A research team led by Professor Hu-Rong Yao from the College of Physics and Energy at Fujian Normal University has made significant progress in the development of layered oxide cathode materials for sodium-ion batteries. Their study introduces an innovative approach that combines electronegativity and configurational entropy to quantify and predict the stacking structures of high-entropy layered oxides.
The performance of layered oxide cathodes (NaₓTMO₂) in sodium-ion batteries is largely determined by their stacking structure—either O3-type or P2-type. While sodium content is traditionally considered the key factor influencing structure type, the relationship becomes increasingly complex in high-entropy or multi-component systems due to the diversity and interactions of transition metals (TMs). Conventional predictors like “cationic potential” prove inadequate in such systems, creating challenges for the rational design of high-performance and structurally stable cathode materials.
To address this, the team proposed a novel physicochemical descriptor: “electronegativity entropy weight (Wχ).” This descriptor integrates ionic electronegativity (IEN) with configurational entropy (S_config) to quantify and predict the stacking structure tendency in high-entropy layered oxides for the first time. Guided by this theoretical framework, the team successfully designed a high-entropy layered oxide cathode material with high Wχ value and a low-sodium-content O3-type structure: Na₀.₆₇Ni₀.₁₈Cu₀.₁₈Fe₀.₁₅Co₀.₁₅Mn₀.₁₇Ti₀.₁₇O₂ (O3-Na₀.₆₇). Remarkably, this material maintains its O3 structure even when sodium content drops to 0.538.
The material exhibits outstanding structural and air stability, excellent cycling performance (retaining 93.02% capacity after 200 cycles), and strong rate capability. It also demonstrates good stability in potassium-ion batteries, suggesting broader applicability. This research provides a novel theoretical framework for the rational design of high-performance electrode materials with complex compositions.
The findings were published on January 8 in Nature Communications, a leading international journal, under the title “Electronegativity and Entropy Design of Layered Oxides for Sodium-ion Batteries.” Fujian Normal University is the first-author affiliation. Master’s student Gan Lu is the first author, and Professor Hu-Rong Yao is the corresponding author. The work was completed in collaboration with Researcher Yu-Guo Guo from the Institute of Chemistry, Chinese Academy of Sciences, and Chuying Ouyang from Contemporary Amperex Technology Co., Limited (CATL).
