SUSTAINABILITY PERSPECTIVES ON LITHIUM-ION BATTERIES

For the last four years, I have had the immense privilege of serving as an Associate Editor for Clean Technologies and Environmental Policy. This opportunity has provided a front-row seat to compelling research aimed at solving global sustainability challenges and a chance to correspond with and learn from authors and reviewers from around the world. The experience has also provided a fascinating education on the scholarly publishing domain and on a wide array of clean technology topics, from the first paper I managed as editor, a techno-economic assessment of biogas-tohydrogen production (Montenegro Camacho et al. 2017), to a recent contribution on the climate mitigation potential of eco-industrial parks (Zhang et al. 2020). I am humbled and honored by this experience and am grateful for the hard work and patience of all of our hard-working contributors. As I wind down my Editorial activities this fall, I will also be wrapping up a significant phase of my own research. For the last seven years, my research group has been studying the sustainability challenges surrounding lithium-ion batteries and their end-of-life management after use in electric vehicles, thanks to funding provided by the National Science Foundation through the Faculty Early Career Development Program (CBET 1254688). This project was motivated by the growing adoption of electric vehicles as a strategy to mitigate global fossil fuel dependence and greenhouse gas emissions from conventional vehicles powered by internal combustion engines. Widespread vehicle electrification hinges on concurrent development and cost effectiveness of energy storage systems, like lithium-ion batteries. Research on novel battery materials, designs, manufacturing, and performance has expanded rapidly in the last decade, yet has only begun to comprehend the potential sustainability challenges inherent to this system. Sustainability challenges span the entire technology life cycle for energy storage systems like lithium-ion batteries (LIBs): from raw material extraction, battery manufacturing, electric vehicle use, and management of LIBs at end-oflife. Raw material impacts typically stem from the resources that provide LIBs with their necessary electrochemical functionality, including the typically graphitic anode and the cathode, which is usually comprised of lithium, cobalt, nickel, and manganese in varied concentrations. While early attention was focused on lithium availability, recent research has demonstrated that cobalt may actually present the greatest concerns with respect to sustainability and long-term availability. Cobalt is primarily sourced in the Democratic Republic of the Congo, a region historically characterized by political instability, social impacts in the mining sector, and lack of supply chain transparency. The global reliance on such a concentrated supply chain introduces risks of resource shortages or price spikes due to disruptions, which may translate to downstream impacts on battery and even vehicle price competitiveness (Leader et al. 2019). Ensuring a long-term, stable supply of cobalt will require expanding the geographic diversity of the supply chain while at the same time developing secondary sources to be obtained through increased recycling (Fu et al. 2020). Efforts to minimize LIB material and manufacturing impact have also been focused on new electrode designs and alternate materials that alleviate cobalt demand and provide performance advantages, such as higher energy and power density or longer lifetime (e.g., Wu and Kong 2018). Such innovations may lead to a slightly greater upstream environmental impact but pay off by significantly reducing electricity consumption and losses during charging and discharging over the battery’s useful life in electric vehicles. These advances also promise to dramatically extend battery lifespan, prompting recent claims by Tesla CEO Elon Musk that a “million-mile battery” is within reach. However, even LIBs with extended lifespans will ultimately require management once they no longer meet the technical specifications for use in vehicle applications.