Changing the energy-storage game with calcium

Compared to lithium-ion batteries, batteries using calcium ions are environmentally safer, cheaper, and more abundant. However, while researchers have suggested calcium-ion batteries (CIBs) can hold double the energy of their lithium counterparts, the observed energy-storage capacities of calcium-ion batteries are far below their theorized values.

Bu et al. reviewed the current progress of calcium-ion-battery research, examining the accomplishments and challenges associated with developing calcium-based cathode materials, exploring the structural and electrochemical properties of these materials, and discussing problems in the field still being solved by researchers.

The review, which is organized according to constituent anion types of cathodes and calcium-ion diffusion properties, is directed towards both beginners and experts in the energy-storage field, especially those who work with calcium-ion batteries.

“Although the capacity of CIBs can be theoretically doubled owing to the divalency of calcium, the observed capacities are still far below to date,” author Seung-Tae Hong said. “Nevertheless, the research progress during the past few years suggests that unexplored opportunities for discovering new cathode materials with improved performances are wide open.”

With the review, the authors hope to stimulate further research and development in the field, where progress could spur further development of electric cars. Compared to smaller electronic devices like laptops, larger electronics require more considerable battery performance than offered by the best lithium-ion battery.

“In the near future, new cathode materials with higher energy densities should be developed further, for which researchers should focus on the structural aspects and Ca-ion intercalation mechanisms of the prospective cathode materials,” Hong said. “Ultimately, appropriate anode and electrolyte materials should also be developed, which can be incorporated into a battery cell.”

Source: “Intercalation-type positive electrode materials for nonaqueous calcium-ion batteries,” by Hyeri Bu, Hyungjin Lee, Dedy Setiawan, and Seung-Tae Hong, Chemical Physics Reviews (2022). The article can be accessed at https://doi.org/10.1063/5.0073087 .