In daily life, lithium-ion batteries have become an indispensable energy source. Whether in mobile phones, laptops, or electric vehicles, lithium batteries play a crucial role. However, the packaging form of lithium batteries varies across different devices, mainly falling into three types: steel-cased, aluminum-cased, and pouch cells. They differ in structure, performance, and application scenarios. This article will explain the differences between these three types of batteries.
Steel-cased lithium batteries
Steel-cased lithium batteries are the earliest form of lithium batteries, typically used in cylindrical batteries. As the name suggests, the casing of these batteries is primarily made of steel. Steel, due to its stable chemical properties and strong impact resistance, is significantly superior to aluminum-cased and pouch lithium batteries. Furthermore, battery manufacturers have optimized the steel casing structure, placing safety devices inside the battery cell, thereby greatly improving the safety of steel-cased cylindrical lithium batteries. In particular, the 26650 cylindrical steel-cased battery cell produced by JUDAP is renowned for its outstanding safety performance.
Although steel casings offer high hardness and impact resistance, effectively protecting internal battery materials from mechanical damage, and their excellent sealing performance reduces the risk of electrolyte leakage, thus improving battery safety, their high density and weight make them less ideal for devices with strict weight requirements.
Aluminum-cased lithium batteries
Aluminum-cased lithium batteries evolved from steel-cased batteries, with the outer shell made of aluminum, typically used in prismatic batteries. Aluminum-cased batteries have lower density and greater plasticity, offering superior manufacturing performance compared to steel and significant production advantages, allowing for customized sizes to meet specific needs. However, aluminum-cased lithium batteries have slightly lower structural strength, significantly less than steel-cased batteries. Therefore, they are usually designed to be more compact to compensate for this deficiency. Nevertheless, aluminum-cased lithium batteries may still be less durable than steel-cased lithium batteries under strong external forces. Therefore, aluminum-cased lithium batteries are more suitable for portable devices requiring lightweight design.
soft-pack lithium battery
Pouch lithium batteries, also known as polymer lithium batteries, have an outer casing primarily composed of an aluminum-plastic film (a composite material of aluminum foil and plastic layers). Due to the absence of a rigid metal casing, pouch lithium batteries offer greater design flexibility.
Soft-pack lithium batteries are lighter than both aluminum-cased and steel-cased lithium batteries, making them the best choice for achieving battery weight reduction. Because soft-pack lithium batteries lack a rigid outer casing, they can be designed in various shapes and sizes to adapt to different device needs, fully utilizing internal space and increasing the packing rate of active materials, thereby improving energy density.
However, because the outer casing of pouch lithium batteries is relatively soft, it is easily squeezed or punctured by external forces, which may lead to electrolyte leakage and pose certain safety hazards. After multiple charge-discharge cycles, pouch lithium batteries may bulge or expand, affecting battery life.
In summary, steel-cased lithium batteries, due to their high strength and excellent safety, are often used in applications requiring high impact resistance, such as starting batteries, UPS systems, and industrial automation equipment. Aluminum-cased lithium batteries, on the other hand, are widely used in wearable devices, electric bicycles, and electric scooters due to their lightweight design and good flexibility. As for pouch batteries, their lightweight nature and design flexibility make them the preferred choice for 3C consumer electronics products.
Different battery packaging methods each have their own advantages and disadvantages. The choice of battery type depends on specific application requirements and design goals. With technological advancements, we may see more optimized battery packaging technologies in the future, bringing greater convenience and safety to our lives.
