiency.

These flow optimization approaches represent the evolution of immersion cooling from simple submersion concepts to sophisticated thermal management systems with engineered flow paths specifically designed to address the complex thermal challenges of high-performance battery systems.

5. Turbulence-Inducing Structures to Enhance Heat Transfer

The thermal performance of immersion cooling systems can be significantly enhanced through engineered turbulence that disrupts boundary layers and increases convective heat transfer coefficients. While laminar flow provides predictable thermal characteristics, deliberately induced turbulence can dramatically improve cooling efficiency in high-power applications.

The immersion-type battery cooling system with integrated vortex generators represents a sophisticated approach to turbulence engineering. This system addresses the fundamental limitations of traditional bottom-cooled designs, where limited contact area and poor thermal conductivity result in inadequate heat transfer and temperature non-uniformity. By immersing battery cells directly in dielectric coolant and incorporating precisely designed vortex generators on the cooling block's inner walls, the system creates controlled turbulent flow patterns around the cells. These vortex generators feature specific geometric configurations—including pillar, triangular, and fan-shaped protrusions—with a calculated minimum clearance of 3 mm from battery surfaces to maintain flow efficiency.

The thermal performance of this system is optimized through precise geometric relationships. The spacing between vortex elements follows the ratio d/L ≥ 0.1 (where d represents the distance between elements and L is battery length), maximizing turbulence generation while preventing excessive pressure drops that would increase pumping power requirements. This carefully engineered turbulence enhances convective heat transfer coefficients by disrupting thermal boundary layers that would otherwise insulate the cell surface from the bulk coolant flow. The result is significantly improved cooling uniformity and increased overall heat transfer efficiency, reducing maximum cell temperatures and minimizing thermal gradients across the battery module.

Complementing this passive turbulence approach, the immersed liquid-cooled energy storage battery module introduces active turbulence generation through mechanical means. This system addresses the limitations of stagnant coolant flow by incorporating a reciprocating assembly with a swinging fin that actively agitates the dielectric coolant. The mechanical motion disrupts laminar flow patterns, creating dynamic turbulence that significantly enhances heat transfer from battery surfaces to the surrounding coolant. The system's mechanical design includes a limit chute and slider mechanism that prevents reciprocating parts from misaligning, ensuring consistent operation of the gear system and long-term reliability.

The performance advantages of active turbulence generation are particularly evident during transient thermal events such as rapid charging or high-power discharge. By continuously disrupting thermal stratification within the coolant, the system prevents the formation of localized hot spots and maintains more uniform temperature distribution throughout the battery module. The mechanical agitation also helps prevent coolant stagnation in complex geometries where natural flow might be restricted, ensuring comprehensive thermal management across all battery surfaces.

These turbulence-enhancing approaches demonstrate how advanced fluid dynamics principles can be applied to immersion cooling systems to overcome the limitations of simple submersion. By precisely controlling flow characteristics through either passive structures or active mechanical systems, these designs achieve superior thermal performance while maintaining the fundamental advantages of direct liquid-to-cell contact that defines immersion cooling.

6. Modular and Scalable Immersion-Cooled Battery Pack Architectures

The practical implementation of immersion cooling in production electric vehicles requires modular architectures that support manufacturing scalability, serviceability, and platform flexibility. Advanced modular designs address these requirements while maintaining optimal thermal performance.

Traditional battery pack designs often employ monolithic cooling structures that limit configurability and complicate manufacturing. The stackable, plug-and-play architecture overcomes these limitations through a modular approach where each cooling unit consists of a fluid distributor plate and housing base enclosing multiple cells. These components feature integrated inlet and outlet channels that align when modules are stacked, creating continuous fluid pathways without requiring external manifolds or complex sealing systems. This design enables high customization flexibility in battery pack capacity and performance through simple addition or removal of modules, significantly enhancing manufacturing efficiency and product adaptability across vehicle platforms.

The thermal performance of this modular system is enhanced through its gravity-assisted and axial flow design. Coolant enters through channels positioned below the battery cells, leveraging natural convection to promote bottom-up flow patterns that align with thermal buoyancy effects. Simultaneously, axial flow through strategic passage openings in the distributor plate ensures even thermal distribution throughout the module. This dual-flow approach maximizes cooling efficiency while minimizing thermal gradients, improving both battery safety and longevity. The integrated venting mechanism within the outlet channels provides an additional safety feature by mitigating pressure buildup during thermal events.

A significant challenge in modular immersion cooling is maintaining unobstructed coolant flow when integrating essential components such as sensing boards and bus bars. The integration of flow openings within sensing boards and bus bars addresses this challenge by enabling direct coolant circulation between battery cells even in densely packed configurations. These openings are strategically positioned along the stacking direction of cells and mounted on the module's end plate, ensuring continuous coolant pathways without compromising electrical connections or sensing capabilities.

This approach to internal flow structure optimization enhances cooling uniformity while maintaining full electronic functionality. By enabling coolant and electronic interfaces to coexist within the same structural envelope, the design simplifies system integration and supports modular scalability across diverse vehicle platforms with varying thermal requirements and spatial constraints.

The modularity of these systems extends beyond manufacturing advantages to include significant benefits for battery lifecycle management. Individual modules can be replaced or serviced without compromising the entire pack, and damaged sections can be isolated to prevent system-wide failures. Additionally, the standardized interfaces between modules facilitate battery pack reconfiguration for different vehicle models, reducing development costs and accelerating time-to-market for new electric vehicle platforms.

7. Immersion Cooling with Electrical Isolation and Safety Features

The direct contact between coolant and electrically active components in immersion cooling systems necessitates sophisticated electrical isolation strategies to ensure operational safety and reliability. Advanced immersion systems incorporate multiple layers of electrical protection while maintaining optimal thermal performance.

Traditional cooling methods such as air cooling, phase change materials, and liquid channel systems typically maintain physical separation between coolant and electrical components, simplifying electrical isolation but limiting thermal efficiency. Immersion cooling fundamentally changes this paradigm by placing dielectric coolant in direct contact with electrically active components, requiring comprehensive electrical safety systems. The immersion cooling battery pack addresses this challenge through a design where battery modules and conductive copper bars are fully submerged in dielectric coolant. This approach significantly shortens thermal diffusion paths and increases effective cooling surface area, enabling more uniform and efficient heat dissipation directly from battery components.

The electrical safety of this system is ensured through an integrated deionization and ion monitoring mechanism that continuously maintains the dielectric properties of the coolant. The system actively monitors ion concentration and removes conductive ions that could compromise electrical isolation. If ion levels exceed predetermined safety thresholds, the system triggers alerts to prevent potential short circuits or electrical hazards. This real-time monitoring and maintenance of coolant dielectric properties creates a robust electrical safety framework suitable for high-density battery environments where fault tolerance is essential. Additionally, an external thermal insulation layer on the battery enclosure minimizes environmental heat transfer, stabilizing internal temperatures and reducing cooling system energy requirements.

For applications where full immersion may not be practical, the partitioned battery module design enables partial submersion of cells within a sealed structure. This configuration addresses the thermal inefficiency of conventional radiator-based systems while maintaining electrical safety. A non-conductive partition wall with specialized through-holes and safety seals allows coolant to contact the middle section of cells directly, where heat generation is most intense. The use of thermally stable, electrically insulating materials such as ceramics or reinforced plastics ensures structural integrity while preventing electrical conduction through the module housing.

The electrical isolation properties of these systems are further enhanced through material selection and structural design. Dielectric coolants with high breakdown voltage provide the primary electrical barrier, while specialized seals and gaskets prevent coolant leakage at electrical interfaces. The physical separation of high-voltage components through compartmentalization adds another layer of protection, creating multiple barriers against electrical faults.

These electrical safety features demonstrate how immersion cooling systems have evolved to address the unique challenges of direct coolant contact with electrically active components. By integrating continuous monitoring, active maintenance of dielectric properties, and multiple physical barriers, these systems maintain the thermal advantages of immersion cooling while ensuring operational safety in high-voltage battery environments.

8. Closed-Loop Immersion Cooling Systems with Internal Circulation

Closed-loop immersion cooling systems with internal circulation represent the integration of immersion cooling principles with sophisticated fluid management to create self-contained thermal regulation systems. These designs address both thermal performance and practical implementation challenges in production vehicles.

Traditional air and liquid cooling methods struggle with uneven temperature distribution and limited heat dissipation capacity, particularly in high-energy-density battery systems. The sealed immersion cooling architecture overcomes these limitations by fully submerging battery modules in dielectric fluid within a closed system. This approach eliminates indirect cold plates and reduces thermal resistance by creating direct heat transfer paths between cells and coolant. The system's compartmentalized structure uses structural beams to isolate individual modules, enabling precise thermal control and modular scalability.

The internal coolant circulation mechanism represents a key innovation in this system. A carefully engineered gap between battery modules and the upper cover creates a dedicated flow path for coolant across the top surface of each module. An integrated diversion structure in the upper cover guides this flow to ensure uniform distribution. The parallel flow channel configuration minimizes hydraulic resistance while maximizing thermal uniformity. This approach not only enhances cooling efficiency during normal operation but also provides inherent thermal runaway mitigation. During cell failure events, the surrounding dielectric fluid acts as both thermal and chemical barrier, suppressing propagation by isolating affected modules from oxygen and rapidly dissipating heat.

For comprehensive thermal management across varying environmental conditions, the comprehensive fluid circulation loop integrates multiple components into a complete thermal regulation system. This closed-loop configuration includes dual inlet/outlet pipe assemblies, a specialized fluorinated coolant pump, and a heat exchanger assembly comprising a plate heat exchanger, compressor, and condenser. The system utilizes 3M FC40 dielectric fluid, selected for its exceptional thermal stability and electrical insulation properties, allowing full submersion of battery components while maintaining electrical safety. An integrated electric heater on the inlet or outlet line ensures functionality in cold environments, while an optional HVAC module extends the system's thermal regulation range to accommodate extreme ambient conditions.

Both systems emphasize long-term reliability and operational safety. The first system's real-time ion detection and deionization unit continuously monitors and maintains coolant dielectric properties, ensuring consistent electrical isolation throughout the battery pack's operational life. The second system's modular coolant flow design achieves uniform temperature control across large battery packs while addressing the integration challenges presented by production vehicle platforms.

These closed-loop immersion cooling systems demonstrate the evolution of battery thermal management from simple heat removal concepts to integrated thermal regulation systems that maintain optimal battery temperature across all operating conditions while ensuring long-term reliability and safety.

9. Immersion Cooling with Heat Pipe Integration

The integration of heat pipes with immersion cooling creates hybrid thermal management systems that combine the advantages of both technologies: the high heat flux capacity of heat pipes and the uniform temperature distribution of immersion cooling. These hybrid systems address specific thermal challenges in electric vehicle battery applications.

Heat pipes offer exceptional thermal conductivity through phase change processes, typically transferring heat 100-1000 times more efficiently than solid copper of equivalent cross-section. When integrated with immersion cooling, they create thermal pathways that can rapidly extract heat from critical regions and redistribute it to cooler areas or external heat exchangers. The dual-stage heat pipe cooling system exemplifies this approach by embedding heat pipes adjacent to battery cells for rapid heat extraction. This system transfers thermal energy first to an internal Peltier-based cooling unit and then to an external air-cooled heat pipe system. The bidirectional capability of the Peltier device enables both cooling during high-load conditions and heating during cold starts, providing comprehensive thermal management across all operating environments.

The thermal performance of this hybrid approach is particularly advantageous during transient conditions such as rapid charging or pulsed high-power discharge. The heat pipes quickly respond to sudden temperature increases, extracting thermal energy before it can create localized hot spots. Meanwhile, the immersion cooling component provides baseline temperature regulation and ensures uniform thermal distribution throughout the battery module. This combination of rapid response and uniform cooling significantly reduces maximum cell temperatures during peak loads while maintaining minimal temperature gradients during steady-state operation.

For cylindrical cell configurations, the hybrid cooling assembly combines U-shaped flat heat pipes with arc-shaped aluminum heat spreaders that conform to cell geometry. This design addresses the thermal contact challenges inherent in cylindrical cells by creating continuous thermal pathways from cell surfaces to heat pipes via thermally conductive interface materials. The heat pipes then channel thermal energy to a liquid-cooled baseplate for final heat rejection. Simultaneously, paraffin-graphite composite phase change materials embedded in structural cavities absorb transient thermal spikes, providing additional thermal buffering during high-load conditions.

A complementary approach balances performance and cost considerations through the jacket structure battery pack with dual-fluid configuration. This system uses water as an external cooling medium circulating through a jacket structure, while a fluorinated dielectric liquid inside the battery enclosure provides direct immersion cooling. This layered approach achieves rapid and uniform heat removal while minimizing the required volume of expensive dielectric coolant. Recessed surfaces on the battery box walls increase heat exchange contact area, enhancing thermal performance without increasing system size. The integrated circulation pump and heat exchanger maintain optimal coolant temperature across varying load conditions.

These heat pipe-integrated immersion cooling systems demonstrate how combining complementary thermal technologies can address the complex thermal management requirements of high-performance electric vehicle batteries. By leveraging the strengths of both heat pipes and immersion cooling, these hybrid systems achieve superior thermal performance across diverse operating conditions while maintaining practical considerations such as cost, weight, and packaging efficiency.

10. Composite or Hybrid Cooling Systems (Air + Liquid, PCM + Liquid, etc.)

As electric vehicle battery systems face increasingly complex thermal challenges, single-mode cooling strategies often prove insufficient for maintaining optimal temperature control across all operating conditions. Composite or hybrid cooling systems address this limitation by integrating multiple cooling technologies into coordinated thermal management architectures.

Phase change materials (PCMs) combined with liquid cooling create particularly effective hybrid systems by leveraging the complementary characteristics of both technologies. PCMs provide passive thermal buffering through latent heat absorption, while liquid cooling offers active heat removal capacity. The hybrid cooling system exemplifies this approach by strategically positioning PCM between adjacent battery cells to absorb localized heat spikes, while a dual-layered liquid cooling pipe arrangement with opposing flow directions surrounds each module. This configuration creates a thermal management system with both passive and active components working in concert. During normal operation, the liquid cooling system maintains baseline temperature control; during transient high-load conditions, the PCM absorbs excess thermal energy; and if coolant flow is disrupted, the PCM continues to provide thermal buffering until normal operation can be restored.

The thermal performance characteristics of this hybrid approach demonstrate significant advantages over single-mode cooling systems. Temperature uniformity improves as the PCM absorbs heat preferentially from hotter regions while the liquid cooling system removes heat from the entire module. Maximum temperature excursions during rapid charging or high-power discharge are reduced as the PCM absorbs thermal spikes before they can affect cell temperature. System reliability increases through the inherent redundancy provided by two distinct cooling mechanisms operating simultaneously.

For applications requiring operation across extreme temperature ranges, the thermal management device integrates additional components including heat pipes, fans, and heating elements. This comprehensive system uses flat heat pipes to efficiently transfer heat from battery cells to a water-glycol coolant circuit. The absorbed thermal energy is subsequently dissipated through a combination of fins, fans, and water pumps, providing multiple heat rejection pathways. For cold-weather operation, the system includes rotatable wind baffles and internal heaters that precondition the battery to optimal operating temperature. The waterproof, dust-proof, and collision-resistant features further enhance system durability and reliability in real-world operating environments.

While PCM-liquid hybrid systems excel in managing thermal gradients and transient events, the integration of immersion cooling with supplementary insulation and flow optimization creates another class of composite solution. The novel immersion-cooled battery architecture submerges battery modules directly in dielectric coolant, eliminating the limitations of channel-based liquid cooling. The system's parallel-flow configuration and specialized upper cover direct coolant uniformly across all module surfaces. External thermal insulation minimizes environmental heat transfer, while embedded deionization and ion monitoring units ensure electrical safety. This approach combines immersion cooling with structural flow management and environmental isolation to achieve superior thermal performance while maintaining system safety and reliability.

These composite cooling strategies represent the evolution of battery thermal management from simple single-mode approaches to sophisticated integrated systems that leverage multiple cooling technologies to address the complex thermal challenges presented by high-performance electric vehicle batteries. By combining complementary cooling mechanisms, these systems achieve superior thermal performance across all operating conditions while maintaining practical considerations such as cost, weight, and packaging efficiency.

11. Structural or Mechanical Enhancements for Immersion Cooling

The thermal performance of immersion cooling systems depends not only on coolant properties and flow characteristics but also on the structural and mechanical design elements that facilitate heat transfer and system integration. Advanced immersion cooling systems incorporate specialized structural features that enhance thermal performance while addressing practical implementation challenges.

Traditional heat exchange structures in battery cooling systems often suffer from limited contact area between coolant and heat exchange surfaces, resulting in thermal bottlenecks that restrict overall system performance. The heat dissipation structure addresses this fundamental limitation through an integrated design that positions a heat exchange plate between a liquid storage member and a heat conductive member. This configuration significantly increases effective surface area for thermal conduction and creates direct heat transfer pathways from battery cells to coolant. The structural arrangement enhances thermal contact efficiency and enables more effective heat extraction, supporting high-power battery configurations while maintaining thermal safety margins.

The thermal performance advantages of this enhanced structure derive from both increased contact area and optimized heat transfer pathways. By creating multiple parallel thermal conduction routes between cells and coolant, the system reduces thermal resistance and minimizes temperature gradients across the battery module. The structural integration of thermal components also improves system compactness and mechanical robustness, making it suitable for space-constrained automotive applications where packaging efficiency is critical.

For applications requiring autonomous thermal management independent of external cooling systems, the closed-loop cooling system incorporates structural elements such as heat conduction elbows, plates, and guiding tubes within a compact battery enclosure. This self-contained system uses an integrated circulation pump to drive coolant through the thermal circuit, transferring heat to a storage box equipped with semiconductor refrigeration for active cooling. A key structural feature is the liquid level sensor that continuously monitors coolant volume and alerts operators when levels fall below predetermined thresholds. This integrated monitoring capability enhances system reliability while reducing maintenance requirements, creating a structurally integrated thermal solution with built-in safety monitoring.

High-power applications with aggressive thermal management requirements benefit from the immersed battery cooling architecture that fully submerges cells in dielectric coolant within a sealed enclosure. This design includes a specialized guide plate between cell rows that creates isolated top and bottom flow channels, improving coolant circulation through strategically positioned communication openings. From a mechanical perspective, the battery cells are secured in fixed slots on internal brackets using structural adhesive, enhancing both vibration resistance and thermal conduction. The enclosure features a reinforced bottom guard plate with internal ribs that ensure mechanical integrity under thermal stress and fluid pressure conditions. This comprehensive structural approach delivers superior heat dissipation capability and mechanical durability, making it particularly suitable for high-voltage, fast-charging electric vehicle platforms.

These structural and mechanical enhancements demonstrate how immersion cooling system performance depends on more than just fluid dynamics and thermal properties. By integrating specialized structural elements that optimize thermal pathways, improve mechanical stability, and enhance system reliability, these designs achieve superior thermal performance while addressing the practical implementation challenges associated with production electric vehicle applications.

12. Flow Distribution and Control Mechanisms in Immersion Systems

The thermal performance of immersion cooling systems depends critically on how effectively coolant is distributed throughout the battery pack. Advanced flow distribution and control mechanisms ensure uniform cooling across all cells while responding dynamically to changing thermal conditions.

Traditional immersion systems often struggle with uneven coolant distribution, leading to thermal gradients that can affect battery performance and longevity. The modular immersion cooling system with individual intake and exhaust runners addresses this challenge through a fundamentally different approach to flow management. Rather than treating the battery pack as a single cooling zone, this system creates independent fluid circuits for each module, enabling precise thermal control at the module level. Each circuit includes a dedicated flow control valve in the intake path that adjusts coolant flow based on real-time temperature measurements from the module outlet. This distributed control architecture allows the system to allocate cooling capacity dynamically, directing additional coolant to modules experiencing higher thermal loads while reducing flow to cooler modules.

The thermal performance advantages of this approach are particularly evident during uneven loading conditions, such as when certain modules experience higher current draw due to cell balancing or varying load profiles. By independently regulating coolant flow to each module, the system maintains more uniform temperature distribution across the entire battery pack, reducing maximum temperature excursions and minimizing thermal stress. The modular isolation also enhances system reliability by containing potential coolant leaks within individual modules rather than affecting the entire pack.

For applications requiring scalable battery configurations, the integrated fluid channels within modular battery modules provide an elegant solution to flow distribution challenges. Each module incorporates a distributor plate and base with interconnected inlet and outlet channels that direct dielectric fluid through the battery cell housing. When modules are stacked vertically, these channels align to create continuous fluid pathways throughout the assembly without requiring external manifolds or complex sealing systems. This design supports flexible battery configurations while ensuring consistent coolant distribution across all modules. The plug-in connections between modules simplify assembly and maintenance while maintaining reliable fluid routing.

Addressing the specific challenge of temperature gradients due to extended coolant paths, the vertically configured immersion system with diverter plate and strip-shaped flow channels fundamentally changes coolant distribution patterns. Instead of horizontal flow that creates significant temperature differences between upstream and downstream cells, this system implements uniform top-down distribution across the entire battery core. Coolant flows vertically from the upper cover plate through strip-shaped channels in the diverter plate, passing through the battery cells and collecting at the bottom plate. This vertical flow architecture significantly shortens coolant travel distance and ensures that all cells receive coolant at similar temperatures, dramatically improving thermal uniformity throughout the pack.

These advanced flow distribution and control mechanisms demonstrate how immersion cooling systems have evolved from simple submersion concepts to sophisticated thermal management architectures with precisely engineered flow patterns. By controlling coolant distribution at both system and module levels, these designs achieve superior thermal performance while addressing the practical challenges of implementing immersion cooling in production electric vehicles.

13. Heat Pipe-Based Thermal Management Systems (Non-Immersion)

While immersion cooling offers comprehensive thermal management through direct coolant contact, heat pipe-based systems provide alternative approaches that achieve high thermal performance without submerging battery components in liquid. These non-immersion systems leverage the exceptional thermal conductivity of heat pipes to create efficient thermal pathways throughout the battery pack.

Heat pipes function as thermal superconductors, transferring heat through phase change processes with minimal temperature gradient. A typical heat pipe can transfer heat 100-1000 times more efficiently than a solid copper rod of equivalent dimensions, making them ideal for creating thermal bridges between battery cells and cooling systems. The PCM heat sink with embedded heat dissipation pipes exemplifies this approach by integrating phase change materials with embedded heat pipes in a composite thermal management system. This design enables passive heat absorption during vehicle operation through the PCM's latent heat capacity, effectively buffering thermal spikes without continuous energy consumption. When the vehicle is stationary or charging, a circulation pump activates to inject coolant through the embedded pipes, extracting accumulated heat from the PCM and preparing it for the next operational cycle.

The thermal performance characteristics of this system are particularly advantageous for electric vehicles with intermittent usage patterns. During driving, the PCM absorbs heat without requiring pump operation, conserving energy and extending range. During charging or parking, the system uses external power to regenerate the PCM's thermal capacity. The integration of high-conductivity materials like aluminum in the heat pipes, combined with program-controlled flow switches and one-way valves, creates a responsive and energy-efficient thermal management system that maintains optimal battery temperature across varying operational states.

For applications requiring more targeted thermal management, particularly at battery poles where thermal gradients are most severe, the hybrid passive cooling system combines cored and gravity heat pipes with a PCM-based heat exchanger. This specialized configuration addresses the thermal challenges associated with battery terminals, where high current density creates localized heating that can affect battery performance and longevity. The cored heat pipe extracts heat from the battery pole and transfers it to a gravity heat pipe, which then dissipates the thermal energy either to a PCM chamber or external cooling fins. The unidirectional heat flow prevents environmental heat from transferring back to the battery, maintaining thermal isolation even in high-temperature environments.

The system's use of high thermal conductivity ceramic plates for inter-pipe heat exchange, combined with modular insertion of heat pipes into battery pole jacks, creates a scalable thermal management solution applicable to large-capacity battery systems. The absence of active components such as pumps or fans results in a passive, energy-conserving approach that maintains reliability through simplified design and reduced potential failure points.

These heat pipe-based thermal management systems demonstrate how non-immersion approaches can achieve high thermal performance through advanced heat transfer mechanisms. By leveraging the exceptional thermal conductivity of heat pipes in combination with phase change materials and strategic thermal pathways, these systems provide effective alternatives to immersion cooling for applications where direct liquid contact with battery components is impractical or undesirable.

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