A systematic search for candidate materials for calcium-ion batteries by scientists at Chung-Ang University

Seoul, South Korea, February 9, 2022 /PRNewswire/ — Electric cars are the future; they will help reduce air pollution and end our dependence on fossil fuels. However, there is one glaring problem with this potentially disruptive technology: the availability of enough lithium (Li) to produce all of these car batteries. The best rechargeable batteries we have today are based on chemical reactions involving Li, which is why Li-ion batteries are found in most portable electronic gadgets. Unfortunately, Li is not abundant on earth and its reserves represent only 0.002% of the earth’s crust. Once electric cars become mainstream, demand for Li will begin to outstrip supply.

One possible solution to this conundrum is to design new types of batteries that rely on more abundant alkali metals instead of Li. Among several potential Li-replacement candidates, calcium (Ca) stands out as a promising metal for rechargeable batteries. . Not only is Ca 10,000 times more abundant than Li, but it can also give similar battery performance in theory. However, there are still major obstacles to the development of Ca-based batteries, one of them being a lack of knowledge about suitable cathode (negative terminal) materials that can effectively store and release Ca reversibly.

In an effort to help identify the best candidate cathode materials for Ca batteries, Assistant Professor Haesun Park from Chung-Ang University, Korea, and his colleagues took a systematic approach. By running high-throughput quantum mechanical simulations based on density functional theory (DFT), the team predicted the battery-relevant properties of various layered materials combining Ca and transition metal oxides.

Most of this work was conducted at Argonne National Lab and as part of a Joint Center for Energy Storage Research (JCESR) project supported by the US Department of Energy. “Calcium battery research is one of JCESR’s main ongoing efforts“, remarks Professor Park.”The stable support of Argonne and the JCESR project has enabled us to meet the challenges of Ca-ion batteries, and their inclusive environments have paved the way for synergistic collaborations.“The associated document has been uploaded to November 6, 2021and was published in Volume 11, Number 48 of Advanced Energy Materials to December 23, 2021.

The scientists examined seven transition metal ions and four types of shell structures for a total of 28 candidate cathodes. Through DFT calculations, they evaluated many important characteristics, including their thermodynamic stability, energy density, synthesis ability, Ca mobility, and electronic structure. This allowed them to identify promising materials for the development of Ca-based batteries.

In particular, scientists have identified cobalt (Co) as a well-rounded transition metal for a layered Ca-based cathode with the formula CaCo2O4. Moreover, they also showed that the combination of different transition metals in the cathode can be a viable strategy to improve certain desired characteristics. “We succeeded in showing that layered transition metal oxides, which are widely used in lithium, sodium and potassium batteries, can be a promising class of materials for Ca cathodes.“, emphasizes Professor Park. “The promising candidate structures and chemical compositions we have found will hopefully encourage further experiments with these materials.

The successful development of low-cost, high-performance Ca-ion batteries will certainly contribute to the necessary transition from traditional cars to electric vehicles, which are more environmentally friendly in many respects. Hopefully, experimental work will cement the findings of this study and pave the way for a greener future.

Title of the original article: Layered Transition Metal Oxides as Ca Intercalation Cathodes: A Systematic First-Principles Evaluation
Newspaper: Advanced Energy Materials
DOI: https://doi.org/10.1002/aenm.202101698

About Chung-Ang University
Website: https://neweng.cau.ac.kr/index.do

Seong Kee Shin
[email protected]

SOURCE Chung-Ang University

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