Improved lithium battery unveiled

Scientists at Tianjin University have developed a high-energy lithium metal battery with an energy density two to three times greater than that of existing lithium-ion batteries, according to findings published in the journal Nature recently.

The breakthrough was achieved by redesigning the battery's electrolyte to improve the movement of lithium ions. With batteries of the same weight, the range of electric vehicles is expected to multiply.

The findings are a significant step in meeting the urgent demand in fields such as electric transportation and the low-altitude economy for high-energy, long-duration rechargeable batteries.

Energy density, the amount of energy that can be stored per mass, is a core performance indicator for batteries.

"For a long time, scientists have hoped to increase the energy density of batteries while ensuring maximum safety, enabling batteries to store more electricity with lighter weight and smaller volume," said Hu Wenbin, a professor at the School of Materials Science and Engineering at Tianjin University and leader of the research team.

Developers have faced challenges in improving the performance of traditional lithium batteries, Hu said. The electrolyte of traditional lithium batteries is generally composed of a single salt and a few solvents, forming a point-like structure. That structure limits the migration capability of lithium ions, resulting in imbalances in the electrolyte and restricting the battery's energy storage and cycling performance.

To address the problem, the team designed an ultra-dispersed electrolyte, or UDE, after years of research.

"Compared with the relatively single composition of traditional electrolytes, this electrolyte integrates multiple solvents and salts, significantly enhancing the disordered solvation micro-environment. It creates a face-like microscopic environment, effectively reducing the kinetic barriers to lithium-ion movement," Hu said.

The new electrolyte design optimizes performance and achieves internationally recognized high energy density targets, Hu added. Pouch cell energy density exceeds 600 watt-hours-per-kilogram, and battery pack energy density exceeds 480 Wh/kg.

By comparison, United States electric car manufacturer Tesla's 4680 battery has an energy density of about 300 Wh/kg, and Chinese electric vehicle company BYD's Blade Battery is around 150 Wh/kg.

"This lays an important foundation for the future application of lithium metal batteries," Hu said.

The team also discovered that within the dispersed microscopic environment formed by the UDE, a solid electrolyte interphase, or SEI, develops inside the battery.

"This robust and stable interface enables the electrode to remain stable during prolonged cycling, which is crucial for enhancing the lifespan of high-performance lithium metal batteries," Hu said.

The researchers used artificial intelligence to screen electrolyte materials, significantly shortening development time. They collaborated with the National University of Singapore and several Chinese companies.

With support from national-level platforms such as Tianjin University's National Industry-Education Platform of Energy Storage and the National Key Laboratory of Precious Metal Functional Materials, the team is promoting commercialization and practical application of the findings.

A pilot production line for high-energy lithium metal batteries is operational, and the technology has been tested in three models of domestically developed micro electric drones. Their flight endurance increased by up to 2.8 times compared with current battery systems.

Zang Yifan contributed to this story.

yandongjie@chinadaily.com.cn