With the upcoming market introduction of silicon anodes in lithium-ion batteries (LIBs), there is a growing concern about their sustainability. However, due to their novelty, existing life cycle assessments (LCA) on the environmental impacts of silicon anodes rely exclusively on
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With the upcoming market introduction of silicon anodes in lithium-ion batteries (LIBs), there is a growing concern about their sustainability. However, due to their novelty, existing life cycle assessments (LCA) on the environmental impacts of silicon anodes rely exclusively on laboratory data about their production process and performance. Moreover, as there are no established manufacturing sites yet, literature assumes predetermined locations despite the significant influence of the location choice on the environmental performance of the anode. Therefore, this study adapts the Suitability–Feasibility–Acceptability (SFA) framework to identify the optimal production location for silicon anode manufacturers on a global scale, considering the general nature and interests of scale-up businesses in the clean energy technology sector. Based on the outcome, this study conducted an LCA using the PEF impact categories to compare the life cycle environmental impacts of a pure hydrogenated amorphous silicon thin film anode, prepared via plasma enhanced chemical vapour deposition (PECVD), to the current market standard of natural and synthetic graphite anodes in a lithium cobalt oxide (LCO) battery for consumer electronics. The life cycle inventory data of the silicon anode's production process was provided by an up-scaling silicon anode manufacturer.
The results of the location study suggest that Europe is the optimal production location for silicon anode manufacturers because of its favourable energy mix. Nevertheless, due to the high electricity consumption of the PECVD process, the findings of the subsequent LCA indicate that a LIB with a silicon anode produced in Europe performs significantly worse than its graphite-based counterparts from China in almost all impact categories, regardless of its higher energy density. Among the graphite-based alternatives, the LIB with a synthetic graphite anode is associated with higher emissions, owing to its energy-intensive graphitisation step. Unlike the emissions of the silicon anode, which are primarily caused by the electricity consumption, the impacts of both graphite anodes are more attributed to copper production given the higher content of primary copper in their current collectors. On the basis of the whole lifecycle, the impacts of the three battery types converge, with electricity being the main contributor in all three product systems. Nevertheless, the ranking in terms of environmental performance remains identical, even in different battery performance and production efficiency scenarios. Moreover, the results prove to be robust with respect to the allocation method and the electricity consumption during the silicon anode production process.
Although the outcomes indicate that graphite anodes are preferable in LIBs, silicon anodes should not be dismissed as a viable alternative, given their early development stage. Since their potential improvements in performance and production efficiencies are uncertain at this point, research around silicon anodes should continue. Furthermore, future studies should regularly update the life cycle inventory data of the production process of silicon anodes and their precursor materials, to critically monitor the development. Finally, based on the results of the scenario analysis, the author encourages silicon anode manufacturers to rather improve several of the anode's production and performance parameters than to focus on one parameter individually.