‘Capture the oxygen!’ The key to extending next-generation lithium-ion battery life

Lithium-ion batteries are indispensable in applications such as electric vehicles and energy storage systems (ESS). By reducing the content of nickel and cobalt while increasing the content of lithium and manganese, the energy density of lithium-rich layered oxide (LLO) materials is 20% higher than that of traditional nickel-based cathodes. LLOs are gaining traction as a more economical and sustainable alternative. However, challenges such as capacity fading and voltage fading during charge-discharge cycles hinder its commercial viability.

While previous studies have identified structural changes in the cathode during cycling as the cause of these problems, the exact reasons behind the instability remain unclear. Furthermore, existing strategies aimed at enhancing the structural stability of LLOs fail to address the root causes hindering commercialization.

The POSTECH team focused on studying the key role of oxygen release in destroying the structural stability of LLO during the charge and discharge process. They hypothesized that improving the chemical stability of the interface between the cathode and electrolyte would prevent oxygen release. Based on this idea, they enhanced the cathode-electrolyte interface by improving the electrolyte composition, thereby significantly reducing oxygen emissions.

The research team’s enhanced electrolyte can maintain an energy retention rate of up to 84.3% even after 700 charge-discharge cycles, which is a significant improvement over the average energy retention rate of traditional electrolytes of only 37.1% after 300 cycles.

Research also shows that structural changes on the surface of LLO materials have a significant impact on the overall stability of the material. By addressing these changes, the team was able to significantly increase the cathode’s lifetime and performance while minimizing unwanted reactions such as electrolyte decomposition inside the battery.

Professor Jihyun Hong commented: “Using synchrotron radiation, we were able to analyze the chemical and structural differences between the surface and interior of the cathode particles. This shows that the stability of the cathode surface is critical to the overall structural integrity of the material. We believe this The research will provide new directions for developing next-generation cathode materials.

This research was supported by the Ministry of Trade, Industry and Energy through the Korea Technology Agency and the Ministry of Science and Information and Communications Technology through the National Research Foundation of Korea until 2024.