Researchers find out why solid-state batteries fail

SHANGHAI — In a significant advancement that could reshape the future of electric vehicles, Chinese researchers have identified a mechanism behind solid-state lithium battery failures.

It came as China has risen to become a global leader in the lithium battery industry. The country is now racing with its international rivals, particularly those from Japan and South Korea, to embrace next-generation battery technologies.

Solid-state batteries, widely regarded as one of the most promising solutions in the coming decade, could revolutionize energy storage. However, overcoming their technical hurdles remains the greatest current challenge. Unlike liquid electrolytes used in conventional batteries, solid electrolytes struggle to absorb the stresses caused by lithium expansion and contraction during charging cycles.

These stresses can cause cracking or the formation of dendrites — tiny, needle-like structures that can trigger short circuits — thus posing major challenges to the industrialization of the technology.

In their new study, the researchers from Tongji University and the Huazhong University of Science and Technology found that solid-state battery failures are closely linked to cycle fatigue of the lithium metal anode.

They also observed that this fatigue adheres to well-defined mechanical principles, like repeatedly bending a paper clip weakens it until it finally breaks.

The discovery, published on Friday in the journal Science, provides a quantitative framework for predicting battery life cycles and opens new pathways for designing longer-lasting energy storage systems.

"The work recognizes the importance of fatigue in the performance of lithium metal anodes in solid-state batteries," noted Jagjit Nanda and Sergiy Kalnaus, two battery scientists from the United States, in a perspective on the research.

The research underscores China's sustained R&D investments in electrochemistry in recent years. These breakthroughs are now fueling China's industrial edge and setting the stage for the country to repeat its success in the upcoming revolution in battery technology.

Solid-state batteries, using solid electrolytes instead of liquid ones, achieve much higher energy density (up to 500 watt-hours per kilogram) than traditional liquid lithium-ion batteries (200-300 Wh/kg). This provides more energy in the same volume and reduces battery size.

They also feature better thermal stability, non-flammability and no risk of liquid leakage, significantly lowering the risk of self-ignition and explosion.

Ouyang Minggao, an expert on new energy power systems and a professor at Tsinghua University, predicted that reaching an energy density of 500 Wh/kg will depend on critical advancements in materials science, with 2027 poised to be a pivotal year for breakthrough innovations.

Chinese battery giants CATL and BYD have set 2027 as their target for small-scale production of solid-state batteries.

Scientific teams are intensifying their collaboration with frontline battery companies to accelerate the commercialization of technologies.

The Shenzhen Institute of Advanced Technology under the Chinese Academy of Sciences has signed a cooperation agreement with BYD, focusing on cutting-edge areas such as solid-state batteries.

China's edge in mass-producing all-solid-state batteries lies in its vast industry and market scales. "With the most complete industrial chain, the largest market, and the most researchers, we are highly confident in China's approach and roadmap for this technology," said Zu Sijie, vice-president of SAIC Motor.

Xinhua