The service life of the battery can be extended -Lithium - Ion Battery Equipment

Can the service life of the battery be "unlimited"? -Lithium - Ion Battery Equipment

Batteries are widely used in daily applications, such as electric vehicles and electronic devices, and are promising candidates for sustainable energy storage. However, as you may have noticed, when you charge the batteries every day, their storage capacity will decline over time. Eventually, we need to replace these batteries, which are not only expensive, but also deplete the rare earth elements used to make them.

One of the key factors to shorten battery life is the degradation of battery structural integrity. In order to prevent structural degradation, a group of researchers from the University of Southern California's Viterbi School of Engineering hope to introduce "stretching" into battery materials so that they can repeat cycles without structural fatigue. The research was led by Ananya Renuka Balakrishna, assistant professor of aerospace and mechanical engineering at WiSEGabilan, Delin Zhang, a doctoral student at Viterbi University of Southern California, and Brian Sheldon, a professor at Brown University. Their work was published in the Journal of Solid Mechanics and Physics.(Lithium - Ion Battery Equipment)

A typical battery works by repeatedly inserting and extracting lithium ions from the electrodes. This insertion and extraction will expand and compress the electrode lattice. Over time, these volume changes will produce microcracks, fractures and defects.

"These microcracks and fractures in the battery materials will lead to structural degradation, which will eventually reduce the battery capacity," Zhang said. "Eventually, the battery will have to be replaced with a new battery."

In order to prevent this situation, the tension of the research intercalation materials (a kind of materials used as lithium ion battery electrodes) stretched these intercalation electrodes in advance. This change of the initial stress state regulates the phase change voltage, so that the electrode pair is more elastic when it breaks or amorphizes (losing its crystallization characteristics).

Wider voltage and larger capacity

Phase transition, when the battery material changes its physical form, is generated by expansion and compression cycles accompanying daily charging and use.

Zhang said, "These phase transitions will make the electrode more vulnerable to structural degradation, especially when the process is repeated so frequently."

The reversibility of phase is the key to allow the battery to maintain high efficiency over time.

Renuka Balakrishna said: "The reversibility can be maximized by ensuring that the materials retain their crystalline form. Under certain voltages, when materials are transferred from one phase to another, they will become powdery, which is not ideal for the efficient operation of the battery."

The researcher therefore asked himself, "Is there any way to keep the crystal form of battery materials while cycling back and forth between energy landscapes?" The answer is to change the structure of the material by introducing an initial stress state.

By stretching the electrode before charging/discharging, the researchers changed the energy map of the electrode from charging state to discharging state. This also allows the battery to operate in a wider voltage range, as shown in the right figure Zhang Delin

Zhang said: "By stretching the electrode before charging and discharging, we are changing the energy map of the electrode from the charging state to the discharging state. This initial strain enables us to reduce the energy barrier of these transitions and prevent the deformation of material failure caused by harmful lattice. This change in the energy pattern helps prevent microcracks and fractures, and protect the sustainability and energy storage capacity of the battery."

Another advantage is that by stretching the electrode, the battery can also operate in a wider voltage window, thus improving its energy storage capacity.

Challenges of modern energy storage

One of the main concerns of the energy storage community is to get rid of the flammable liquid electrolytes commonly used in batteries and put them into solid materials. This brings new challenges.

It is well known that solid objects will deteriorate with time when they are repeatedly pressed. Once a crack is introduced, both sides of the surface will lose contact. As far as the battery is concerned, it will cause a simple mechanical problem; Renuka Balakrishna said that without such a connection, it would be difficult to transport ions in the material.

Zhang decided to try to tackle this mechanical challenge while moving towards safer and more sustainable batteries. The researchers said that the novelty of this method is that you can extend the life of existing materials by introducing basic mechanical concepts, rather than looking for new materials to extend battery life.



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