Used batteries from electric vehicles could fulfill two-thirds of China's grid storage requirements by 2050, according to a study by researchers at Tsinghua University. These second-life batteries would charge during periods of abundant renewable energy and release power during peak demand. The approach could reduce costs by 2.5 percent while supporting a shift to carbon-neutral power systems.
Electric vehicle batteries are usually retired when they drop to about 80 percent of their original capacity. However, researchers argue that these batteries retain enough power for grid storage applications, where degradation affects performance less than in vehicles. Ruifei Ma at Tsinghua University in China and colleagues estimate that repurposed EV batteries could satisfy 67 percent of China's storage demand by 2050.
Renewable energy sources like wind and solar fluctuate, creating shortages during peak times such as mornings, evenings, and winter. Traditionally, gas and coal plants address these gaps, but battery storage is expanding in countries including China, the US, the UK, and Australia. The study projects that second-life batteries, used until 40 percent capacity, would see rapid growth after 2030, reaching a total capacity of 2 trillion watts by 2050. In contrast, reliance on new batteries and pumped hydro would achieve only half that amount.
Gill Lacey at Teesside University in the UK notes, “There’s still plenty of power left in them, and used as storage, they tend not to degrade as quickly.” Rhodri Jervis at University College London emphasizes sustainability: “We shouldn’t be throwing away these materials that cost a lot of money to mine and process and turn into batteries when we’ve got 80 per cent usable capacity left in the cells.”
In 2024, over 17 million EVs were sold globally, representing 20 percent of car sales, with nearly two-thirds purchased in China. This influx will increase available used batteries, potentially making them more economical than new lithium-ion ones, despite falling prices for the latter.
Challenges include screening damaged batteries, grouping similar ones, and installing sensors for temperature and voltage to prevent fires. Lacey adds, “Clearly the risks are higher, so you need to mitigate those with your safety and isolation and balancing and all the rest of it being more robust.” A project by US start-up Redwood Materials in Nevada demonstrates feasibility, using decade-old batteries for a 63-megawatt-hour data center system costing under $150 per kilowatt-hour and providing power for over 24 hours.
The findings appear in Cell Reports Sustainability (DOI: 10.1016/j.crsus.2025.100613).
