Novel Calcium-Ion Battery Technology Enhances Energy Storage Efficiency and Sustainability

Why It Matters

By leveraging abundant calcium and scalable organic frameworks, the technology could reduce reliance on scarce lithium and lower battery costs for renewable‑energy storage and electric vehicles.

Key Takeaways

• Quasi-solid-state electrolytes enable 0.46 mS cm⁻¹ conductivity.
• Calcium-ion cell retains 74.6% capacity after 1,000 cycles.
• Redox COFs provide rapid Ca²⁺ transport via carbonyl channels.
• Specific capacity reaches 155.9 mAh g⁻¹ at low current.
• CIBs offer abundant, low‑cost alternative to lithium‑ion.

Pulse Analysis

The rapid expansion of renewable power and electric mobility has intensified scrutiny of lithium‑ion batteries, whose raw‑material constraints and recycling challenges threaten long‑term scalability. Calcium, the fifth‑most abundant element on Earth, offers a comparable electrochemical window while promising lower material costs and a smaller environmental footprint. Transitioning to calcium‑ion chemistry could therefore diversify the supply chain and mitigate geopolitical risks associated with lithium mining.

The HKUST team’s innovation lies in embedding redox‑active covalent organic frameworks (COFs) within a quasi‑solid‑state electrolyte matrix. These carbonyl‑rich COFs create ordered channels that align with Ca²⁺ ions, delivering an ionic conductivity of 0.46 mS cm⁻¹ and a transport coefficient exceeding 0.53 at ambient temperature—metrics that rival or surpass many liquid electrolytes. By combining experimental electrochemistry with atomistic simulations, the researchers demonstrated that the ordered pore architecture accelerates ion hopping, resulting in stable cycling performance and high specific capacity.

Commercially, a calcium‑ion battery that maintains 74.6% capacity after 1,000 cycles could challenge lithium‑ion dominance in grid‑scale storage and medium‑range electric vehicles. The use of organic frameworks also opens pathways for low‑temperature processing and recyclable electrode designs, aligning with circular‑economy goals. As the industry seeks sustainable, cost‑effective alternatives, further scaling of COF synthesis and integration with existing manufacturing lines will be critical to translating laboratory success into market‑ready products.

Novel calcium-ion battery technology enhances energy storage efficiency and sustainability

Feb 14, 2026

Researchers develop high‑performance quasi‑solid‑state calcium‑ion batteries using redox covalent organic frameworks, achieving strong cycling stability as a sustainable alternative to lithium‑ion technology

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 journal Advanced Science (“High‑Performance Quasi‑Solid‑State Calcium‑Ion Batteries from Redox‑Active Covalent Organic Framework Electrolytes” – https://dx.doi.org/doi:10.1002/advs.202512328).

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 struggled, 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 (COFs) 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 COF 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.”

The study was a collaboration between researchers at HKUST and Shanghai Jiao Tong University.

Source: Hong Kong University of Science and Technology (Content may be edited for style and length)