Rubber electrolytes produce cheap, reliable and safe EV batteries

Electric vehicles (EVs) require cheaper, more efficient and longer lasting batteries that won’t burst during use or pollute the environment if they are to become widely popular. Scientists at the Georgia Institute of Technology believe they have identified rubber – a common material – as a possible and beneficial alternative to existing rubber lithium-ion batteries.

Professor Seung Woo Lee (left) and Michael J. Lee (right) demonstrated a more cost effective and safe solid polymer electrolyte (rubber material) for solid state batteries. Image Credit: Georgia Institute of Technology.

Due to their improved mechanical properties, elastomers, or so-called synthetic rubbers, are widely used in commercial products and modern applications such as wearable electronics and soft robotics. Scientists determined that when engineered into a 3D structure, the material acts as a highway for rapid lithium-ion transport with excellent mechanical toughness, leading to longer rechargeable batteries that can go quite a distance.

The study carried out in partnership with the Korea Advanced Institute of Science and Technology was published in the journal Nature.

A liquid electrolyte displaces ions in conventional lithium-ion batteries. In addition, the battery is very unstable – even minor damage can cause electrolyte to leak, resulting in fire or explosion. The industry has been forced to consider solid-state batteries, which can be made from inorganic ceramic materials or organic polymers for safety reasons.

Most of the industry is focused on building inorganic solid state electrolytes. But they are difficult to manufacture, expensive and not environmentally friendly..

Seung Woo Lee, Associate Professor, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology

Lee is also part of a group of researchers who have discovered an organic rubber-based polymer that outperforms other materials.

Solid polymer electrolytes remain popular due to their low production costs, gentle nature, and non-toxicity. In addition to this, conventional polymer electrolytes lack the ionic conductivity and mechanical stability required for solid-state battery performance.

New 3D design helps increase energy density and performance

Using rubber electrolytes, Georgia Tech engineers solved common problems such as slow lithium-ion transport and poor mechanical properties. The ability of the material to form an interconnected three-dimensional (3D) plastic crystalline phase inside the robust rubber matrix was a major breakthrough. Thus, increased ionic conductivity, excellent mechanical properties and electrochemical stability have all been achieved through this unique structure.

This rubber electrolyte can be created by a basic polymerization process at relatively low temperatures, which results in robust and elegant integrations on the surface of the electrodes. These special properties of rubber electrolytes help prevent lithium dendrite formation and allow ions to move faster, allowing solid-state batteries to operate reliably even at room temperature.

Rubber has been used everywhere because of its high mechanical properties, and it will allow us to make cheaper, more reliable and safer batteries..

Seung Woo Lee, Associate Professor, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology

Michael Lee, a graduate mechanical engineering researcher also said, “Higher ionic conductivity means you can move more ions at the same time. By increasing the specific energy and energy density of these batteries, you can increase EV mileage.”

Currently, scientists are investigating ways to improve battery performance by improving cycle time and reducing charging time through advanced ion conductivity. To date, their efforts have resulted in a two-fold increase in cell performance or flow time.

The research could benefit Georgia’s reputation as an EV innovation hotspot. As part of its ongoing partnership with the institute to develop new solid-state batteries that are safe and more energy-dense than ordinary Li-ion batteries, SK Innovation – a global energy and petrochemical company – is funding a study additional on the Electrolyte Material.

SK Innovation recently began construction of a new electric vehicle battery plant in Commerce, Georgia, which is expected to produce 21.5 gigawatt hours of lithium-ion batteries per year by 2023.

All-solid-state batteries can significantly increase the mileage and safety of electric vehicles. Fast-growing battery companies, including SK Innovation, believe bringing all-solid-state batteries to market will be a game-changer in the electric vehicle market.

Kyounghwan Choi, Director, SK Innovation

Thanks to the ongoing project in collaboration with SK Innovation and Professor Seung Woo Lee of Georgia Tech, there are high expectations for the rapid application and commercialization of all-solid-state batteries.added Choi.

Journal reference:

Lee, M.J. et al. (2022) Elastomeric electrolytes for high energy solid state lithium batteries. Nature.


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