The advantageous of liquid electrolytes for calcium-ion batteries (CIBs) traits include high ionic conductivity and effective transportation of calcium ions, which are essential for efficient battery performance. However, several challenges and drawbacks have been identified.
Like magnesium, calcium is divalent: that is, it happily donates two electrons to a variety of acceptors—and that makes it extremely reactive. This causes anodes made of calcium metal to react with various chemical species and typically form a resistive layer on the surface, which degrades battery performance.
The functioning voltage, capacity, and energy density of a battery heavily rely on the crucial contribution of electrodes. During the charging process of calcium batteries, calcium ions transfer from the cathode through electrolyte to the anode, where they deposit.
In the post-lithium-ion battery era, calcium-ion batteries (CIBs) have aroused extensive attention because of their strong cost competitiveness, low standard redox potentials, and high safety. However, the related research is progressing slowly due to the constraints of the development of electrode materials.
When considering the future of calcium batteries electrolyte, it may be worth exploring Grignard-based electrolytes as a potential solution for addressing the passive layer issue. Glyme-based electrolytes and boron-clusters can also be suggested for further research.
However, calcium batteries have a significant drawback: decomposition of Ca is almost impossible. In traditional organic electrolytes, calcium electrodes exhibit a process that is surface-film-controlled, similar to that observed in lithium .