LMFP – a new generation of lithium battery cathode material

Introduction of LMFP materials

LMFP and lithium iron phosphate are both phosphate-based materials, and the core difference is only the addition of manganese and the decrease of iron. LMFP (LiMnxFe1-xPO4) is a new type of phosphate lithium ion battery cathode material formed on the basis of lithium iron phosphate (LiFePO4) doped with a certain proportion of manganese (Mn).

Therefore, industry experts pointed out that LMFP battery is a mixed product of lithium iron phosphate and lithium manganese phosphate. The industry generally believes that LMFP batteries can retain the advantages of high thermal stability and low cost of lithium iron phosphate batteries, and can also use manganese materials to increase battery voltage to make up for the shortcomings of low energy density of lithium iron phosphate.

In terms of data, LMFP batteries can increase the energy density of LiFePO4 battery by about 15%, so they are also called an upgraded version of lithium iron phosphate.

Preparation method of LMFP

LMFP is an improved material for ferromanganese phosphate, so its preparation route is similar to that of lithium iron phosphate. The preparation methods of LMFP can be divided into two categories: solid-phase method and liquid-phase method.

Specifically, the solid-phase method includes a high-temperature solid-phase method, a carbothermal reduction method, and the like. The method has the advantages of simple and mature process, low preparation cost, easy realization of large-scale industrialization, and the ability to process more raw materials at one time. The disadvantage is that the mixing uniformity of the product is poor, it is difficult to control the crystal form and particle size, and the quality is poor.

Liquid phase methods include solvothermal method, sol-gel method, co-precipitation method and the like. The advantages are good tolerance to raw materials, high product quality, good electrochemical performance, charge and discharge performance, etc.

The disadvantage is that the treatment is relatively complicated, the process control is difficult, the process is difficult, and the possibility of manganese ion dissolution is higher than that of the solid-phase method. If manganese ions are doped to the lithium site, the rate performance and cycle life will be affected.

Comparison of performance characteristics of LMFP

In the current field of power batteries, the mainstream application materials are olivine-structured lithium iron phosphate and layered ternary nickel-cobalt-manganese materials (NCM). As a positive electrode development material based on lithium iron phosphate, LMFP has its own advantages and disadvantages compared with the two.

Compared with lithium iron phosphate, the high voltage characteristics of manganese make LMFP have a higher voltage platform, and the high voltage platform can be raised to 4.1V. This also leads to a higher energy density when the specific capacity is the same, and the energy density is 10%-20% higher than that of lithium iron phosphate under the same conditions.

But the disadvantage is that the introduction of manganese significantly reduces the conductivity of the material. But it is worth noting that a higher voltage platform also means higher requirements on the electrolyte, and there are relatively few types of electrolytes that meet the discharge characteristics.

Compared with the layered structure of ternary NCM materials, LMFP has the same olivine structure as lithium iron phosphate, and the structure is more stable during charge and discharge. Even if all the lithium ions are intercalated during the charging process, the structure will not collapse, so the safety is better and the cost is lower.

In particular, manganese exists widely in nature, and the global manganese ore resources are very rich. my country is also the world’s largest production base of electrolytic manganese, which has extremely outstanding cost economy.

However, the disadvantage is that compared with high-efficiency ternary materials, the specific capacity and energy density of LMFP are still very low, and the gap in electrical conductivity is even greater. This has also led to more applications of LMFP in small power fields such as motorcycle battery pack with relatively low performance requirements.

LMFP battery industrialization accelerated

In the past, the commercialization of LMFP batteries has been limited by its low conductivity and rate performance, and the progress has been slow. However, with the continuous progress and application of modification technologies such as carbon coating and nano-technology, LMFP batteries perform better in high-rate charge and discharge, greatly improving their charging speed and power output.

In addition, the safety of LMFP batteries has also been significantly improved. Carbon coating technology can increase the stability of the battery and reduce the risk of the battery overheating at high temperatures or in an overcharged state, thereby greatly reducing the potential risk of fire and explosion. These safety improvements have made LMFP batteries more popular in electric vehicles, as users value safety more.

Due to these improvements, the commercialization process of LMFP batteries is accelerating, and the related industrial chain has also been further developed. According to the survey data, the shipment of LMFP cathode materials will be 2,000 tons in 2022, mainly in the small-scale shipment of electric two-wheel vehicles at present, and is expected to be shipped on a large scale in the power field in 2023.

With the accelerated research and development of head battery companies, it is estimated that China’s LMFP cathode material shipments are expected to exceed 15,000 tons in 2023, and the market size is expected to exceed 1 billion RMB. In 2025, the shipment of LMFP cathode materials is expected to exceed 200,000 tons, and the market size is expected to exceed 10 billion RMB. At present, battery and material companies are acting collectively, and some manufacturers already have LMFP technology reserves.

Application prospect of LMFP battery

At present, LMFP batteries are still in the early stage of commercialization, and it will take time before large-scale application. In the future development of LMFP, on the one hand, it is the application of pure LMFP, which has significant cost advantages, safety performance and higher energy density than LFP compared with ternary materials.

However, the main limitation lies in the low conductivity. In order to improve this problem, methods such as coating, doping and nanonization can be used to improve its conductivity. On the other hand, compounding LMFP with ternary 523, LCO and other materials can further integrate the advantages of materials.

Complementary to achieve short-board complementarity, to achieve an increase in energy density, with more comprehensive and comprehensive battery performance, but at the same time the corresponding production costs will also be greatly increased.

To sum up, LMFP has a good cost performance and development space. According to the analysis, in the future, with the introduction and application of technical modification schemes such as carbon coating, ion doping, and nanotechnology, LMFP is expected to be popularized in electric vehicles.