Ternary lithium-ion batteries, or simply ternary lithium-ion batteries, are composed of ternary polymers, namely lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide. Ternary lithium is a polymer containing three metal elements, namely nickel (Ni), cobalt (Co), and manganese (Mn) or aluminum (Al), which serves as the positive electrode of the ternary lithium-ion battery; lithium is an electrolyte with lithium hexafluorophosphate as the electrolyte, and the negative electrode material is generally graphite.
There are two common naming conventions for batteries:
① Named after the most important element in the battery.
② Named after the battery's core reaction mechanism or characteristics, such as flexible batteries that emphasize foldable properties.
Because the cathode material usually determines the energy density of a lithium-ion battery, which is one of the most important characteristics of lithium-ion batteries, it is often named after the cathode material. We often talk about ternary lithium-ion batteries, and lithium iron phosphate batteries belong to this category.
What is the relationship between the three elements?
The widespread adoption of ternary lithium batteries isn't solely due to their catchy and memorable name; it's also because the polymer of nickel, cobalt, and manganese (or aluminum) plays a crucial role within the battery's internal structure. So, what exactly are the functions of these three metals?
1. Nickel ingot
Nickel is an active metal in the transition metal group. Its important use is to improve the volumetric energy density of batteries, which is a key breakthrough in improving driving range. However, excessive nickel content can cause nickel ions to occupy lithium ion positions (nickel-metal hydride mixing), resulting in a decrease in capacity.
2. Cobalt powder
Cobalt is also an active metal in the transition metal group. It can suppress the mixing of cations, thereby improving stability and extending battery life. In addition, it also determines the charging and discharging speed and efficiency (rate performance) of the battery. However, excessive cobalt content will lead to a reduction in actual capacity.
3. Aluminum or manganese
The purpose of manganese or aluminum is to reduce material costs, since nickel and cobalt mentioned above are very expensive rare metals, and they can also improve the safety and stability of batteries.
Advantages of ternary lithium-ion batteries
Ternary lithium-ion batteries offer a good balance between capacity and safety, making them a battery with excellent overall performance.
High energy density is the biggest advantage of ternary lithium-ion batteries, and voltage platform is an important indicator of battery energy density, which determines the basic performance and cost of the battery. The higher the voltage platform, the greater the specific capacity. Therefore, for batteries of the same size, weight, and even the same ampere-hour, ternary lithium-ion batteries with higher voltage platforms have a longer driving time.
The discharge voltage platform of a single ternary lithium-ion battery is as high as 3.7V, while that of lithium iron phosphate is 3.2V, and that of lithium titanate is only 2.3V. Therefore, from the perspective of energy density, ternary lithium-ion batteries have an absolute advantage over lithium iron phosphate, lithium manganese oxide, or lithium titanate.
