リチウムイオン電池を安価で持続可能に代替する電池の提案 (Rensselaer Researchers Propose an Affordable and Sustainable Alternative to Lithium-Ion Batteries)

Calcium ion intercalation into electrode materials is challenging due to the large size and high charge density of calcium ions relative to lithium. Here, we report oxide structures containing big open spaces (heptagonal and hexagonal channels) as a prospective solution. This could open avenues for high-performing calcium–ion batteries that offer a cost-effective and sustainable alternative to lithium-based batteries.

Looming concerns regarding scarcity, high prices, and safety threaten the long-term use of lithium in energy storage devices. Calcium has been explored in batteries because of its abundance and low cost, but the larger size and higher charge density of calcium ions relative to lithium impairs diffusion kinetics and cyclic stability. In this work, an aqueous calcium–ion battery is demonstrated using orthorhombic, trigonal, and tetragonal polymorphs of molybdenum vanadium oxide (MoVO) as a host for calcium ions. Orthorhombic and trigonal MoVOs outperform the tetragonal structure because large hexagonal and heptagonal tunnels are ubiquitous in such crystals, providing facile pathways for calcium–ion diffusion. For trigonal MoVO, a specific capacity of ∼203 mAh g⁻¹ was obtained at 0.2C and at a 100 times faster rate of 20C, an ∼60 mAh g⁻¹ capacity was achieved. The open-tunnel trigonal and orthorhombic polymorphs also promoted cyclic stability and reversibility. A review of the literature indicates that MoVO provides one of the best performances reported to date for the storage of calcium ions.