Membrane technology prevents battery drain

The technology, which was inspired by how living cell membranes transport proteins in the body, controls how charge flows inside a battery. Lithium-ion batteries have membrane separators that conduct charge and physically separate the anode and the cathode from each other. But existing batteries lose charge over time, leading to thermal runaway that can cause dangerous fires in consumer electronics and electric vehicles. The researchers say their membrane, when used with a specially designed electronic control unit, can shut down charge transport and prevent thermal runaway.

“Research over the last 50-plus years has focused on advancing the chemistry of battery electrodes to increase capacity,” said Vishnu-Baba Sundaresan, an assistant professor of mechanical and aerospace engineering at Ohio State and leader of the study.

“We’ve done that, but the increase in capacity has come at the cost of robustness and the ability to rapidly charge and discharge batteries. Electric vehicle design is mature enough now that we know the limit they’re reaching is because of the chemistry of lithium-ion batteries.”

The study, published in the journal Energy and Environmental Science, explains how the Ohio team combined an electrically conductive polymer with a polycarbonate filter used for air and water testing. By controlling how they grew the conductive polymer chains on the polycarbonate surface, the researchers found they could control the density of openings in the resulting membrane.When the battery is charging or discharging, the conductive polymer shrinks to open the holes. When the battery isn’t in use, the polymer swells to close the holes.

During testing the membrane allowed the batteries to function normally, but reduced charge loss to zero when the batteries were not in use. According to the researchers, the same technology could prevent power leakage in supercapacitors, which provide high power and rapid recharge capability.