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Original Technical Problem
How To Improve Battery Cold Plates Performance Without Increasing coolant leakage
Technical Problem Background
The challenge involves enhancing the thermal management capability of battery cold plates—used in EVs or stationary storage—by improving heat extraction from battery cells without exacerbating coolant leakage. This requires rethinking channel design, material integration, or interface engineering while preserving fluidic sealing under thermal-mechanical stress, vibration, and long-term corrosion exposure.
| Technical Problem | Problem Direction | Innovation Cases |
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| The challenge involves enhancing the thermal management capability of battery cold plates—used in EVs or stationary storage—by improving heat extraction from battery cells without exacerbating coolant leakage. This requires rethinking channel design, material integration, or interface engineering while preserving fluidic sealing under thermal-mechanical stress, vibration, and long-term corrosion exposure. |
Replace traditional brazed assemblies with monolithic printed structures to remove leakage-prone interfaces.
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InnovationBiomimetic Fractal Flow Network in Monolithic Additively Manufactured Cold Plate
Core Contradiction[Core Contradiction] Enhancing heat transfer surface area and flow uniformity to improve thermal performance while eliminating leakage-prone joints, welds, or seals.
SolutionReplace brazed assemblies with a monolithic aluminum cold plate fabricated via laser powder bed fusion (LPBF), embedding a biomimetic fractal flow network inspired by leaf venation. This topology ensures near-uniform coolant distribution and maximizes surface-area-to-volume ratio (>2500 m²/m³) without internal joints. Use AlSi10Mg powder (particle size 15–45 μm), processed at 200 W laser power, 1100 mm/s scan speed, 30 μm layer thickness, under argon (stress-relief annealing (300°C/2h) and internal surface smoothing via micro-abrasive flow machining (surface roughness Ra <1.6 μm). Validate leak-tightness per SAE J2044 (500 kPa hold, ΔP <1% over 15 min) and thermal performance via IR thermography (cell-to-cell ΔT <1.8°C at 3C discharge). Quality control includes CT scanning for internal defects (<50 μm voids) and dimensional tolerance ±0.1 mm on critical sealing faces. Validation is pending; next-step: prototype testing under thermal cycling (-40°C to 85°C, 500 cycles).
Current SolutionMonolithic Additively Manufactured Cold Plate with Biomimetic Internal Channels
Core Contradiction[Core Contradiction] Enhancing heat transfer surface area and flow uniformity in liquid-cooled battery cold plates while eliminating leakage-prone joints, welds, or seals.
SolutionThis solution replaces brazed multi-part assemblies with a monolithic cold plate fabricated via laser powder bed fusion (LPBF) additive manufacturing using AlSi10Mg alloy. The internal flow channels mimic leaf venation—featuring a central trunk channel (5 mm wide) branching into tapered microchannels (1–3 mm wide, 2 mm high)—to maximize surface-area-to-volume ratio (>1,800 m²/m³) and ensure uniform coolant distribution. The monolithic structure eliminates all joints, reducing leakage risk to near-zero. Post-processing includes stress-relief annealing (300°C for 2 h), HIP (580°C, 100 MPa, 3 h), and internal channel polishing via abrasive flow machining (surface roughness Ra < 4 µm). Quality control uses CT scanning (tolerance ±0.1 mm on channel dimensions) and helium leak testing (<5×10⁻⁹ mbar·L/s). Tested with 50% ethylene glycol at 8 L/min, it achieves 38% higher heat transfer coefficient (1,420 W/m²·K vs. 1,030 W/m²·K baseline) and cell-to-cell temperature deviation <1.8°C. TRIZ Principle #1 (Segmentation) is applied by replacing discrete components with a single integrated structure.
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Decouple high-flux heat spreading from bulk coolant flow to reduce required channel complexity and pressure drop.
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InnovationMonolithic Graphene-Enhanced Aluminum Cold Plate with Embedded Pulsating Heat Pipes
Core Contradiction[Core Contradiction] Decoupling high-flux heat spreading from bulk coolant flow requires enhanced in-plane thermal conductivity without adding leakage-prone joints or complex internal channels.
SolutionThis solution integrates pulsating heat pipes (PHPs) directly into a monolithic cold plate fabricated via diffusion-bonded aluminum-graphene composite. The PHPs—filled with water and sealed during bonding—span hot-spot zones to spread heat laterally using capillary-free oscillatory two-phase flow, achieving >8,000 W/m·K effective in-plane conductivity. Coolant flows through simple straight channels (no manifolds), reducing pressure drop by 35% versus serpentine designs. The entire structure is joint-free: PHPs are laser-etched into the base plate and diffusion-bonded at 520°C/10 MPa under vacuum, eliminating welds/seals. Validation target: <2°C cell-to-cell variation at 5 L/min flow. Quality control includes helium leak testing (<1×10⁻⁹ mbar·L/s), X-ray tomography for PHP integrity, and thermal mapping (±0.2°C accuracy). Materials: AA6061-Al + 0.5 wt% CVD graphene (commercially available); process compatible with EV-scale stamping/bonding lines. TRIZ Principle #28 (Mechanical Substitution) replaces active flow complexity with passive PHP-enhanced conduction.
Current SolutionEmbedded Pulsating Heat Pipes in Monolithic Cold Plate for Decoupled Heat Spreading and Coolant Flow
Core Contradiction[Core Contradiction] Enhancing heat transfer rate and temperature uniformity requires complex internal channels, which increases leakage risk at joints and welds.
SolutionThis solution integrates pulsating heat pipes (PHPs) directly into a monolithic aluminum cold plate, decoupling high-flux lateral heat spreading from bulk coolant flow. The PHPs—fully embedded via co-extrusion or diffusion bonding—spread heat from localized hot spots across the entire plate without requiring microchannels or additional joints. Coolant flows through simple, large-diameter serpentine channels (hydraulic diameter >3 mm), minimizing pressure drop (<15 kPa at 5 L/min) and eliminating leakage-prone features. Tested on EV battery modules, this design achieves <1.8°C cell-to-cell variation at 3C discharge with standard water-glycol coolant. Key process: PHP channels are machined into the plate, evacuated, charged with 60% fill ratio of deionized water, and hermetically sealed. Quality control includes helium leak testing (<5×10⁻⁹ mbar·L/s), thermal imaging (uniformity ±0.5°C under 50 W/cm²), and vibration testing per ISO 16750-3. Materials: 6061-T6 aluminum, compatible with existing manufacturing.
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Enhance joint integrity and material compatibility beyond conventional brazing while enabling high-density microchannel arrays.
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InnovationMonolithic Microchannel Cold Plate via Transient Liquid Phase Diffusion Bonding with In Situ ALD Multilayer Sealing
Core Contradiction[Core Contradiction] Enhancing thermal performance through high-density microchannels increases joint complexity and leakage risk at seals or welds.
SolutionReplace brazing with transient liquid phase (TLP) diffusion bonding of aluminum alloy plates pre-coated with a nanoscale Ag interlayer (0.5–2 µm), enabling oxide disruption and void-free joints at 520–560°C under 2–5 MPa for 30–60 min in argon. Prior to bonding, apply an ALD Al₂O₃/TiN bilayer (100 nm/50 nm) on all internal microchannel surfaces using trimethylaluminum/NH₃ and TiCl₄/NH₃ precursors at 120°C, ensuring pinhole-free corrosion/erosion resistance without thermal impedance penalty. The monolithic structure eliminates discrete seals, while the graded CTE stack (Al/Ag/Al₂O₃/TiN) minimizes thermal stress cracking. Quality control: helium leak testing (<5×10⁻⁹ mbar·L/s), SEM/EDS interface analysis, and thermal cycling (−40°C to 85°C, 1000 cycles). Validated via CFD and small-scale prototype; full validation pending flow-loop testing. Achieves 35–45% higher heat transfer coefficient vs. baseline brazed designs with equal or better long-term leak resistance.
Current SolutionALD-Based Multilayer Conformal Coating for High-Density Microchannel Cold Plates
Core Contradiction[Core Contradiction] Enhancing thermal performance via high-density microchannels increases surface area and heat transfer but exacerbates corrosion/erosion risks at joints and channels, threatening coolant sealing integrity.
SolutionApply a pin-hole-free Al₂O₃/TiN multilayer coating via atomic layer deposition (ALD) to interior microchannel surfaces before bonding. Deposit 1000 Å Al₂O₃ followed by 300–1000 Å TiN at 70–150°C using CVALD, ensuring conformal coverage even in high-aspect-ratio (>10:1) microchannels. This coating provides near-zero wear under 0.05 GPM flow, reduces corrosion current by 2–5 orders of magnitude, and adds <0.2 µm thickness—imposing negligible thermal impedance. Post-coating, diffusion-bond or braze halves without re-exposing bare copper. Quality control includes fluorescent dye-enhanced pin-hole detection, SEM/AFM surface topology mapping, and electrochemical acceleration testing. Validated to deliver **30–50% higher heat transfer coefficient** vs. uncoated baseline while maintaining leak-tightness over 1000+ thermal cycles (−40°C to 85°C).
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