Revolutionary Advancement Promises Longevity for Lithium-Ion Batteries

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A team of researchers, headed by Professor Jihyun Hong from the Department of Battery Engineering at the Graduate Institute of Ferrous & Eco Materials Technology within POSTECH, in collaboration with Dr. Gukhyun Lim, has introduced a revolutionary method to improve the longevity of lithium-rich layered oxide (LLO) material, a next-gen cathode substance for lithium-ion batteries (LIBs). This advancement, which markedly prolongs battery life, was documented in the esteemed energy journal Energy & Environmental Science.

Lithium-ion batteries are vital in sectors such as electric vehicles and energy storage systems (ESS). The lithium-rich layered oxide (LLO) material presents up to 20% enhanced energy density compared to traditional nickel-based cathodes by minimizing the content of nickel and cobalt while augmenting the lithium and manganese proportions. As a more cost-effective and sustainable option, LLO has received considerable interest. Nonetheless, issues such as capacity deterioration and voltage decline during cycling have impeded its commercial applicability.

While earlier investigations have pinpointed structural alterations in the cathode during cycling as the reasons for these challenges, the precise causes of instability have remained mostly ambiguous. Moreover, prevailing methods aimed at improving the structural reliability of LLO have not addressed the fundamental issues, hindering commercial use.

The POSTECH team concentrated on the critical influence of oxygen release in destabilizing the LLO structure throughout the charging and discharging phases. They proposed that enhancing the chemical stability of the interface between the cathode and the electrolyte could avert oxygen from being released. Expanding on this concept, they fortified the cathode-electrolyte interface by optimizing the electrolyte composition, which led to a significant decrease in oxygen emissions.

The research group’s improved electrolyte retained an impressive energy retention rate of 84.3% even after 700 charge-discharge cycles, a remarkable enhancement compared to standard electrolytes, which achieved merely an average of 37.1% energy retention after 300 cycles.

The study further indicated that alterations in the surface structure of the LLO material had a considerable effect on the overall stability of the material. By tackling these changes, the team was capable of dramatically enhancing the lifespan and performance of the cathode while also reducing undesirable reactions such as electrolyte decomposition within the battery.

Professor Jihyun Hong remarked, “Utilizing synchrotron radiation, we were able to investigate the chemical and structural distinctions between the surface and interior of the cathode particles. This demonstrated that the stability of the cathode surface is essential for the overall structural integrity of the material and its efficacy. We believe this research will pave the way for advancing next-generation cathode materials.”

Reference: Lim G, Cho MK, Choi J, et al. Decoupling capacity fade and voltage decay of Li-rich Mn-rich cathodes by tailoring surface reconstruction pathways. Energy Environ Sci. 2024;17(24):9623-9634. doi: 10.1039/D4EE02329C

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