Fig. 1: Electronegativity entropy weight concept and theoretical validation.
From: Electronegativity and entropy design of layered oxides for sodium-ion batteries
a Stacking layered structure of NaxTMO2. b Relationship between cationic electronegativity and anionic electron cloud. c The two-dimensional differential charge density maps projected along the (001) plane of O3-Na0.667TMO2 (TM: Ni, Cu, Co, Fe, Mn, Ti). The difference charge density (\(\triangle \rho\)) is defined as \(\triangle \rho=\rho ({{{\rm{system}}}})-\rho ({{{\rm{a}}}}{tom})\), where \(\rho ({{{\rm{system}}}})\) denotes the charge density of the system, and \(\rho ({{{\rm{a}}}}{tom})\) is the superposition of atomic charge densities calculated by setting ICHARG = 12. The yellow and blue colors, respectively, represent positive and negative iso-surfaces. The value of the iso-surface is 0.02 e/Bohr3. d Relationship between \({W}_{\chi }\) value and \({\Delta \chi }_{{{{\rm{TM}}}}}\) of statistic P2- and O3-type. e Spearman’s rank correlation coefficient heat map of materials with different configurational entropy. f Distribution of Absolute Spearman Values.
