🔋 1,000 charges and still going strong: a breakthrough in calcium-ion batteries

Tomorrow's batteries could operate with an element much more common than lithium. Researchers have just passed a major milestone by creating a calcium-ion battery capable of retaining over 74% of its capacity after one thousand cycles. This performance hints at robust and durable energy storage systems.

The success of this prototype relies on the use of quasi-solid electrolytes made from redox-active covalent organic frameworks. These materials combine high ionic conductivity with efficient calcium-ion transport at room temperature. Their ordered pores promote ion mobility, contributing to the overall stability.


Calcium has several advantages for replacing lithium. More abundant on Earth, it operates within a comparable electrochemical window, making it an interesting candidate. However, previous versions of calcium-ion batteries struggled to ensure smooth ion circulation and long-term durability.

The team from the Hong Kong University of Science and Technology, led by Professor Yoonseob Kim, has managed to overcome these hurdles. Their quasi-solid electrolytes, rich in carbonyl groups, form a structured pathway for calcium ions. This method accelerates their transport and limits wear during repeated cycles.

In practice, the resulting battery achieves a reversible specific capacity of 155.9 mAh g⁻¹ under low current and maintains respectable performance at higher current densities. These characteristics make it a serious contender against current lithium-ion batteries, with potential applications in electric vehicles and renewable energy storage.

This work, published in Advanced Science, was carried out in partnership with Shanghai Jiao Tong University. Professor Kim believes this technology can contribute to a more sustainable energy future by offering efficient storage solutions with a lower environmental impact.