May 29, 2025: Chinese EV battery giant CATL has released details of a prototype “breakthrough” lithium metal battery (LMB) it claims marks a paradigm shift for developing batteries that are both energy-dense and built to last.
According to research* published in the journal Nature Nanotechnology, reported on May 28, CATL’s ‘optimized’ LMB prototype has reached a cycle life of 483 cycles — deploying proprietary technology that can be incorporated into latest battery designs to achieve an energy density of over 500 Wh/kg.
This marks a significant step toward commercial viability for applications like electric vehicles and electric aviation, the company said.
Previous research has focused on enhancing cell performance by optimizing solvation structures and solid-electrolyte interphases, but these approaches often compromised lifespan, falling short of delivering commercially viable solutions.
Limited progress has been made to understand the failure mode of LMBs, due to the challenges involved in accurately quantifying the consumption of active lithium and electrolyte components during cycling.
CATL said its research team overcame this barrier by developing and refining a suite of analytical techniques to track the evolution of active lithium and each electrolyte component throughout the battery’s life cycle.
This approach transformed a ‘black box’ into a ‘white box’, unveiling the critical depletion pathways driving cell failure, according to the battery maker.
The team discovered that, contrary to previous assumptions, the dominant cause of cell failure is not solvent breakdown, dead lithium accumulation, or solvation environment disruption, but the continuous consumption of the electrolyte salt LiFSI — with 71% of it consumed by end of life.
These results highlight the need to broaden industry focus beyond Coulombic efficiency (CE), long considered the key metric for LMBs, to also include electrolyte durability as a critical factor for sustained performance.
CATL used a diluting agent of a lower molecular weight to optimize the electrolyte formulation. This increased the LiFSI salt’s mass fraction, improved ionic conductivity, and reduced viscosity, without increasing the total mass of electrolyte used.
The resulting prototype, while exhibiting the same CE as the previous iteration, doubled the cycle life to 483 cycles, and can be adopted in new designs with an energy density over 500 Wh/kg.
Ouyang Chuying, co-president of R&D at CATL and executive deputy director of the firm’s ‘21C Lab’ at its Ningde headquarters, said: “Our findings underscore that LiFSI salt consumption and, importantly, overall salt concentration is a fundamental determinant of battery longevity.”
CATL invested about RMB18.6 billion ($2.6 billion) in R&D in 2024.
Earlier this month, the company launched an initial public offering in Hong Kong, just weeks after unveiling three transformative EV battery types including a sodium ion design with a claimed range of 500km.
*The published researched is online.
