$3750 (-0,87 %) Chinese battery manufacturer CATL has announced a breakthrough in lithium metal battery (LMB) technology through quantitative mapping, breaking new ground in electrolyte strategy, according to the company. "This groundbreaking research, published in Nature Nanotechnology, enables LMBs with high energy density and extended lifetime, solving a long-standing challenge in the field," CATL wrote in a press release. The optimized prototype has achieved a lifetime of 483 cycles and can be integrated into modern designs to achieve an energy density of more than 500 Wh/kg. "This is a significant step towards commercial viability for applications such as electric vehicles and electric aviation," explains CATL.
Due to their intrinsically high energy density, LMB batteries are considered a potential next-generation battery system, especially for high-end applications such as electric cars and especially long-range electric commercial vehicles and electric aviation, the company explains further. However, these batteries have long had to compromise between energy density and service life.
Previous research has focused on improving cell performance by optimizing solvation structures and solid electrolyte phase interfaces. "However, these approaches were often at the expense of service life, so that no commercially viable solutions could be achieved. Due to the difficulties in accurately quantifying the consumption of active lithium and electrolyte components during cycling, only limited progress has been made in understanding the failure behavior of LMB," explains CATL.
Diluent provides the solution
To overcome this hurdle, CATL's research and development team developed and refined a series 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" and revealed the critical drain paths that lead to cell failure.
The team discovered that, contrary to previous assumptions, the main cause of cell failure is not solvent degradation, accumulation of inactive lithium or disruption of the solvation environment, but the continuous consumption of the electrolyte salt LiFSI, 71 percent of which is depleted by the end of life. "These results underscore the need to expand the industry's focus beyond Coulombic efficiency (CE), long considered a key metric for LMBs, to include electrolyte durability as a critical factor in sustainable performance," writes CATL.
Building on these findings, CATL optimized the electrolyte formulation by introducing a lower molecular weight diluent, it adds. This adjustment increased the mass fraction of LiFSI salt, improved ionic conductivity and reduced viscosity without increasing the overall mass of the electrolyte used. "While the resulting LMB prototype has the same CE as the previous version, it doubles the cycle life to 483 cycles and can be used in new designs with an energy density of over 500 Wh/kg," the press release states. This breakthrough heralds a paradigm shift in the development of batteries that are both high-energy and long-lasting.
Same weight, twice as much energy
By way of comparison, an NMC battery currently used by most manufacturers has an energy density of around 250 Wh/kg, which is around half as much as the new battery from CATL. The energy density of LFP batteries, which Tesla and many other manufacturers are increasingly using, is generally even less than 200 Wh/kg. And even solid-state batteries, which are seen as a beacon of hope, have not yet achieved such good values as CATL's LMB battery. For a vehicle battery with a capacity of 100 kWh, the material alone weighs 400 kilograms, whereas for an LMB battery it would only be 200 kilograms. With the same weight, the battery could therefore supply 200 kWh of energy, which would enable almost 100,000 kWh of total energy with regard to the service life reported by CATL. This would allow an electric car to drive around 500,000 kilometers.
