Solving Three Defects of Lithium-ion Battery by New Solid State Battery

The first all-solid battery was developed by a team of engineers led by 94-year-old John Goodenough, a professor at the Austin School of Engineering at Texas University and one of the inventors of lithium batteries. The safer, faster charging and longer life of rechargeable batteries will provide new options for smartphones, electric cars and energy storage stations.

John Goodenough, one of the inventors of lithium batteries, in his Battery Materials Laboratory: Cochrane Engineering College

Goodenough, along with Maria Helena Braga, a senior researcher at Cochrane College, made the breakthrough. The advantages of the low-cost all-solid battery they developed are: not only no combustion risk, but also long service life, high volume energy density, and fast charging and discharging power. The findings are published in the journal Energy and the Environment.

"Cost, safety, energy density, charging and discharging rates and service life are important factors that determine whether electric vehicles can be accepted by the public. We believe that this result has solved many of the problems facing the battery today. " said Goodenough.

The researchers demonstrated that the energy density of the new battery is three times that of today's lithium batteries. For an electric car, the energy density of the battery determines its mileage. The higher the energy density of the battery, the farther the car can run after each charge. This new battery formula also increases the battery's charge and discharge times, which in turn extends the battery's service life. In addition, the new battery charges faster(within minutes, it is no longer the usual hours).

Today's lithium batteries use liquid electrolytes to transfer lithium ions from the anode(the negative electrode of the battery) to the cathode(the positive electrode of the battery). If the battery is charged too quickly, dendrites, also known as "metal whiskers," will form in the battery and penetrate the liquid electrolyte to form a short circuit, which may cause an explosion or fire. After abandoning liquid electrolytes, the researchers used a glass electrolyte that allowed the researchers to use alkali metals as electrodes without dendritic formation.

In traditional batteries, alkali metals(lithium, sodium, potassium) can not be used as electrodes. But in all-solid batteries, alkali metal electrodes increase the energy density of the cathode and also extend the battery's service life. Researchers in the laboratory observed that the battery can charge and discharge more than 1,200 times without maintaining a low trough resistance.

In addition, because the electrolyte of the solid-state battery can maintain a high conductivity at minus 20 degrees Celsius, the car using this battery can still operate normally in a sub-zero environment. This all-solid battery can also work at minus 60 degrees Celsius.

Kraga, a senior researcher at Cochrane College, began developing solid-state electrolyte batteries at the University of Porto in Portugal. Two years ago, she began working on the project with Professor Goodenough, a researcher at the University of Austin, Andrew J. Murchison. Braga also revealed that it was Professor Goodenough's understanding of the composition and nature of solid glass electrolytes that allowed it to be applied to batteries, a technology that has been patented by the University of Austin's Technology Commercialisation Office.

The glass electrolyte allows researchers to electroplate alkali metals to the anode and cathode without worrying about the formation of dendrites, and also simplifies the battery manufacturing process.

Another advantage of this battery is that the manufacturing material does not affect the environment. "Glass electrolytes can replace lithium with sodium, which is widely distributed in seawater and is easily available. " said Braga.

Professor Goodenough and Graga are continuing their battery research and patent applications. Next, they hope to work with battery makers to develop and test new batteries for electric vehicles and energy storage devices.

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