Research on Lithium Manganese Iron Phosphate Industry: Overview and Material Characteristics
Aug,05,24
1、 Introduction to Lithium Manganese Iron Phosphate Fundamentals
1） Characteristics of lithium manganese iron phosphate: higher energy density than lithium iron, lower cost than ternary
Lithium manganese iron phosphate is a solid solution of lithium iron phosphate and lithium manganese phosphate.
The manganese element enhances the voltage platform, thereby increasing the energy density of the iron lithium system.
Its advantage is the increase in voltage platform, with an energy density increase of up to 21% compared to iron lithium.
The disadvantage is that the crystal structure undergoes distortion after adding manganese, resulting in poorer cycling and rate performance.
High cost-effectiveness, better energy density/low-temperature performance than iron lithium, and better safety/economy than ternary.
Mixing with ternary systems is currently the mainstream route and is expected to become a long-term trend.
Manganese iron lithium combines the safety and low cost of iron lithium, while increasing energy density by 10-20%.
It is expected to replace power iron lithium, and the penetration rate is expected to increase to 10%+in 25 years.
Currently, the mainstream ratio in the industry is 6/4.
Lithium manganese iron phosphate cathode material has gradually become the main current cathode material for lithium-ion batteries due to its high energy density,
good electrochemical performance, safety, and cycling stability.
It is widely used in electric vehicles, energy storage systems, aerospace and other fields, and has broad application prospects.
High manganese is the development trend in the future.
Lithium manganese iron phosphate can simultaneously compensate for the shortcomings of lithium iron phosphate and ternary materials,
and is therefore considered a potential substitute material for lithium iron phosphate and ternary 5-series.
From the perspective of pairing, manganese iron lithium can be mixed with high nickel ternary to obtain products that combine safety and high energy density,
and form a series of endurance solutions.
In the second half of 2023, major mainstream cathode manufacturers will actively expand their production capacity of lithium manganese iron phosphate,
and the industry market has huge prospects.
It is expected that by 2025, the demand for lithium manganese iron phosphate will reach 173.5 GWh,
and the unit consumption of lithium manganese iron phosphate cathode materials will be 2200 tons/GWh, resulting in a demand of 382000 tons.
The upstream manganese ore industry has a significant impact on the cost side of positive electrode manufacturers.
The manganese ore industry in China has a large market demand, and from the perspective of enrichment and current reserves,
China's manganese ore resources are mainly concentrated in the southwest and northwest regions.
Among them, the total reserves of manganese ore resources in five provinces (regions) including Guangxi, Hunan, Yunnan, Hubei,
and Xinjiang account for 70% of China's total manganese ore reserves.
However, due to factors such as low quality of local manganese ore resources, difficulty in mining, and high transportation costs,
there is a large supply gap for local manganese ore, and the market is highly dependent on external factors.
In the past five years, the demand for manganese ore in the Chinese market has shown an upward trend,
with the current import volume of manganese ore in China accounting for more than 70%.
In the future, benefiting from the rapid rise of new energy vehicles in China,
expanding the application of steel, and increasing the proportion of lithium manganese iron phosphate as a positive electrode material,
the demand for local manganese ore market will be further expanded.
2) Application scenarios of lithium manganese iron phosphate: from two wheeled vehicles to four-wheel vehicles
At present, lithium manganese iron phosphate batteries are mainly used in the two wheeler market.
In the future, with further technological breakthroughs, it is expected to account for about 30%, 50%,
and 20% of the market share in the fields of power batteries, two wheelers, and energy storage.
In the power scenario, pure manganese iron has economic advantages and improved low-temperature performance.
After technological progress, it has penetrated a large number of iron based vehicle models,
and the energy density of composite routes has been further improved to meet the differentiated needs of terminals.
Mixed use in the two wheeled vehicle scenario, with a short validation cycle and being the first to implement.
In the energy storage scenario, it is not yet possible to meet the long-term cycle requirements in the short term,
and the pure cost is lower than that of lithium iron phosphate, with long-term penetration potential.
Lithium manganese iron phosphate has a longer range and lifespan than LFP batteries, which has been validated in the two wheeler market.
Xiaoniu has successfully applied the 18650 lithium manganese iron phosphate battery produced by Tianneng in its latest F0, C0, and G2 series electric vehicles.
After the application of lithium manganese iron phosphate batteries, the weight of the battery pack for the Xiaoniu electric vehicle is only 5.6kg,
which can achieve an ultra long range of up to 60km. At the same time, its performance in low-temperature environments has increased by 25% compared to the previous generation product.
Image: Niu Niu Electric equipped with lithium manganese iron phosphate two wheeled vehicle
2、Material properties of lithium manganese iron phosphate
1） Lithium manganese iron phosphate compared to lithium iron phosphate
Advantages: Improved energy density, improved low-temperature performance, and relatively stable safety;
Disadvantages: Slightly low compaction density, poor cycling at room temperature, easy cycling at high temperature, and significant decay of manganese leaching.
2） Lithium manganese iron phosphate compared to ternary materials
Advantages: Improved safety performance, significantly reduced costs, and longer theoretical cycle life;
Disadvantage: The energy density, low-temperature performance, and rate performance are not as good as three yuan.
LMFP has a 20% higher energy density than LFP and higher safety compared to ternary materials.
LMFP (chemical formula LiFexMn1-xPO4) is a solid solution of lithium iron phosphate (chemical formula LiFePO4,
abbreviated as LFP) and lithium manganese phosphate (chemical formula LiMnPO4, abbreviated as LMP).
The crystal structures of LMFP and LFP are both ordered olivine structures, and lithium ions migrate through channels in the structure, with high safety and chemical stability.
The theoretical specific capacities of LMFP and LFP are both 170mAh/g, while LMFP has a higher voltage platform and a theoretical energy density 20% higher than LFP,
which can to some extent break through the energy density bottleneck currently faced by LFP.
Compared with ternary materials, LMFP has similar energy density as ternary five series materials, but higher safety, lower price, and environmental friendliness.
As one of the internal components of LMFP, LMP has the advantages of high energy density, high safety,
and stability, but significant electrochemical performance defects hinder its application.
LMP has a theoretical voltage of 4.1V, which is 0.7V higher than LFP's 3.4V.
Based on similar discharge specific capacity and compaction density calculations, the theoretical energy density of LMP is 697Wh/kg,
which is about 20% higher than LFP's 578Wh/kg.
However, LMP has extremely poor conductivity and cycling performance, resulting in its actual specific capacity and rate performance being far inferior to LFP. The specific manifestations are:
(1) LMP has very low electronic conductivity and ion diffusion coefficient, which makes it difficult to fully utilize the material capacity;
(2) LMP will undergo side reactions with electrolytes, producing products such as Li4P2O7,
and some manganese ions will undergo disproportionation reactions and dissolve in the electrolyte, reducing cycling performance;
(3) The delithiated manganese phosphate will be affected by the Jahn Teller effect, resulting in distorted crystal structure and loss of capacity.
LMP and LFP have the same crystal structure and can form LMFP solid solutions in any ratio, combining high voltage and performance advantages.
The low LFP voltage results in limited room for energy density improvement.
Drawing on the design concept of ternary materials, transition metal phosphate mutual doping modification technology has been widely studied.
LMP and LFP have the same crystal structure and can form LMFP solid solutions in any ratio of mutual solubility.
Multiple studies have shown that iron ion doping can improve the electrochemical activity of manganese in LMP,
thereby enhancing the discharge specific capacity, rate performance, and cycling performance of the material.
The high voltage of LMP can also increase the energy density of the material. In the actual charging and discharging process, unlike the single voltage platform of LFP,
LMFP has two voltage platforms, corresponding to the 4.1V voltage formed by the oxidation-reduction of manganese and the 3.4V voltage formed by the oxidation-reduction of iron.
The 4.1V voltage platform appears first during the discharge process, reflecting the lithium ion insertion process of LMP.
After the lithium insertion in LMP is completed, the voltage platform will drop to 3.4V, reflecting the lithium ion insertion process of LFP.
The proportion of manganese iron has a critical impact on the performance of LMFP.
In theory, LMP and LFP have the same specific capacity, and the high voltage platform of LMFP can enhance the energy density of the positive electrode material.
In the actual discharge process, as the ratio of manganese to iron changes, the specific capacity of the voltage platform corresponding to manganese and iron in LMFP also changes.
Although higher manganese content can maintain a higher voltage platform, it will reduce the specific capacity of the material, thereby reducing the effect of improving energy density.
In addition, different production processes and raw materials can also lead to different specific capacities and properties of the products.
Therefore, the manganese iron ratio should be specifically selected according to the process and the performance requirements of the materials.
Currently, there is no unified ratio standard in the industry.
3）Mixed use is currently the mainstream route, and pure use is more economical.
The manganese iron lithium voltage is matched with high nickel ternary, which can provide a new material solution for composite.
After composite, a product with both safety and high energy density can be obtained, and a series of flexible solutions can be formed to meet terminal needs.
Currently, the Ningde Times hybrid solution M3P battery has been installed in the Chery Intelligent S7 model,
equipped with a "ternary lithium-ion+iron manganese phosphate lithium battery",
which was launched at the end of November 2023. The specific situation still needs further observation.
Pure use is more cost-effective and is expected to become a long-term trend.
The pure use route will initially target overseas customers and increase the volume of high-end lithium iron vehicles in the short term.
With continuous technological breakthroughs, the economic advantages brought by the increase in energy density will gradually be reflected,
and it is expected to fully replace the power lithium iron scenario.
In summary, manganese iron lithium phosphate has a higher energy density than iron lithium, a lower cost than ternary materials,
and a similar energy density to ternary five series materials.
It is also safer, cheaper, and environmentally friendly, making it an important upgrade direction for positive electrode materials.
After manganese iron lithium and ternary composite, products with both safety and high energy density can be obtained,
and a series of flexible solutions can be formed to meet terminal needs.
Mixing is currently the mainstream route, and pure use is more economical.
Pure use products have entered the two wheeler terminal market and have seen a significant increase in volume.
The power sector is expected to move from two wheelers to four wheelers after market maturity, and the energy storage end has penetration potential.
