Researchers at the University of Maryland (UMD) and US Army Research Lab (ARL) have taken a critical step on the path to high energy batteries by improving their water-in-salt battery with a new type of chemical transformation of the cathode that creates a reversible solid salt layer, a phenomenon yet unknown in the field of water-based batteries.
Building on their previous discoveries of the water-in-salt electrolytes reported in Science in 2015, the researchers added a new cathode. This new cathode material, lacking transition metal, operates at an average potential of 4.2 volts with excellent cycling stability, and delivers an unprecedented energy density comparable, or perhaps higher than, non-aqueous Li-ion batteries. The authors report their work on May 9 in the journal Nature.
“The University of Maryland and ARL research has produced the most creative new battery chemistry I have seen in at least 10 years,” said Prof. Jeffrey Dahn of Dalhousie University in Canada, an expert in the field not affiliated with the research. “However, it remains to be seen if a practical device with long lifetime can be created.”