Researchers at the Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT) in China have developed a groundbreaking modification to the cathode for all-solid-state lithium batteries (ASLB), significantly enhancing their energy density and life cycle.
According to a press release from the institute, this research marks a major step forward in the development of next-generation high-performance batteries.
As the world shifts away from fossil fuels and towards electrifying transportation, the role of batteries becomes increasingly critical. Although batteries have been used for centuries, lithium-ion batteries have achieved the highest energy densities to date. However, with the rapid expansion of solar and wind power and the growing demand for electric vehicles, lithium battery technology is nearing its limits, potentially becoming a bottleneck in the transition to greener energy solutions.
Lithium-ion batteries, while effective, have several drawbacks, including sensitivity to extreme temperatures, fire risks, and relatively short life cycles. These challenges have driven researchers to explore improvements in battery technology. Solid-state batteries, which promise to replace lithium-ion batteries, are hindered by the limitations of their cathode design.
The Challenge with ASLB Cathodes
The cathodes in ASLBs are typically composed of heterogeneous composites containing multiple additives that, while electrochemically inactive, play a crucial role in improving conduction. However, these additives are incompatible with layered oxide cathodes, which expand and contract during operation. To address this issue, researchers at the Solid Energy System Technology Center (SERGY) at QIBEBT developed a cathode homogenization strategy using a zero-strain material known as Li1.75Ti2(Ge0.25P0.75S3.8Se0.2)3, or (LTG0.25PSSe0.2).
This material exhibits mixed ionic and electronic conductivity, allowing efficient charge transport during charging and discharging without the need for additional inactive additives in the cathode.
“Our cathode homogenization strategy challenges the conventional heterogeneous cathode design,” explained Cui Longfei, a researcher at QIBEBT involved in the study. “By eliminating the need for inactive additives, we enhance energy density and extend the battery’s cycle life.”
Testing and Results
To validate the improved performance of ASLBs, the researchers conducted extensive testing using a homogeneous cathode. The results showed a specific capacity of 250 mAh per gram, compared to the 100-200 mAh per gram typically seen in standard lithium-ion batteries.
At the cell level, the homogeneous cathode delivered a high energy density of 390 Wh per kg, significantly outperforming the 200-300 Wh per kg of conventional lithium-ion batteries. In addition to superior capacity, the cathode demonstrated a volume change of just 1.2 percent over 20,000 cycles at room temperature.
“This approach is a game-changer for ASLBs,” added Zhang Shu, another researcher at SERGY. “The combination of high energy density and extended cycle life opens up new possibilities for the future of energy storage.”
Interestingly, the technology is also applicable to other battery types facing similar challenges with heterogeneous cathodes, including lithium-ion batteries, lithium-sulfur batteries, sodium-ion batteries, and fuel cells.
“The commercialization potential for high-energy-density ASLBs is now more achievable,” remarked Cui Guanglei, professor and head of SERGY. “Our universal strategy for designing multifunctional homogeneous cathodes can overcome the energy, power, and lifespan barriers in energy storage, paving the way for real-world applications.”
By Impact Lab
