Researchers at The Hong Kong University of Science and Technology (HKUST) have achieved a breakthrough in calcium-ion battery (CIB) technology, which could transform energy storage solutions in everyday life. Utilizing quasi-solid-state electrolytes (QSSEs), these innovative CIBs promise to enhance the efficiency and sustainability of energy storage, impacting a wide range of applications from renewable energy systems to electric vehicles. The findings are published in the international journal Advanced Science titled "High-Performance Quasi-Solid-State Calcium-Ion Batteries from Redox-Active Covalent Organic Framework Electrolytes".
The urgency for sustainable energy storage solutions is growing critical worldwide. As the world accelerates its shift to green energy, the demand for efficient and stable battery systems has never been more pressing. Today's mainstream lithium-ion batteries (LIBs) face challenges due to resource scarcity and near-limited energy density, making the exploration of alternatives like CIBs essential for a sustainable future.
CIBs hold great promise due to their electrochemical window comparable to that of LIBs and their abundance on Earth. However, they have struggles, particularly in achieving efficient cation transport and maintaining stable cycling performance. These obstacles currently limit the competitiveness of CIBs against commercially available LIBs.
To overcome these challenges, the research team led by Prof. Yoonseob KIM, Associate Professor of the Department of Chemical and Biological Engineering at HKUST, has developed redox covalent organic frameworks to serve as QSSEs. These carbonyl-rich QSSEs demonstrated remarkable ionic conductivity (0.46 mS cm-1) and Ca2+ transport capability (>0.53) at room temperature. Combining experimental and simulation studies, the team revealed that Ca2+ rapidly transports along the aligned carbonyl groups within the ordered COFs pores.
This innovative approach led to the creation of a full calcium-ion cell that exhibited a reversible specific capacity of 155.9 mAh g-1 at 0.15 A g-1 and maintained over 74.6% capacity retention at 1 A g-1 after 1,000 cycles, showcasing the potential of redox COFs to advance CIB technology.
Prof. Kim said, "Our research highlights the transformative potential of calcium-ion batteries as a sustainable alternative to lithium-ion technology. By leveraging the unique properties of redox covalent organic frameworks, we have taken a significant step towards realizing high-performance energy storage solutions that can meet the demands of a greener future."
This study was a collaboration between researchers at HKUST and Shanghai Jiao Tong University.
