First Italian manufacturer of supersport electric motorcycles, Energica Motor Company Spa is a leading innovator in the EV market.
Thanks to the close involvement in the MotoE™ racing series (Energica was chosen by Dorna as single manufacturer for FIM Enel MotoE™ World Cup. The first edition of the World Cup concluded recently, celebrating rider Matteo Ferrari from Team Trentino Gresini MotoE as championship winner) Energica’s technological advancement had an important boost, being able to count on a unique element of competitive advantage represented by MotoE™ itself: Energica is, indeed, the only firm in the world to have an exclusive testing ground to try new technical solutions – with some of the best riders worldwide. This support proved to be unlike anything else for Energica R&D, both for the racing and the production sides.
Being among the top players in EV market means collaborating with technical partners who produce technological innovation and new top-level solutions in a very short time.
Since its establishment, Energica has availed itself the partnership with CRP Technology. CRP Technology is worldwide leading innovator of Additive Manufacturing with Windform® materials for LS technology. CRP was born - like Energica - from the entrepreneurial vision of Cevolini family.
The following case study explains how CRP Technology supported Energica in developing and manufacturing of cell pouch frame. The cell frames were tested on battery pack prototypes, both for the racing and the production sides.
The challenge
Energica motorcycles use a high-energy lithium polymer (Li-NMC) battery.
The battery is contained in sealed housing: battery cells, the Battery Management System (BMS) and all the necessary systems to ensure the safety of the vehicle.
Energica is the only manufacturer in the world that has designed, patented and adopted a cooling system for the battery pack that is superior thanks to its specific ventilation paths that limit the stress on the batteries. This provides considerable benefits to both performance of the vehicle and the life of the battery.
Energica’s R&D department constantly carries out research on new cells placed on the market, in order to evaluate their use in industrial production. This activity allows Energica to be at the forefront of the most advanced technology.
The activity starts from the validation of the single cell (initial screening) and evolves in testing battery pack prototypes on the road. The tests conducted on the cells are part of Energica's know-how, and therefore cannot be disclosed in detail.
In this specific case, the study was conducted on pouch cells.
In order to carry out the tests required by Energica procedure, the team of engineers at Energica decided to provide each pouch cell with a surrounding case, with the function of support and reinforcement.
To test the battery pack prototype on the road, the casing of each pouch cell had to be manufactured using a high-performance material with excellent mechanical properties and using advanced technology that met Energica’s requirements.
Due to these reasons, Energica has relied on CRP Technology: Experience and know-how gained in over many years of activity as supplier of innovative and cutting-edge technological solutions for the most competitive and demanding industrial sectors, CRP Technology has supported Energica from the early stages of design and development to the construction of the cell casing with professional 3D printing and Windform® material.
The solution
Following the examination of Energica’s needs and the analysis of the 3D files of the application, CRP Technology has opted to use selective laser sintering technology with Windform® FR2, the new material from Windform® TOP-LINE family of high performance composite material for Additive Manufacturing, which is flame retardant and glass-fiber reinforced.
“Having built functional prototypes of pouch cell casings for various tests, including road tests - states Engineer Franco Cevolini, CTO and VP at CRP Technology - it was clear we should use a material with specific characteristics, namely: polyamide-based material, electrically insulated, stiff, resistant to temperature and flame retardant.”
Windform® FR2 was the clear choice because it is the only material on the market with all these characteristics.
“To be more specific – comments Eng. Cevolini - flame retardant characteristics are very important, because it guarantees self-extinguishing in case of operating anomalies, which are a result of a temporary voltage peak, with consequent localized melting, followed by combustion initiation.
As example: - Cevolini adds - If an ignition/combustion occurred in a localized portion of the cell casing, and the polymer were flame retardant, then the combustion would be extinguished.
Instead, if the material were not flame retardant, then serious problems would arise, because the combustion would degenerate into a fire. Windform® FR2 prevents such an occurrence.”
Stiffness is also very important: "The material chosen for the pouch casing– Cevolini states –had to have a high mechanical performance in order to guarantee an overall stiffness to the battery pack prototype. In order to withstand the volumetric expansion that cells undergo during the charge and discharge cycles.
Indeed, the expansion generates pressure: the cell casings therefore had to be able to withstand these stresses.
Outcome
After Energica Motor Company’s approval, CRP Technology 3D Printing Department proceeded with the manufacturing and delivery of the pouch casings.
This appliacation has allowed, once again, to highlight the perfect combination of selective laser sintering technology and Windform® composite materials.
Thanks to Windform® FR2, indeed, in a very short time and with excellent and highly promising results in terms of mechanical, electrical and thermal features, it was possible to carry out all the tests on the battery pack prototype and testing protocols required by Energica.
In-depth analysis: Potential issues of pouch cells and their resolution using 3D printing and Windform® FR2 composite material
Issue no.1: Swelling
Swelling can occur as part of gas generation during charge and discharge. It is a concern, which should not be underestimated
Giampiero Testoni, CTO at Energica Motor Company, “In a test-ready battery pack prototype (images 7 and 8), each cell must be in position and not move. Stability must be assured by the cell casing.
Therefore, cell casings play a fundamental role: they must be resistant and contain the swelling of the cell, without breaking.”
Energica, assisted by CRP Technology, has verified that Windform® FR2 and selective laser sintering process guarantee a high level of precision of the pouch cells to maintain their position inside the battery pack.
"The cell casings in Windform® FR2 – Testoni adds – allow a certain degree of freedom of movement” to swell and contract without deforming, without going out of position, without interfering with one another.”
Issue No.2: Heat Rejection
Swelling of pouch cells generates heat that must be dissipated. To aid this heat rejection a metal plate with two lateral structures is attached to each pouch cell and holder. The function of the plate is cooling: the heat is transferred to the lateral structures and dissipated to the outside, in combination with the cooling system patented by Energica.
[Figure 10 and 11 represent the area most affected by the increase in heat. This section must not undergo deformation: any loss of preload of the screw could generate sparks with the potential of fire.]
Tests have proven Windform® FR2 glass-fiber reinforced and flame-retardant composite material maintains required stiffness, and does not deform with the increase in heat.
“When a polymer begins to heat up, it loses its mechanical characteristics and undergoes deformation – adds Engineer Franco Cevolini -. It does not happen with Windform® FR2 because it is a composite material and it preserves its stiffness. Windform® FR2 deflection temperature under load is higher than any other non-composite materials with the same flame-retardant characteristics”.
“We rely on CRP Technology and its 3D Printing Department because they have the right composite material to satisfy every need, in particular to support a complex project such as Energica electric motorcycles. I am not referring to an ordinary motorcycle, but to a high voltage and power, electric motorcycle that has specific needs. CRP Technology is the right partner to support customers in their everyday challenges. ”
- Giampiero Testoni, CTO Energica Motor Company