Internal Heating of the Lithium-Ion Batteries Based on Alternating Pulse Current and Methods of Its Implementation

The lithium-ion batteries (LIB), in comparison with alkaline and lead-acid batteries, have a high specific energy density, long service life and high charging speed. These qualities are inherent in LIB under normal operating conditions at a positive temperature. However, at low temperatures, the operation of LIB without heating leads to almost complete loss of all its positive properties and to rapid degradation. The preheating during operation at low temperatures makes it possible to effectively operate the LIB in accordance with the technical characteristics and working life declared by the manufacturers. Currently, various technical solutions have been widely used for heating based on external heating methods, which, despite the simplicity of the physical implementation principles have a number of significant disadvantages. In the last few years, the world's leading automakers of electric vehicles have begun to actively implement technical solutions for heating LIB based on internal heating by continuous and pulsed electric current of constant or variable polarity various forms, formed by energy from an external source or directly from the battery itself. This article briefly discusses the reasons for the use of heating systems to ensure the safety of the LIB resource at low temperatures and provides basic theoretical calculations explaining the mechanism of internal heating. The authors reviewed and inves-tigated existing solutions for the circuit design of internal heating methods based on alternating current of various shapes, analyzed and evaluated their effectiveness and considered possible ways to improve it.