Study on new self-heating technique for lithium-ion batteries at low temperature

Abstract

: In this dissertation, a new method of increasing the temperature of a lithium-ion battery at low temperature using self-heating is proposed. First, the characteristic of lithium-ion batteries, which increase the temperature increase rate at low temperatures, are studied. It is confirmed that the lithium-ion battery cell structure having high power characteristics increases the current at low temperature to increase the heating rate. In addition, it is also confirmed that the heating rate can be increased by lowering the electrolyte resistance at low temperature by using an electrolyte with a low freezing point. Using this characteristics, a new low-temperature lithium-ion battery for optimal selfheating is proposed. Second, as a method for heating a lithium-ion battery at a low temperature, a new self-heating technique using a variable frequency is proposed compared to the conventional selfheating technique using a fixed frequency. Frequency variable self-heating technology can search a resonance frequency point that allows the maximum current to flow at low temperatures. At this resonance frequency point, the heating speed of the lithium-ion battery can be maximized.