Japanese Researchers Develop Flame-Retardant Electrolyte for Safer Batteries

Image by bunzellisa.

The University of Tokyo, Kyoto University, and Japan's National Institute for Materials Science (NIMS) announced on November 28, 2017, that they have developed a fire-extinguishing organic electrolyte as an alternative to conventional flammable organic electrolytes used in lithium-ion batteries and other charging and discharging secondary batteries. The new electrolyte is expected to help accelerate the development of strong, long-lasting batteries with significantly better safety performance.

While much research has gone into realizing higher energy densities in the secondary batteries used in everything from electric vehicles to smart grids, the conventional flammable organic electrolytes used in these batteries carry a high risk of ignition and explosion. Thus, a new approach to securing battery safety is strongly needed.

The new salt-concentrated electrolyte is composed of only a flame-retardant solvent and salt and is therefore resistant to flames. Moreover, when the temperature of the electrolyte rises to over 200 degrees Celsius, it generates vapor, which serves as a fire-extinguishing agent. These characteristics can significantly reduce the risk of batteries ignition, and have already been achieved with electrolytes that do not contain any flammable carbonic acid ester solvents.

Carbonic acid ester solvents were once considered essential to the stable functioning of the carbonaceous anode in batteries, but the researchers have demonstrated that their new electrolyte is capable of more than 1,000 charging-discharging cycles with negligible electrode degradation, whereas the capacity of sodium ion cells using a conventional electrolyte was significantly reduced after more than 100 cycles. It has also been confirmed that the new electrolyte is highly compatible with cathode and sufficiently tolerant of voltage, which indicates the possibility of longer-lasting batteries.