Is lithium iron phosphate battery safe?

The lithium iron phosphate battery refers to a lithium ion battery using lithium iron phosphate as a positive electrode material. The positive electrode materials of lithium ion batteries mainly include lithium cobaltate, lithium manganate, lithium nickelate, ternary materials, lithium iron phosphate and the like. Among them, lithium cobaltate is the positive electrode material used in most lithium ion batteries.

Safety performance improvement

The P-O bond in the lithium iron phosphate crystal is stable and difficult to decompose, and does not collapse or heat like a lithium cobaltate or form a strong oxidizing substance even at a high temperature or overcharge, and thus has good safety. It has been reported that in the actual operation, a small part of the sample was found to have a burning phenomenon in the acupuncture or short-circuit test, but there was no explosion event. In the overcharge experiment, a high-voltage charge that was several times higher than the self-discharge voltage was used, and it was found that there was still Explosion phenomenon. Nevertheless, its overcharge safety has been greatly improved compared to the ordinary liquid electrolyte lithium cobalt oxide battery.

Life improvement

The lithium iron phosphate battery refers to a lithium ion battery using lithium iron phosphate as a positive electrode material.

The long-life lead-acid battery has a cycle life of about 300 times, and the highest is 500 times. The lithium iron phosphate power battery has a cycle life of more than 2000 times, and the standard charge (5 hour rate) can be used up to 2000 times. The same quality lead-acid battery is "new half year, old half year, maintenance and maintenance for half a year", up to 1~1.5 years, while lithium iron phosphate battery is used under the same conditions, the theoretical life will reach 7~8 years. Considering comprehensively, the performance price ratio is theoretically more than four times that of lead-acid batteries. High-current discharge can be quickly charged and discharged with high current 2C. Under the special charger, the battery can be fully charged within 1.5 minutes of 1.5C charging, and the starting current can reach 2C, but the lead-acid battery has no such performance.

Good temperature performance

The peak temperature of lithium iron phosphate can reach 350 ° C -500 ° C while lithium manganate and lithium cobaltate are only around 200 ° C. Wide operating temperature range (-20C--+75C), high temperature resistance, lithium iron phosphate electric heating peak up to 350 °C-500 °C and lithium manganate and lithium cobaltate only around 200 °C.

High capacity

It has a larger capacity than ordinary batteries (lead acid, etc.). 5AH-1000AH (single)

No memory effect

Rechargeable batteries work under conditions that are often not fully discharged, and the capacity will quickly fall below the rated capacity. This phenomenon is called the memory effect. There are memories like nickel-metal hydride and nickel-cadmium batteries, but lithium iron phosphate batteries do not have this phenomenon. No matter what state the battery is in, it can be used with charging, no need to discharge and recharge.

Light weight

The volume of the lithium iron phosphate battery of the same specification capacity is 2/3 of the volume of the lead-acid battery, and the weight is 1/3 of the lead-acid battery.

Environmental protection

The battery is generally considered to be free of any heavy metals and rare metals (Ni-MH batteries require rare metals), non-toxic (SGS certified), non-polluting, in line with European RoHS regulations, is an absolute green battery certificate. Therefore, the reason why lithium batteries are favored by the industry is mainly environmental considerations. Therefore, the battery has been included in the “863” national high-tech development plan during the “Tenth Five-Year Plan” period, and has become a national key support and encouragement development project. With China's accession to the WTO, the export volume of electric bicycles in China will increase rapidly, and electric bicycles entering Europe and the United States have been required to be equipped with non-polluting batteries.

However, some experts said that the environmental pollution caused by lead-acid batteries mainly occurs in the production process and recycling process of enterprises. In the same way, lithium batteries are good in the new energy industry, but it cannot avoid the problem of heavy metal pollution. Lead, arsenic, cadmium, mercury, chromium, etc. in the processing of metal materials may be released into dust and water. The battery itself is a chemical substance, so there may be two kinds of pollution: one is the process waste pollution in the production process; the other is the battery pollution after the scrap.

Lithium iron phosphate batteries also have their disadvantages: for example, poor low temperature performance, low tap density of the positive electrode material, and a lithium iron phosphate battery having a capacity of more than lithium cobalt oxide, and thus have no advantage in terms of a micro battery. When used in a power battery, a lithium iron phosphate battery, like other batteries, needs to face battery consistency problems.

Power battery comparison

At present, the most promising cathode materials for power lithium-ion batteries are modified lithium manganate (LiMn2O4), lithium iron phosphate (LiFePO4) and lithium nickel cobalt manganese oxide (Li(Ni, Co, Mn)O2) material. Nickel-cobalt-manganate ternary materials are generally considered to be difficult to become the mainstream of power-type lithium-ion batteries for electric vehicles due to the lack of cobalt resources and high nickel and cobalt, and the price fluctuations, but can be related to spinel manganate. Lithium is mixed in a certain range.

Industry application

Carbon coated aluminum foil brings technological innovation and industrial upgrading to the lithium battery industry

Improve lithium battery performance and improve discharge rate

With the increasing demand for battery performance by domestic battery manufacturers, new energy battery materials are widely recognized in China: conductive materials & conductive coated aluminum foil/copper foil.

The advantage is that when the battery material is processed, it often has a high rate of charge and discharge performance, a large specific capacity, but the cycle stability is poor, the attenuation is serious, and so on, and has to make a trade-off.

This is a magical coating that takes the performance of the battery and brings it to a new era.

The conductive coating is composed of dispersed nano-conductive graphite coated particles and the like. It provides excellent static conductivity and is a layer of protective energy absorbing layer. It also provides good occlusion protection. The coating is waterborne and solvent based and can be applied to aluminum, copper, stainless steel, aluminum and titanium bipolar plates.

Carbon coated coatings bring the following improvements to the performance of lithium batteries

1. Reduce the internal resistance of the battery and suppress the increase of dynamic internal resistance during the charge and discharge cycle;

2. Significantly improve the consistency of the battery pack and reduce the battery composition;

3. Improve the adhesion and adhesion of the active material and the current collector, and reduce the manufacturing cost of the pole piece;

4. Reduce polarization, improve rate performance, and reduce thermal effects;

5. Prevent corrosion of the current collector by the electrolyte;

6. The combination factor further extends battery life.

7. Coating thickness: conventional one-sided thickness of 1 ~ 3μm.

In recent years, Japan and South Korea have mainly developed power-type lithium-ion batteries using modified lithium manganate and lithium nickel cobalt manganese ternary materials as cathode materials, such as Panasonic EV Energy, a joint venture between Toyota and Matsushita, Hitachi, Sony, and New Kobe. Motor, NEC, Sanyo Electric, Samsung and LG, the United States mainly develops lithium-ion batteries with lithium iron phosphate as a positive electrode material, such as A123 Systems and Valence, but major US automakers choose manganese-based cathode materials for their lithium-ion batteries in their PHEVs and EVs. It is said that A123 Company of the United States is considering entering the field of lithium manganate materials, while European countries such as Germany mainly adopt electric vehicle cooperation with other national battery companies, such as Daimler-Benz and France Saft Alliance, German Volkswagen and Japan Sanyo Agreement. Wait. At present, Volkswagen in Germany and Renault in France are also developing and producing power lithium-ion batteries with the support of their governments.

The page contains the contents of the machine translation.