Lithium iron phosphate (LiFePO4), as a new type of lithium-ion battery cathode material, has the advantages of high safety, long cycle life, high discharge platform and low cost. In recent years, the application of lithium iron phosphate in the energy field has received widespread attention and research.
1. Advantages of lithium iron phosphate battery:
Compared with other types of batteries, lithium batteries have the following significant advantages.
①High working voltage. The working voltage of lithium cobalt oxide lithium-ion battery is 3.6V, the working voltage of lithium manganate lithium-ion battery is 3.7V, the working voltage of lithium iron phosphate battery is 3.2V, while the working voltage of nickel metal hydride and nickel cadmium battery is only 1.2 V.
②High energy density. The theoretical energy density of lithium battery cathode materials can reach more than 200W·h/kg. In practical applications, due to irreversible capacity loss, the energy density is usually lower than this value, but it can also reach 140W·h/kg. This value is still for nickel-cadmium batteries. 3 times that of nickel-metal hydride batteries and 1.5 times that of nickel-metal hydride batteries.
③Long cycle life. At present, the number of cycles of lithium batteries can reach more than 1,000 times under deep discharge conditions; under low discharge depth conditions, the number of cycles can reach tens of thousands, and its performance is far superior to other similar batteries.
④The self-discharge is small. The monthly self-discharge rate of lithium-ion batteries is only 5% to 9% of the total capacity, which greatly alleviates the power loss problem caused by self-discharge when traditional secondary batteries are placed.
⑤No memory effect. Lithium iron phosphate battery packs do not have this phenomenon. No matter what state the battery is in, it can be charged and used at any time. There is no need to discharge it completely before charging it.
⑥High environmental protection. Compared with the environmental pollution problems that may be caused by the disposal of traditional lead-acid batteries, nickel-cadmium batteries and even nickel-hydrogen batteries, lithium iron phosphate materials do not contain any heavy metals and rare metals, are non-toxic, and are pollution-free in both production and use. They are truly Sense of green battery.
⑦Fast charging: Lithium batteries can be charged and discharged quickly at a high current of 2C. The battery can be fully charged within 40 minutes with a special charger at 1.5C, and the starting current can reach 2C. However, lead-acid batteries currently do not have this performance.
⑧Safety: Safety comes from the stability of the cathode material and reliable safety design. Lithium iron phosphate batteries have undergone strict safety tests and will not explode even in violent collisions.
⑨High temperature resistance: The thermal peak of lithium iron phosphate battery can reach 350~500℃, the operating temperature range is wide (-20~+75℃), and 100% capacity can still be released under high temperature (60℃).
Lithium iron phosphate battery characteristics
2. Disadvantages of lithium iron phosphate battery :
- the preparation of lithium iron phosphate , iron oxide may be reduced to elemental iron in a high-temperature reducing atmosphere. Elemental iron can cause micro-short circuits in batteries and is a taboo substance in batteries. This is also the main reason why Japan has not used this material as a cathode material for power lithium-ion batteries.
- Lithium iron phosphate has some performance defects, such as low tap density and compaction density, resulting in low energy density of lithium-ion batteries. The low-temperature performance is poor, and even nanonization and carbon coating do not solve this problem. Although some manufacturers claim that the capacity retention rate of lithium iron phosphate batteries at low temperatures is not bad, that is when the discharge current is small and the discharge cut-off voltage is very low. In this situation, the device simply cannot start working.
- The preparation cost of materials and the manufacturing cost of batteries are high, and the battery yield is low and the consistency is poor. Although the nanonization and carbon coating of lithium iron phosphate improve the electrochemical performance of the material, it also brings other problems, such as reduced energy density, increased synthesis cost, poor electrode processing performance, and harsh environmental requirements. Although the chemical elements Li, Fe and P in lithium iron phosphate are abundant and the cost is low, the cost of the prepared lithium iron phosphate product is not low. Even if the initial research and development costs are removed, the process cost of the material plus the high The cost of preparing batteries will make the cost per unit of energy storage higher.
- Product consistency is poor. At present, there is no lithium iron phosphate material factory in China that can solve this problem. From the perspective of material preparation, the synthesis reaction of lithium iron phosphate is a complex multi-phase reaction, including solid phase phosphate, iron oxide and lithium salt, plus carbon precursor and reducing gas phase. In this complex reaction process, it is difficult to ensure the consistency of the reaction.
- Intellectual Property Issues. At present, the basic patent of lithium iron phosphate is owned by the University of Texas in the United States, and the carbon coating patent is applied for by a Canadian. These two basic patents cannot be bypassed. If patent royalties are included in the cost, the product cost will further increase. In addition, judging from the experience in R&D and production of lithium-ion batteries, Japan is the first country to commercialize lithium-ion batteries and has always occupied the high-end lithium-ion battery market.
3. Application areas of lithium iron phosphate battery packs:
Because lithium iron phosphate power batteries have the above characteristics and are produced in various capacities, they have been widely used. Its main application areas are:
Electric vehicle field
Lithium iron phosphate batteries are widely used in electric vehicles due to their high safety and long cycle life. Compared with traditional lithium-ion batteries, lithium iron phosphate batteries have better thermal stability and overcharge resistance, which can effectively avoid battery short circuits, explosions and other safety issues. At present, my country’s electric light vehicles, mainly electric bicycles, are showing a booming trend. Power lithium iron phosphate battery packs have begun to be used in some high-end models. In terms of electric vehicle development, lithium-ion batteries have become the mainstream. In China, more than half of the electric vehicles developed by many automobile R&D and production companies use lithium batteries, and there is a trend of gradual expansion. Lithium iron phosphate batteries can not only provide reliable power output, but also achieve long cruising range, meeting people’s needs for electric vehicles.
Energy storage field
Lithium iron phosphate batteries also have broad application prospects in the field of energy storage. Their high energy density and long cycle life make lithium iron phosphate batteries ideal for grid energy storage systems. The lithium iron phosphate battery energy storage system can cope with the peak and valley power demand of the power grid and provide stable power output. It can also be used as an energy storage device for renewable energy sources (such as solar energy and wind energy). In the energy storage field, lithium iron phosphate batteries currently account for more than 94%, including new batteries and ladder batteries, which are mainly used in UPS, backup power supply, communication energy storage and other fields. In addition, the application of lithium iron phosphate batteries in 5G base stations has also shown rapid growth, opening up new market opportunities.
Mobile power field
Because lithium iron phosphate batteries have high energy density and low cost, they are also widely used in the field of mobile power sources. People can use lithium iron phosphate batteries to create lightweight mobile power devices to meet the demand for electricity in daily life and work. Applications in Portable Electrical Appliances At present, electrical appliances that require portable power such as mobile phones, notebook computers, and micro cameras have become an indispensable part of people’s lives. In terms of power supply, lithium batteries are the mainstream choice in the market without exception.
Military equipment field
Application in military equipment and aerospace industry In military equipment, lithium iron phosphate batteries are mainly used as power starting power supply, wireless communication radio power supply, micro unmanned reconnaissance aircraft power supply, etc. In addition, such as laser sights, night vision Lithium-ion batteries are now commonly used in devices, pilot rescue radio power supplies, etc. In the aerospace field, lithium batteries have been used in geostationary orbit satellites and low-orbit communication satellites as power for launches, in-flight corrections, and ground operations.
In conclusion
Lithium iron phosphate, as a new type of lithium-ion battery cathode material, is widely used in many fields. Its application prospects in the fields of electric vehicles, energy storage, mobile power supplies and new energy vehicles have attracted much attention. With the continuous advancement of technology and reduction of costs, it is believed that the application fields of lithium iron phosphate batteries will continue to expand.
