Chinese Firm’s Breakthrough EV Battery Hits 500 WH/KG Energy Density, 483-Cycle Life

China’s Contemporary Amperex Technology Co., Limited (CATL), a global leader in battery innovation, has announced a transformative advancement in lithium metal battery (LMB) technology. By introducing a quantitative mapping approach and rethinking electrolyte strategy, CATL has engineered a lithium metal battery prototype with an unprecedented combination: over 500 Wh/kg energy density and a 483-cycle lifespan.

Lithium metal batteries are widely considered the future of high-end energy storage thanks to their intrinsically high energy density. Yet, a major hurdle has persisted for years a trade-off between energy output and cycle durability. While past studies have tried to optimize electrolyte composition and solid-electrolyte interphases, those gains often came at the cost of shorter battery life, especially under real-world conditions.

CATL noted, “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.”

To overcome this knowledge gap, CATL’s R&D team refined a powerful set of analytical techniques that allowed them to track the evolution of every active component from lithium to the electrolyte throughout the battery’s entire lifespan. This marked a major leap from conventional trial-and-error models.

The team’s diagnostics revealed a surprising culprit behind LMB failure. Contrary to long-standing beliefs, it wasn’t just dead lithium or solvent degradation at fault, but rather, the continuous consumption of the electrolyte salt, lithium bis(fluorosulfonyl)imide (LiFSI). By the end of a typical battery’s life, 71% of this salt had been consumed, causing critical ion depletion and performance collapse.

“Our findings underscore that LiFSI salt consumption and, importantly, overall salt concentration is a fundamental determinant of battery longevity,” explained Ouyang Chuying, Co-president of R&D at CATL.

Armed with this new insight, the researchers engineered a next-generation electrolyte formulation. The key move was introducing a lower molecular weight diluent, which allowed for a higher proportion of LiFSI salt without increasing the total electrolyte mass. The result: enhanced ionic conductivity, reduced viscosity, and no compromise on electrochemical performance.

With this optimized formulation, CATL’s lithium metal battery prototype doubled its previous cycle life, reaching 483 full cycles, a milestone previously thought unattainable in LMB design, while maintaining high Coulombic efficiency.

The implications of this work are profound. A stable LMB with 500+ Wh/kg energy density is a game-changer for electric vehicles, offering greater range and lighter weight, and for electric aviation, where every gram matters.

“We saw a valuable opportunity to bridge the gap between academic research and its practical application in commercial battery cells,” said Chuying.

With the black box of battery failure now decoded, CATL is pushing the envelope on commercializing this technology. The newly proposed electrolyte model maximizes LiFSI content while keeping viscosity and conductivity in check, creating a realistic path toward long-lasting, high-performance batteries.

This breakthrough is published in Nature Nanotechnology.