In recent years, the race to develop more efficient and high-energy-density lithium batteries has been ongoing. Researchers have been focusing on enhancing the performance of all-solid-state lithium batteries (ASSLBs), particularly through the development of amorphous solid electrolytes (SEs). A recent study conducted by a research team led by Prof. Yao Hongbin from the University of Science and Technology of China (USTC) has made significant progress in this area. Their findings, published in the Journal of the American Chemical Society, highlight the construction of a glassy Li-ion conduction network and the development of amorphous tantalum chloride SEs with high Li-ion conductivity.
Compared to ceramic SEs, amorphous SEs demonstrate unique glassy networks that allow for intimate solid-solid contact and exceptional Li-ion conduction percolation. These inherent characteristics make amorphous SEs highly conducive to fast Li-ion conduction, which is vital for the effective utilization of high-capacity cathodes and stable cycling. By leveraging these advantages, the energy density of ASSLBs can be significantly increased. However, the low areal capacity of thin-film cathodes and poor room-temperature ionic conductivity have been limitations in the past.
To overcome these challenges, the research team focused on developing amorphous SEs with high Li-ion conductivity and ideal chemical stability. Crystalline halides, such as fluorides, chlorides, bromides, and iodides, showed promise due to their high voltage stability and ionic conductivity. However, there have been limited studies on developing amorphous chloride SEs. In this study, the researchers proposed a new class of amorphous chloride SEs with high Li-ion conductivity. These SEs demonstrated excellent compatibility with high-nickel cathodes, paving the way for high-energy-density ASSLBs with a wide temperature range and stable cycling.
Structural Features and Characterization
To understand the structural features of the LiTaCl6 amorphous matrix, the research team employed advanced techniques such as random surface walking global optimization, global neural network potential (SSW-NN) function, solid-state nuclear magnetic resonance lithium spectroscopy, X-ray absorption fine-structure fitting, and low-temperature transmission electron microscopy. These techniques allowed for a comprehensive analysis and characterization of the matrix, providing valuable insights into its composition and behavior.
High-Performance Composite Solid Electrolyte Materials
Based on the flexibility of component design, the research team prepared a series of high-performance and cost-effective Li-ion composite solid electrolyte materials. These materials exhibited the highest room-temperature Li-ion conductivity of up to 7 mS cm-1, meeting the practical application requirements of high-magnification ASSLBs. This breakthrough in composite SEs overcomes the limitations of traditional crystalline SEs’ structure and component design, opening new possibilities for constructing high-performance ASSLBs with high-nickel cathodes.
Applicability and Future Directions
Researchers have verified the applicability of ASSLBs constructed based on amorphous chloride SEs over a wide temperature range. The batteries achieved a stable operation rate of 3.4 C, translating to nearly 10,000 cycles, even in freezing environments of -10°C. The flexibility and fast ionic conductivity of the amorphous chloride SEs, combined with their excellent chemical and electrochemical stability, provide a solid foundation for further advancements in SE design and the construction of high-energy-density ASSLBs. This research breakthrough opens new avenues for realizing the potential of high-nickel cathodes in ASSLBs.
The development of amorphous solid electrolytes with high Li-ion conductivity is a significant advancement in the field of lithium batteries. The research conducted by Prof. Yao Hongbin’s team, in collaboration with Prof. Shang Cheng and Prof. Tao Xinyong, demonstrates the potential of amorphous tantalum chloride SEs for realizing high-energy-density ASSLBs. By overcoming the limitations of traditional crystalline SEs, these amorphous SEs provide a foundation for the future design and construction of high-performance ASSLBs. The research team’s findings open new possibilities for the field and highlight the importance of continued exploration and innovation in lithium battery technology.