In modern battery technology, battery aluminum foil occupies a key and diverse position. Its application spans the core components inside the battery and the external protective packaging. Each application has a profound impact on the battery performance, safety and stability.
In lithium-ion batteries, the battery and aluminum foil is best known as the positive current collector, which is its most critical application in the battery system. The current collector is responsible for collecting the battery active materials to generate current and smoothly conduct it to the external circuit.
At the same time, it also provides a carrier for the positive active materials to attach, which is a key link in realizing the efficient conversion of chemical energy inside the battery into electrical energy.
From the perspective of material properties, although the conductivity of metal aluminum is inferior to that of copper, its weight is only about half of that of copper wire when transmitting the same amount of electricity. This feature makes aluminum foil unique in improving the energy density of lithium-ion batteries and an ideal choice for reducing battery weight and improving overall performance.
In addition, the price of aluminum is relatively low, which can effectively control costs in large-scale applications. During the dynamic process of battery charging and discharging, a dense oxide film will naturally form on the surface of the aluminum foil. This film is like a solid shield, which greatly enhances the corrosion resistance of the aluminum foil and ensures the long-term stable operation of the current collector in a complex electrochemical environment.
With the rapid development of the lithium battery industry, the pursuit of battery energy density and driving range continues to rise, and the thickness of positive electrode aluminum foil is also continuously optimized. A few years ago, the commonly used thickness was 15-20μm, but now it has been greatly reduced to 8-10μm.
The thinning of thickness means that more active materials can be accommodated in the limited battery space, thereby directly improving the energy storage capacity of the battery. Take a pure electric vehicle as an example. If its lithium-ion battery pack uses thinner aluminum foil as the positive electrode current collector, the driving range can be significantly increased under the same battery volume, bringing users a more convenient travel experience.
In order to further improve the performance of aluminum foil as a current collector, carbon-coated aluminum foil came into being. This innovative material builds an excellent two-dimensional or multi-dimensional conductive network structure by coating a specific functional coating on the surface of aluminum foil, optimizing battery performance from multiple dimensions.
Aluminum foil also plays an indispensable role in the field of battery outer packaging, and is mainly used in the production of aluminum-plastic film and shell of batteries. As the key packaging material of soft-pack batteries, aluminum-plastic film is composed of a variety of materials, among which the aluminum foil layer is at the core. It provides excellent barrier properties for batteries and can effectively block the intrusion of external impurities such as oxygen and moisture.
In daily use, if the battery is exposed to a humid environment, once moisture enters the battery, it will react chemically with the electrolyte to produce gas, causing the battery to bulge or even fail. Aluminum foil can minimize this risk with its good barrier properties and ensure the stability of the chemical system inside the battery.
At the same time, battery hacks aluminium foil has a certain degree of flexibility and mechanical strength. While ensuring the integrity of the battery package, it can adapt to the slight deformation of the battery in different usage scenarios, providing reliable physical protection for the battery.
In the application of battery shells, the shell made of aluminum foil or aluminum alloy materials not only provides solid physical protection for the internal components of the battery, preventing damage to the battery caused by collision and extrusion, but also because of its good heat dissipation performance, it can timely dissipate the heat generated by the battery during the charging and discharging process, maintain the stability of the internal temperature of the battery, and avoid safety hazards and performance degradation caused by overheating.