Long-range EV batteries could last 2.8 times longer thanks to new gel electrolyte

A research team affiliated with UNIST has introduced a gel-like material that can extend the lifespan and improve safety of high-voltage electric vehicle (EV) batteries designed for long-distance driving.

This innovative electrolyte actively prevents the production of reactive oxygen species (ROS), a major cause of battery degradation, extending battery life by 2.8x and reducing expansion by 6x.

A research team led by Professor Hyun-Kon Song from UNIST’s School of Energy and Chemical Engineering, in collaboration with Dr. Seo-Hyun Jung from the Korea Institute of Chemical Technology (KRICT) and Dr. Chihyun Hwang from the Korea Electronics Technology Institute (KETI), developed an anthracene-based semi-solid gel electrolyte (An-PVA-CN) gel polymer electrolyte (GPE) that fundamentally blocks the release of ROS from electrodes. During high voltage charging.

The research results are published in the journal Advanced Energy Materials.

High-voltage lithium-ion batteries (LIBs) charged at 4.4V or higher offer greater energy storage, but they also come with risks. The increased voltage destabilizes the oxygen in the nickel-rich cathode, converting it to gas-forming ROS, increasing the risk of explosion and shortening battery life.

The anthracene component of the new electrolyte binds to unstable surface oxygen and prevents the formation of ROS called single oxygen (1O2), which can cause further degradation. In addition, anthracene scavenges and removes existing reactive oxygen species, providing bilayer protection.

Another important component, the nitrile (-CN) group, stabilizes the nickel metal in the cathode, preventing it from dissolving and structural deformation during charging.

Lead author Jeongin Lee explained, “The unique feature of this study is to prevent ROS generation directly at the source. Previous approaches either neutralized ROS after they were generated or controlled the release of oxygen by manipulating electrodes.”

A battery equipped with this electrolyte retained 81% of its initial capacity after 500 charge/discharge cycles at a high voltage of 4.55V, while a conventional battery lost less than 80% of its capacity after just 180 cycles.

This represents an almost three-fold increase in lifespan. Additionally, gas evolution and resulting swelling was also significantly reduced. The gel electrolyte limited expansion to about 13 micrometers, compared to 85 micrometers for traditional batteries, a reduction of about one-sixth.

Professor Song said: “This study demonstrates that the oxygen reaction in high-voltage batteries can be controlled at the electrolyte design stage. This principle could be applied to the development of lightweight LIBs for aerospace applications and large-scale energy storage systems.”