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New harmful electrode materials come out, allowing batteries to provide more than 40% of capacity in 20 seconds

wallpapers News 2020-09-16
Scientists at the University of California, San Diego (UC San Diego) have discovered a new harmful electrode material that can safely charge lithium-ion batteries within a few minutes and withstand thousands of charge and discharge cycles. This new type of negative electrode is called disordered rock salt, which is composed of the abundant lithium, vanadium and oxygen atoms on the earth. The arrangement is similar to ordinary table salt used in the kitchen but more random. In commercial applications requiring high energy density and high power, such as electric cars, vacuum cleaners or electric drills, this material has a bright future.
This research was co-led by Professor Ping Liu and the nano-engineers in the laboratory of Professor Shyue Ping Ong.

At present, there are two commonly used anode materials for lithium-ion batteries. The most common is the graphite anode, which has a very high energy density and can support electric vehicles to travel hundreds of miles on a single charge. However, due to the lithium metal electroplating process, if the negative graphite electrode is charged too fast, it will be prone to fire and explosion. An alternative to graphite anodes-lithium titanate anodes are safer and can be set quickly, but the energy density is significantly reduced, causing the battery to be charged more frequently.

The new type of disordered rock salt anode Li3V2O5 discovered by the researchers is in an essential middle position: it is safer than graphite, but at least it can provide 71% more energy than lithium titanate. "Its capacity and power are slightly lower than graphite, but it is faster, safer, and has a longer service life. Moreover, it has a lower voltage, which is more energy-efficient than the currently used commercial fast-charging lithium titanate anode. The density has been dramatically improved. Therefore, using this material, a fast-charging, long life, and a safe battery can be made without sacrificing too much energy density.

For a long time, the battery field has been looking for a harmful electrode material with a potential slightly higher than graphite to realize a safe and fast-chargeable lithium-ion battery. This material fills essential knowledge and application gaps and can be used as a natural alternative solution for today's lithium-ion battery manufacturing process.

In this study, the research team found that their disordered rock salt anode can reversibly cycle two lithium ions at an average voltage of 0.6V. This is higher than the 0.1V of the negative graphite electrode. At high charging rates, the elimination of the lithium metal electroplating process can make the battery saver, but it is lower than the voltage when lithium titanate is inserted into lithium-1.5V, so more can be stored energy.

Researchers have shown that the number of charges and discharge cycles of the Li3V2O5 negative electrode can exceed 6000. Simultaneously, the capacity decay is negligible, and it can charge and discharge quickly, providing more than 40% of the capacity within 20 seconds. Due to the unique low-energy barrier redistribution lithium insertion mechanism, the voltage is low, and the energy transfer rate is high.

Li3V2O5 works through a different charging mechanism from other electrode materials. Because the lithium ions are rearranged in a certain way, the voltage is low, and the lithium diffuses rapidly.

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