Managing End-of-Life Lithium-ion Batteries: An Environmental and Economic Assessment.
详细信息
文摘
The growing market for lithium-ion batteries raises concerns about sustainable management of those batteries at end of life. Launching relevant policies requires a comprehensive understanding of potential economic values as well as environmental performance of end-of-life lithium-ion batteries. However,both recyclers and policymakers are facing a number of unanswered questions,including 1) how battery technology trajectory would affect the incentives for recycling? 2) what strategies are available to improve material recovery efficiency? and 3) what is the potential for nanoparticle release during end-of-life processing,particularly for next-generation lithium-ion batteries who contain nano-scale cathode materials? This dissertation aims to fill these research gaps. Multi-criteria optimization modeling and fundamental material characterization methods were used to quantify environmental and economic trade-offs for end-of-life lithium-ion batteries. Results show that potential material recovery values decrease as battery cathode chemistry transitions to low-cost cathode materials,as a majority of potentially recoverable value resides in the base metals contained in the cathode. Cathode changes over time will result in a heavily co-mingled waste stream,further complicating waste management and recycling processes. An optimization model was developed to analyze the economic feasibility of recycling facilities under possible scenarios of waste stream volume and composition. Sensitivity analysis shows that the profitability is highly dependent on the expected mix of cathode chemistries in the waste stream and resultant variability in material mass and value. Estimated current collection rate of end-of-life lithium-ion batteries turned out to be extremely low,indicating more opportunities and higher profitability for local recycling facilities if this rate can be improved. Aiming to achieve segregation of high value metallic materials in lithium-ion batteries,a pre-recycling process,including mechanical shredding and size-based sorting steps,which can be easily scaled up to the industrial level,has been proposed. Sorting results show that contained metallic materials can be effectively segregated into size fractions at different levels. In addition,using this pre-recycling process as a case study,the nanoparticle exposure potential during mechanical processing has been proactively investigated by using both traditional and nano-enabled lithium-ion batteries. Results show that a substantial amount of nanoparticles released during the mechanical shredding but not the size-based sorting process. Additionally,shredding nano-scale LiFePO4 cathode batteries may have a higher potential for nanoparticle exposure. Facing the rapidly growing volume of spent lithium-ion batteries,the results suggest policy or other incentives may be necessary to promote a robust collection and recycling infrastructure as the economic incentives will likely decrease as the chemistry transitions away from cobalt-based cathodes. This dissertation also demonstrates the importance of implementing a battery labeling system as recyclers will likely face a co-mingled waste stream. Specifying recycling-relevant information would increase the effectiveness of the pre-recycling system.