LiFePO4 Battery

The lithium iron phosphate battery is a lithium-ion battery using lithium iron phosphate (LiFePO4) as the positive electrode material and carbon as the negative electrode material.
During the charging process, some of the lithium ions in the lithium iron phosphate are extracted, transferred to the negative electrode through the electrolyte, and embedded in the negative electrode carbon material; at the same time, electrons are released from the positive electrode and reach the negative electrode from the external circuit to maintain the balance of the chemical reaction. During the discharge process, lithium ions are extracted from the negative electrode and reach the positive electrode through the electrolyte. At the same time, the negative electrode releases electrons and reaches the positive electrode from the external circuit to provide energy for the outside world.
LiFePO4 batteries have the advantages of high working voltage, high energy density, long cycle life, good safety performance, low self-discharge rate and no memory effect.
Battery Structural Features
The left side of the lithium iron phosphate battery is a positive electrode composed of an olivine structure LiFePO4 material, which is connected to the positive electrode of the battery by an aluminum foil. On the right is the negative electrode of the battery composed of carbon (graphite), which is connected to the negative electrode of the battery by a copper foil. In the middle is a polymer separator, which separates the positive electrode from the negative electrode, and lithium ions can pass through the separator but electrons cannot. The interior of the battery is filled with electrolyte, and the battery is hermetically sealed by a metal casing.

Features of lithium iron phosphate battery
Higher energy density

According to reports, the energy density of the square aluminum shell lithium iron phosphate battery mass-produced in 2018 is about 160Wh/kg. In 2019, some excellent battery manufacturers can probably achieve the level of 175-180Wh/kg. The chip technology and capacity are made larger, or 185Wh/kg can be achieved.
good safety performance
The electrochemical performance of the cathode material of lithium iron phosphate battery is relatively stable, which determines that it has a stable charging and discharging platform. Therefore, the structure of the battery will not change during the charging and discharging process, and it will not burn and explode. It is still very safe under special conditions such as charging, squeezing, and acupuncture.

Long cycle life

The 1C cycle life of lithium iron phosphate batteries generally reaches 2,000 times, or even more than 3,500 times, while the energy storage market requires more than 4,000-5,000 times, ensuring a service life of 8-10 years, which is higher than 1,000 cycles of ternary batteries. The cycle life of long-life lead-acid batteries is about 300 times.
Industrial application of lithium iron phosphate battery

Application of new energy vehicle industry

my country’s “Energy-saving and New Energy Vehicle Industry Development Plan” proposes that “the overall goal of my country’s new energy vehicle development is: by 2020, the cumulative production and sales of new energy vehicles will reach 5 million units, and my country’s energy-saving and new energy vehicle industry scale will rank in the world. front row”. Lithium iron phosphate batteries are widely used in passenger cars, passenger cars, logistics vehicles, low-speed electric vehicles, etc. due to their advantages of good safety and low cost. Influenced by policy, ternary batteries occupy a dominant position with the advantage of energy density, but lithium iron phosphate batteries still occupy irreplaceable advantages in passenger cars, logistics vehicles and other fields. In the field of passenger cars, lithium iron phosphate batteries accounted for about 76%, 81%, 78% of the 5th, 6th, and 7th batches of the “Catalogue of Recommended Models for the Promotion and Application of New Energy Vehicles” (hereinafter referred to as the “Catalogue”) in 2018. %, still maintaining the mainstream. In the field of special vehicles, lithium iron phosphate batteries accounted for about 30%, 32%, and 40% of the 5th, 6th, and 7th batches of the “Catalogue” in 2018, respectively, and the proportion of applications has gradually increased.
Yang Yusheng, an academician of the Chinese Academy of Engineering, believes that the use of lithium iron phosphate batteries in the extended-range electric vehicle market can not only improve the safety of vehicles, but also support the marketization of extended-range electric vehicles, eliminating the mileage, safety, price, and cost of pure electric vehicles. Anxiety about charging, subsequent battery issues, etc. During the period from 2007 to 2013, many car companies have launched projects of extended-range pure electric vehicles.

Start the application on the power

In addition to the characteristics of power lithium batteries, the starter lithium iron phosphate battery also has the ability to output high power instantaneously. The traditional lead-acid battery is replaced by a power lithium battery with an energy less than one kilowatt hour, and the traditional starter motor and generator are replaced by a BSG motor. , not only has the function of idling start-stop, but also has the functions of engine shutdown and coasting, coasting and braking energy recovery, acceleration booster and electric cruise.

Applications in the energy storage market

LiFePO4 battery has a series of unique advantages such as high working voltage, high energy density, long cycle life, low self-discharge rate, no memory effect, green environmental protection, etc., and supports stepless expansion, suitable for large-scale electric energy storage, in renewable Energy power stations have good application prospects in the fields of safe grid connection of power generation, power grid peak regulation, distributed power stations, UPS power supplies, and emergency power supply systems.
According to the latest energy storage report recently released by GTM Research, an international market research organization, the application of grid-side energy storage projects in China in 2018 continued to increase the consumption of lithium iron phosphate batteries.
With the rise of the energy storage market, in recent years, some power battery companies have deployed energy storage business to open up new application markets for lithium iron phosphate batteries. On the one hand, due to the characteristics of ultra-long life, safe use, large capacity, and green environmental protection, lithium iron phosphate can be transferred to the field of energy storage, which will extend the value chain and promote the establishment of a new business model. On the other hand, the energy storage system supporting the lithium iron phosphate battery has become the mainstream choice in the market. According to reports, lithium iron phosphate batteries have been tried to be used in electric buses, electric trucks, user-side and grid-side frequency regulation.
1. Renewable energy power generation such as wind power generation and photovoltaic power generation is safely connected to the grid. The inherent randomness, intermittency and volatility of wind power generation determine that its large-scale development will inevitably have a significant impact on the safe operation of the power system. With the rapid development of the wind power industry, especially most of the wind farms in my country are “large-scale centralized development and long-distance transmission”, the grid-connected power generation of large-scale wind farms poses severe challenges to the operation and control of large power grids.
Photovoltaic power generation is affected by ambient temperature, solar light intensity and weather conditions, and photovoltaic power generation presents the characteristics of random fluctuations. my country presents a development trend of “decentralized development, low-voltage on-site access” and “large-scale development, medium and high voltage access”, which puts forward higher requirements for power grid peak regulation and safe operation of power systems.
Therefore, large-capacity energy storage products have become a key factor in solving the contradiction between the grid and renewable energy generation. The lithium iron phosphate battery energy storage system has the characteristics of fast conversion of working conditions, flexible operation mode, high efficiency, safety and environmental protection, and strong scalability. Local voltage control problem, improve the reliability of renewable energy power generation and improve power quality, so that renewable energy can become a continuous and stable power supply.
With the continuous expansion of capacity and scale, and the continuous maturity of integrated technology, the cost of energy storage systems will be further reduced. After long-term safety and reliability tests, lithium iron phosphate battery energy storage systems are expected to be used in renewable energy such as wind power and photovoltaic power generation. It has been widely used in the safe grid connection of energy generation and the improvement of power quality.
2 power grid peak regulation. The main means of power grid peak regulation has always been pumped storage power stations. Because the pumped-storage power station needs to build two reservoirs, the upper and lower reservoirs, which are greatly restricted by geographical conditions, it is not easy to construct in the plain area, and the area is large and the maintenance cost is high. The use of lithium iron phosphate battery energy storage system to replace the pumped storage power station, to cope with the peak load of the power grid, not limited by geographical conditions, free site selection, less investment, less land occupation, low maintenance cost, will play an important role in the process of power grid peak regulation.
3 Distributed power stations. Due to the defects of the large power grid itself, it is difficult to guarantee the quality, efficiency, safety and reliability requirements of power supply. For important units and enterprises, dual power supplies or even multiple power supplies are often required as backup and protection. The lithium iron phosphate battery energy storage system can reduce or avoid power outages caused by power grid failures and various unexpected events, and ensure safe and reliable power supply in hospitals, banks, command and control centers, data processing centers, chemical material industries and precision manufacturing industries. Play an important role.
4 UPS power supply. The continuous and rapid development of China’s economy has led to the decentralization of UPS power supply users’ needs, which has caused more industries and more enterprises to have continuous demand for UPS power supply.
Compared with lead-acid batteries, lithium iron phosphate batteries have the advantages of long cycle life, safety and stability, green environmental protection, and low self-discharge rate. will be widely used.

Applications in other fields

Lithium iron phosphate batteries are also widely used in the military field due to their good cycle life, safety, low temperature performance and other advantages. On October 10, 2018, a battery company in Shandong made a strong appearance at the first Qingdao Military-Civilian Integration Technology Innovation Achievement Exhibition, and exhibited military products including -45℃ military ultra-low temperature batteries.