The safety information of lithium-ion battery
With lithium-ion battery technology continues to update and development of its light weight, high capacity, long life advantages of gradually consumers. The market has expanded from the phone to the camera, DVD, model aircraft, toys and many other fields. In recent years, lithium-ion battery in electric tools, backup power, electric bicycles, light electric vehicles and other large equipment on the application of increasing concern, but these devices require batteries with high capacity, high-power conditions. Lithium-ion battery can meet the high safety, high power, long life’s basic requirements, is one of many experts and scholars to explore an important issue.
Power safety of lithium-ion battery generally refers to inappropriate use as power batteries, functional failure, accidents and abuse of the battery bulging leakage, temperature and pressure than the standard, or even an explosion and fire and other accidents, resulting in users at risk of life and property . Explosion and fire which is the most serious security incidents. Lithium-ion battery fire led to an explosion of internal abuse of the reasons are complex, but most are caused by the high temperature and pressure, both of which can be attributed to the cause of most of the lithium-ion battery thermal runaway reaction, that is, fever. The fever generally include: battery electrode SEI film decomposition, embedded lithium and the reaction solvent, so the decomposition of cathode material.
Cathode materials are the key advantages of large lithium manganese
Lithium-ion battery in the power of security issues, the electrode material in the cathode material is the key, but also lead to safety problems of lithium ion battery main reason. For high energy density, high security, environmental protection and affordable battery electrode materials is the key to development. Is now used as cathode materials are lithium cobalt oxide, lithium manganese oxide, lithium nickel-cobalt and manganese lithium iron phosphate. The data obtained on the domestic point of view, lithium cobalt oxide battery security risks for large, generally not used as a battery cathode materials; the use of lithium manganese more common; nickel cobalt manganese lithium domestic use less, in the China Taiwan and Japan, some manufacturers use.
As the manganese-rich (especially in China, the world’s third largest reserves), low cost, environmentally friendly, and lithium manganese oxide has a high discharge voltage, mature technologies, good safety and layered with other cathode materials can not match charge or discharge capacity, so its current momentum in the promotion of lithium batteries, lithium manganese oxide has a great advantage. Although the specific capacity is relatively low, but the larger battery itself does not constitute a significant weakness. Lithium manganese oxide as cathode material of the lithium ion battery has a good safety and thermal stability. But when there are capacity lithium manganese oxide decreases fast (especially in high temperature conditions), short life cycle of disadvantage and hinder the fact that with the process.
Lithium Nickel Cobalt Manganese advantage is the high specific capacity, excellent cycling performance. Made of lithium-ion battery has a very high specific energy, suitable for strict restrictions on the weight and size but requires high energy areas. As the use of cobalt, nickel and other metals, nickel, cobalt and manganese lithium after the price of lithium cobalt oxide. However, lithium nickel cobalt manganese present in the power battery applications yet to be assessed on the domestic application of the material is usually the way through the doped to improve their safety performance, but did not see the scale of application.
Lithium iron phosphate and abundant, low cost, high specific capacity and excellent high-temperature cycle performance and high security, is one of promising cathode material for battery power. Lithium iron phosphate as cathode material for a new battery used in a warming trend in recent years. As the restrictions on patent issues, Europe and North America to mass-production lithium iron phosphate few manufacturers, the market basically monopolized by a few vendors. Although many domestic manufacturers of lithium-ion iron phosphate lithium battery on the research and development into production, but the level of technology and process differences, product quality varies greatly.
Additives, electrolyte safety
Power lithium-ion battery design also affect the safety of the battery.
Manufacturers only in the positive and negative ratio, binder type, diaphragm assembly means very ear type and welding, assembly through the form of careful calculation and control, can be made it quite chip internal current distribution rational, Dianchi polarization of small, good heat dissipation and efficient and safe. For safety considerations, power battery is usually in the design to take into account when the exception occurs, the battery system, heat transfer to the environment The pace of the rate greater than the system generated heat, as this determines the probability of occurrence of thermal runaway reactions .
To further enhance the battery’s safety, many manufacturers in the electrolyte to the battery of functional additives. These additives prevent overcharge, anti-flatulence, improve the role of low-temperature and flame retardant. It is worth mentioning that the electrolyte is to add flame retardants to improve battery safety is an important direction. The purpose of adding flame retardants to improve the combustion of oxygen index electrolyte. As we all know, when the material when the oxygen index of more than 27 substances are flame retardant, flame retardants have been developed close to or reach this target. The battery electrolyte, the additive index for the single function of the development is not difficult, the difficulty lies in ensuring the safety of the electrolyte must be balanced, while other conventional performance. Various functions for the electrolyte balance, multi-functional groups, research and development of composite additives is also the direction.
Essential for the protection board
To enhance the safety of lithium-ion battery power, and protect the board is equipped with necessary equipment battery. In most cases, lithium protection board should have control of the working conditions of lithium-ion battery capabilities which working conditions, including voltage, current, and temperature. As the special lithium-ion battery, making power lithium-ion battery protection board must be used together to ensure complete safety and reliability of the whole system. Multiple strings and the battery pack more than the matching assembly, long-term use of 过程 individual differences that inevitably exist, to protect Ban (Huo Battery Management System) Yao Fuze on Zhengzu battery’s voltage, current and temperature and even Rongliang monitor, Bi Xu achieve accuracy and prompt action to play its due role. Meanwhile, due to differences in the performance of individual batteries in the same charge and discharge current, battery voltage and the sections available capacity will be different, with the number of cycles increased, the difference in battery performance will become increasingly significant, and thus would greatly reduced the battery performance, life expectancy shortened. For the performance of battery at or near performance levels of individual cells, each cell must be balanced so that each monomer within the battery charge and discharge performance deterioration due to the minimum. Most manufacturers have adopted a balanced protection plate on the lithium-ion rechargeable batteries for maintenance.
Therefore, in the lithium-ion battery safety factors, the electrode material is a critical factor, the current testing standards to ensure that the materials to industry system and only lithium manganese lithium iron phosphate. Manufacturers generally use good safety performance and compatibility of electrolyte additives to protect the power lithium-ion batteries to better use. In addition, the lithium ion protection plate provides a function for the protection of lithium batteries, can maximize the protection of safe and reliable battery power to use. Charge balance functions ensure the practical power to high safety lithium-ion battery Long working life. From the future trend, power lithium-ion battery, special protection panels and equipment is a joint development of the three scientific development.
Via: The safety information of lithium-ion battery
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