Join us for the first part in a three-part series exploring the role of the smallest common denominator in a battery module or pack, the battery cell. This week we’re kicking it off with the importance of energy density to the cell selection process.
Contact: Betsy Barry
Energy density is one of the most important characteristics of battery cells, making it a central parameter in battery pack design because it impacts the overall performance of the energy storage system. Energy density refers to the amount of energy that can be stored in a given mass or volume of a battery and is typically expressed in watt-hours per kilogram (Wh/kg), or watt-hours per liter (Wh/L). Battery cells with higher energy density store more energy in a smaller/lighter package, making them more practical for certain applications where space or weight are important design considerations.
While the concept seems straightforward, as with other aspects of battery cells and systems, energy density is more complex than it initially appears, as there are different factors to consider when evaluating a battery’s energy density.
There are two ways to measure energy density: volume and weight. Both reveal distinct aspects of a battery’s performance capability and can present different constraints in battery system design. Volumetric energy density is important for applications where physical space matters, such as consumer electronics. Gravimetric energy density is critical when weight is a key factor, as in automotive and aerospace applications.
In short, there are several reasons why energy density is crucial in battery pack design, and here are a few:
Range and Run Time: In applications like electric vehicles (EVs), a higher energy density allows for a longer driving range or usage time between charges.
Weight and Size: Energy density is directly related to the weight and size of the battery pack. A higher energy density means that more energy can be stored in a smaller/lighter package, which is important in applications where space and weight are paramount, such as in portable electronics or aerospace applications.
Cost: Manufacturing and material cost is often tied to the mass of the battery. Higher energy density batteries can potentially reduce the overall amount of material required, which, in turn, can impact cost.
Performance: Higher energy density batteries can have better power-to-weight ratios, leading to improved overall system performance. This is critical in applications where rapid charging and discharging are necessary, as with EVs or electronic devices.
Innovation: In addition to improving battery technology, more energy-dense batteries have the potential to spur innovation in new, novel applications where size, weight, and range are otherwise limiting design factors.
Sustainability: Batteries with higher energy density can contribute to reducing the environmental impact of energy storage systems by allowing for more energy to be stored in a smaller space, potentially reducing the need for large-scale installations and minimizing the environmental footprint associated with manufacturing and disposal. Similarly, they can reduce the total material needed to meet the energy requirements of the application.
Choosing the right battery cell is the first step in designing an energy storage system that will meet your application’s requirements & exceed your customer’s expectations.
An important factor in this decision is the battery cell’s energy density.
The impact of energy density on battery pack design traverses a range of crucial considerations, influencing the efficiency, practicality, and sustainability of energy storage systems. As a defining characteristic, energy density becomes a linchpin in determining the overall performance of battery cells, with far-reaching implications for diverse applications. And while it is important in battery system design, it is not the only consideration. Next week we will look at power density, and next, we’ll compare both energy density and power in battery pack design.