Category: abiotic

Lithium iron phosphate electrode materials are mainly used in a variety of lithium ion batteries. In 1997, John b. Goodenough et al. (Texas state university) also reported the reversibility of LiFePO4 in and out of lithium after NTT in Japan first revealed AyMPO4(A is an alkali metal, M is A combination of CoFe :LiFeCoPO4) as A lithium battery anode material.

The simultaneous publication of olivine structures (LiMPO4) in the United States and Japan has brought great attention to this material and led to extensive research and rapid development. Compared with the traditional lithium ion secondary battery cathode materials, spinel LiMn2O4 and lamellar LiCoO2, LiMPO4 has wider source of raw materials, lower price and no environmental pollution.

Functional purposes

Application fields of lithium iron phosphate mainly include:

(1) energy storage equipment

Energy storage equipment for solar and wind power systems, and uninterruptible power system UPS, which are used in conjunction with solar cells as energy storage equipment (byd is already producing such batteries);

The power tools class

High power electric tools (wireless), electric drill, lawn mower, etc.

The light electric vehicle is (3)

Electric locomotive, electric bicycle, recreational vehicle, golf cart, electric booster, cleaning vehicle, hybrid electric vehicle (HEV), recent 2-3 years' goal;

Of small equipment

Medical equipment: electric wheelchairs, electric transport vehicles), toys (remote control electric aircraft, car, boat);

It shall set it on

Mineral lamp, imbedded medical device (lithium iron phosphate is non-toxic, lithium battery can only meet the requirements of lithium iron), replace lead acid, nickel hydrogen, nickel cadmium, lithium cobalt, lithium manganese battery in the application of small electrical appliances.

(6) mobile power supply

After long-term research, German new energy company Deboch has successfully developed and mass produced lithium iron phosphate battery made of composite nano-materials, which improves the unit capacity ratio and overcomes the problem that lithium iron phosphate is too large per unit volume and is not suitable for the field of digital products. Now a single 32650(diameter 32mm, length 65mm) battery, capacity breakthrough 6000mAh, through the combination of two, can reach 12000mAh. The 38.4wh mobile power is enough to charge the 5.3wh (1432mAh) iPhone4S nearly six times, making it ideal for long-distance outdoor travel.

performance

Folding high energy density,

Its theoretical specific capacity is 170 mAh/g, actual specific capacity of product can be more than 140 mAh/g (0.2 C, 25 ° C).

Folding safety,

Is the safest lithium ion battery anode material; Free from any heavy metal elements harmful to human body;

Long folding life

Under 100%DOD condition, it can charge and discharge more than 2000 times; (reason: the crystal lattice of lithium iron phosphate has good stability, and the insertion and release of lithium ions have little effect on the crystal lattice, so it has good reversibility. The deficiency is that the electrode ionic conductivity is poor, not suitable for large current charge and discharge, in the application of obstruction. Solution: the electrode surface is coated with conductive materials and doped for electrode modification.

The service life of lithium iron phosphate battery is closely related to its service temperature. If the service temperature is too low or too high, there will be great potential problems in the charging and discharging process and the service process. Especially for electric vehicles in north China, the lithium iron phosphate battery cannot be normally supplied in autumn and winter or the power supply is too low, so the operating environment temperature should be adjusted to maintain its performance. At present, the problem of space limitation needs to be considered in the domestic thermostatic working environment of lithium iron phosphate battery.

Folding charging performance

Lithium batteries made of lithium iron phosphate anode material can be charged at a high rate and can be fully charged within one hour at the soonest.

Specific physical parameters:

Bulk density :0.7g/cm

Vibration density :1.2g/cm

The median diameter: 2-6 um

Specific surface area < 30 m ^ 2 / g

Smear parameters:

LiFePo4: C: PVDF = 90:3:7

Compacted density of polar plates :2.1-2.4g/cm

Electrochemical properties:

Test condition: half battery, 0.2c, voltage 4.0-2.0v

Number of cycles :2000

Domestic lithium iron phosphate material manufacturer:

Domestic: yantai zhuoneng tianjin beitui tianjin bamo tianjin strang hangzhou jinma energy yunnan huilong beida hunan ruixiang tiehu energy Taiwan changyuan Taiwan likai zhengzhou longtai hangzhou sainz jiangxi jinli technology shenzhen beitui and so on

International: Canada Phostech, the United States Valence, the United States A123, Japan SONY. A123, the largest and heavily backed by the us government, is now bankrupt.

novelty

Lithium iron phosphate is a new kind of electrode material for lithium ion batteries. It is characterized by large discharge capacity, low price, non - toxicity and no environmental pollution. The countries of the world are competing to achieve industrialized production.

But its energy density is low, affect capacitance.

At present, the main production method is the high temperature solid phase synthesis method.

The performance of lithium ion battery mainly depends on the positive and negative electrode materials, lithium iron phosphate as the positive electrode material of lithium ion battery is only in recent years, domestic development of large capacity lithium iron phosphate battery is July 2005. Its safety performance and cycle life is other materials can not be compared, these are the most important technical indicators of power batteries. The cycle life of 1C is up to 2000 times. Single battery overcharge voltage 30V does not burn, puncture does not explode. Lithium iron phosphate anode materials to make large capacity lithium ion batteries easier to use in series. In order to meet the needs of frequent charging and discharging of electric vehicles. It is an ideal anode material for the new generation of lithium ion batteries.

This project belongs to the development of functional energy materials in high-tech projects, and is the key support area of national "863" plan, "973" plan and "11th five-year" high-tech industry development plan.

At present, lithium ion battery is still dominated by small capacity and low power battery. Medium-large capacity and medium-high power lithium ion battery has begun to test water for large-scale production, which gradually makes lithium ion battery widely used in medium-large capacity UPS, medium-large energy storage battery, power tools and electric vehicles.

Important part of folding

So far, the most studied anode materials are derivatives of LiCoO2, LiNiO2, LiMn2O4 and above, such as lini 0.8co0.2o2 and lini 1/3co1/3mn1/3o2.

LiCoO2 is the only large-scale commercialized anode material. Currently, over 90% of commercialized lithium ion batteries use LiCoO2 as the anode material. The research of LiCoO2 is mature and has good comprehensive performance, but it has high price, low capacity and some security problems.

LiNiO2 has low cost, high capacity, difficult preparation, poor consistency and reproducibility of material properties, and serious safety problems. LiNi0.8 co0.2o2 can be regarded as a solid solution of LiNiO2 and LiCoO2. LiNiO2 and LiCoO2 have both advantages and were once considered as a new type of positive electrode material most likely to replace LiCoO2. At the same time, because it contains more expensive Co, the cost is also higher.

Spinel LiMn2O4 has low cost and good safety, but poor cycling performance, especially at high temperature. It has certain solubility in the electrolyte and poor storage performance.

The new ternary composite oxide nickel-cobalt manganate lithium (lini1/3co1/3mn1/3o2) material concentrates the advantages of LiCoO2, LiNiO2, LiMn2O4 and other materials: the cost is the same as lini0.8co0.2o2, the reversible capacity is large, the structure is stable, the security is good, between lini0.8co0.2o2 and LiMn2O4, the cycle performance is good, the synthesis is easy; But because it contains more expensive Co, the cost is also higher. The cost, high temperature performance and safety of anode materials are very important for medium and large capacity and high power lithium ion batteries.

The above positive electrode materials of LiCoO2, LiNiO2, LiMn2O4 and their derivatives still cannot meet the requirements. Therefore, research and development of new anode materials that can be used in medium-large capacity and medium-high power lithium ion batteries have become a hot topic at present.

LiFePO4 anode materials with orthogonal olivine structure have gradually become a new research hotspot at home and abroad. Preliminary study shows that this new type of cathode material has the advantages of LiCoO2, LiNiO2, LiMn2O4 and their derivatives cathode materials. Moderate working voltage (3.4v); Good platform characteristics, extremely stable voltage (can be comparable to power supply); Large theoretical capacity (170mAh/g); Stable structure and excellent safety performance (O and P are firmly combined with strong covalent bond, making it difficult for the material to decompose oxygen); Its high temperature performance and thermal stability are obviously better than other anode materials. Good cycling performance; The volume effect is good when it is combined with carbon anode material. Good compatibility with most electrolyte systems and good storage performance; Non-toxic, for the real green material.

Compared with the anode materials of LiCoO2, LiNiO2, LiMn2O4 and their derivatives, LiFePO4 anode materials have outstanding advantages in cost, high temperature performance and safety, and are expected to be the preferred anode materials for medium and large capacity and high power lithium ion batteries.

Industrialization and popularization application of the material to reduce the cost for lithium ion batteries, improve the safety of the battery, expand the lithium-ion battery industry, promote the large scale, high power lithium ion battery has very important significance, will make the lithium ion battery in large capacity UPS, large energy storage batteries, electric tools, the application of electric cars to become a reality.

Folding defect

However, the low density of lithium iron phosphate has been ignored and avoided by people, and has not been solved, which hinders the practical application of materials. The theoretical density of lithium cobalt oxide is 5.1g/cm, and the vibrational density of commercial lithium cobalt oxide is generally 2.0-2.4g/cm. The theoretical density of lithium iron phosphate is only 3.6g/cm, which itself is much lower than lithium cobalt oxide.

In order to improve the conductivity, conductive carbon materials are added, and the bulk density of the materials is significantly reduced, so that the vibrational density of general carbon-doped lithium iron phosphate is only 1.0-1.2g/cm3. Such a low packing density means that lithium iron phosphate has a much lower volume to volume ratio than lithium cobalt oxide, and the resulting batteries will be very bulky, not only with no advantages, but also difficult to use in practice.

Therefore, increasing the bulk density and volume specific capacity of lithium iron phosphate has a decisive significance for the practical application of lithium iron phosphate. The morphology, diameter and distribution of powder directly affect the bulk density.

For example, Ni(OH)2 is a positive electrode material for nickel-metal hydride batteries and nickel-cadmium batteries. Previously, the flake Ni(OH)2 was used, and its vibrational density was only 1.5-1.6g/cm. At present, the vibrational density of spherical Ni(OH)2 can reach 2.2-2.3g/cm3. Spherical Ni(OH)2 has basically replaced the flake Ni(OH)2, and significantly improved the energy density of nimh and nicd batteries.

Based on the research results of high-density spherical Ni(OH)2, the laboratory has successfully developed a series of high-density spherical anode materials for lithium ion batteries, including LiCoO2, LiMn2O4 lini0.8co0.2o2, lini1/3co1/3mn1/3o2 and so on.

Among them, the vibrational density of LiCoO2 and lini 0.8co0.2o2 has reached 2.9g/cm, much higher than that of similar commercial materials. The research and practical application show that the spherical product not only has outstanding advantages such as high bulk density, large volume ratio and capacity, but also has excellent fluidity, dispersibility and machinability, which is very beneficial to the coating of positive material slurry and electrode sheet and improving the quality of electrode sheet. In addition, compared with irregular particles, the surface of regular spherical particles is easier to be covered with a complete, uniform and firm modification layer, so spherical products are more likely to further improve the comprehensive performance through surface modification.

On this basis, we propose that spheroidization is the development direction of anode materials for lithium ion batteries. At present, LiFePO4 anode materials reported at home and abroad are all composed of irregular particles, and the bulk density and energy density of powders are relatively low. Therefore, this project is committed to the spheroidization of LiFePO4 material particles to improve the bulk density and volume specific capacity of the material. On this basis, the advantages of surface coating of spherical materials are brought into play, and the comprehensive properties of the materials are further improved by surface modification of spherical particles. In the process of spherification and surface modification of LiFePO4 material particles, the excellent achievements in improving the conductivity of lithium iron phosphate have been fully used for reference, absorption and utilization. Finally, LiFePO4 anode material with spherical shape, high bulk density, high volume specific capacity and high conductivity was prepared, so that it can be applied to medium-large capacity and medium-high power lithium ion batteries, promoting the industrialization of this material.

At present, the research room adopts ferric salt or trivalent iron salt, phosphoric acid or phosphate, ammonia water as raw materials, synthesizes high-density spherical iron phosphate precursor by controlling crystallization technology, and then blends with lithium source and carbon source for heat treatment, and synthesizes carbon-doped high-density spherical iron phosphate by carbon-thermal reduction method. The lithium iron phosphate powder material is composed of monodisperse spherical particles, particle size 5-10 m, high bulk density (vibration density up to 1.6-1.8g/cm), good fluidity, good machinability, reversible capacity 140mAh/g.

Folding industry technology

At present, all countries have put the battery industry in an important position in the national development strategy, supporting funds and various policies are very strong, lithium ion battery for electric vehicles has become a hot spot in the market and research and development. The main anode materials studied include lithium manganate (LMO), lithium iron phosphate (LFP) and nickel-cobalt manganese (NCM).

Lithium iron phosphate battery is a new type of lithium battery with high promotion value and is one of the core products for the future development of the battery industry. Compared with other power batteries have incomparable advantages. At present, lithium iron phosphate products are in the embryonic stage of industry. The future market of lithium iron phosphate products is huge. As an emerging industry with strategic investment value, lithium iron phosphate products are worthy of attention and investment from industrial capital or venture capital.

Fold and edit the preparation method of this section

Folding solid phase synthesis

1.1 high temperature solid phase reaction method: it is the most commonly used and the most mature synthesis method at present.

1.2 carbon thermal reduction (CTR): the synthesis method is simple, easy to operate, and the price of raw materials is low. It is suitable for mass production.

1.3 microwave synthesis method: short synthesis time, low energy consumption, suitable for laboratory research.

1.4 mechanical alloying method

Folding liquid phase synthesis

2.1 liquid phase co-precipitation method

2.2 sol-gel method

2.3 hydrothermal synthesis method

Folding other synthesis methods

Discharge plasma sintering, spray pyrolysis and pulsed laser deposition are also used in the synthesis of lithium iron phosphate.

Folding purpose

Lithium ion batteries are mainly used as anode materials in the manufacture of mobile phones, laptops and other portable electronic devices.

Lithium ion battery as anode material: aluminum foil coated in the application of lithium battery advantages

1. Inhibit the polarization of the battery, reduce the thermal effect, and improve the multiplier performance;

2. Reduce the internal resistance of the battery, and significantly reduce the dynamic increase of internal resistance during the cycle;

3. Improve the consistency and increase the cycle life of the battery;

4. Improve the adhesion between the active material and the collector fluid, and reduce the manufacturing cost of the electrode sheet;

5. Protect the collecting fluid from electrolyte corrosion;

6. Improve the processing performance of lithium iron phosphate and lithium titanate.

Conductive coating

It is a breakthrough technological innovation to apply functional coating to the surface treatment of battery conductive substrate. The coating of carbon aluminum foil/copper foil is to evenly and finely coat aluminum foil/copper foil with dispersed nano conductive graphite and carbon cladding particles. It can provide excellent static conductivity and collect microcurrent of active material, so that the contact resistance between positive/negative material and collector can be greatly reduced, and the adhesion between them can be improved, the amount of binder can be reduced, and the overall performance of the battery can be significantly improved.

Coating water (agent system) and oil (organic solvent system) two types.

Performance advantages of carbon aluminum foil/copper foil

1. Significantly improve the consistency of battery pack usage and significantly reduce the cost of battery pack. Such as :· significantly reduce the cell dynamic resistance increase; · improve the voltage difference consistency of the battery pack; · extend battery life; · significantly reduce the cost of battery pack.

2. Improve the adhesion of active materials and collector fluid, and reduce the manufacturing cost of electrode sheet. Such as:

· improve the adhesion of positive material and collector using water-based system;

· improve the adhesion of nanoscale or submicron anode materials and collectors;

· improve adhesion of lithium titanate or other high-capacity anode materials and collectors;

· improve the pass rate of pole sheet and reduce the manufacturing cost of pole sheet.

Test chart of adhesion of battery sheet coated with aluminum foil and light foil

The adhesion force was increased from 10gf to 60gf(using 3M tape or 100 blade method), and the adhesion force was significantly improved.

3. Reduce polarization, increase magnification and gram capacity, and improve battery performance. Such as:

· partially reduce the proportion of adhesive in the active material and increase the capacity of gram;

· improve the electrical contact between the active substance and the collecting fluid;

· reduce polarization and improve power performance.

Battery performance diagram of different aluminum foil

Among them, c-al is carbon-coated aluminum foil, e-al is etched aluminum foil, and u-al is light aluminum foil

4. Protect and collect fluid to extend battery life. Such as:

· prevent collector pole corrosion and oxidation;

· improve the surface tension of collector pole and enhance the easy coating performance of collector pole;

· you can replace the high cost of etching foil or replace the original standard foil with a thinner foil.

Battery cycle curves of different aluminum foils (200 weeks)

Where (1) is light aluminum foil, (2) is etched aluminum foil, and (3) is coated aluminum foil

Folding edit this section of material shortcomings

1. Poor electrical conductivity. This question is the crux of it all. The fact that lithium iron phosphate has not been widely used this late is a major problem. However, this problem can be solved perfectly by adding C or other conductive agents. The specific capacity of 160mAh/g or above has been reported in the laboratory. The lithium iron phosphate material produced by our company has been added with conductive agent in the production process, so it is not necessary to add it when making batteries. Actually the material should be :LiFePO4/C, such a composite material.

2. Low vibration density. Generally, it can only reach 1.3-1.5g/ml. The low vibrational density can be said to be the biggest disadvantage of lithium iron phosphate. This disadvantage determines that it has no advantage in small batteries such as mobile phone batteries. Even though it has low cost, good safety performance, good stability and high cycle times, if it is too large, it can only replace lithium cobalt oxide in small amount. This disadvantage does not stand out when it comes to power batteries. Therefore, lithium iron phosphate is mainly used to make power batteries.

Industrial technology and product status analysis of lithium iron phosphate

At present, all countries have put the battery industry in an important position in the national development strategy, supporting funds and various policies are very strong, lithium ion battery for electric vehicles has become a hot spot in the market and research and development. The main anode materials studied include lithium manganate (LMO), lithium iron phosphate (LFP) and nickel-cobalt manganese (NCM). Current status of anode materials for lithium-ion power batteries

Lithium iron phosphate battery is a new type of lithium battery with high promotion value and is one of the core products for the future development of the battery industry. Compared with other power batteries have incomparable advantages. At present, lithium iron phosphate products are in the embryonic stage of industry. The future market of lithium iron phosphate products is huge. As an emerging industry with strategic investment value, lithium iron phosphate products are worthy of attention and investment from industrial capital or venture capital.

Fold and edit the development prospect of this section

Folding China's energy conservation and emission reduction policies

With the end of the Copenhagen conference, "emission reduction and low carbon" has become a hot word. The Chinese government made a clear target at the meeting:

In 2020, carbon emissions per unit of GDP (carbon intensity) will be reduced by 40%~45% compared with 2005, which is a qualitative change of China's energy conservation and emission reduction policy from energy intensity to carbon emission intensity. In the long run, China's development of low-carbon economy is an inevitable choice. In this context, in order to maintain relatively stable economic growth, a large number of industries are bound to seek major breakthroughs in emission reduction technology. Therefore, in the future, China's new energy sector needs technological breakthroughs to achieve the 2020 emission reduction target.

For some developed countries, because their energy structure is relatively "clean", low-carbon and energy-saving are closely related. Based on the economic development stage of urbanization and industrialization in China, its energy demand has obvious rigid characteristics, that is, the demand for high energy power grows synchronously with the rapid economic development. For China's coal-based energy structure, reducing the carbon intensity per unit of GDP is to a large extent through increasing clean energy and reducing coal consumption per unit of GDP, which requires changing the current domestic energy structure and developing new energy structure.

Therefore, with the promotion and application of low-carbon economy technology, clean energy technology and other new technologies, the increase of GDP will not be fully proportional to carbon emissions, and will provide strong support for the further realization of China's emission reduction goals.

"Eight advantages" of folding industry

First, it conforms to the national policy orientation

Lithium iron phosphate industry in line with the national industrial policy guidance, the development of all countries in the energy storage battery and power battery in the height of national strategic level, matching funds and policy support is very big, China is also very support in this aspect, focus on nickel metal hydride batteries in the past, is now looking more focus on lithium iron phosphate batteries.

The second represents the future development direction of battery

Lithium iron phosphate battery, as a kind of utility model lithium battery, represents the future development direction of battery. It is the most ideal power cell ever invented. Although there are some technical and price defects, but after all, has been on the road to commercialization. Industry experts generally agree that the lithium iron phosphate technology is not an obstacle to the industry's development (of which A123, Valence, Phostech have no precedent), and that the price could drop significantly with the expansion of capacity, and could even become the cheapest power battery in the future.

The third large market capacity

The market of lithium iron phosphate industry is beyond imagination. According to the analysis of relevant materials, the global market capacity of anode materials is tens of billions, and the market capacity of batteries is more than 500 billion.

Fourth, steady and rapid development

According to the law of development of battery industry, both materials and batteries basically show a stable growth trend and can resist the influence of periodicity and national macro-control. As a new material and battery -- lithium iron phosphate, with the development of the stock market and the penetration of the incremental market, its growth rate is significantly faster than the overall development rate of the battery industry.

Fifth, it has a wide range of applications

Lithium iron phosphate batteries are widely used in the following fields:

(1) energy storage equipment

Energy storage equipment for solar and wind power systems; Uninterruptible power system UPS; Used in conjunction with solar cells for energy storage (byd already makes such cells);

The power tools class

High power power tools (wireless); Electric drill, lawn mower, etc.

The light electric vehicle is (3)

Electric locomotives, electric bicycles, recreational vehicles, golf carts, hybrid vehicles, electric wheelchairs, electric lifts, cleaning vehicles; Hybrid electric vehicle (HEV), domestic development goals in the recent 2-3 years;

Of small equipment

Medical equipment: electric sickness, electric wheelchair, electric scooter, oxygen respirator; Toys (remote control electric aircraft, car, boat);

It shall set it on

A miner's lamp. Implanted medical devices (lithium iron phosphate is non-toxic, lithium battery only lithium iron can meet the requirements);

• in the military and aerospace fields

Such as UPS, communication equipment, telemetry system, unmanned reconnaissance aircraft and other military energy storage equipment; It is also one of the best power cells in the military and aerospace fields.

The sixth industry is highly profitable

The lithium iron phosphate industry has a very high profit margin. The gross profit of anode materials is over 70%, while the gross profit of battery cells is also over 50%. And with strong market support ahead, the industry will maintain high margins for a long time, initially five years.

Seventh, there are certain technical barriers

Lithium iron phosphate industry has a certain threshold, not who will do it will be successful, especially in the field of materials, technical barriers are very high, can avoid too much competition. As a new company entering this industry, it is definitely more sensible to choose materials rather than batteries, because there are many existing lithium battery manufacturers, especially the big ones, whose position is difficult to be shaken. They have more advantages in entering lithium iron phosphate batteries.

Eighth not subject to foreign markets

The lithium iron phosphate industry will not be overly dependent on foreign markets, nor will the raw materials and equipment be subject to foreign enterprises. The whole domestic industrial chain is relatively mature. At the same time, there is little difference in the research and industrialization of lithium iron phosphate at home and abroad, almost at the same starting line. This is very different from the solar cell industry. The polysilicon raw material (referred to in the past) needed for solar cells and the terminal application market are at both ends of the street. They are greatly affected by foreign policies and market changes.

To sum up, domestic lithium iron phosphate has a broad market space, and it is a rare opportunity for the rapid development of lithium ion battery. Although there are still many problems in the development, but I believe that in the near future, through the joint efforts of all enterprises, will be able to promote the rapid development of China's battery industry.