The development of efficient, cheap, compact, and reliable storage systems is getting increasingly crucial. Special attention must be given to Li Ion batteries, which stand out for the stability of their open circuit voltage (VOC), current capability, and compactness [1]. Such features make them suitable for a large scale of applications. Unfortunately, the design of electric/electronic systems embedding batteries as power supply/storage is still challenging because of the lack of simple and trustworthy circuital models accounting for complex thermo electrochemical mechanisms. In this abstract, a SPICE compatible compact electrical model of batteries including thermal and chemical effects (hereinafter referred to as macrocircuit) is proposed (Fig. 1). The macrocircuit was customized on a Li ion pouch cell battery in the NMC technology (schematically depicted in Fig. 2), its capacity being C=20 Ah; however, the model can be adapted to a generic product. First, in both the charge and discharge phases, self heating effects are considered along with their impact on the overall electrical behavior of the system. Furthermore, for each simulation, the initial conditions of the state of charge (SoC) of the battery can be defined; the SoC can be then monitored during the simulation run. The macrocircuit is composed by: (i) a core including a voltage generator VOC and a passive network, the values of which are allowed to vary with both the SoC and the cell average temperature (Tavg); (ii) a thermal feedback block (TFB) based on Foster I equivalent network, which provides Tavg as an output; (iii) some behavioral modeling blocks devoted to evaluate the SoC and the dissipated power (PD). It must be remarked that PD is given by the algebraic sum of two components, namely, the irreversible (PD,irr) and the reversible (PD,rev) one. While the former is always positive being it given by the Joule heating dissipation over the core, the latter accounts for the endothermic/exothermic chemical reactions dictated by the entropic coefficient dU/dT occurring in the battery; therefore, PD,rev can also be negative, thus reducing the overall PD and providing cooling effects. The modeling of the above quantities was based on the meticulous experimental campaign conducted in [2]. In order to prove the accuracy of the macrocircuit, simulative results obtained in the OrCAD SPICE software package [3] were compared with the counterpart performed in the FEM environment, which was used as a reference. The 3 D structure and the corresponding multiphysics FEM problem was (i) calibrated by means of the experimental data shown in [4], and simulations were run in COMSOL [5]. Given the initial state of charge SoC0=80% and Tamb=25°C, the discharge of the battery was emulated by defining an outgoing current at 4.5 C (i.e., 90 A). A good agreement between results carried out through the macrocircuit and FEM simulations was achieved in terms of dissipated power (Fig. 3), cell average temperature (Fig. 4), and voltage at the battery terminals (Fig. 5). It must be remarked that each FEM simulation required approximately 10 minutes, while a few seconds were needed by making use of the proposed model. As a further advantage, the model is prone to be adopted in complex SPICE simulations of circuits for applications in power electronics (such as DC/DC converters, inverters, and rectifiers) as well as to study the electrical connection of several pouch cells forming a battery pack.

SPICE Modeling of Li Ion Pouch Battery Cell Including Thermo Electrochemical Effects

Antonio Pio Catalano
Primo
;
Ciro Scognamillo
Secondo
;
Marcello Iasiello;Pierluigi Guerriero;Vincenzo D'Alessandro
Ultimo
2022

Abstract

The development of efficient, cheap, compact, and reliable storage systems is getting increasingly crucial. Special attention must be given to Li Ion batteries, which stand out for the stability of their open circuit voltage (VOC), current capability, and compactness [1]. Such features make them suitable for a large scale of applications. Unfortunately, the design of electric/electronic systems embedding batteries as power supply/storage is still challenging because of the lack of simple and trustworthy circuital models accounting for complex thermo electrochemical mechanisms. In this abstract, a SPICE compatible compact electrical model of batteries including thermal and chemical effects (hereinafter referred to as macrocircuit) is proposed (Fig. 1). The macrocircuit was customized on a Li ion pouch cell battery in the NMC technology (schematically depicted in Fig. 2), its capacity being C=20 Ah; however, the model can be adapted to a generic product. First, in both the charge and discharge phases, self heating effects are considered along with their impact on the overall electrical behavior of the system. Furthermore, for each simulation, the initial conditions of the state of charge (SoC) of the battery can be defined; the SoC can be then monitored during the simulation run. The macrocircuit is composed by: (i) a core including a voltage generator VOC and a passive network, the values of which are allowed to vary with both the SoC and the cell average temperature (Tavg); (ii) a thermal feedback block (TFB) based on Foster I equivalent network, which provides Tavg as an output; (iii) some behavioral modeling blocks devoted to evaluate the SoC and the dissipated power (PD). It must be remarked that PD is given by the algebraic sum of two components, namely, the irreversible (PD,irr) and the reversible (PD,rev) one. While the former is always positive being it given by the Joule heating dissipation over the core, the latter accounts for the endothermic/exothermic chemical reactions dictated by the entropic coefficient dU/dT occurring in the battery; therefore, PD,rev can also be negative, thus reducing the overall PD and providing cooling effects. The modeling of the above quantities was based on the meticulous experimental campaign conducted in [2]. In order to prove the accuracy of the macrocircuit, simulative results obtained in the OrCAD SPICE software package [3] were compared with the counterpart performed in the FEM environment, which was used as a reference. The 3 D structure and the corresponding multiphysics FEM problem was (i) calibrated by means of the experimental data shown in [4], and simulations were run in COMSOL [5]. Given the initial state of charge SoC0=80% and Tamb=25°C, the discharge of the battery was emulated by defining an outgoing current at 4.5 C (i.e., 90 A). A good agreement between results carried out through the macrocircuit and FEM simulations was achieved in terms of dissipated power (Fig. 3), cell average temperature (Fig. 4), and voltage at the battery terminals (Fig. 5). It must be remarked that each FEM simulation required approximately 10 minutes, while a few seconds were needed by making use of the proposed model. As a further advantage, the model is prone to be adopted in complex SPICE simulations of circuits for applications in power electronics (such as DC/DC converters, inverters, and rectifiers) as well as to study the electrical connection of several pouch cells forming a battery pack.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/897405
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