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Industrial Modular Battery Pack Concept Addressing High Energy Density, Environmental Friendliness, Flexibility and Cost Efficiency for Automotive Applications

Periodic Reporting for period 2 - iModBatt (Industrial Modular Battery Pack Concept Addressing High Energy Density, Environmental Friendliness, Flexibility and Cost Efficiency for Automotive Applications)

Reporting period: 2019-04-01 to 2021-03-31

The current commercial battery technology that will dominate the market for a least 10 additional years is based on lithium, an element which is concentrated in specific parts of the world outside Europe. It is known that lithium ion (Li-ion) battery technology, with all its advantages in performance, is nevertheless still far from preventing the range anxiety effect on vehicle users. Several challenges are being addressed in the state of the art at cell electrochemistry and BMS development levels but these approaches are out of the scope of this topic. The challenge is, then, to maximize the energy density of Li-ion packs through the optimization of the structural design and components of a battery pack (BP) for a given cell form factor. In this sense the strategy is to increase the energy density by reducing the weight of the BP while keeping structural integrity and easy assembly and manufacturing.
On the other hand, vehicle manufacturing is one of the most important businesses worldwide and specifically for Europe is one of the pillars of our economy, both for all the direct and indirect labor generated around automotive industry. It is now the moment to compete in the BP design and manufacturing field, where Europe has significant strengths. European industry must offer a product whose life time is optimized for the intended application and can be easily extended. Besides the cell, a BP is composed of structural materials to keep the safety of the BP, electrical components to drive the energy and power of the battery and the cooling system to thermally balance the BP. All the knowhow to design and manufacture them is available within European SMEs and large industries.
All the above mentioned energy density increase, BP cost reduction and enhancement of European SME and large industries competitiveness must be accomplished keeping in mind the impact of our activities on the environment. Thus, eco-design of the BP, environmentally friendly considerations towards the BP manufacturing process and use of automated manufacturing are addressed from the perspective of minimizing the ecological footprint of the product to be developed and improving the current method of BP parts recovery in the recycling process.
Based on the know-how and suitable facilities of the Consortium regarding chemistries used in automotive industry, commercial high energy density cells behaviour were analysed and modelled in WP2 in order to fit the main goal of energy density for the proposed vehicles. In WP3, the core pack initial design was improved to reach density and modularity targets, in order to achieve a universal modular architecture. This WP was in close contact with WP4 and WP5, where the BP cooling system and the BP industrial manufacturing means were defined simultaneously. The goal of WP4 was to define and develop the cooling system of the BP consisting on a hybrid system composed of heat conducting elements and a heat exchanger. On the other hand, in WP4 an alternative direct liquid cooling design was developed and manufactured, whose outputs were compared with the selected cooling system for the iModBatt definitive battery packs. In WP5 the automated module assembly unit was designed, manufactured and validated. WP5 also took care of the analysis of the whole BP production workflow and the BP (dis)assembly steps. Finally, WP7 produced the final LCA and covered two innovative BP reuse / second life cases that were proposed in the project. Based on the developed models in WP2, the feasibility of those use scenarios was evaluated and best-use recommendations proposed. In addition, a tool for preliminary evaluation on BP recycling processes selection was developed.
On the other hand, some critical roadblocks were found in WP6. Initial performance tests on modules were performed with no issues, but the outcome of more demanding tests for the module resulted in a questionable module safety. While discussing those results at module level, an underperformance of the insulation at BP level lead us in agreement with our Project Officer to stop the rest of the testing roadmap. Hence, no BP testing at lab or in the vehicle were performed due to lack of minimum safety measures of the BP.
Although some of the scheduled tasks in the project could not be fulfilled, the expected impacts were achieved even if not validated, due to this lack of some conclusive tasks. The COVID crisis also hit the project, which lead us together with the accumulated two partners withdrawal to extend the project deadline for 6 months, till March 2021.
Results of iModBatt were disseminated through peer reviewed publications. In addition two patents were generated.
The increase in the energy density of the BP can be reached based on the weight reduction of the BP by gathering the electrical and thermal strategies as well as optimizing the BP overall design. The overall weight of the iModBatt BP equals the weight of the REN Zoe series BP. This is already an important milestone since the REN Zoe series BP is an optimized product, outcome of the mass production process and the iModBatt REN BP is still a TRL 7 prototype with margin for improvement when serialized. The proposed iModBatt design, once correctly fitted as a final product and using the mass production means can result in a 255.21 kg device, with a reduction of 12 % in weight with respect to the REN ZOE series BP. The on-board rated energy of the REN Zoe series BP is 44.6 kWh vs. 44.95 kWh of the iModBatt BP. Considering the achieved energy and weight reduction by the iModBatt BP, the energy density improvement with respect to the baseline BP is 14.52 % (176.13 Wh/kg vs. 153.8 Wh/kg).
iModBatt proposes a reduced manufacturing cost by introducing a BP module smart manufacturing unit that was designed, built and validated during the project. iModBatt’s modularity concept eases the automated activity and makes it flexible to add/modify any tooling for further customization. Additionally, since the life of the BP is expected to be extended (through reuse and second life), it is considered that this will decrease the overall cost of the BP. The cost in time for manufacturing and validation is drastically reduced in the automated module assembly line. Assuming that the machine cost is the same as the personnel cost with a cost per hour of 40 €/h, this indicates a cost reduction of 80 % from 21.2 €/module of the manual assembly to 4.4 €/module of the automated assembly. This cost reduction should be more precisely adjusted according to the actual cost/h of the automated assembly machine, but there is a clear reduction in the whole BP assembly time, since an iModBatt REN BP is composed of 26 modules, so one BP assembly time is optimized from 13.78 h to 2.86 h (80 % reduction).
The main activities in iModBatt have been led by EU industrial partners that in some cases have also concluded their work with a patent filing which will benefit each partners’ business plan or any future joint business, if it is the case.
An accurate LCA analysis was accomplished according to the REN and EGO iModBatt BPs bill of materials and manufacturing processes taking into account eco-design parameters and it was proved how the inherent capability of extending the life of a product behind the iModBatt concept is beneficial for the environmental impact.
Project concept