NSTU developed an internal heating system for lithium-ion batteries with high-frequency alternating current in the range of 5-15 kHz and higher, which allows electric vehicles to be started at low temperatures.
Vladimir Gertel, a graduate student of the Department of Electronics and Electrical Engineering at the NSTU NETI Faculty of Radio Engineering and Electronics, proposed an original system for heating lithium-ion batteries at low temperatures, which will allow extending the life of both the battery itself and the electric car several times. According to the developer, the use of lithium-ion batteries at temperatures below -20 ° C threatens their rapid degradation.
"Working in harsh conditions results in electric vehicles with a reduction in power reserve by almost half, reduced power and dynamics, significant losses of energy for heating and an increase in charging time by up to 10 times," said Vladimir Gertel, adding that in severe frosts, a discharged battery cannot be charged without preheating.
The scientist suggests solving these problems using an internal lithium-ion battery heating system with high-frequency alternating current, which consists of a lithium-ion battery (LIB), an electronic unit with two power terminals and an external communication interface connector. The system can be presented in three versions: as a temperature control module for use as part of power generation and backup power systems, an external heating unit connected to the control panel, and an OEM component of an embedded temperature control system.
In any of the variants, the flow of electric current through the internal resistance of the battery cells leads to the conversion of electrical energy into thermal energy and uniform heating of their volume without the occurrence of a temperature gradient and affecting the operational life of the battery. The key scientific solution is to use the high—frequency range of 5-15 kHz and higher: at these frequencies, the ohmic resistance of the battery is stable and independent of temperature, which completely eliminates the risk of lithium coating on the electrodes, which is the main cause of battery degradation during low-temperature heating. The advantages of the development also include a heating rate of up to 10.0 ° C / min, an increase in charging speed of almost 2.5 times compared to an unheated battery at the same low temperatures and an efficiency of more than 90%.
The experimental sample is already ready, and it is planned to create a prototype for the electric vehicle format and patent the development in the near future. According to Vladimir Gertel, the project already has interested parties — several domestic companies. "In the future, interest in the topic of battery heating will only grow, especially since such technology has not yet been introduced in Russia, this topic is being studied in China, but it needs to be developed here," the scientist emphasized.
Earlier, the engineers of NSTU-NETI, within the framework of the Priority 2030 program, together with the Krasnoyarsk scientific and production enterprise Radiosvyaz, released the first batch of electric charging stations capable of operating at extremely low temperatures.