Modular energy efficient and solid-state Battery Thermal Management System

Abstract

The lithium-iron-phosphate (LiFePO 4 ) battery is becoming the favored choice of electrochemical energy storage for electric vehicles (EV) and hybrid vehicles (HV) due to its high energy density and low self-discharge. However, battery operating temperature plays a vital role on the reliability, lifespan, safety and performance of EV and HV. Battery Thermal Management System (BTMS) must keep the operating temperature of the battery pack between 20 °C and 40 °C in order to achieve good performances and long lifespan. To this day, this task remains a challenging subject for the electric vehicle (EV) development. BTMS consumes energy from the on-board battery pack, thus reducing the range of the vehicle. In order to reduce this adverse impact, this paper presents a novel approach that takes advantage of the non-uniform surface distribution of li-ion battery cell, which results from complex reactions inside the cell. First, li-ion hotspots were identified and found next to the positive and negative tabs. Then, thermoelectric coolers (TEC) are mounted next to the tabs and in the center of the li-ion battery. The control circuit is designed to turn on and off TECs in order to reduce the parasitic power feeding the BTMS. Experimental results show the feasibility of this system.