U.S. scientists develop calcium ion battery, said to replace the lithium battery is just around the corner

The search for cheap, abundant, safe and sustainable battery chemistries is even more critical in the context of soaring lithium-ion battery material prices and predicted shortages. Calcium ions have been considered for batteries, but their larger size and higher charge density relative to lithium pose challenges for their insertion into electrode materials.

Researchers at Rensselaer Polytechnic Institute now report progress in solving this problem and unlocking the potential of high-performance calcium ion batteries. Nikhil Koratkar, the John A. Clark and Edward T. Crossan Professor of Engineering at Rensselaer, said, "Calcium ions are divalent, so the insertion of one ion will provide two electrons for each ion during battery operation. This makes the calcium ions less massive and bulky, making for an efficient battery."

However, the larger size and higher charge density of calcium ions relative to lithium can compromise diffusion kinetics and cycling stability. The team overcame this problem by developing oxide structures containing large voids (heptagonal and hexagonal channels). The study demonstrated a water-based calcium ion battery using orthorhombic and triangular crystals of molybdenum vanadium oxide (MoVO) as the "host" for the calcium ions.

The researchers demonstrated that calcium ions can be quickly inserted and extracted from the material, and that these tunnels act as conduits for reversible and rapid ion transport. The results show that MoVO offers one of the best properties reported to date for storing calcium ions.

Calcium ion batteries may replace lithium ion technology in the near future as the battery chemistry of choice to power our society," Koratkar said. This work could lead to a new class of high-performance calcium-based batteries that are affordable and sustainable because they use materials that are abundant and safe on the planet. Such batteries could find a wide range of uses in portable and consumer electronics, in electric vehicles, and in grid and renewable energy storage."