Whoever controls electrolytes will pave the way for electric vehicles

Tokyo, Japan (SPX) Jun 25, 2024 - Professor Soojin Park, Seoha Nam, a PhD candidate, and Dr. Hye Bin Son from the Department of Chemistry at Pohang University of Science and Technology (POSTECH) have achieved an important development in creating a gel electrolyte-based battery that is both stable and commercially viable. Their research was recently published in the international journal Small.

Lithium-ion batteries are widely used in portable electronics and energy storage, including electric vehicles. However, the liquid electrolytes in these batteries pose a fire and explosion risk, prompting research to find safer alternatives. One option is the semi-solid-state battery, which uses a gel-like electrolyte, offering enhanced stability, energy density, and a longer lifespan.

Creating gel electrolytes usually involves prolonged heat treatment at high temperatures, which can degrade the electrolyte, reducing battery performance and increasing production costs. Additionally, the interface resistance between the semi-solid electrolyte and the electrode is a challenge in the fabrication process. Previous studies have struggled to apply their findings to commercial battery production due to complex methods and issues with large-scale applications.

Professor Soojin Park's team addressed these challenges using a bifunctional cross-linkable additive (CIA), dipentaerythritol hexaacrylate (DPH), combined with electron beam (e-beam) technology. The conventional pouch-type battery manufacturing process includes electrode preparation, electrolyte injection, assembly, activation, and degassing steps. The researchers enhanced DPH's dual functionality by adding an e-beam irradiation step after the degassing process. The CIA acted as an additive to facilitate a stable interface between the anode and cathode surfaces during activation and as a crosslinker to form a polymer structure during e-beam irradiation.

The team's pouch-type battery, using a gel electrolyte, significantly reduced gas generation from battery side reactions during initial charging and discharging, achieving a 2.5-fold decrease compared to conventional batteries. It also minimized interfacial resistance due to strong compatibility between electrodes and the gel electrolyte.

The researchers developed a high-capacity battery of 1.2 Ah (ampere-hour) and tested its performance at 55 degrees Celsius, an environment that accelerates electrolyte decomposition. Batteries using conventional electrolytes experienced substantial gas generation, leading to rapid capacity reduction and swelling after 50 cycles. In contrast, the team's battery showed no gas generation and maintained a 1 Ah capacity even after 200 cycles, demonstrating its enhanced safety and durability.

This research is significant because it enables the rapid mass production of safe and commercially viable gel electrolyte-based batteries within existing pouch battery production lines.

Professor Soojin Park of POSTECH commented, "This achievement in stability and commercial viability is poised to be a breakthrough in the electric vehicle industry." He added, "We hope this advancement will greatly benefit not only electric vehicles but also a wide range of other applications that rely on lithium-ion batteries."

Research Report:Mitigating Gas Evolution in Electron Beam-Induced Gel Polymer Electrolytes Through Bi-Functional Cross-Linkable Additives