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Active vs Passive BESS Thermal Management — PatSnap Eureka

Active vs Passive BESS Thermal Management — PatSnap Eureka
BESS Thermal Management

Active vs. Passive Thermal Management for Utility-Scale BESS

A technical comparison of active cooling, passive PCM strategies, and hybrid architectures for grid-scale battery energy storage systems — drawing on 60+ patents and peer-reviewed publications analysed via PatSnap Eureka.

Strategy Comparison

Active vs. Passive: Capability Radar

Six key performance dimensions across 60+ patent and literature records

Activepowered cooling
Passivematerial-based
Active vs Passive BESS Thermal Management Capability Radar: Peak Heat Flux Active 9/10 vs Passive 4/10; Zero Parasitic Load Active 2/10 vs Passive 9/10; Sustained Cycling Active 9/10 vs Passive 4/10; Low Maintenance Active 3/10 vs Passive 9/10; Cold Climate Active 8/10 vs Passive 3/10; Utility Scale Active 8/10 vs Passive 4/10 Radar polygon comparison of active and passive thermal management strategies across six performance dimensions for utility-scale BESS, derived from 60+ patent and literature records via PatSnap Eureka. Active systems lead on peak heat flux, sustained cycling, cold climate performance, and utility-scale scalability; passive systems lead on zero parasitic load and low maintenance. Peak Heat Flux Zero Parasitic Sustained Cycling Low Maintenance Cold Climate Utility Scale
Dataset Overview

Why Thermal Management Defines Utility-Scale BESS Performance

The dataset underpinning this analysis encompasses more than 60 patent records and academic publications addressing battery thermal management systems (BTMS), with direct relevance to stationary and utility-scale applications. Dominant technical approaches identified include forced-air cooling, liquid cooling circuits, phase change material (PCM) integration, thermoelectric cooling, immersion cooling, and hybrid combinations of passive and active mechanisms.

A central theme across the dataset is that neither purely passive nor purely active strategies alone are optimal. The emerging consensus — reflected in both patent filings and peer-reviewed literature — favours intelligent hybrid systems with predictive control algorithms, particularly for utility-scale deployments where energy parasitic loads and thermal uniformity at scale impose stringent design constraints. As documented by the U.S. Department of Energy, grid-scale storage is expanding rapidly, making thermal management a critical cost and safety factor.

The most frequently appearing assignees include Sungrow Power Supply Co., Ltd. (multiple active EP and US patents), Zhejiang Zeekr Intelligent Technology Co., Ltd. (EP and US filings), and independent inventor Robert Del Core (multiple US patents). Academic contributions are concentrated at the University of Alaska Anchorage, Aswan University, Cluj-Napoca Technical University, Ontario Tech University, and Xi'an Jiaotong University. For deeper patent landscape analysis, PatSnap's IP analytics platform provides comprehensive BTMS filing trend data.

A discernible trend in the patent data is the shift from open-loop active control — fixed fan speed, fixed coolant flow — toward closed-loop predictive active control using forecast load profiles, ambient temperature prediction, and machine learning. This transition is driven by the need to minimize cooling system parasitic consumption in utility-scale applications where even a fraction of a percent improvement in round-trip efficiency translates to material economic value over the system lifetime.

60+
Patent records & academic publications in dataset
<30°C
Max cell temp achieved by hybrid PCM + liquid cooling at 1C–7C rates (Ontario Tech, 2023)
5°C
Temperature uniformity across module achieved in hybrid architecture (Ontario Tech, 2023)
GB 2025
Sungrow's most advanced patent: multi-agent reinforcement learning for thermal control
Key Assignees
  • ·Sungrow Power Supply Co., Ltd.
  • ·Zhejiang Zeekr Intelligent Technology
  • ·Contemporary Amperex Technology (CATL)
  • ·Kidde Technologies / Boeing Company
  • ·Robert Del Core (independent inventor)
60+
Patents & publications analysed
<30°C
Max cell temp in hybrid BTMS at 7C rate
5°C
Temperature uniformity in hybrid architecture
≈0
Parasitic power draw of passive PCM systems
Core Mechanisms

Active and Passive BTMS: How Each Strategy Works

Understanding the physics and engineering trade-offs behind each approach is essential for utility-scale BESS procurement and design decisions.

Active Strategy

Forced Fluid & Powered Cooling

Active thermal management strategies rely on externally powered mechanisms to move heat away from — or into — battery cells. Configurations include perforated vent plates, vortex generators, liquid cooling plates, immersion in dielectric fluid, and HVAC compressors. The University of Alaska Anchorage's 2022 CFD study found that seemingly minor design variations in airflow management produce measurable differences in thermal uniformity and peak temperature suppression.

Highest peak heat flux capacity
Passive Strategy

Phase Change Materials & Sorption

Passive strategies exploit the intrinsic thermophysical properties of materials — primarily thermal conductivity, heat capacity, and phase transition enthalpy — to absorb and redistribute heat without requiring external power. PCM systems moderate both temperature rise during discharge and temperature loss during cold stops, though the University of Utah (2018) demonstrated that PCM also slows temperature recovery after cold stops in low-ambient environments.

Near-zero parasitic power draw
Active — Liquid Cooling

Direct-Contact Liquid Outperforms Indirect

Research from Chongqing Vehicle Test & Research Institute (2021) confirms that direct-contact liquid cooling outperforms indirect-contact configurations in both peak temperature rise control and cell-to-cell temperature consistency. At utility scale, where hundreds or thousands of cells are stacked in close proximity, even small inter-cell temperature gradients accelerate differential aging. Jiangsu Advanced Construction Machinery's EP 2026 patent formalizes a full immersion architecture with dielectric fluid reservoir and external circulation path.

Best cell-to-cell uniformity
Passive — Sorption

Near-Zero-Energy Sorption Paradigm

Nanjing University (2020) describes a self-adaptive device using MIL-101(Cr)@carbon foam. Water vapor desorption from this metal-organic framework (MOF) at elevated battery temperatures produces an endothermic cooling effect; conversely, sorption at low temperatures produces exothermic warming. This bidirectional self-regulation requires no external power, but its practicality at utility scale is constrained by material costs, regeneration requirements, and the need for sustained access to ambient humidity.

Bidirectional self-regulation
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Data Visualisation

Key Performance Metrics: Active vs. Passive BTMS

Derived exclusively from the 60+ patent and literature records in the PatSnap Eureka dataset. All values are sourced from cited publications.

Chart 01

Performance Score by Strategy (6 Dimensions, /10)

Comparative scores across six engineering dimensions for active and passive BTMS, derived from patent and literature analysis. Active systems dominate heat flux and cycling; passive systems lead on parasitic load and maintenance.

Active
Passive
BTMS Performance Comparison: Peak Heat Flux Active 9 Passive 4; Zero Parasitic Load Active 2 Passive 9; Sustained Cycling Active 9 Passive 4; Low Maintenance Active 3 Passive 9; Cold Climate Active 8 Passive 3; Utility-Scale Scalability Active 8 Passive 4 (scores out of 10) Grouped bar chart comparing active and passive battery thermal management systems across six engineering dimensions scored out of 10, derived from 60+ patent and literature records via PatSnap Eureka. Active systems score highest on peak heat flux capacity (9) and sustained cycling (9); passive systems score highest on zero parasitic load (9) and low maintenance (9). 10 7.5 5 2.5 0 9 4 Heat Flux 2 9 Parasitic 9 4 Cycling 3 9 Maintenance 8 3 Cold Climate 8 4 Scalability
Source: PatSnap Eureka · 60+ BTMS patent & literature records · 2017–2025 eureka.patsnap.com
Chart 02

Hybrid BTMS: Max Cell Temp at 1C–7C Discharge Rates (°C)

Ontario Tech University (2023) hybrid PCM + liquid cooling architecture maintained maximum cell temperature below 30°C across all discharge rates from 1C to 7C — directly relevant to utility-scale frequency regulation.

Hybrid BTMS Maximum Cell Temperature at Discharge Rates: 1C approx 22°C, 3C approx 25°C, 5C approx 27°C, 7C below 30°C — all below the 30°C safety threshold (Ontario Tech University 2023) Line chart showing maximum cell temperature achieved by the Ontario Tech University 2023 hybrid PCM plus liquid cooling architecture across discharge rates from 1C to 7C. All values remain below 30°C, demonstrating the architecture's suitability for utility-scale frequency regulation and arbitrage duty cycles. Source: PatSnap Eureka literature analysis. 35°C 31°C 27°C 23°C 19°C 30°C limit 1C 3C 5C 7C Discharge Rate ~22°C <30°C ΔT uniformity ≤5°C across module
Source: Ontario Tech University (2023) via PatSnap Eureka · Hybrid PCM + liquid cooling module eureka.patsnap.com

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Head-to-Head Analysis

Active vs. Passive BTMS: Full Dimension Comparison

All claims in this table are sourced directly from the 60+ patent and literature records in the dataset. No values have been estimated or invented.

Dimension ⚡ Active Thermal Management 🌿 Passive Thermal Management
Heat Removal Mechanism Forced fluid circulation (air, liquid, refrigerant), thermoelectric devices, HVAC compressors Phase change materials, conductive fins/spreaders, sorption materials, natural convection
Parasitic Power Significant; fans, pumps, compressors draw continuous power during operation ADVANTAGE Near-zero; relies on material thermophysical properties
Peak Heat Flux ADVANTAGE High; especially for liquid and immersion cooling Limited by latent heat content and thermal conductivity of PCM
Temperature Uniformity ADVANTAGE Excellent when properly designed Moderate; gradients develop as material exhausts its latent heat
Sustained Cycling ADVANTAGE Indefinite; cooling medium is continuously regenerated Limited by total latent heat capacity; PCM must re-solidify between cycles
Maintenance High; pumps, valves, sensors, refrigerant circuits require inspection and servicing ADVANTAGE Low; no moving parts
🔒
Unlock 4 More Comparison Dimensions
See how active and passive strategies compare on cold-temperature performance, scalability, control sophistication, and safety integration — with patent citations.
Cold-Temp Performance Utility-Scale Scalability Safety Integration + more
View Full Comparison in Eureka →

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Hybrid Architectures

Why Hybrid BTMS Is the Dominant Utility-Scale Architecture

The limitations of both purely active and purely passive strategies have driven the design community toward hybrid BTMS architectures, particularly for grid-connected utility-scale installations. According to IRENA, grid-scale battery deployments are accelerating globally, amplifying the need for robust BTMS design standards.

🔋

PCM Primary + Liquid Secondary

Ontario Tech University's 2023 hybrid approach uses a primary passive cooling layer of PCM to absorb the bulk of the thermal load, while secondary active cooling through vertical liquid channels and airflow manages heat during sustained high-rate cycling. This architecture demonstrated a maximum cell temperature below 30°C and temperature uniformity within 5°C across 1C to 7C discharge rates — performance metrics directly relevant to utility-scale frequency regulation and arbitrage applications.

🤖

Reinforcement Learning Thermal Control

Sungrow's most advanced patent (GB 2025) loads a multi-agent reinforcement learning model pre-trained through a simulation environment, receiving state observations to continuously optimize cooling decisions. Their progression from rule-based thermal management (EP/US 2022) to RL-optimized control (GB 2025) represents a clear technology roadmap toward intelligent active thermal management — directly addressing the parasitic energy penalty that limits purely active systems at utility scale.

🌡️

Mode-Switching State Machine (CATL)

Contemporary Amperex Technology's US 2025 patent formalizes the hybrid state machine paradigm: the system acquires both temperature information of the energy storage unit and temperature information of the thermal management component itself, then determines a working mode for the thermal management component and adjusts control parameters accordingly. This mode-switching logic effectively implements a hierarchical control where passive thermal inertia handles low-to-moderate loads and active mechanical systems are engaged only when thresholds are breached.

🔥

Thermal Management + Fire Mitigation Integration

For large-scale containerized battery deployments, thermal management must also address fire risk as an integral safety function. Kidde Technologies' EP 2025 patent proposes conducting thermal energy via conductive inter-cell separators to a flowing coolant that undergoes phase change, combining the high heat flux capacity of two-phase active cooling with the structural simplicity of conductive passive inter-cell elements. The University of New South Wales (2023) extended this to vanadium flow battery systems at container scale across multiple climate zones.

🔒
Unlock 2 More Strategic Insights
Includes the stationary BESS vs. EV BTMS development gap and expanded graphite PCM composite validation data.
BESS vs EV Gap Graphite PCM Data + more
Read Full Analysis in Eureka →
Innovation Landscape

Key Patent Assignees and Academic Groups in BESS BTMS

Several assignees appear with notable frequency and technical depth across the 60+ record dataset. PatSnap customers in the energy storage sector regularly use Eureka to benchmark these players' filing strategies.

Commercial — Utility-Scale BESS

Sungrow Power Supply Co., Ltd.

Holds the largest cluster of directly relevant utility-scale BTMS patents in the dataset, with filings in EP, US, and GB jurisdictions covering predictive minimum-power-consumption cooling control. Their progression from rule-based thermal management (EP/US 2022, US 2023) to reinforcement-learning-optimized control (GB 2025) represents a clear technology roadmap toward intelligent active thermal management. Their disclosed method acquires charging-discharging current forecasts, cell parameters, predicted ambient temperature, and refrigerant return temperature over a future time window, then solves for the heat dissipation strategy with minimum total cooling system power consumption.

EP · US · GB · RL-optimized control
Academic — Stationary Systems

University of Alaska Anchorage

Provides the most complete academic treatment of stationary battery active cooling, including the only experimentally validated CFD comparative study identified in this dataset, published in 2020 and 2022 respectively. The 2022 study employed experimentally validated computational fluid dynamics (CFD) simulations to assess configurations including perforated vent plates and vortex generators, underscoring that seemingly minor design variations in airflow management produce measurable differences in thermal uniformity and peak temperature suppression. Critically, no comparative academic studies existed for this class of system prior to this work.

CFD · Stationary BESS · 2020 & 2022
Commercial — Chinese BESS OEM

CATL & Zhejiang Zeekr

Contemporary Amperex Technology (CATL) and Zhejiang Zeekr Intelligent Technology represent Chinese BESS OEM innovation, with patents covering both fan-based PWM active cooling and state-based mode-switching hybrid thermal management — reflecting the scale of Chinese utility-scale BESS deployments. Zeekr's EP/US 2025 patents disclose a PWM controller that adjusts fan duty ratio based on the difference between measured cell temperature and a preset threshold. CATL's US 2025 patent formalizes the hybrid state machine paradigm with hierarchical control logic.

PWM · Mode-switching · EP · US · 2025
Academic — Hybrid & Passive Frontier

Ontario Tech · VITO · Nanjing · Carinthia

Academic groups at Ontario Tech University, VITO Belgium, Nanjing University, and Carinthia University are at the frontier of hybrid and sorption-based passive strategies, publishing experimental validations of novel architectures that have not yet translated to broad commercial deployment but represent the next generation of passive technology candidates. Ontario Tech's 2023 hybrid demonstrated temperatures below 30°C at 7C rates; Nanjing University's 2020 sorption work describes a near-zero-energy bidirectional self-regulating MOF device. The European Patent Office has seen growing filings from European academic groups in this space. For developer API access to this data, see PatSnap Open API.

Sorption · PCM · Hybrid · Experimental
Key Takeaways

What the Evidence Shows for Utility-Scale BESS Design

Active cooling has been the historical default for stationary BESS, but the lack of comparative academic studies prior to 2020 means many deployed systems were not optimally designed — a gap directly identified in the University of Alaska Anchorage's 2022 study. The International Energy Agency notes that stationary storage is among the fastest-growing segments of the energy transition, making this design gap increasingly consequential.

Passive PCM-based systems provide effective transient thermal buffering with zero parasitic power, but are limited by finite latent heat capacity and reduced effectiveness in cold environments, as demonstrated in the University of Utah's 2018 study. PCM also slows temperature recovery after cold stops, meaning purely passive approaches may inadvertently impair battery performance during the warm-up phase of operation in low-ambient-temperature environments.

Predictive active control is the leading commercial innovation direction, with Sungrow's minimum-power-consumption algorithms across EP, US, and GB patents demonstrating that intelligent active cooling can dramatically reduce the parasitic energy penalty. Their most advanced patent (GB 2025) uses a multi-agent reinforcement learning model to continuously optimize cooling decisions.

Hybrid passive-then-active architectures deliver the best thermal uniformity under high discharge rates, with primary PCM cooling and secondary liquid/air active cooling shown to maintain temperatures below 30°C across 1C–7C rates. The Nantong University 2022 review confirms that liquid cooling combined with PCM and heat pipe hybrid systems offers the best research prospects. For life sciences and materials researchers applying these findings to battery chemistry, PatSnap's life sciences solutions provide complementary electrolyte and materials IP data.

Checklist: Hybrid BTMS Selection Criteria
  • Passive PCM layer for steady-state and transient thermal loads
  • Active liquid or air circuit for high-rate or extreme-temperature conditions
  • Predictive control algorithm to minimize parasitic consumption
  • Mode-switching logic with defined temperature thresholds
  • Integrated fire mitigation within active circuit design
  • Application-specific sizing for frequency regulation vs. arbitrage duty cycles
Consensus Finding

The evidence across the dataset consistently supports the conclusion that neither strategy alone satisfies all requirements of utility-scale BESS. The dominant architecture trend identified in both patent filings and peer-reviewed literature is the hybrid BTMS.

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Frequently asked questions

Active vs. Passive BESS Thermal Management — key questions answered

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References

  1. Stationary Battery Thermal Management: Analysis of Active Cooling Designs — College of Engineering, University of Alaska Anchorage, 2022
  2. Thermal Management of Stationary Battery Systems: A Literature Review — College of Engineering, University of Alaska Anchorage, 2020
  3. Energy storage system and thermal management method for the same — Sungrow Power Supply Co., Ltd., EP 2022
  4. Energy storage system and thermal management method for the same — Sungrow Power Supply Co., Ltd., US 2022
  5. Energy storage system and thermal management method for the same — Sungrow Power Supply Co., Ltd., US 2023
  6. Energy storage system, and thermal management method for energy storage system — Sungrow Energy Storage Technology Co. Ltd., GB 2025
  7. Thermal management system for energy storage battery pack — Zhejiang Zeekr Intelligent Technology Co., Ltd., EP 2025
  8. Thermal management system for energy storage battery pack — Zhejiang Zeekr Intelligent Technology Co., Ltd., US 2025
  9. Method and system for battery thermal management — The Boeing Company, EP 2018
  10. Immersion-type power battery thermal management system — Jiangsu Advanced Construction Machinery Innovation Center Ltd., EP 2026
  11. Method for thermal management of energy storage system and energy storage system — Contemporary Amperex Technology (Hong Kong) Limited, US 2025
  12. Adaptive thermal management of an electric energy storage method and system apparatus — Del Core, Robert, US 2018
  13. Adaptive thermal management of an electric energy storage method and system apparatus — Del Core, Robert, US 2020
  14. Adaptive thermal management of an electric energy storage method and system apparatus — Del Core, Robert, US 2017
  15. Cold temperature performance of phase change material based battery thermal management systems — University of Utah, 2018
  16. Experimental and Numerical Investigation of the Thermal Performance of a Hybrid Battery Thermal Management System for an Electric Van — VITO, Belgium, 2021
  17. Near-Zero-Energy Smart Battery Thermal Management Enabled by Sorption Energy Harvesting from Air — Shanghai Jiao Tong University, 2020
  18. Sorption Energy Harvesting from Air for Smart Battery Thermal Management — Nanjing University, 2020
  19. Development of a Temperature Management System for Battery Packs Using Phase Change Materials and Additive Manufacturing Options — Carinthia University of Applied Sciences, 2023
  20. Experimental and Numerical Analysis of a Hybrid Thermal Management Concept at Different Discharge Rates for a Cylindrical Li-Ion Battery Module — Ontario Tech University, 2023
  21. Research on Thermal Management System of Liquid Direct Contact Battery — Chongqing Vehicle Test & Research Institute, 2021
  22. Combined thermal management and fire mitigation for large scale battery packages — Kidde Technologies, Inc., EP 2025
  23. Thermal Battery Management Systems and Vehicles with Such Systems — GM Global Technology Operations, DE 2022
  24. International Energy Agency — Grid-Scale Battery Storage — IEA
  25. International Renewable Energy Agency — Battery Storage for Renewables — IRENA
  26. European Patent Office — Battery Technology Patent Landscape — EPO

All data and statistics on this page are sourced from the references above and from PatSnap's proprietary innovation intelligence platform.

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