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Project VALUABLE, led by HSSMI, has been instrumental in shedding light on second life opportunities for li-ion batteries. As the project closed at the end of March, we are now sharing our findings in order to generate discussion amongst the public and, in particular, those who are looking to continue the research that VALUABLE began. In this blog series, we will be discussing a different battery-related topic each time – from testing and legislation to end of life, recycling and remanufacturing. This time, we take a look at Design for End of Life (DfEoL).
Designing products for manufacture often seeks to enable simpler, faster and cost effective production processes while ensuring a product remains robust and fit for purpose. Design for End of Life (DfEoL) typically aims to achieve similar benefits but for the reverse process, disassembly and recovery of materials and value. While the objectives are similar, the design requirements often are not. Current battery pack designs utilise irreversible joining methods such as sealants, adhesives and welded components to prevent water ingress, loosening under vibration and ensure strong conductive joints. These methods, however, can limit the effectiveness and efficiency of disassembly techniques leading to destructive or partial disassembly – limiting the potential recoverable value. The lithium-ion cell represents a large proportion of the battery and vehicle cost, and recovery of this value for second life or remanufacture purposes can lead to a reduction in cost for the manufacturer and in turn the customer.
Implementing DfEoL principles into battery assembly, and keeping in mind the potential to disassemble a product and recover materials and value at its end of life, could present an attractive opportunity to OEMs if the control of the battery and its remaining value were to be retained with the OEM once the product reaches its end of life. For example, servitised models of consumption could help OEMs retain this value as they would be providing the customer with access to the battery’s service rather than ownership of it.
Ideally, a business case in favour of implementing DfEoL principles should be based on increased future production volumes and warranty cases. However, at the moment there is a lack of information on failure rates and failure mode analysis for electric vehicle traction batteries to make sensible assumptions and build such a model. As such, the trade-off for an OEM is largely uncertain.
Discussions in the VALUABLE Industrial Advisory Board have led to some recommendations on how it may be possible to implement DfEoL without compromising design for manufacture. These include:
– Enhancing component shapes instead of utilising less robust joining methods, i.e. extended connection tabs in pouch type cells would allow cutting and welding back the battery cell into a module for a second life application;
– Refining the component joining methods, i.e. reducing excessive welding so that the battery is robust enough to resist vibration and shocks but the joints can still be unwelded;
– Exploring alternative battery integrations within the vehicle architecture to ease access for repair and dismantling.
Further research and analysis is still needed to enable OEMs to make well-informed decisions about how to implement DfEoL concepts.
The information contained in this article has been generated through discussions in the project VALUABLE Industrial Advisory Board.
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