Extended Kaya Identity for Primary and Secondary Material Production for Lithium-ion Batteries

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Growing global affluence and the need to reduce the related environmental impacts lead to an increased use of high-tech products. From a life cycle perspective, environmental impacts are increasingly being shifted from the use stage towards the material production stage. The currently used Kaya identity enables a structured analysis of environmental impacts along a product life cycle and distinguishes between primary and secondary materials used. However, the origin of the impacts of material supply are presented in a very aggregated way as an average of all materials used which hinders a targeted engineering of material production processes. In this paper, we identify general technical variables with a high influence on environmental impacts and material quantity of primary and secondary material production for Lithium-ion batteries. The findings are used to extend the Kaya identity by technical variables such as process efficiencies, material specific recovery rates and material qualities for both primary and secondary material production. Further, we will guide the user to quantify the variables to promote further usage in industry. We present the extended Kaya identity exemplary for a current and future primary lithium production and a mechanical-hydrometallurgical recycling of spent Lithium-ion batteries. The results demonstrate the importance of considering process individual technical variables to assess the overall environmental impacts of a product system and to enable a target driven engineering of environmental hotspots.