SK On presents its latest research and development successes in solid-state batteries. The battery manufacturer sees great potential in photonic sintering technology that uses intense light energy to produce solid electrolyte, which is familiar from printed circuit board manufacturing.
SK On is working with Korean universities and institutions on solid-state battery research – and claims to have recently published important findings from its development projects in renowned journals. The company reports that patent applications have also been submitted for several research results at home and abroad. The South Koreans’ main focus was further improving solid-state batteries’ cycle life and further developing the manufacturing process. The keywords here are ‘photonic sintering technology’ and ‘LMRO cathode materials.’
Photonic sintering is a process in which intense light energy is used to strengthen the bond between powder particles, resulting in a solid mass with increased strength, durability and improved material properties. With a research group from the Korea Institute of Ceramic Engineering and Technology, SK On transferred this technology, traditionally used for producing printed circuit boards, to manufacturing oxide-rich inorganic-organic hybrid solid electrolytes.
Hybrid because solid electrolytes are broadly categorised into sulphide-based, oxide-based and polymer-based types, and in the research work in focus here, oxide-based materials were combined with a gel polymer electrolyte through photonic sintering. “Experimental results showed that batteries using this hybrid electrolyte demonstrated excellent cycle life,” writes SK On. The approach differs significantly from the previous process: “Oxide-based electrolyte materials typically require high-temperature heat treatment at over 1,000 degrees Celsius for more than 10 hours. However, productions costs, along with challenges such as brittle fractures*have posted significant obstacles to scalability,” explains SK On. Photonic sintering, on the other hand, is faster and takes place at low temperatures.
To improve the photonic sintering process, the research team first identified inorganic dyes that minimise energy loss through exposure to light and applied them to oxide electrolyte materials. According to the battery manufacturer, the use of sintering technology made it possible to create a porous microstructure with optimum uniformity.
In another study, SK On and a team from Seoul National University investigated the potential of lithium- and manganese-rich layered oxide cathodes (LMRO cathodes) for sulphide-based solid-state batteries. The South Koreans provide the following introduction to the topic: “LMRO cathode materials are cost efficient because they are based on manganese, which is cheaper than nickel and cobalt. However, when used with liquid electrolytes in conventional lithium-ion batteries, LMROs face challenges like gas generation, voltage decay and capacity loss, prompting efforts to explore their use in [all-solid-state batteries] ASSBs.”
Through various analyses, the group found that oxygen released during charging and discharging under high-temperature and high-voltage conditions oxidises the sulphide solid electrolyte, leading to a deterioration in performance. To overcome this problem, the team developed a special coating material that suppresses the release of oxygen and increases the life of the battery.
“These achievements are the result of SK On’s proactive R&D efforts and exceptional technical capabilities, creating synergy with experts from academia and institutions,” says Kisoo Park, Head of SK On’s R&D Division. “We will remain committed to advancing R&D to drive leadership in the next-generation battery sector.”
SK On is currently developing two types of solid-state batteries: a polymer-oxide composite variant and a sulfide-based variant, with commercial prototypes expected by 2027 and 2029, respectively. The company’s solid-state battery pilot plant, which is currently being built at the Korean research centre in Daejeon with the help of Solid Power, is scheduled for completion in the second half of 2025.
SK On regularly publishes updates on its R&D progress. Last summer, for example, the company announced that it had created a solid polymer electrolyte for lithium metal batteries that can be operated at room temperature.
