<p>Electrifying the transport sector will require manufacturing of lithium-ion batteries and extensive mining of their embedded critical minerals, like lithium. Research has quantified the future demand for lithium-ion batteries, their constituent materials and their environmental impacts, but typically without contextualizing these impacts within the benefits of fleet-level decarbonization. We conduct a life cycle assessment of the United States projected light-duty electric vehicle fleet (2025–2050) and compare it to a counter-factual scenario where all electric vehicles are instead internal combustion engine vehicles to determine the environmental benefits enabled by lithium-ion batteries in electric vehicles. Results show that electric vehicles will reduce primary energy consumption by 20%, material extraction (including fossil fuels) by 34% and carbon dioxide equivalent (CO₂e) emissions by 61% compared to an internal combustion engine-only future. This translates into 300–600&#xa0;kg CO₂e avoided per kilowatt-hour of lithium-ion battery, or 5–12 tons CO₂e avoided per kg of lithium extracted. Under conditions of high battery recycling rates, avoided emissions can increase to 20 tons CO₂e per kg of lithium. However, electric vehicle deployment increases metal extraction by 117% and critical minerals extraction by 179%. Actions to reduce the metal intensity of EVs are needed such as increasing LIB durability, improving EV energy efficiency, and enhancing battery recycling and metal recovery rates to avoid new mining and multiply the climate benefits of battery mineral extraction.</p>