The article compares different types of batteries for electric vehicles to find the most efficient and long-lasting option. They looked at a regular single-cell battery system and two hybrid systems that combine different types of lithium-ion cells. By using a special control method, they found that the hybrid systems are better at balancing power and energy efficiency, especially when the high energy cells are old. The hybrid systems also perform better in low battery charge situations, making them a promising option for electric vehicles.