Researchers at Worcester Polytechnic Institute, with colleagues in Korea and Illionois, have developed high-entropy lithium-rich layered oxide cathodes (HE-LLO) for Li-ion batteries. A paper on their work is published in Journal of Power Sources.

High-entropy oxides (HEOs) are emerging as promising cathode materials for Li-ion batteries (LIBs) due to their stable solid-state phase and compositional flexibility. Herein, we investigate the structural and electrochemical properties of a novel non-equimolar high-entropy cathode material, termed high-entropy Li-rich layered oxide (HE-LLO, Li_1.15Na_0.05Ni_0.19Mn_0.56Fe_0.02Mg_0.02Al_0.02O_1.97F_0.03), in comparison to a pristine Li-rich layered oxide (PR-LLO, Li_1.2Ni_0.2Mn_0.6O₂). The incorporation of multiple cations (Na⁺, Al³⁺, Mg²⁺, Fe³⁺) and anion (F⁻) into HE-LLO introduces compositional diversity, enhancing structural stability through the entropy stabilization effect.

Theoretical calculations confirm a significantly higher configurational entropy in HE-LLO compared to PR-LLO, supporting its high-entropy nature. Electrochemical evaluations demonstrate that HE-LLO exhibits considerable capacity retention, preserving 76.8 % of its discharge capacity at 0.5C after 200 cycles, compared to only 36.2 % for PR-LLO.

Even under high-temperature conditions, HE-LLO outperformed PR-LLO, maintaining 76.1 % of its discharge capacity after 100 cycles at 5C, while PR-LLO retained only 12.4 %. These enhancements are attributed to the improved phase reversibility and higher Li⁺ ion diffusion coefficients of HE-LLO, validated by ex-situ characterizations using a synchrotron X-ray technique, along with density functional theory (DFT) calculations. These findings highlight the promise of non-equimolar HEOs as a novel design strategy for high-performance cathode materials.

—Kim et al.

Kim et al.

The team said that the challenges faced by layered oxide cathodes can be addressed by introducing the concept of high-entropy—characterized by the incorporation of five or more elements—with configurational entropy meeting or exceeding 1.5R, where R represents the ideal constant (R = 8.314 J/mol·K). The flexibility of combining these elements offers a distinct advantage, allowing for tailored material design to modify the cathode properties. While the high-entropy strategy was initially applied to traditional metal alloys, it has recently been extended to include non-equimolar metal oxides.

Resources

• Jaemin Kim, Songge Yang, Yu Zhong, Geoffrey Tompsett, Seonghun Jeong, Junyoung Mun, Neelam Sunariwal, Jordi Cabana, Zhenzhen Yang, Yan Wang, High-entropy Li-rich layered oxide cathode for Li-ion batteries, Journal of Power Sources, Volume 628, 2025, 235915, ISSN 0378-7753, doi: 10.1016/j.jpowsour.2024.235915