Common Cathode Materials for Lithium-Ion Batteries and Their Characteristics
Cathode materials are one of the key factors determining battery performance. Whether a battery has high energy density, good safety, or long cycle life is, to a large extent, directly related to the choice of cathode material. At present, mainstream lithium-ion battery cathode materials can generally be divided into several major categories: layered oxides, spinel-structured materials, and phosphate-based materials. Below, we explain their characteristics and application scenarios in a clear and accessible way.
I. Layered Oxide Cathode Materials: The Core Route to High Energy Density
Layered oxides are currently the most widely used class of cathode materials. Typical representatives include lithium cobalt oxide (LiCoO₂), lithium nickel oxide (LiNiO₂), and the ternary materials developed on their basis.
Lithium cobalt oxide was the first cathode material to be successfully commercialized for lithium-ion batteries and is still extensively used in consumer electronics such as smartphones, tablets, and laptops. Its advantages include a stable structure, a well-defined voltage plateau, mature manufacturing processes, and good cell consistency. However, its practical reversible capacity is not particularly high, and it is highly sensitive to overcharge. Once the charging voltage is too high, the material structure can become unstable, significantly increasing safety risks. In addition, the high price of cobalt resources limits its application in large-scale fields.
Lithium nickel oxide was developed mainly to increase capacity. Compared with lithium cobalt oxide, it offers higher reversible capacity and, in theory, greater potential for improving energy density. In practice, however, it is extremely sensitive to synthesis conditions. Nickel ions tend to migrate into lithium layers, leading to structural instability, degraded cycle performance, and poor safety. As a result, pure lithium nickel oxide has not achieved large-scale commercialization.
Against this background, ternary materials emerged. By introducing cobalt and manganese (or aluminum) into nickel-based systems to form Ni–Co–Mn (NCM) or Ni–Co–Al (NCA) compositions, a better balance can be achieved among capacity, stability, safety, and cost. In these materials, nickel mainly contributes to capacity, manganese helps stabilize the structure, and cobalt improves electronic conductivity and rate capability. Ternary materials have become the mainstream choice for power batteries and some high-end consumer electronics, and they remain a key direction for the future evolution of cathode materials.
II. Spinel Lithium Manganese Oxide: A Compromise Between Cost and Safety
Spinel-type LiMn₂O₄ is another important cathode material. Unlike layered materials, it features three-dimensional lithium-ion diffusion channels, allowing fast lithium-ion transport and good rate performance. At the same time, it contains no cobalt, resulting in lower raw material costs, and it exhibits relatively high thermal stability.
This material has a discharge plateau around 4 V, and its structure remains relatively stable within conventional voltage ranges, giving it certain advantages in safety and overcharge tolerance. However, LiMn₂O₄ also has clear drawbacks, particularly its rapid capacity fading at elevated temperatures. This is mainly associated with manganese dissolution and the Jahn–Teller effect in the structure, both of which contribute to performance degradation.
Through element doping (such as aluminum) or surface coating treatments, its high-temperature cycling stability and rate performance can be improved to some extent. After modification, lithium manganese oxide still retains competitiveness in cost-sensitive applications with high safety requirements, especially in early power battery applications and certain niche scenarios.
III. Phosphate Cathode Materials: Strengths in Safety and Cycle Life
Spinel-type LiMn₂O₄ is another important cathode material. Unlike layered materials, it features three-dimensional lithium-ion diffusion channels, allowing fast lithium-ion transport and good rate performance. At the same time, it contains no cobalt, resulting in lower raw material costs, and it exhibits relatively high thermal stability.
This material has a discharge plateau around 4 V, and its structure remains relatively stable within conventional voltage ranges, giving it certain advantages in safety and overcharge tolerance. However, LiMn₂O₄ also has clear drawbacks, particularly its rapid capacity fading at elevated temperatures. This is mainly associated with manganese dissolution and the Jahn–Teller effect in the structure, both of which contribute to performance degradation.
Through element doping (such as aluminum) or surface coating treatments, its high-temperature cycling stability and rate performance can be improved to some extent. After modification, lithium manganese oxide still retains competitiveness in cost-sensitive applications with high safety requirements, especially in early power battery applications and certain niche scenarios.
III. Phosphate Cathode Materials: Strengths in Safety and Cycle Life
Among phosphate-based cathode materials, lithium iron phosphate (LiFePO₄) is the most representative. Its most prominent feature is an extremely stable crystal structure, excellent thermal stability, and a low tendency for oxygen release or thermal runaway, giving it inherent advantages in safety.
Lithium iron phosphate has a discharge plateau of about 3.4 V, a theoretical capacity of 170 mAh/g, and a practical reversible capacity close to 160 mAh/g. Compared with layered materials, its main disadvantages are low electronic conductivity and relatively slow lithium-ion diffusion, which result in less favorable rate performance under normal conditions.
To address these issues, the industry widely adopts strategies such as carbon coating, nano-sizing, and doping modification, significantly improving the practical performance of lithium iron phosphate. Today, modified LiFePO₄ is widely used in energy storage systems, electric commercial vehicles, and applications with extremely high safety requirements.
IV. Other Emerging Cathode Materials and Development Trends
In addition to the mainstream materials mentioned above, researchers continue to explore various new cathode material systems. For example, LiMnPO₄ offers a higher voltage plateau but suffers from poor kinetic performance, making practical application challenging. Fe–Mn solid-solution phosphates attempt to strike a balance between safety and higher voltage. Some high-voltage phosphate materials and vanadium-based materials show promising performance potential, but limitations related to electrolytes, voltage windows, or resource costs mean that they are still at the research stage or in limited-scale applications.
There is no absolute “best” cathode material for lithium-ion batteries. Different material systems each have their own strengths in terms of energy density, safety, cycle life, and cost.
