Maria Montero

Are lithium ion batteries here to stay? The promise…

Researchers are racing to find new and different ways to improve the stability and longevity of lithium-ion batteries, and companies are ready to invest.

Lithium ion batteries have been an industry staple for years. Where many are looking for alternative energy sources, others are looking for ways to improve current technologies. From adding zinc to adding cobalt to developing new battery structures, vLarge amounts of research money are being pumped in to increase the energy density of lithium-ion batteries while making them safer and smaller.

Another competitor in this field is the concept of silicon composite battery anodes, which increase the possibility of a large increase in the energy density of the lithium ion battery.

Silicone based anodes for lithium ion batteries

When a lithium ion battery is charged, the lithium ions flow to the anode, which in most cases today is made of carbon. Those ions and carbon form an energy-rich complex, ready to break down and release electrical energy as the battery discharges. A given amount of stored energy requires that a corresponding volume of the lithium carbon compound be generated.

A new area of ​​lithium-ion battery research is to replace the carbon anode with an anode made up largely of silicon. As the battery charges, an energy-dense lithium-silicon compound forms.

The key difference is that a given amount of energy can be stored in a smaller volume of lithium and silicon than could previously have been stored in a lithium-carbon complex.

The result is that, to store any amount of energy, the required battery volume based on a silicon anode will be smaller than its carbon anode predecessor.

The problem is that the silicon anode enlarges when charged and becomes smaller when discharged. This increase and decrease in the size of the anode causes structural damage to the battery, leading to failure.

Stop the destruction of the silicon anode during charge and discharge cycles

A possible solution to this battery size problem was described in a 2017 thesis written by Marte Skare from the Norwegian University of Science and Technology. The suggestion can be inferred from the title of the article: “A method for controlled oxide and carbon coating of silicon nanoparticles as anode in lithium-ion batteries.”

Instead of using elemental silicon, silicon nanoparticles were used. They are coated, coincidentally with the carbon, and the coating reduces the swelling of the electrode, making the use of silicon electrodes more plausible.

Coating silicon with carbon. Image from the Norwegian University of Science and Technology.

Also working in the research area is the University of Kiel in Kiel, Germany, which claims that its Institute for Materials Sciences has been studying silicon as an energy resource for more than 30 years. In 2017, they launched what is known as the PorSSi project, which is abbreviated as porous Si film anodes for lithium-sulfur-silicon energy storage. The project works with RENA Technologies.

A solid silicon wafter. Image from the University of Kiel.

According to Dr. Sandra Hansen, PorSSi project leader, “Theoretically, silicon is the best material for anodes in batteries. It can store up to 10 times more energy than graphite anodes in conventional lithium-ion batteries.” Part of the reason Hansen believes in the potential of silicon is the fact that it is extraordinarily abundant, second only to oxygen.

Li-Ion forever? Batteries versus other energy sources

Speaking of abundant resources, silicone-based batteries will need to compete with other power sources that seek to increase resource effectiveness.

These days, solar or wind power that is not immediately needed is dedicated to pumping water down to contain containers located a few stories up. Then when the sun is not shining and the wind is not blowing, the raised water is allowed to descend to ground level, generating electricity in the manner of a generator located at the bottom of a waterfall.