32700 battery

New technology: Closed 32700 battery performance is similar to lithium-air battery?

New chemical methods are expected to overcome the defects of lithium-air batteries.

At the same weight, lithium-air batteries (lithium-air batteries) can provide more power, so they are widely used in electric vehicles and other mobile electronic devices. However, lithium-air batteries have many disadvantages: high heat generation (a large amount of chemical energy is converted into heat energy instead of providing it to the device), short life, expensive and complicated manufacturing process (charging and discharging air in the battery requires expensive equipment and is very troublesome).

Recently, MIT nuclear engineering professor Li Ju, postdoctoral fellow Zhi Zhu (transliteration, Zhi Zhu) and five other authors working at MIT, Argonne National Laboratory and Peking University published an article in the journal Nature Energy, reporting a new technology called "nano lithium cathode", which can be used to manufacture closed lithium batteries with performance similar to lithium-air batteries to overcome the above problems.

Li Ju said that one of the weaknesses of lithium-air batteries is that the charging and discharging voltages are not equal. The discharge voltage is 1.2 volts lower than the charging voltage, so during each charging process, up to 30% of the energy is lost in the form of heat energy. "If you charge too fast, your 32700 battery may really burn up."

Lock up the gas

When traditional lithium-air batteries are discharged, they use oxygen in the air to react chemically with the lithium in the battery. When charging, the oxygen in the lithium oxide is released into the atmosphere.

The new nano lithium cathode battery also uses the role of oxygen and lithium. The difference is that when discharging, oxygen is no longer released in the form of gas, but is enclosed in solids. Specifically, oxygen is enclosed in three solid compounds in three redox states - Li2O, Li2O2 and LiO2, which are wrapped in cobalt dioxide glass.

The benefit of this is that the voltage difference between the nano lithium cathode battery during charging and discharging is reduced by 5 times - from 1.2 volts to 0.24 volts, so only 8% of the energy is lost in the form of heat energy during charging. This means that car batteries can be charged faster without worrying about overheating and fire.

The second disadvantage of lithium-air batteries is that oxygen released in the form of gas can damage the ion channels in the battery, thus reducing the life of the 32700 battery.

The new technology uses cobalt dioxide glass to enclose lithium and oxygen in nanometer-scale spaces. Scientists call this structure nanolithium. In this way, the transformation of LiO2, Li2O2, and Li2O will not change the macroscopic structure of the material. In addition, since nanolithium particles themselves are very unstable, cobalt dioxide glass with nanochannels can stabilize them just enough. Cobalt dioxide also plays the role of catalyst in charging and discharging.

Li Ju said that traditional lithium-air batteries are actually just lithium-oxygen batteries. Because water vapor and carbon dioxide in the air will react with lithium, lithium-air batteries must be equipped with a huge auxiliary system to remove water vapor and carbon dioxide, which is a very difficult step. The new solid 32700 battery no longer has this problem.

Built-in overcharge protection

The new solid 32700 battery also has a built-in overcharge protection function, because the chemical reaction in the battery will self-regulate through negative feedback, and the reaction will automatically stop when the battery is fully charged. If a traditional battery is overcharged, it will cause irreversible damage to the battery or even explode. However, the solid 32700 battery was charged continuously for 15 days in the experiment, and the charging power was 100 times the battery capacity, but the battery was intact.

In the charge and discharge experiment, the solid 32700 battery was charged and discharged 120 times, and the capacity only lost 2%, which means that it far exceeds the life of traditional lithium-air batteries. Since the solid 32700 battery does not require an auxiliary air purification system, it can be easily applied to electric vehicles and even grid-level energy storage stations.

Since the solid oxygen cathode is much lighter than the cathode of a lithium-ion battery, the new solid 32700 battery can store twice as much power as a lithium-ion battery of the same weight. As the technology improves, the power of the new battery can be doubled again.

A greater advantage of the new battery is that it does not need to use expensive rare materials. The carbonate electrolyte of the battery is very cheap. In addition, cobalt dioxide glass is 50% lighter than nano lithium particles. Therefore, compared with lithium-air batteries, the new battery is very cheap, safe, and has the potential for large-scale application. The research team plans to complete the manufacture of a practical prototype within one year.

Xulei Ji, an associate professor at Oregon State University who did not participate in the project, said that the performance of the new 32700 battery technology is a significant improvement over traditional lithium-air batteries. Superoxide solutes work well in carbonate dielectrics without the intervention of oxygen. During the charging and discharging process, the cathode materials are solid, so the new battery is easy to install and use.

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