A Million-Mile Battery: For More Than Just Electric Vehicles

This briefing by RMI discusses how improvements in lithium-ion (Li-ion) battery cycle life—specifically the pursuit of batteries capable of lasting a million miles—can enable critical energy transition applications beyond electric vehicles (EVs), including vehicle-to-grid (V2G) services, fast charging, and long-duration energy storage using second-life batteries.

• While energy density and safety are often prioritized, improvements in battery degradation and cycle life are critical for expanding EV adoption and enabling new applications like vehicle-to-grid services, long-duration storage, and second-life battery uses.
• Different Li-ion chemistries offer different trade-offs: NMC and NCA cathode chemistries are optimized for energy density but have shorter cycle lives if routinely discharged completely, whereas lithium iron phosphate (LFP) is heavier and less energy dense but possesses a longer cycle life.
• Improved battery longevity is necessary to make vehicle-to-grid (V2G) charging economically viable, as current battery decay from charge and discharge cycles makes warranty providers reluctant to trade mobility capabilities for small grid reimbursements.
• Better battery performance would improve the economics of long-duration storage by reducing the need for buffer capacity—currently 10 to 30 percent overbuild—and decreasing the fear of degradation costs, allowing projects to use their fully installed capacity more often.
• Second-life Li-ion batteries could provide an economic solution for long-duration storage, but this requires a standardized ecosystem for collection, testing, and recycling, as well as improved longevity to provide confidence in the remaining energy content of repurposed batteries.

APA

RMI (2020). A Million-Mile Battery: For More Than Just Electric Vehicles. https://rmi.org/resources/a-million-mile-battery-for-more-than-just-electric-vehicles/

Chicago

RMI. A Million-Mile Battery: For More Than Just Electric Vehicles. 2020. https://rmi.org/resources/a-million-mile-battery-for-more-than-just-electric-vehicles/.

Wikipedia

{{cite report |author=RMI |title=A Million-Mile Battery: For More Than Just Electric Vehicles |date=24 June 2020 |url=https://rmi.org/resources/a-million-mile-battery-for-more-than-just-electric-vehicles/ |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{rmi2020millionmile, author = {{RMI}}, title = {{A Million-Mile Battery: For More Than Just Electric Vehicles}}, institution = {RMI}, year = {2020}, month = jun, url = {https://rmi.org/resources/a-million-mile-battery-for-more-than-just-electric-vehicles/}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }