Pukyong National University

Pukyong National University Research Team Overcomes Performance Degradation Limits of NCA Cathode Materials for Secondary Batteries

-Professors Ko Min-sung and Chae Soo-jong publish in the international journal <Journal of Materials Chemistry A>

-Developed impurity control technology in microstructure for high-quality NCA cathode implementation

A research team from Pukyong National University has developed a technology that can reduce structural defects and resolve performance degradation issues in NCA(Ni0·80Co0·15Al0·05) cathode materials ― a key component in high-energy-density secondary batteries.

Professors Ko Min-sung (Department of Metallurgical Engineering) and Chae Soo-jong (Department of Energy and Chemical Materials) led the team that developed an ion-exchange-based modification technique capable of removing anionic impurities in NCA precursors, successfully overcoming the structural limitations of conventional manufacturing methods.

This research was published in Volume 13, Issue 23 (2025) of the internationally renowned journal Journal of Materials Chemistry A (IF=9.5), which covers the fields of energy and materials science.

The process developed by the research team effectively removes sulfate ion (SO₄²-)-based impurities ― a major cause of structural instability in conventional synthesis methods ― thereby suppressing the degradation of NCA cathode materials and enhancing their electrochemical stability.

In traditional sulfate-based co-precipitation methods, residual sulfate ions remain within the layered double hydroxide (LDH) structure of the synthesized NCA precursor. During subsequent heat treatment, these sulfate ions react with lithium to form lithium sulfate (Li₂SO₄), which promotes particle agglomeration and inhibits the formation of a stable crystalline structure. This leads to increased side reactions within the electrode and limits lithium-ion diffusion, ultimately resulting in decreased overall electrochemical performance ― a long-standing structural limitation in NCA cathode production.

To address this issue, the research team introduced a novel ion-exchange strategy using chloride ions (Cl-). This method selectively removed sulfate ions, significantly enhancing the crystallinity of the precursor and successfully suppressing the occurrence of side reactions. Due to its simplicity, the process can be easily incorporated into existing manufacturing methods, making it highly practical and scalable for industrial applications.

Experimental results confirmed that the NCA cathode material modified through this ion-exchange approach achieved a capacity of 196.5 mAh/g, demonstrating the stable realization of its inherent performance. Notably, the sulfate ion content ― identified as a major cause of performance degradation ― was reduced by up to 80%, resulting in a more stable crystal structure and uniformly secured lithium-ion pathways, which led to an overall improvement in electrochemical performance.

The modified NCA cathode material recorded an improved initial coulombic efficiency of 91.4%, higher than that of the unmodified material. After 150 charge-discharge cycles, the capacity retention rate also increased by approximately 12%, demonstrating significantly enhanced long-term durability. In high-rate discharge conditions, performance improved by around 11%, indicating better output characteristics as well.

Professor Ko Min-seong stated, “This technology is not limited to NCA cathode materials with a specific composition. It holds great potential for application in various types of cathode systems for secondary batteries. By effectively overcoming the structural limitations that previously hindered the intrinsic performance of NCA materials, further performance enhancements are expected through additional modification processes.”

This research was supported by the National Research Foundation of Korea (Key Research Institute Support Program) and the Korea Institute of Energy Technology Evaluation and Planning (Energy Human Resource Development Program).