Cathode material is the core material of lithium batteries and the most critical factor determining battery performance. It directly impacts the final energy density, voltage, lifespan, and safety of the battery product, and is also the most expensive component of a lithium battery.
Lithium batteries are often named after their cathode material, such as ternary lithium batteries, which use ternary materials as cathode materials.
Different cathode materials differ significantly and have different applications. Common cathode materials can be divided into lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium iron phosphate (LFP), and ternary materials (NCM).
Lithium cobalt oxide was the first cathode material to be commercialized. Its energy density is higher than that of rechargeable batteries such as nickel-metal hydride and lead-acid batteries, and it was the first to demonstrate the development potential of lithium batteries. However, it is very expensive and has a low cycle life. Lithium cobalt oxide batteries are only suitable for 3C electronic products.
Although lithium manganese oxide is low in cost, its energy density is poor. It was used in some areas of early slow electric vehicles, such as electric bicycles. Nowadays, it is mainly used in power tools and energy storage, and is rarely seen in power batteries.
Currently, the two main technologies used in electric vehicles are ternary lithium batteries and lithium iron phosphate batteries. In 2020, they ranked first and second respectively in terms of the proportion of lithium battery cathode materials shipped.
The core advantage of ternary materials lies in their high energy density. For the same volume and mass, their battery life is significantly longer than other technologies. However, their drawbacks are also very obvious: poor safety, and a relatively low ignition point when subjected to impact or high-temperature environments.
Lithium iron phosphate (LFP) is the opposite of ternary materials. While its energy density and range are average, its safety is outstanding. Its unique olivine crystal structure and spatial framework make it resistant to deformation, allowing it to remain stable even at high temperatures. Ternary materials begin to decompose and release oxygen at approximately 150°C to 250°C, leading to electrolyte combustion. In contrast, LFP decomposes at around 600°C, giving it a significant safety advantage.
In addition, lithium iron phosphate batteries have a significant advantage in lifespan, with a cycle life far exceeding that of other technologies, which addresses two key demands of electric vehicle consumers: safety and durability.
