Electric cars find it difficult to cope with extreme temperatures, chiefly due to effects on the electrolyte solutions in their lithium-ion batteries.
Currently, scientists have produced new electrolytes including multiple additives that function better over a broad temperature range. The study outcomes have been published in ACS Applied Materials & Interfaces.
Lithium-ion batteries are extensively employed in laptop computers, cell phones, and electric vehicles. The electrolyte solutions contained in these batteries conduct ions between the cathode (positive electrode) and anode (negative electrode) to power the battery.
Ethylene carbonate, an essential component of a majority of these solutions, helps develop a protective layer, avoiding further decomposition of electrolyte components upon interaction with the anode. However, ethylene carbonate has a high melting point, restricting its performance at low temperatures.
Wu Xu and teammates earlier demonstrated that they could expand the temperature range of lithium-ion batteries by partially substituting ethylene carbonate with propylene carbonate and by including cesium hexafluorophosphate. However, they intended to extend the temperature range even more, so that lithium-ion batteries could operate well from −40 to 140 °F.
The scientists investigated the impacts of five electrolyte additives on the performance of lithium-ion batteries within this temperature range. They discovered an optimized combination of three compounds that they incorporated into their prior electrolyte solution.
This new combination resulted in the creation of highly conductive, robust, and uniform protective layers on the anode as well as the cathode. Batteries that consist of the optimized electrolyte had significantly improved discharging performance at −40 °F and long-term cycling stability at 77 °F, together with slightly enhanced cycling stability at 140 °F.
The study was funded by the U.S. Department of Energy.