Active vs Passive BESS Thermal Management — PatSnap Eureka
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.
Active vs. Passive: Capability Radar
Six key performance dimensions across 60+ patent and literature records
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.
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.
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 capacityPhase 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 drawDirect-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 uniformityNear-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-regulationKey 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.
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.
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.
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 |
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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.
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.
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 controlUniversity 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 & 2022CATL & 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 · 2025Ontario 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 · ExperimentalWhat 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.
Active vs. Passive BESS Thermal Management — key questions answered
Active thermal management strategies rely on externally powered mechanisms to move heat away from — or into — battery cells, including forced fluid circulation, thermoelectric devices, and HVAC compressors. Passive strategies exploit the intrinsic thermophysical properties of materials — primarily their thermal conductivity, heat capacity, and phase transition enthalpy — to absorb and redistribute heat without requiring external power input.
Purely passive PCM systems have finite heat absorption capacity bounded by the latent heat storage of the material — once the PCM is fully melted (or frozen), it ceases to provide temperature regulation, making passive-only systems vulnerable during sustained high-rate charge-discharge cycles characteristic of grid frequency regulation service. PCM also slows temperature recovery after cold stops, meaning that in low-ambient-temperature environments, purely passive PCM approaches may inadvertently impair battery performance during the warm-up phase of operation.
Sungrow's 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. The coolant flows through a cell liquid cooling plate and a plate heat exchanger in an internal circuit, with the strategy updated dynamically. Their 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.
The Ontario Tech University (2023) hybrid approach — a primary passive cooling layer of PCM absorbing the bulk of the thermal load, with secondary active cooling through vertical liquid channels and airflow managing heat during sustained high-rate cycling — demonstrated a maximum cell temperature below 30°C and temperature uniformity within 5°C across 1C to 7C discharge rates.
Sorption-based passive thermal management uses a self-adaptive device based on 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 is inherently passive — it 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.
No. The University of Alaska Anchorage's 2020 literature review identifies the gap between electric vehicle BTMS development — which has undergone significant academic and commercial development — and stationary system thermal management, which has lagged considerably despite the rapid growth of grid-scale storage deployment. Active cooling has long been the default approach for stationary batteries, yet no comparative academic studies existed for this class of system prior to the 2022 University of Alaska Anchorage study.
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References
- Stationary Battery Thermal Management: Analysis of Active Cooling Designs — College of Engineering, University of Alaska Anchorage, 2022
- Thermal Management of Stationary Battery Systems: A Literature Review — College of Engineering, University of Alaska Anchorage, 2020
- Energy storage system and thermal management method for the same — Sungrow Power Supply Co., Ltd., EP 2022
- Energy storage system and thermal management method for the same — Sungrow Power Supply Co., Ltd., US 2022
- Energy storage system and thermal management method for the same — Sungrow Power Supply Co., Ltd., US 2023
- Energy storage system, and thermal management method for energy storage system — Sungrow Energy Storage Technology Co. Ltd., GB 2025
- Thermal management system for energy storage battery pack — Zhejiang Zeekr Intelligent Technology Co., Ltd., EP 2025
- Thermal management system for energy storage battery pack — Zhejiang Zeekr Intelligent Technology Co., Ltd., US 2025
- Method and system for battery thermal management — The Boeing Company, EP 2018
- Immersion-type power battery thermal management system — Jiangsu Advanced Construction Machinery Innovation Center Ltd., EP 2026
- Method for thermal management of energy storage system and energy storage system — Contemporary Amperex Technology (Hong Kong) Limited, US 2025
- Adaptive thermal management of an electric energy storage method and system apparatus — Del Core, Robert, US 2018
- Adaptive thermal management of an electric energy storage method and system apparatus — Del Core, Robert, US 2020
- Adaptive thermal management of an electric energy storage method and system apparatus — Del Core, Robert, US 2017
- Cold temperature performance of phase change material based battery thermal management systems — University of Utah, 2018
- Experimental and Numerical Investigation of the Thermal Performance of a Hybrid Battery Thermal Management System for an Electric Van — VITO, Belgium, 2021
- Near-Zero-Energy Smart Battery Thermal Management Enabled by Sorption Energy Harvesting from Air — Shanghai Jiao Tong University, 2020
- Sorption Energy Harvesting from Air for Smart Battery Thermal Management — Nanjing University, 2020
- Development of a Temperature Management System for Battery Packs Using Phase Change Materials and Additive Manufacturing Options — Carinthia University of Applied Sciences, 2023
- 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
- Research on Thermal Management System of Liquid Direct Contact Battery — Chongqing Vehicle Test & Research Institute, 2021
- Combined thermal management and fire mitigation for large scale battery packages — Kidde Technologies, Inc., EP 2025
- Thermal Battery Management Systems and Vehicles with Such Systems — GM Global Technology Operations, DE 2022
- International Energy Agency — Grid-Scale Battery Storage — IEA
- International Renewable Energy Agency — Battery Storage for Renewables — IRENA
- 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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