Thermal characteristics of pouch lithium–ion battery capacitors based on activated carbon and LiNi1/3Co1/3Mn1/3O2

Abstract

Lithium–ion battery capacitors (LIBCs) are internal hybrid energy storage devices that incorporate structural characteristics of lithium–ion batteries (LIBs) and lithium–ion capacitors (LICs) for extensive applications in electric vehicles and energy storage systems. But, most of the existing researches have concentrated on the electrochemical performance of LIBC cells, with less research on thermal behaviors of them. Therefore, this work systematically investigates the thermal characteristics of LIBC cells during discharge from 1C to 160C. The discharge capacity is reduced along with an increase in discharge rate, with the highest temperature occurring at 80C discharge rate, where it reaches 51.74 °C. The share of irreversible heat generation, reversible heat generation and other heat generation with respect to total heat generation are quantified. With the discharge rate increasing to 160C, the share of irreversible heat generation is nearly 89.2 % of the total heat generation. Meanwhile, it obtains 263.21 W heat generation rate. Moreover, the LIBC cell's internal resistance is obtained by intermittent current method and electrochemical impedance spectroscopy (EIS) method, while the heat generation is calculated to estimate cell's temperature rise. The intermittent current method makes possible the selection of various timescales for calculating the polarization internal resistance with more accurate calculation of the temperature rise.