This paper presents a comparative study of various heat sinks and their effectiveness in managing the temperatures of lithium-ion battery packs as a function of charging and discharging of the battery pack. The biggest challenges that affect large lithium-ion battery packs are safety, cost, and low-temperature performance. Thermal management of the battery is one of the main strategies that can be employed to mitigate these inherent challenges of mechanical, electrical, and thermal abuse. Capacity degradation and power loss are two main problems that happen due to temperature deviation. Rapid internal temperature changes that stem from non-linear change in thermal resistance and internal heat generation can in turn cause non-uniform temperature distribution. A coupled thermal-electrochemical numerical simulation study is conducted to compare the Li-ion battery pack cooling under various operating conditions with heat sinks with different fin geometries (square and circular) and, macro-channel heat sink(square and circular pipes). This paper studies the cooling performance of the various thermal management systems to maintain optimum operating temperature and uniform temperature distribution of the 12-pack 21700 Li-ion battery pack with discharging rates of 4-24. The circular macrochannel cooling with water as coolant was inferred to provide the best overall average battery pack temperature with a decrease of 20% ensuring optimum operation.