Lithium-ion (Li-ion) battery technology has a strong presence in the world market and will stay strong for the coming years. Li-ion rechargeable batteries are commonly used in electric vehicles and portable electronic devices. The challenge is to maximise the energy density, reduce costs and extend the lifetime of Li-ion battery packs (BPs). A way to improve the energy density is reducing the weight of BPs while maintaining their structural integrity, easy assembly and manufacturing. The EU-funded iModBatt project designed and manufactured a high energy density modular BP, flexible enough for use in automotive and small stationary applications with minimum environmental impact. “This BP is well suited for industrial automated assembly with an easy disassembly design, making it possible to shift from primary applications to secondary ones and to facilitate BP recyclability or parts replacement if necessary,” explains Iosu Cendoya, iModBatt project coordinator.
Lighter, high energy BP
The increase in the energy density of a BP can be reached based on the weight reduction of the BP by gathering the electrical and thermal strategies and optimising the overall BP design. The weight of the iModBatt BP equals that of the Renault Zoe (REN Zoe) series BP (290 kg vs 291.21 kg of iModBatt’s). This is an important milestone since the REN Zoe series BP is an optimised product, the outcome of a mass production process, and the iModBatt REN BP is still a preliminary prototype with a margin for improvement when serialised. As a result of the analysis of the iModBatt BP parts that contribute to the overall weight, the team concluded that a reduction of 36 kg is feasible over the 291.21 kg. “The iModBatt design, once correctly fitted as a final product using mass production, can result in a 255.21 kg device, a 12 % weight reduction with respect to the REN Zoe vehicle series BP,” adds Cendoya. In addition, the onboard rated energy of the REN Zoe series BP is 44.6 kWh vs 44.95 kWh of the iModBatt BP. The iModBatt BP achieved energy and weight reduction with a 14.52 % energy density improvement with respect to the baseline BP (176.13 Wh/kg vs 153.8 Wh/kg). An accurate life cycle assessment was also conducted to consider eco-design parameters. Extending the life of a product behind the iModBatt concept was quantified and proved beneficial from an environmental impact point.
Lower BP cost and huge reduction in assembly time
iModBatt proposes a reduced manufacturing cost by introducing a BP module smart manufacturing unit designed, built and validated during the project. This modularity concept eases the automated activity and makes it flexible to add/modify any tooling for further customisation. Additionally, since the life of the BP is expected to be extended (through reuse and second life), the overall BP cost is expected to decrease. “The cost in time for manufacturing and validation was also drastically reduced in the automated module assembly line, and the BP assembly time was optimised from 13.78 h to 2.86 h (an almost 80 % reduction),” concludes Cendoya.
iModBatt, BP, energy density, battery pack, Li-ion, lithium-ion, electric vehicles, automotive industry