LiFePO4 batteries are used in the industrial

 

Lithium iron phosphate battery is a lithium-ion battery that uses lithium iron phosphate (LiFePO4) as the positive electrode material and carbon as the negative electrode material. The rated voltage of the monomer is 3.2V, and the charge cut-off voltage is 3.6V~3.65V.

Application of lithium iron phosphate (LiFePO4) battery

1.Application of the new energy automobile industry

Lithium iron phosphate batteries are widely used in passenger cars, buses, logistics vehicles, low-speed electric vehicles, etc. due to their safety and low-cost advantages. Although, in the current new energy passenger vehicle field, it is subject to the state’s subsidy policy for new energy vehicles. Influence, relying on the advantages of energy density, ternary batteries occupy a dominant position, but lithium iron phosphate batteries still occupy an irreplaceable advantage in fields such as passenger cars and logistics vehicles. In the field of passenger cars, lithium iron phosphate batteries remain mainstream. In the field of special-purpose vehicles, the proportion of lithium iron phosphate batteries is gradually increasing. 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 anxiety of pure electric vehicles such as mileage, safety, price, charging, and subsequent battery issues.

2. Start the application on the power supply

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

3. Application of energy storage market

Lithium iron phosphate 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, and green environmental protection. It also supports stepless expansion and is suitable for large-scale electric energy storage. Energy power stations have good application prospects in such fields as safe grid connection, grid peak shaving, distributed power stations, UPS power supplies, and emergency power systems.

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 environmental protection, lithium iron phosphate can be transferred to the energy storage field, which will extend the value chain and promote the establishment of new business models. On the other hand, energy storage systems supporting lithium iron phosphate batteries have become a mainstream choice in the market. According to reports, lithium iron phosphate batteries have tried to be used in electric buses, electric trucks, user-side, and grid-side frequency modulation.

1) Safe grid connection of renewable energy power generation

The inherent randomness, intermittent news, 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 wind farms in my country are “large-scale centralized development and long-distance transmission”, the grid-connected power generation of large-scale wind farms pose severe challenges to the operation and control of large-scale power grids.

Photovoltaic power generation is affected by ambient temperature, sunlight intensity, and weather conditions, and photovoltaic power generation has 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” simultaneously, which puts forward higher requirements for power grid peak shaving and safe operation of the power system.

Therefore, large-capacity energy storage products have become a key factor in solving the contradiction between the power grid and renewable energy power generation. The lithium iron phosphate battery energy storage system has the characteristics of fast working condition conversion, flexible operation mode, high efficiency, safety, and environmental protection, and strong scalability. Engineering applications have been carried out in the national wind and solar storage and transmission demonstration project, which will effectively improve equipment efficiency and solve Local voltage control problems, 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 wind power, photovoltaic power generation, etc. Safe grid connection of energy power generation and improvement of power quality are widely used.

2) Lithium iron phosphate battery for grid peak shaving

The main method of power grid peak shaving has always been pumped storage power stations. As the pumped storage power station needs to build two reservoirs, the upper and lower reservoirs are restricted by geographical conditions, it is not easy to construct in plain areas, and it covers a large area and high maintenance cost. Use lithium iron phosphate battery energy storage system to replace pumped storage power station, cope with grid peak load, free of geographical conditions, freedom of location, less investment, less land occupation, low maintenance cost, and will play an important role in the process of power grid peak regulation.

3) Lithium iron phosphate battery for distributed power station

The shortcomings of large-scale power grids make it difficult to guarantee the quality, efficiency, safety, and reliability requirements of the power supply. For important units and enterprises, dual power supplies or even multiple power supplies are often required as backup and protection. Lithium iron phosphate battery energy storage system can reduce or avoid power outages caused by grid failures and various accidents, and ensure a safe and reliable power supply for hospitals, banks, command and control centers, data processing centers, chemical materials industries, and precision manufacturing industries. Play an important role.

4) Lithium iron phosphate battery for UPS power supply

The sustained and rapid development of China’s economy has brought about the decentralization of UPS power users’ demand, which has caused more industries and more enterprises to have a continuous demand for UPS power.

Compared with lead-acid batteries, lithium iron phosphate batteries have the advantages of long cycle life, safety and stability, environmental protection, and low self-discharge rate. With the continuous maturity of integration technology, the cost continues to decrease. Lithium iron phosphate batteries are used in UPS power batteries. Will be widely used.

4. Applications in other fields

Lithium iron phosphate battery is also widely used in the military field because of its good cycle life, safety, low-temperature performance, and other advantages. Grepow battery company made a strong appearance at the military-civilian integration technology innovation exhibition, exhibiting military products including -45℃ military ultra-low temperature battery.

If you are interested in our products, please don’t hesitate to contact us at any time!
Email: info@grepow.com
Grepow Website: https://www.grepow.com/

Wide temperature-range Ni-MH battery -40℃ to 80℃

 

The temperature has one of the greatest impacts on the charge and discharge performance of batteries. The electrode/electrolyte interface is considered the heart of the battery, and the electrochemical reactions at this interface are closely related to the ambient temperature. If the temperature drops, the reaction rate of the electrode also drops.

When NiMH batteries are charged and discharged, multiple factors must be considered: the surrounding environment of the batteries but especially battery performance and service life under extreme temperatures.

We will explore what occurs to NiMH batteries, particularly wide temperature-range NiMH batteries, when under low and high temperatures.

Wide temperature-range NiMH batteries

Wide temperature-range NiMH batteries, as their name implies, are a type of NiMH batteries with a wide working-temperature range and excellent performance at -40°C to 80°C. In other words, these batteries can operate efficiently at both low and high temperatures, and their temperature limitations are greatly reduced.

Under low temperatures

The discharge efficiency of ordinary nickel-hydrogen batteries are significantly reduced at low temperatures. At -20°C, the lye reaches its freezing point and the battery charging speed greatly diminishes. Charging at low temperatures (below 0°C) increases the internal pressure of the battery and possibly causes the safety valve to open.

In order to charge effectively, the ambient temperature range must be controlled between 5℃ to 30℃. Generally, charging efficiency increases with the rise of temperature. However, when the temperature rises above 45℃, the performance of the battery degrades, and the cycle life of the battery greatly shortens.

Under low temperatures, the viscosity of electrolyte becomes higher, the proton transfer rate inside the electrode becomes slower, and the ohmic internal resistance also increases, which leads to larger polarization of the battery during discharge. Some batteries cannot discharge at low temperatures due to large polarization.

Under high temperatures

Under high temperature, the viscosity of the electrolyte decreases, and the hydrophilic ability of various materials increases. Liquid absorption also increases, which leads to the expansion of the electrode sheet, and liquid starts to leak from poor electrical receptivity.

The following is the electrochemical principle of charging and discharging Ni-MH batteries with KOH as the electrolyte (7moL/LKOH+15g/LLiOH).

Charge

Positive Pole: Ni(OH)2+OH-→NiOOH+H2O+e-

Negative Pole: M+H2O+e-→MH+OH-

Total Response: M+Ni(OH)2→MH+NiOOH

Discharge

Positive Pole: NiOOH+H2O+e-→Ni(OH)2+OH-

Negative Pole: MH+OH-→M+H2O+e-

Total Response: MH+NiOOH→M+Ni(OH)2

In the above formula, M is the hydrogen storage alloy and MH is the hydrogen storage alloy with adsorbed hydrogen atoms. The most commonly used hydrogen storage alloy is LaNi5.

Characteristics of a wide temperature-range Ni-MH battery

The following are a couple of the characteristics of a Grepow’s wide temperature-range Ni-MH battery:

The charging and discharging efficiency of 0.2C at -40℃ can reach 80%

The charging and discharging efficiency of 0.2C at 80℃ can reach 85%

Ni-MH battery technology has been tried, tested and proven for commercial and industrial applications especially in automotive batteries and outdoor power supplies in high and cold temperatures. Its safety and reliability are unparalleled in the market.

Grepow Inc. offers a variety of Ni-MH batteries with a wide temperature range. These batteries provide new electrode-development technologies that can achieve a long life, and they have good usability and stability with compatible sizes.

For more information on batteries, stay tuned to our blog or our Battery Monday channel.

If you are interested in our products, don’t hesitate to contact us at any time!

Email: info@grepow.com

Grepow Website: https://www.grepow.com/

the causes of lithium batteries to swell

Lithium-ion polymer batteries are widely used due to their long life and high capacity. However, there are some issues that can arise, such as swelling, unsatisfactory safety performance, and accelerated cycle attenuation.

This article will primarily focus on battery swelling and its causes, which can be divided into two categories: the first is a result of a change in thickness of the electrode, and the other is a result of the gas produced by the oxidation and decomposition of electrolytes.

The change in thickness of the electrode pole piece

When a lithium battery is used, the thickness of the electrode pole pieces, especially the graphite negative electrodes, will change to a certain extent.

Lithium batteries are prone to swelling after high-temperature storage and circulation, and the thickness growth rate is about 6% to 20%. Of this, the expansion rate of the positive electrode is only 4%, the negative electrode’s is more than 20%.

The fundamental reason for the increase in the thickness of the lithium battery pole piece is due to the nature of graphite. The negative electrode graphite forms LiCx (LiC24, LiC12, LiC6, etc.) when lithium is inserted, and the lattice spacing changes, resulting in microscopic internal stress and an expansion of the negative electrode.

[caption id="attachment_3476" align="aligncenter" width="505"] The figure is the schematic diagram of the structure change of the graphite anode plate in the process of placement, charge, and discharge.[/caption]

The expansion of graphite negative electrodes is mainly caused by irreversible expansion after lithium insertion. This part of the expansion is mainly related to the particle size, the adhesive, and the structure of the pole piece. The expansion of the negative electrode causes the core to deform, which in turn causes the following: a cavity between the electrode and the diaphragm, micro-cracks in the negative electrode particles, breaking and reorganizing of the solid electrolyte interface (SEI) membrane, the consummation of electrolytes, and deterioration of the cycle performance.

There are many factors that affect the thickness of the negative pole piece although the properties of the adhesive and the structural parameters of the pole piece are the two most important reasons.

The commonly used bonding agent for graphite negative electrodes is SBR. Different bonding agents have different elastic modulus and mechanical strength and have different effects on the thickness of the pole piece. The rolling force after the pole piece is coated also affects the thickness of the negative pole piece in battery use.

When the amount of SBR added is inconsistent, the pressure on the pole piece during rolling will be different. Different pressures will cause a certain difference in the residual stress generated by the pole piece. The higher the pressure, the greater the residual stress, which leads to physical storage expansion, a full electric state, and an increase in the expansion rate of the empty electric state.

The expansion of the anode leads to the deformation of the coil core, which affects the lithium intercalation degree and Li + diffusion rate of the negative electrode, thus seriously affecting the cycle performance of the battery.

Bloating caused by lithium battery gas production

The gas produced in the battery is another important cause of battery swelling. Dependent on whether the battery is in a normal temperature cycle, high-temperature cycle, or high-temperature shelving, it will produce different degrees of swelling and gas production.

According to the current research results, cell bloating is essentially caused by the decomposition of electrolytes. There are two cases of electrolyte decomposition: one is that there are impurities in the electrolyte, such as moisture and metal impurities, which cause the electrolyte to decompose and produce gas. The other is that the electrochemical window of the electrolyte is too low, which causes decomposition during the charging process.

After a lithium battery is assembled, a small amount of gas is generated during the pre-formation process. These gases are inevitable and are also the source of irreversible capacity loss of the battery.

During the first charging and discharging process, the electrons from the external circuit to the negative electrode react with the electrolyte on the surface of the negative electrode to generate the gas. During this process, the SEI is formed on the surface of the graphite negative electrode. As the thickness of the SEI increases, electrons cannot penetrate and inhibit the continuous oxidation and decomposition of the electrolyte.

When a battery is used, the internal gas production gradually increases due to the presence of impurities in the electrolyte or excessive moisture in the battery. These impurities in the electrolytes need to be carefully removed. Inadequate moisture control may be caused by the electrolyte itself, improper battery packaging, moisture, or damage to the corners. Any overcharge and over-discharge, abuse, and internal short-circuiting will also accelerate the gas production rate of the battery and cause battery failure.

In different systems, the degree of battery swelling is different.

For instance, in the graphite anode system battery, the main causes of gas swelling are the SEI film formation, excessive moisture in the cell, abnormal chemical conversion process, poor packaging, etc.

In the lithium titanate anode system, battery swelling is more serious. In addition to the impurities and moisture in the electrolyte, lithium titanate cannot form an SEI film on its surface like a graphite-anode system battery to inhibit its reaction to the electrolyte.

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Email: info@grepow.com
Grepow Website: https://www.grepow.com/