Design and Development of an Automated Lithium-Ion Battery Temperature and Internal Pressure Monitoring Device

Abstract

Commercial Lithium-Ion batteries (LIBs) are an emerging source of power and energy used in many of emerging applications such as electric vehicles, aircraft backup power, and renewable energy. However, they have short life cycles and will degrade with use and time. LIB aging, which contains different failure mechanisms, is a complicated interrelated process of mechanical and chemical degradations, leading to the formation of solid electrolyte interface (SEI) layer on the electrodes. Numerous experiments have investigated the effects of LIB degradation using Electrochemical Impedance Spectroscopy (EIS); a method used to inspect the impedance of an electrochemical system over a range of frequencies. EIS measurements, coupled with other more conventional methods, can evaluate changes in internal resistance, conductance, capacity, potential, self-discharge, charge acceptance, and cumulative charge/discharge cycles. However, these methods still do not provide a full understanding of LIB aging. Hence, complementary strategies are needed to help achieve better results and predictability during high-rate cycling. To offer as an alternative method, a few studies have focused on the internal gas evolution along with operating temperatures of Li-ion cells to be directly linked to the aging/failure mechanisms of LIBs. This was accomplished by designing a custom gas test chamber that allowed monitoring and measure both internal pressure and temperature of a LIB while being cycled. In the present study, an improved design of the existing gas test chamber was proposed and tested. The proposed design is able to achieve the following: 1) improved puncturing mechanism using automation, 2) improved pressure monitoring system by minimizing the free volume, 3) minimized the heat transfer away from the cell using better insulation, 4) improved temperature monitoring system by adding the use of pyrometers (infrared thermometer) to measure the temperature along with the thermocouples.