The outer casing materials of lithium batteries generally have two types of aluminum and steel. The lithium battery casings made of this material have their own characteristics. So which one is better?

First, aluminum shell

The aluminum case is a battery case made of aluminum alloy material, which is mainly used on a square lithium battery. The lithium battery is packaged in an aluminum case because its light weight is safer than steel case.

The aluminum shell is designed with square and rounded corners. The aluminum shell is usually made of aluminum-manganese alloy. The main alloy components are Mn, Cu, Mg, Si, Fe, etc. These five alloys are used in the lithium battery aluminum shell. Different functions, such as Cu and Mg, improve strength and hardness, Mn improves corrosion resistance, Si enhances the heat treatment effect of magnesium-containing aluminum alloy, and Fe can increase high temperature strength.

The aluminum shell alloy material construction has significant safety performance considerations, which can be expressed in terms of material thickness and bulging coefficient. The reason why the lithium battery of the same capacity is lighter than the steel case is because the aluminum case can be made thinner. From the working mechanism of the lithium battery, during charging, lithium ions are deintercalated and the positive electrode expands in volume; during discharge, lithium ions are embedded from the positive electrode and the negative electrode is expanded; both of which cause solid expansion, and the bulging coefficient can be reduced by a suitable alloy formulation.

Second, the steel shell

Most of the early square lithium battery casings were steel shells, which were mostly used in mobile phone batteries. Later, due to the low energy ratio of the steel shell and poor safety, they were gradually replaced by aluminum shells and soft-package lithium batteries.

However, among the column type lithium batteries, there is another kind of scene. Most manufacturers use steel as the material of the battery casing. Because of the physical stability of the steel material, the pressure resistance is much higher than that of the aluminum shell material. After the structure is optimized, the safety device has been placed inside the battery core, and the safety of the steel-shell battery has reached a new height. At present, most of the battery cells of the notebook battery are made of steel shell.

Is the lithium battery case material good for steel or aluminum? I believe that everyone has already understood after reading the above content. In summary, the steel shell and the aluminum shell have their own advantages, so the selection process also needs to be selected according to their own needs.