New lithium empty battery, application foreground beyond imagination

In a new concept of battery cathode, the nanoparticles of lithium oxide compounds are embedded in a spongy cobalt oxide lattice to keep the battery stable. At the same time, the material can be packaged in batteries, similar to traditional sealed batteries, but can provide more energy.

In electric vehicles and portable electronic devices, lithium-air batteries have a bright future because they can provide higher energy in the same quality. But the batteries also have great disadvantages: they lose a lot of injected energy as heat, and the batteries gradually degenerate. Moreover, they also require expensive additional components to transport or output oxygen. It is an open battery structure, which is the opposite of traditional sealed batteries.

But the chemical battery can be used in a traditional, fully sealed battery. This new change indicates that similar theoretical properties can be applied to lithium air batteries while overcoming all these disadvantages. The cathode battery called nanolithia is a new battery concept that was published in the paper in the journal NatureEnergy through JuLi and postdoctoral ZiZhu and five people at the Massachusetts Institute of Technology. JuLi is a professor at the Battle Energy Alliance of Nuclear Science and Engineering at the Massachusetts Institute of Technology. The Massachusetts Institute of Technology is from Argonne National Laboratory and Peking University in China.

Li explained that one of the disadvantages of lithium air batteries is that the voltage does not match when it comes to charged and discharged batteries. The output voltage of the battery exceeds 1.2 volts, but the voltage at this time is lower than the voltage used for charging. Obviously, there is a power loss during each charging cycle. "You waste 30 percent of your electricity as heat when you charge it, and in fact, if you charge it too fast, the battery might burn up," he said. "

Traditional lithium air batteries absorb oxygen from the external air during the discharge cycle to drive the chemical reaction, and oxygen is released into the atmosphere again during the reverse reaction of the charging cycle. In the new round of charging and discharging, the electrochemical reaction between lithium and oxygen occurs as usual, but the reaction at this time no longer reduces oxygen to a gaseous form.

In contrast, oxygen exists inside the solid and is directly Redox converted between its three valence States, while bound to three different solid compounds Li2O, Li2O2, and LiO2 and mixed them in a cup. This reduces the voltage loss by one-fifth, from 1.2 V to 0.42 V, so only 8 % of the electricity becomes hot. "For cars, this means faster charging, less heat emission from batteries, and better energy efficiency," Li said. "

This method helps to overcome another drawback of lithium air batteries: As the process of charging and discharging electrochemical reactions progresses, oxygen is converted between gas and solids. At this time, the material needs to undergo a huge volume change, thus disturbing the conductive path in the structure., which in turn severely limits its service life. The new idea is to create nanoscale particles that contain lithium and oxygen in a cup, so that it is tightly confined to the cobalt oxide lattice.

The researchers defined these particles as nanolithias. In this form, LiO2, Li2O2, and Li2O can all occur inside solid materials. Nanolithia particles are usually very unstable, so the researchers embedded them in the cobalt oxide lattice, forming a sponge material whose pore diameter is only a few nanometers. This model is beneficial to the stability of particles and can also act as a catalyst for their transformation.

Li explained: "Traditional lithium air batteries are really dry batteries because they are difficult to remove water and carbon dioxide." Therefore, the incoming air must be carefully cleaned and injected into the battery. You need a lot of ancillary systems to remove carbon dioxide and moisture, which is often difficult to do. But the new battery does not need any external air to avoid this problem. The team also noted that the new battery itself would be protected by overcharging, in which case the chemical reaction itself would be limited. When overcharged, the reaction is transformed into a different form to hinder further reactions.

Li said: "For a typical battery, if you overcharge, it can cause irreversible damage or explosion, but for a nanolithia battery, we overcharge for 15 days to 100 times its capacity, and it will not cause any damage." In the circular experiment, a new laboratory version of the battery showed a capacity loss of less than 2 % through 120 cycles, indicating that the battery has a long service life. Since lithium-air cells can be installed and operated like traditional solid lithium-ion cells, without any auxiliary components, they can easily adapt to existing devices or conventional battery-designed cars, electronics, and even grid scale power storage.

The team members said: "Since these 'solid oxygen' cathode are lighter than traditional lithium-ion battery cathode, the new design can store twice the energy for a given cathode weight." "With further development, the battery will eventually be able to double its capacity again," Li said. "Everything doesn't require any expensive components or materials," Li said. For example, the electrolytes they use are the cheapest carbonates. "Cobalt oxide is less than 50 percent heavier than nanolithia," Li said. "In short, the new battery system, which is cheap, is very scalable and safer than lithium air batteries. "I believe that its application prospects will be unlimited.

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