Scientists have developed a new X-ray imaging technique that will allow them to visualize and study thee electrochemical reactions in lithium-ion rechargeable batteries containing iron fluoride.
This breakthrough could help improve energy storage in fields such as portable electronics and electric microgrids, the University of Wisconsin-Madison reported.
"Iron fluoride has the potential to triple the amount of energy a conventional lithium-ion battery can store," said Song Jin, a UW-Madison professor of chemistry and Wisconsin Energy Institute affiliate. "However, we have yet to tap its true potential."
The scientists used a state-of-the-art transmission X-ray microscope to collect chemical maps from coin cell batteries filled with iron fluoride during batter cycling to discover how well they performed.
"In the past, we weren't able to truly understand what is happening to iron fluoride during battery reactions because other battery components were getting in the way of getting a precise image," Li said.
The new technique accounted for background signals that would usually interfere with the accuracy of the image, allowing the researchers to measure the chemical changes iron fluoride undergoes to store and discharge energy on the nanoscale.
Iron fluoride comes with two major challenges: it doesn't recharge well in its current form; and the materials don't discharge as much energy as they take in, causing a reduction in energy efficiency. The new imaging method pinpointed each individual reaction, to help understand what was causing the first problem of capacity decay.
"In analyzing the X-ray data on this level, we were able to track the electrochemical reactions with far more accuracy than previous methods, and determined that iron fluoride performs better when it has a porous microstructure," Li said.
The study also made some preliminary insights into why reduced energy efficiency occurs when there is a disparity in energy discharge, and offers some solutions for the future.
"If we can maximize the cycling performance and efficiency of these low-cost and abundant iron fluoride lithium ion battery materials, we could advance large-scale renewable energy storage technologies for electric cars and microgrids," Jin said.
The findings were published in a recent edition of the journal Nature Communications.
