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SELF-sustained and Smart Battery Thermal Management SolutIon for Battery Electric Vehicles

Periodic Reporting for period 2 - SELFIE (SELF-sustained and Smart Battery Thermal Management SolutIon for Battery Electric Vehicles)

Reporting period: 2020-06-01 to 2021-05-31

Nowadays, no EV can accept an ultra-fast charging rate, but several automakers are working on electric cars able to accept that kind of power. SELFIE makes its biggest impact here, ensuring that the EVs, in the not so distant future, can accept this high charge rate without reduction on battery lifetime and to store the energy efficiency in their batteries with minimal losses.
The overall objective is to develop and demonstrate a novel self-sustained compact battery system, consisting of:
- A smart modular battery pack, which has excellent internal thermal conductivity properties, a refrigerant cooling system and thermal storage system (heat buffer) capable to absorb excess heat due to fast charging, and which is thoroughly insulated from the outside;
- An advanced battery thermal management system that is capable to keep the battery temperature effectively within the optimal window and to prevent overheating (and battery degradation) due to fast charging.
Importantly, it was originally intended to propose a fast-charging capability up to 180kW However, the SELFIE battery pack is based on the Fiat Doblò EV requirement which was characterized by CRF according to the use cases defined in WP1 (in D1.1) to establish the performance of the baseline reference solution (with liquid cooling).
Therefore, this results in the capability to safely handle fast-charging power up to 140 kW (5C) and to reduce the charging times to 10 min @ 140 kW (15 min @ 100 kW) as the SELFIE battery system is capable to effectively absorb the excess heat released during fast charging. In order to not affect the objectives of SELFIE, battery technology was selected to meet the fast-charging requirement. More detailed can be found in the D1.2.
The total battery system will be integrated into the Fiat Doblò and validated in test bench set-up, on a test track and the road to achieving TRL 7. And to prove that it is possible to achieve high range with a compact and affordable battery module.
In the end, SELFIE will significantly increase user acceptance of EVs by enabling fast-charging; offering significant cost reductions and elimination of range anxiety compared to other propulsion technologies.
From the beginning of the project to the end of the period covered by the report, the work performed can be distinguished per work package:

In WP1 (CRF), the specification and requirements of the SELFIE system to be applied in the Doblo BEV, through the definition of electrical, thermal, dimensional and gravimetric parameters as well as representatives use-case scenarios to be applied during validation testing were defined. In D1.2 on cell choice for the module, looking with critical eye the different cell arrangement proposed for the SELFIE was also provided. In D1.3 Concept and Test plan to be executed on the SELFIE system was described considering functional verification, lab characterization and on the road final verification.

In WP2 (LBF), with reference to WP1 and the battery selection, the first draft of the SELFIE battery system was proposed.The design and simulation of each component comprising the SELFIE battery system and the thermal management unit are detailed in D2.1 which was used for assessment of the overall performances of the SELFIE pack at the system level. The achievement of design freeze of the detailed CAD of the battery pack enabled to begin the manufacturing of the housing of the the battery pack.

In WP3 (VCC), the simulation platform derived from the GHOST project was successfully developed and will be used at the end of the project to simulate complete thermal management system. Mock-up tests were conducted and efforts were made to enhance the heat transfer performance of PCM integrated in aluminium foil in CSD by doubling the heat transfer area. Numerical investigations were conducted to rectify the drawbacks and to derive a stable operating refrigeration system. The vehicle integration of thermal system and control system development on bench test will be conducted in parallel in PR3.

In WP4 (IMECAR), worked on the CAD design adjustments regarding cradle and battery pack regarding the assembly process. Spacer materials between cells for swelling tolerance, electrical isolation and thermal pad to be used along with the rest of bill of materials (BOM) have been determined. Functional and safety verification tests of the battery system to be carried at IMECAR have been determined.

In WP5 (ViF), the Hazard Analysis and risk assessment (HARA) of the system was done. In Task 5.1 (ST5.1.1) a process model concerning functional safety was created with the tool EPF-Composer based on ISO 26262 the automotive standard for functional safety. A Methodology for multi-concern assurance along with functional safety concept for the battery system (T5.1) is available. In Task 5.2 the experimental setup is prepared for evaluating thermal and electrical performance of battery module at lab level and testing is ongoing.

In WP6 (CRF), the complete characterization of a baseline vehicle - Nissan eNV200, was identified, instrumented and tested in a climatic chamber with rolling bench. The details are available in the technical report (Part B). The Finite Element analysis was conducted numerically for structural assessment by measuring the stress distribution on all structures, verifying that the structure loading does not lead to critical local stress conditions.

In WP7 (I2M), the official project website was launched and represents the principal means of disseminating and exploiting the project results. The first version of Dissemination Plan sets the overall dissemination policy to be followed (D7.2). The project flyer was updated.The four newsletter have been published to reach wide audience and non-subscribers. In total, 5 open access publications were achieved. The project was disseminated at 11 conferences.
Considering SELFIE thermal management, the main expected results are:

The integration of new components and functionalities on the vehicle which enables long-duration trips (e.g. 700-1000 km day trips across different Members states) with no more than 60-90 minutes additional travel time (for charging) and without additional degradation
impact on the FEV power train including the battery which comprises of the development of :
- a new smart heat storage housing structures, consisting of smart and cost-efficient material structures allowing function integration (polymers, phase change materials (PCM) and inserts) to reduce the temperature.
- a novel battery cooling plate with indirect cooling enabling a high heat transfer rate and therefore a good thermal connection from the battery to the cooling and heating system.
- a novel PCM heat buffer which is dedicated for fast charging energy management.
- an innovative cooling module in the front end that will increase the airflow rate. The increment of flow rate is ensured without any additional electric power, allowing a decrease in the energy consumption of the cooling module.
- a cold storage device allowing the A/C system to run alternatively at two low-pressure levels. Changing the low-pressure level between 3.5 and 5.5 bars will increase the system of global efficiency.
- a novel high conductive material such as gap fillers between the battery cells to reduce the temperature peak.

Finally, the overall efficiency increase of the new functionalities and full-size implementation and demonstration.