New Solid Lithium Battery: Loss of 2 % of 120 times capacity of charging and discharging with self-charged function

Lithium-air batteries provide more power at the same weight and are therefore widely used in electric vehicles and other mobile electronic devices. However, lithium-air batteries have many disadvantages: high heat(a large amount of chemical energy is converted into heat energy and not provided to equipment), short life, expensive and complex manufacturing processes(charging air into the battery requires expensive equipment, And very troublesome).

Recently, Liju, a professor ofspecial engineering at the Massachusetts Institute of Technology, and Zhuzhi and five other authors working at MIT, Argonne National Laboratory and Peking University wrote in the journal Nature Energy. A new technology called "nanolithium cathode" is reported, which can be used to make closed lithium batteries with properties similar to lithium-air batteries to overcome the above problems.

Liju said that one of the weaknesses of lithium-air batteries is that the voltage of charging and discharge varies, and the discharge voltage is 1.2 volts lower than the charging voltage, so the energy lost in the form of heat energy during each charging process is as high as 30 %. "If you charge too fast, your lithium battery might actually burn. "

Lock up the gas.

When traditional lithium-air batteries discharge, they use oxygen in the air to react with lithium in the battery. When charged, the oxygen in the lithium oxide is released into the atmosphere.

The new nanometer lithium cathode battery also uses oxygen and lithium. The difference is that when discharged, oxygen is no longer released in the form of gas but is enclosed in a solid. Specifically, oxygen is enclosed in three solid compounds-Li2O, Li2O2, and LiO2-in three oxidative States, and these three substances are enclosed in cobalt dioxide glass.

The advantage of this is that the nanolithium-cathode battery reduces the voltage difference when charging and discharging by five times -- from 1.2 volts to 0.24 volts, so only 8 % of the energy is lost in the form of heat energy when charging. This means that car batteries can be charged at a faster rate without having to worry about overheating fires.

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

The new technology uses cobalt dioxide glass to wrap lithium and oxygen in nanoscale space. Scientists call this structure nanolithium. In this way, the transformations of LiO2, Li2O2, and Li2O do not change the macroscopic structure of the material. In addition, because the nanolithium particles themselves are very unstable, the cobalt dioxide glass energy with nanoscale channels is just enough to stabilize them. Cobalt dioxide also plays the role of a catalyst in charging and discharging.

Liju said that traditional lithium-air batteries are actually only lithium-oxygen batteries because water vapor and carbon dioxide in the air react with lithium, so lithium-air batteries must be equipped with huge auxiliary systems to remove water vapor and carbon dioxide. This is a very difficult step. The new solid lithium battery no longer has this problem.

Self-contained overcharge function

The new lithium-solid battery also has its own anti-charging function, because the chemical reaction in the battery will self-regulate through negative feedback, and when the electricity is full, the reaction will stop automatically. If the traditional battery is overcharged, it will cause irreversible damage to the battery and even explode. However, solid lithium batteries were continuously charged for 15 days in the experiment, and the charge was 100 times the battery capacity, but the battery was unscathed.

In the charging and discharging experiment, the solid lithium battery was recharged 120 times and the capacity was lost only 2 %, which means that it far exceeds the life of the traditional lithium-air battery. Since solid lithium batteries do not require an auxiliary air purification system, they can be easily applied to electric vehicles and even grid storage stations.

Since the solid oxygen cathode is much lighter than the cathode of a lithium ion battery, the new solid lithium battery can store twice as much power as an equivalent weight lithium ion battery. With the improvement of technology, the power of the new battery can be doubled again.

The greater advantage of the new battery is that it does not need to use expensive and rare materials. The battery's carbonate electrolyte is very cheap. In addition, cobalt dioxide glass is 50 % lighter than nanolithium particles. Therefore, compared with lithium-air batteries, new batteries are very cheap, safe, and have the potential for large-scale applications. The research team plans to complete the production of practical prototypes within one year.

Jixulei, an associate professor at Oregon State University who did not participate in the project, said the new lithium battery technology has made significant improvements over conventional lithium-air batteries. Superoxide solute works well in carbonate dielectric and does not require oxygen intervention at all. In the process of charging and discharging, the cathode materials are all solid, so the installation and use of the new battery is very convenient.

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