A breakthrough in battery research could enable smartphones to last more than twice as long between charges.
The claim comes from a team of researchers at Northwestern University, Illinois who found ways to stabilise a new battery with a record-high charge capacity.
Based on a lithium-manganese-oxide cathode, the researchers claim to have realised one of the highest-ever reported capacities for all transition-metal-oxide-based electrodes.
"It's more than double the capacity of materials currently in your cell phone or laptop," said Christopher Wolverton, Professor of Materials Science and Engineering in Northwestern's McCormick School of Engineering, who led the study.
"This sort of high capacity would represent a large advancement to the goal of lithium-ion batteries for electric vehicles."
Published in Science Advances, the study explains how lithium-ion batteries work by shuttling lithium ions back and forth between the anode and the cathode.
"The cathode is made from a compound that comprises lithium ions, a transition metal and oxygen," the study reads. "The transition metal, typically cobalt, effectively stores and releases electrical energy when lithium ions move from the anode to the cathode and back. The capacity of the cathode is then limited by the number of electrons in the transition metal that can participate in the reaction."
A research team in France in 2016 first discovered that by replacing the traditional cobalt with less expensive manganese, a cheaper electrode with more than double the capacity is possible. But it was not without its challenges.
The battery's performance degraded so significantly within the first two cycles that researchers did not consider it commercially viable. They also did not fully understand the chemical origin of the large capacity or the degradation.
After composing an atom-by-atom picture of the cathode, Wolverton's team discovered the reason behind the material's high capacity: it forces oxygen to participate in the reaction process. By using oxygen in addition to the transition metal to store and release electrical energy, the battery has a higher capacity to store and use more lithium.
The Northwestern team has now turned its focus to stabilising the battery in order to prevent its swift degradation.
"Armed with the knowledge of the charging process, we used high-throughput computations to scan through the periodic table to find new ways to alloy this compound with other elements that could enhance the battery's performance," said Zhenpeng Yao, co-author of the study.
The team predicts that mixing either of the elements chromium and vanadium with lithium-manganese-oxide will produce stable compounds that maintain the cathode's unprecedented high capacity. The next thing the team has to do is test these theoretical compounds in the laboratory.
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