What is the difference between steel shell, aluminum shell and soft-pack lithium battery?
In daily life, lithium-ion batteries have become an indispensable source of energy for us. Whether it is mobile phones, laptops, or electric cars, lithium batteries play a vital role. However, in different devices, the packaging material of lithium batteries are different, and they are mainly divided into three types: steel shell, aluminum shell and soft-pack. They have certain differences in structure, performance and application scenarios. This article will tell you the differences between these three types of batteries.
Steel Shell Lithium Battery
Steel shell lithium batteries are one of the earliest forms of lithium batteries, typically used in cylindrical battery. As the name suggests, these batteries have a shell primarily made of steel. Steel is favored for its stable chemical properties and strong impact resistance, making it superior to aluminum and soft-pack lithium batteries. Manufacturers have optimized the steel shell structure by placing safety devices inside the battery core, significantly enhancing the safety of cylindrical steel shell lithium batteries. Notably, the 26650 cylindrical steel shell cells produced by PLB Battery are renowned for their exceptional safety performance.
While the steel material provides high hardness and strong impact resistance, effectively protecting the internal components from mechanical damage, and offers good sealing to minimize electrolyte leakage, its higher density results in a heavier weight. This makes it less ideal for applications where weight is a critical factor.
Aluminum Shell Lithium Battery
Aluminum shell lithium batteries are developed from steel shell batteries, with the shell material made of aluminum, typically used in prismatic battery. Aluminum shell batteries have a lower density and greater plasticity, offering better production performance than steel, along with customization options for size based on demand. However, the structural strength of aluminum shell lithium batteries is somewhat lower, and they are not as strong as steel shell batteries. Consequently, aluminum shell lithium batteries are usually designed to be more compact to compensate for this deficiency. Despite this, aluminum shell batteries may still be less durable than steel shell batteries when subjected to strong external forces. Therefore, aluminum shell lithium batteries are more suitable for portable devices that require lightweight designs.
Soft-Pack Lithium Battery
Soft-pack lithium batteries, also known as polymer lithium batteries, have a shell primarily made of aluminum-plastic film (a composite of aluminum foil and plastic layers). Without a rigid metal shell, soft-pack lithium batteries offer high design flexibility.
These batteries are lighter than both aluminum shell and steel shell lithium batteries, making them the best choice for lightweight applications. Their lack of a hard shell allows for various shapes and sizes, adapting to different device requirements and maximizing internal space to increase the packing density of active materials, thus enhancing energy density.
However, the softer shell of soft-pack lithium batteries makes them susceptible to external pressure or punctures, which can lead to electrolyte leakage and pose certain safety risks. Additionally, after multiple charge and discharge cycles, soft-pack lithium batteries may experience swelling, which can affect their lifespan.
In summary, steel shell lithium batteries are commonly used in applications that require high impact resistance due to their high strength and excellent safety, such as starting batteries, UPS systems, and industrial automation equipment. Aluminum shell lithium batteries, on the other hand, are widely used in portable devices like wearables, electric bicycles, and electric scooters because of their lightweight and good plasticity. As for soft-pack lithium batteries, their lightweight and design flexibility make them the preferred choice for 3C consumer electronics.
Each battery packaging material has its own advantages and disadvantages, and the choice of which type to use depends on specific application requirements and design goals. With advancements in technology, we can expect to see more optimized battery packaging solutions in the future, bringing greater convenience and safety to our lives.