There are various types of lithium-ion batteries, and different types of batteries are differentiated by the use of different cathode materials.

In this article, I will describe the advantages, disadvantages and applications of lithium manganate cathode materials, as well as the main preparation methods.

What is Lithium Manganate?

Lithium manganate, with the chemical formula LiMn2O4, has a cubic spinel crystal structure and contains three lithium ion space transport channels. Therefore, compared with other cathode materials, lithium manganate cathode material has a higher ion diffusion rate and is suitable for lithium-ion batteries that require high rate charging.

Lithium manganate is one of the most promising lithium-ion cathode materials. Spinel-type lithium manganate belongs to the cubic crystal system, Fd3m space group, with a theoretical specific capacity of 148mAh/g.

Due to the three-dimensional tunneling structure, lithium ions can be reversibly de embedded from the spinel lattice without inducing structural collapse, resulting in excellent multiplicity performance and stability.

What does lithium manganate do?

It is mainly used as a cathode material for lithium-ion batteries used in the manufacture of portable electronic devices such as mobile phones and notebook computers. The main use of lithium manganese oxide is for new energy batteries, and other uses include power tools, electric toys, and other energy storage tools that require mobility. Lithium manganese oxide ion battery parts for pneumatic tools, medical equipment, hybrid and new energy vehicles.

Advantages and disadvantages of lithium manganate

Lithium manganate is said to have a spinel structure, which refers to its crystal shape when applied to lithium batteries. A layered structure also exists when lithium manganate is not used in lithium batteries.

The spinel structure is relatively more stable than the layered structure (although based on the chemistry, it seems to be possible to think of the stability of the different shapes in the geometry as well), so the spinel structure is still used in practical applications.

In addition to lithium manganate, lithium cobaltate and lithium ternary battery cathode also have spinel structure, but the spinel structure of lithium manganate is very distinctive compared to its two counterparts.

Advantages:

l Abundant reserves of manganese, which can significantly reduce the cost of batteries and facilitate large-scale industrial production and application.

l Batteries with LiMn2O4 positive electrodes are safe and resistant to overcharging and discharging even without protection circuits; they have good multiplication performance and are resistant to low temperatures.

l Manganese is non-toxic and non-polluting, and the solution of its recycling problem has accumulated rich experience in primary batteries, so the use of LiMn2O4 cathode materials is conducive to environmental protection.

Drawbacks:

The material itself is unstable, needs to be mixed with other materials, has poor high temperature performance, poor cycling performance and fast decay.

These disadvantages of lithium manganate are due to the properties of manganese. However, due to the widespread availability of manganese, it has significant cost advantages.

The main preparation methods of lithium manganate

At present, there are six methods for the preparation of lithium manganate, which are classified as high temperature solid phase method, melt impregnation method, microwave synthesis method, hydrothermal synthesis method, co-precipitation method and sol-gel method.

Among them, there are two main types of lithium manganate on the market: type AB, type A refers to the material used for power batteries, which is characterised by the main considerations of safety and recycling, and type B refers to the alternatives for mobile phone batteries, which is mainly characterised by its high capacity 

① The basic process of high-temperature solid-phase method is as follows: mixing → roasting → grinding → sieving → product. The solid phase method has the advantages of simple operation process, mass production and low cost.

② Melt impregnation method refers to the better method of preparing spinel-type lithium manganate by solid-phase method.

Negative electrode materials with excellent electrochemical performance can be obtained, but they are not conducive to industrialisation due to the complexity of operation and harsh conditions.

③The microwave synthesis method is significantly different from the conventional high-temperature solid-phase method in the synthesis of materials. Materials with excellent electrochemical properties are prepared using this method and the synthesis reaction time can be greatly reduced.

④ Hydrothermal synthesis LiMn2O4, the anode material for lithium-ion batteries synthesised by hydrothermal synthesis, has a stable crystal structure and a uniform crystalline state, so the synthesised material has excellent physical and electrochemical properties.

⑤ The lithium-ion battery materials prepared by the co-precipitation method not only have higher electrochemical capacity and longer cycle life, but also have the advantages of simple process, convenient operation and fast reaction speed.

⑥ The sol-gel method is actually a branch of the co-precipitation method. The LiMn2O4 produced has excellent physical and electrochemical properties, but it is not favourable for industrial production due to problems such as high cost.

Comparison of lithium manganate and other lithium battery materials

Compared with traditional cathode materials such as lithium cobaltate, lithium manganate has the advantages of abundant resources, low cost, no pollution, good safety and good multiplier performance.

It is an ideal cathode material for power batteries, but its poor cycling performance and electrochemical stability greatly limit its industrialisation. Secondly, compared with Li-ion ternary battery/LiFePO4 battery, Li-Mn2O4 battery has the advantage of being cheaper. The temporary problem is the number of cycles. He has several super hot application scenarios.

Electric two-wheelers are used in a more hostile environment than cars, and the probability of wading and collision is higher than that of cars. From an economic point of view, the cost of the battery pack should not be too high.

Compared with LiFePO4 material, LiMn2O4 is cheaper and safer. Compared with LiFePO4 material, LiMn2O4 will not be so easy to drop out in low temperature in winter, and the charging performance will remain the same. But now there are also lithium iron phosphate batteries for low temperature, but the cost is also very high. Eventually lithium manganate becomes one of the good choices.

According to statistics, the share of lithium manganese-acid batteries in lithium batteries for two-wheelers is 42 per cent in FY19, 45 per cent in FY20 and 56 per cent in FY21.

Prospects for Lithium Manganate

According to statistics, 85-90 per cent of China's current manganese consumption structure is used in the iron and steel industry, and about 5-10 per cent is used in the battery industry and the chemical industry. In recent years, the rapid development of new materials, electric vehicles and other green manufacturing industries will provide a broad market for electrolytic manganese dioxide, lithium manganate, high purity manganese sulphate and other anode materials.

China shipped 510,000 tonnes of cathode materials, of which 66,000 tonnes of lithium manganate was shipped, accounting for 13%. Although demand for low-end digital batteries and exports to other countries decreased in the first half of the year due to the epidemic, demand for electric two-wheeler batteries, which began to explode during the epidemic, supported the lithium Manganate market.

China's lithium manganate output reached 92,900 tonnes, up 21.6% year-on-year, and is expected to reach 109,000 tonnes. At present, there are more than 40 lithium manganate anode material enterprises in China, and 90% of their production capacity is generally below 10,000 tonnes. There is a lack of leading enterprises, and industry integration is just around the corner.