PRISMATIC CELLS VS. CYLINDRICAL CELLS: A COMPARISON

In the rapidly evolving landscape of battery technology, the choice between different types of lithium-ion batteries can significantly impact the performance and application of various devices. ACE's prismatic cells and cylindrical cells offer distinct advantages and applications. Let's delve into the key differences between these two cell types and explore their potential implications.

Exploring Prismatic Cells

Prismatic cells represent a chemistry enclosed within a rigid casing, typically with a rectangular shape. This design facilitates efficient stacking of multiple cells within a battery module. Prismatic cells come in two variations: stacked or rolled and flattened electrode sheets (anode, separator, cathode). The design of stacked prismatic cells enables the release of more energy at once, enhancing performance. In contrast, flattened prismatic cells offer greater energy storage, enhancing durability.

Primarily utilized in energy storage systems and electric vehicles, prismatic cells shine in applications demanding higher energy capacity. Their larger size makes them less suitable for compact devices like cellphones or e-bikes. However, for energy-intensive applications, prismatic cells emerge as a reliable choice.

Unveiling Cylindrical Cells

Cylindrical cells, as the name suggests, come enclosed within rigid cylindrical cans. Their compact, round shape facilitates stacking in devices of various sizes. This shape also prevents swelling caused by gas accumulation within the casing, a phenomenon that can compromise other cell formats.

A cylindrical lithium-ion battery is characterized by its cylindrical shape, thus earning the name "cylindrical lithium-ion battery." These batteries are classified based on their anode materials and include variants like lithium cobalt oxides (LiCoO2), lithium manganese (LiMn2O4), lithium nickel manganese cobalt (LiNiMnCoO2 or NMC), lithium aluminum nickel cobalt (LiNiCoAlO2 or NCA), lithium iron phosphate(LiFePO4), and lithium titanate (Li4Ti5O12).

Initially popularized in laptops, cylindrical cells made their mark with Tesla's use in electric vehicles. These cells are essential components of e-bikes, medical devices, and even satellites, where their unique shape ensures resistance to atmospheric pressure variations.

Key Differences: Size, Connections, and Power

The differences between prismatic and cylindrical cells extend beyond their shapes. Notable distinctions include size, the number of electrical connections, and power output.

Size

Prismatic cells are substantially larger than cylindrical cells, housing more energy per cell. To illustrate, a single prismatic cell may store as much energy as 20 to 100 cylindrical cells. The smaller size of cylindrical cells renders them suitable for applications requiring lower power, expanding their range of use. Cylindrical cells, as the name suggests, have a cylindrical shape resembling traditional AA batteries. Prismatic cells are more rectangular and flat, while pouch cells are flexible and often enclosed in a soft pouch.

Connections

The number of electrical connections required in a battery pack is another crucial difference. This factor directly affects the overall complexity and reliability of the battery system. Prismatic cells, being larger and having higher energy density, require fewer cells to achieve a specific energy capacity compared to cylindrical cells. This means that battery packs using prismatic cells have fewer electrical connections, resulting in potentially fewer points of failure during manufacturing and usage. On the other hand, cylindrical cells, due to their smaller size, require more cells to achieve the same energy capacity, leading to a higher number of connections.

Power Output and Performance

Power output is a critical factor for various applications, from smartphones needing quick charging to electric vehicles requiring high acceleration. Cylindrical cells often exhibit better power output capabilities compared to prismatic cells. This advantage arises from their smaller size and higher number of connections, allowing for a more distributed power delivery. As a result, cylindrical cells are commonly chosen for high-performance applications like electric vehicles and power tools. Prismatic cells, on the other hand, are preferred for energy-intensive applications, where steady and sustained power delivery is more critical than instantaneous bursts.

The Prismatic Revolution

The ongoing evolution of the electric vehicle (EV) industry introduces a dynamic shift in battery preferences. Although cylindrical cells currently dominate the EV sector, prismatic cells present compelling reasons to potentially take the lead.

Prismatic cells offer cost reduction opportunities by streamlining manufacturing steps. Their larger design enables the creation of more sizeable cells, minimizing the need for intricate electrical connections during production.

Furthermore, prismatic cells align well with the lithium-iron phosphate (LFP) chemistry, leveraging abundant and cost-effective materials. LFP batteries rely on resources widely available, in contrast to other chemistries reliant on costly elements like nickel and cobalt.

As the adoption of LFP prismatic cells gains traction, notable shifts occur. Asian EV manufacturers incorporate LiFePO4 batteries in prismatic formats, while Tesla introduces prismatic batteries manufactured in China for specific car models.

However, the LFP chemistry poses limitations, including lower energy density compared to other chemistries, rendering it unsuitable for high-performance vehicles. Battery management systems also encounter challenges in predicting LFP cell charge levels.

Conclusion

The choice between prismatic and cylindrical cells extends beyond shape. Considerations encompass size, connections, and power output, aligning with distinct applications and future trends in battery technology. As the quest for more efficient and sustainable energy solutions continues, the competition between these two cell types advances the evolution of battery-powered innovations. Coincidentally, ACE offers both prismatic and cylindrical batteries. If you're interested, you can give them a try.