MIT researchers believe they have taken the first positive steps toward developing compact lithium-ion batteries, according to new research published in Advanced Energy Materials.
This essentially means that batteries will be able to store more energy, so they need much less charging to operate.
The team's report, co-authored by graduate students Frank McGrogan and Tushar Swamy, investigated the mechanisms of lithium sulfides, which could one day replace liquid as a more stable, solid form of electrolyte.
Replacing liquid electrolytes with solid ones could be a big move. These batteries would likely be able to store more energy per battery than existing ones. They would also be much less unstable, as dendrites, which are metal protrusions that sometimes grow through liquid electrolyte layers, would be less likely to form.
The research team looked at the fracture toughness of sulfide, which is essential for its role as a material in lithium-ion batteries. If it is too brittle and cannot handle the stresses of continuous power, it could crack and create space for dendrites to form.
The research faced a major hurdle, however: the sulfide is so sensitive at room temperature that it cannot be tested in air. To test the material, the team placed the sulfide in a bath of mineral oil to prevent it from reacting before measuring its mechanical properties.
After testing, the researchers concluded that the material does indeed crack under high-pressure conditions, “like a brittle piece of glass.”
That said, the knowledge gained could allow the team to build new battery systems by "calculating how much pressure the material can tolerate before it cracks," said MIT associate professor Krystyn Van Vliet, who contributed to the research.
Frank McGrogan agrees. Since his team can study the properties of sulfide and design new battery systems around that knowledge, it could one day have potential for use.
