A cell level design and analysis of lithium-ion battery packs

Abstract

The world is gradually adopting electric vehicles (EVs) instead of internal combustion (IC) engine vehicles that raise the scope of battery design, battery pack configuration, and cell chemistry. Rechargeable batteries are studied well in the present technological paradigm. The current investigation model simulates a Li-ion battery cell and a battery pack using COMSOL Multiphysics with built-in modules of lithium-ion batteries, heat transfer, and electrochemistry. This model aims to study the influence of the cell’s design on the cell’s temperature changes and charging and discharging thermal characteristics and thermal runaway propagation characteristics of a battery and a battery pack composed of 18,650 and 4680 cylindrical batteries. The charge and discharge C-rates are varied. An event-based thermal runaway of the cell and a battery pack is presented finally. Based on the findings, it can be determined that the cell’s temperature is closely connected to the geometry of the cell, the C-rate, the active mass loading of the electrodes, and the operating temperature. For 18,650 and 4680 types, a projected capacity is 2.71 Ah and 21.8 Ah, heat generated is 1.19 Wh and 3.44 Wh, and the cell temperature at a constant discharge rate of 1C is 21.08 °C and 147.57 °C respectively. 4680 battery occupies four times less space, eight times less number of cells, and 20% less current collector materials utilized than the 18,650 battery, for a common capacity of 100 KWh.