Seoul National University of Science and Technology Boosts Li-ion Battery Performance Using Surface Technology

In a step to advancing the lithium-ion battery technology, a research team led by Prof. Dongwook Han from Seoul National University of Science and Technology (South Korea) developed an innovative technique to enhance the high-voltage LNMO cathodes. By engineering a Li-vacant topotactic subsurface with a protective K₂CO₃ surface layer on cathode particles, they enhanced the stability, longevity and performance of Li-ion batteries. This breakthrough holds a transformative potential for electric vehicles, offering efficient energy solutions.

Image credit: Dongwook Han from Seoul National University of Science and Technology

With the rising global demand for cost-effective sustainable batteries, lithium-ion batteries are at the forefront as energy storage solutions. However, achieving a high energy density with long-term stability in such batteries is essential to extend the usage time of electric devices. LiNi₀.₅Mn₁.₅O₄ (LNMO), known for its thermal stability and cost-effectiveness, is a promising material for high-voltage cathodes. Yet, its application is limited by undesirable side reactions such as electrolyte decomposition, which decreases its performance over time.

In a pioneering study, Prof. Dongwook Han, a professor from Seoul National University of Science and Technology, and his team of researchers introduced a dual engineering approach to enhance the performance of LNMO cathodes. The team engineered Li-vacant subsurface pathways to improve lithium-ion migration and a K₂CO₃-enriched protective layer to protect the cathode from electrolyte decomposition. Their study was made available online on October 10, 2024, and was published in Volume 499 of the Chemical Engineering journal on November 1, 2024.

"To enhance the performance of LNMO cathodes, we introduced a K₂CO3-enriched external surface and a partially delithiated subsurface of LNMO particles through a KOH-assisted wet chemistry method. The synergistic effect of these layers results in a remarkable electrochemical charge/discharge cycling performance and increased thermal stability of LNMO cathodes," says the lead author, Prof. Han.

The surface-engineered cathodes were prepared in a two-step process. First, the regular LNMO (R-LNMO) cathodes were synthesized using co-precipitation-assisted hydrothermal followed by solid-state reactions. The prepared R-LNMO cathodes were then subjected to surface modification by treating the particles with an aqueous solution of KOH. This resulted in the formation of surface-modified LNMO, or simply LNMO_KOH.

The LNMO_KOH and R-LNMO cathode particles were tested for their physicochemical and electrochemical characteristics using advanced techniques. The findings were remarkable, suggesting enhanced thermal stability and better energy storage in the LNMO_KOH particles. The cathodes exhibited a discharge capacity of ~110 mAh/g with 97% capacity retention after 100 cycles, a notable improvement from the 89 mAh/g discharge capacity and the 91% retention of untreated LNMO cathodes. Moreover, the engineered material also showed potential for faster charging with reduced impurities and increased porosity within its structure. 

Reflecting on the broader applications of his study, Prof. Han states, “Our technology is not limited to LNMO but can also be applied to commercial cathode materials, including high-performance Li[Ni1-y-zCoyMnz]O2 (NMC) and LiFePO4 (LFP). We believe this will advance the applications of batteries in large-scale electric vehicles and energy storage systems by enabling high energy density and exceptional safety.”

Seoul National University of Science and Technology I https://en.seoultech.ac.kr/