Dr XU Zhenglong, Member of the Research Institute for Advanced Manufacturing (RIAM), and his research team developed new materials for high-energy, long-life and low-cost calcium rechargeable batteries, which have great potential for large-scale energy storage applications.
The growing demand for electric vehicles and stationary energy storage systems for a “zero carbon” society also calls for next-generation batteries that are more energy-efficient, less costly and safer than conventional lithium (Li)-ion batteries. Among the few available options, calcium (Ca) rechargeable batteries using divalent charge carriers can store a larger amount of energy in a certain amount of mass, and are more affordable due to the higher abundance of Ca in the Earth’s crust (46600 ppm) as compared to that of Li (20 ppm). However, the lack of suitable electrode materials is the bottleneck for this new battery technology. Dr Xu’s team is exploring advanced materials for viable calcium rechargeable batteries.
For anode materials, using an identified electrolyte, i.e., calcium borohydride (Ca(BH4)2) in dimethylacetamide, the research team inserted Ca2+ ions into commercial graphite through a co-intercalation mechanism. They achieved a large energy storage capacity and unprecedentedly fast discharge/charge capability. For cathode materials, the team developed open-framework sodium vanadium fluorophosphates, which function as ultrastable and fast-kinetic Ca2+ intercalation hosts, with a capacity degradation rate of just 0.02% over 2,000 cycles. Other naturally abundant materials, such as perylene tetra-carboxylic diimide, were also investigated as suitable materials for green and long-cycling organic calcium batteries.
In sum, the team demonstrated the feasibility of manufacturing cost-effective electrode materials for the new calcium battery technology. Their findings can bridge the scientific and technical gaps in the battery landscape that current commercial Li-ion batteries cannot address.