The Department of Chemistry at Pohang University of Science and Technology (POSTECH), led by Professor Soojin Park, along with PhD candidate Seoha Nam and Dr. Hye Bin Son, has made a significant advancement in developing a gel electrolyte-based battery that is both stable and suitable for commercial use.
Portable electronics and electric vehicles heavily rely on lithium-ion batteries. However, the current liquid electrolytes used in these batteries present a considerable fire and explosion hazard, driving ongoing research into finding safer options.
One such alternative is the semi-solid-state battery, which offers a middle ground between traditional lithium-ion batteries with liquid electrolytes and solid-state batteries. By utilizing a gel-like electrolyte, these batteries provide improved stability, energy density, and a relatively longer lifespan.
The creation of gel electrolytes typically requires prolonged exposure to high temperatures, which may degrade the electrolyte and result in decreased battery performance and higher production costs. Moreover, the interface resistance between the semi-solid electrolyte and the electrode presents a challenge during manufacturing.
Previous research has faced difficulties in directly applying their discoveries to current commercial battery production lines due to complex manufacturing methods and issues with large-scale implementation.
Professor Soojin Park’s team addressed these obstacles by employing a bifunctional cross-linkable additive (CIA), dipentaerythritol hexaacrylate (DPH), in conjunction with electron beam (e-beam) technology. The traditional pouch-type battery manufacturing process involves electrode preparation, electrolyte injection and assembly, activation, and degassing steps.
After the degassing process, the researchers boosted DPH’s dual functionality by adding an extra e-beam irradiation step after the degassing process. The CIA served as both an additive to create a stable interface between the anode and cathode surfaces and as a crosslinker to create a polymer structure during the e-beam irradiation process.
By utilizing a gel electrolyte, the team’s pouch-type battery significantly decreased gas generation from battery side reactions during initial charging and discharging, achieving a 2.5-fold reduction compared to traditional batteries. Additionally, it minimized interfacial resistance effectively by ensuring strong compatibility between electrodes and the gel electrolyte.
Afterward, the researchers developed a high-capacity battery with a rating of 1.2 Ah (ampere-hour) and tested it at 55 degrees Celsius, an environment that accelerates electrolyte decomposition. Under these conditions, conventional electrolyte-based batteries produced significant gas and experienced a rapid capacity reduction with battery swelling after 50 cycles. In contrast, the team’s battery exhibited no gas production and maintained a capacity of 1 Ah even after 200 cycles, showcasing its improved safety and longevity.
This study holds particular importance as it paves the way for the efficient mass production of gel electrolyte-based batteries with both safety and commercial feasibility, utilizing existing pouch battery production lines.
“This achievement in stability and commercial viability is poised to be a breakthrough in the electric vehicle industry.” Professor Soojin Park of POSTECH commented, “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.”
Journal reference:
- Seoha Nam, Hye Bin Son, Chi Keung Song, Chang-Dae Lee, Yeongseok Kim, Jin-Hyeok Jeong, Woo-Jin Song, Dong-Hwa Seo, Tae Sung Ha, Soojin Park. Mitigating Gas Evolution in Electron Beam-Induced Gel Polymer Electrolytes Through Bi-Functional Cross–Linkable Additives. Small, 2024; DOI: 10.1002/smll.202401426