The battery thermal management system (BTMS) for lithium-ion batteries can provide proper operation conditions by implementing metal cold plates containing channels on both sides of the battery cell, making it a more effective cooling system. The efficient design of channels can improve thermal performance without any excessive energy consumption. In addition, utilizing phase change material (PCM) as a passive cooling system enhances BTMS performance, which led to a hybrid cooling system. In this study, a novel design of a microchannel distribution path where each microchannel branched into two channels 40 mm before the outlet port to increase thermal contact between the battery cell and microchannels is proposed. In addition, a hybrid cooling system integrated with PCM in the critical zone of the battery cell is designed. Numerical investigation was performed under a 5C discharge rate, three environmental conditions, and a specific range of inlet velocity (0.1 m/s to 1 m/s). Results revealed that a branched microchannel can effectively improve thermal contact between the battery cell and microchannel in a hot area of the battery cell around the outlet port of channels. The designed cooling system reduces the maximum temperature of the battery cell by 2.43 °C, while temperature difference reduces by 5.22 °C compared to the straight microchannel. Furthermore, adding PCM led to more uniform temperature distribution inside battery cell without extra energy consumption.