Copyright Interesting Engineering
Increasing the amount of component that stores energy Researchers also highlighted that the key to improving batteries is increasing the amount of active material — the component that stores energy and impacts battery performance — in the electrodes. “Traditionally, active material makes up only 30% to 50% of commercial battery cells,” said Hangtao Sun, assistant professor of industrial and manufacturing engineering (IME) and principal investigator on the project. “By simply making the electrode thicker, we can increase the overall amount of active material and boost the total energy of the battery.” Increasing electrode thickness requires making structure highly porous The research team also pointed out that increasing electrode thickness typically requires making the structure highly porous — more than 40% empty space — to allow charges to easily move around. However, that extra porosity reduces how much active material and, in turn, energy the battery can store overall. Although packing the electrodes more densely seems like an obvious solution to increase power, Sun explained how the compacted structure restricts charge transport, weakening the battery’s performance. Synthetic boundaries play key role To overcome this trade-off, Sun’s team designed synthetic boundaries within its electrodes, which act as a “reservoir” for charges and allow for quick travel across the system. Using these boundaries, the electrodes can be made five to 10 times thicker and twice as dense as conventional electrodes, significantly increasing energy density within a limited volume, according to a press release. Sun pointed out that the resulting batteries demonstrated a potential energy density exceeding 500 watt-hours per kilogram at the cell level, a power level that could enable electric vehicles to achieve a much longer driving range per charge. “By creating a three-dimensional network of synthetic boundaries in our electrodes, we can increase the energy output while simultaneously increasing density and thickness, overcoming a limitation of current commercial electrodes,” said Sun. Transient liquid-assisted densification process Published in Nature Communications, the paper explores a geology-inspired, transient liquid-assisted densification process that produces dense, thick electrodes with multifunctional synthetic secondary boundaries. The research team claimed that these boundaries provide multiple benefits, including strain resistance that mitigates mechanochemical degradation, as demonstrated by operando full-field strain mapping. These help offer enhanced charge transport across boundary phases in thick and dense electrodes. “We were able to increase the toughness by a factor of 10 and improve the ultimate strength of the electrode by three times compared to hot-pressed electrodes made without a liquid additive,” Sun said. Sun also highlighted that the team developed digital imaging correlation as a tool to monitor the strain response of electrodes in real time during battery operation. Unlike complex synchrotron-based techniques, this method is affordable with standard laboratory equipment, offering researchers a practical way to visualize and study how batteries degrade.
