CATL announced a breakthrough in lithium metal battery technology

CATL, the world's largest electric vehicle battery manufacturer, has announced a breakthrough in lithium metal battery (LMB) technology through a statistical analysis method called Quantitative Mapping.

What is known

The findings were published in the journal Nature Nanotechnology. CATL claims to have entered the previously uncharted territory of electrolyte strategy. The innovative approach enables the creation of LMBs with high energy density and extended lifetime, solving a long-standing problem in the field. The optimised prototype has achieved a lifetime of 483 cycles and can be integrated into current designs to achieve energy densities of more than 500Wh/kg, marking a significant step towards commercial viability for LMB applications in electric vehicles and electric aviation.

LMBs represent one of the promising areas of next-generation batteries due to their inherently high energy density. Especially for high-performance applications such as electric vehicles with long range. However, these batteries have long faced a trade-off between energy density and cycle life. Previous research has focused on improving cell performance by optimising solvation structures and electrolyte interfaces. And these approaches have often come at the expense of lifetime, failing to provide commercially viable solutions. Limited progress has been made in understanding the failure mode of LMBs due to the difficulty in accurately quantifying the consumption of active lithium and electrolyte components during cycling.

To overcome this hurdle, CATL's R&D team developed and refined a set of analytical methods to track the evolution of active lithium and each electrolyte component over the life cycle of the battery. This approach turned a "black box" into a "white box," revealing critical depletion pathways leading to cell failure. The team found that, contrary to previous assumptions, the dominant cause of cell failure is not solvent degradation, accumulation of "dead" lithium, or solvation disturbance, but the continuous consumption of LiFSI electrolyte salt, with 71% of it consumed by the end of life. These findings emphasise the need to broaden the industry focus beyond Coulomb battery efficiency(CE), long considered a key metric for LMB, and to include electrolyte longevity as a critical factor for sustained performance.

Based on these findings, CATL optimised the electrolyte composition by introducing a diluent with a lower molecular weight. This adjustment increased the mass fraction of LiFSI salt, improved ionic conductivity and reduced viscosity, while not increasing the total mass of electrolyte used. The resulting LMB prototype, while exhibiting the same CE as the previous iteration, doubles the cycling life to 483 cycles and can be used in new designs with energy densities greater than 500Wh/kg. In simpler words, CATL promises both efficient and long-life batteries.

The research was conducted at CATL's 21C Lab, which is focused on developing next-generation battery technologies. CATL has invested a total of about 18.6 billion yuan (US$2.59 billion) in research and development in 2024.

Source: CATL