About the safety of power batteries

During the period of "May Day", there are electric bus serial fire incidents in XieDao resort parking lot, Chaoyang district, Beijing. The fire destroyed new 89 energy vehicles. An electric passenger train costs millions of yuan. It is estimated that the fire loss is nearly one hundred million yuan. Although later, thespecial said the fire is caused by catkin accumulation, people still focus on the new energy car battery safety.

In recent years, in our country is determined to develop under the background of new energy vehicles, especially after 2014, including national and local levels high "subsidies" series, a strong policy, driven by the development of new energy automotive industry is overwhelming. And increase in the number with the commercial application of electric cars, electric cars lithium ion power battery spontaneous combustion and explosion fire occurs frequently, it is the key to the development of the electric car industry time, any electric vehicle safety accident to manufacturing enterprises have a significant impact, not only is a heavy blow to the whole industry. Power battery is the core components of the electric cars, electric cars, fire or explosion, people tend to be the first think of the problem of battery, so now the batteries of electric cars is really safe?

Battery mechanism analysis of lithium titanate material safety performance is better

Angle to analyze from the battery mechanism, fire explosion of the lithium ion battery is the result of the lithium ion battery thermal runaway, the root cause is mainly under the right conditions between the electrodes and the electrolyte produced severe chemical exothermic reaction. Has commercial used in lithium ion power battery anode materials with lithium iron phosphate, nickel and cobalt, aluminum nickel and cobalt acid lithium manganese acid lithium and lithium manganese acid, etc.; Anode materials mainly include graphite or and its composite materials and lithium titanate, etc.; The electrolyte is mainly composed of organic solvent and lithium salt, the main components of the diaphragm is a composite material of polypropylene, polyethylene or both.

For the anode material, lithium iron phosphate when the highest temperature of thermal decomposition takes place, the least amount of heat energy that is released by the decomposition, safety is the best of the anode material. Anode materials, the reaction of the graphite anode and electrolyte temperature minimum, the most easy to react with the electrolyte, the highest gives off heat, and the temperature of the lithium titanate cathode decomposition reaction not only higher than that of graphite and the reaction of the electrolyte, and gives off heat is far lower than the graphite reaction gives off heat, so the safety of the lithium titanate material is much higher than graphite anode.

In addition, power battery in charging and discharging cycle, battery material will happen some physical and chemical changes are caused by the decay of battery performance, to some extent, these changes will affect the safety of the battery. In fact, the postpartum and the actual use of the battery, battery such as fire accident happen. The existing research achievements of safety for without circulation of fresh cells cannot fully explain the mechanism of the accident. Different materials, different capacity and design in the process of cell cycle electrochemical or abuse resistant behavior may differ. According to different anode materials used, the common power battery on the market at present is divided into two categories, carbon negative electrode system and lithium titanate battery cathode system.

Due to the carbon negative after the intercalated-li potential and the potential of metallic lithium is very close, deposition of metallic lithium, generally occurred in the cathode surface. Lithium ion during the migration to the cathode surface, part of the lithium ion is not in the cathode active material to form stable compounds, but after winning electronic deposit in the cathode surface to become lithium metal, and gradually form a lithium dendrite. Along with the increase of cycles, the internal polarization intensified, lithium dendrite with the growth, the cycle of lithium ion battery may penetrate the diaphragm, is caused by negative short circuit. Battery after after a nearly one thousand - cycle, due to the change of structure of battery materials of expansion and contraction of (keep) and the accumulation of side reaction products (lithium), carbon anode surface there are many convex. This change not only affects the electrode structure and activity, also can make the diaphragm stress deformation, increase the possibility of damage. Battery in short circuit, hot extrusion, overcharge experiment easily happened out of control.

Compared with the carbon anode materials, lithium titanate material is known as the "material" zero strain, high stability, a higher intercalated-li potential (+ / 1.55 Vvs. Li Li), fundamentally eliminate the production of metal lithium dendrite, reduces the risk of internal short circuit in the battery. Between lithium titanate and electrolyte low reactivity, hardly generated SEI film, thus has the very good cycle stability and security, its temperature cycle life can reach more than 25000 times. Under the high temperature lithium titanate can absorb oxygen produced by the anode decomposition, reduces the risk of thermal runaway, improved the security of the battery. Lithium titanate instead of carbon materials for lithium ion battery cathode, in order to guarantee the safety of the lithium ion battery, improve the circulation of the battery performance and service life provides a solid foundation.

Lithium titanate firm practice battery security mission

The security of the power battery more depends on the material itself and the manufacturing process, and lithium titanate battery with high safety, can effectively solve the safety hidden trouble for new energy battery application of frustration. Lithium titanate battery in one of the most important security, has incomparable advantages. Follow the new gb, lithium titanate battery after acupuncture, electric drills, cutting, such as "cruel" experiment, has not happened the phenomenon such as fire, explosion, withstood the test of safety test. Lithium titanate battery technology market acceptance, has been with ternary lithium battery and lithium iron phosphate batteries in power market situation of the three pillars of lithium-ion batteries.

Lithium battery is lithium titanate electric life expectancy, the highest degree of safety in the battery. Lithium titanate battery cycle life is long, can achieve more than ten thousand times of charge and discharge cycle, higher than the normal lithium battery. Lithium titanate and fast charging performance is very good, the charging rate is not only to the lithium iron phosphate and three yuan is 6 c, also can realize electrochemical supercapacitors charging ratio of 10 c. On the other hand, this proved lithium titanate application is very extensive.

Current lithium titanate battery technology is mature, domestic market is mainly used in bus and shuttle buses in electric applications, and other fields, the domestic production of lithium titanate material earlier, micro macro with silver, Toshiba abroad in 2007, is based on the lithium titanate cathode of lithium ion battery. Represented by silver lung of lithium titanate battery now have passed the industry recognized "five big problem", achieve six minutes fast charging, wide temperature (+ 60 ℃ to 50 ℃ -), 30 years cycle life, don't fire explosion fine properties such as high security, high efficiency. But lithium titanate battery low energy density is its biggest drawback, at present, lithium titanate battery and lithium iron phosphate battery energy density of the gap is narrowing. It is reported, silver long fourth generation high energy density lithium titanate battery, compared with the third generation costs fell by 40%, the energy density increased by 60%.Titanium silver long research and development of hydrogen technology, also will solve the problem of the battery energy density, and through the titanate combination of lithium batteries and fuel cells, successfully solve the problem of new energy vehicle range.

Fulfills "the blue sky the future, the electric car will be thespecial", the development trend of industry inside and outside the focus of attention, to operating companies more security can increase customer confidence in the electric car, also can promote the development of new energy vehicles in China. From the recent electric car accidents, we should be alert to solve the problem of the safety of the battery is the primary, the energy density dramatically slowing the pace of ascension can be appropriately, battery reliability and durability of the attention should be given a more important position. High-energy means high risk, power battery safety above all.

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