Novel high-entropy oxides for energy storage and conversion: From fundamentals to practical applications

High-Entropy Oxide of (BiZrMoWCeLa)O2 as a Novel Catalyst for Vanadium Redox Flow Batteries

“…These materials incorporate various metal cations within their crystal structure, resulting in intriguing and unexpected functional properties arising from the interactions between different cations. , Moreover, novel synthetic techniques are employed to create this entropy-stabilized oxide system, known as HEO, which rapidly forms uncomplicated solid solution structures due to the high configurational entropy of mixing, as shown in eq . , HEOs consist of at least five metallic elements, each with equal or nearly equal fractions. , Moreover, the rise in configurational entropy causes entropy stabilization of HEOs when configuration entropies exceed 1.5 R . This can enhance the likelihood of stabilizing a single-phase crystal structure, prompting the term “entropy-stabilized oxides” for such materials. , In our materials, we achieved the maximum configuration entropy using the following equation. This resulted in achieving S config = 1.75 R and a single-phase crystal structure. S c o n f i g = − R false[ false( ∑ i = 1 N x i .25em ln nobreak0em0.25em⁡ x i false) c a t i o n ‐ s i t e + false( ∑ j = 1 M x j .25em ln nobreak0em0.25em⁡ x j false) a n i o n ‐ s i …”

“… 18 , 22 HEOs consist of at least five metallic elements, each with equal or nearly equal fractions. 23 , 24 Moreover, the rise in configurational entropy causes entropy stabilization of HEOs when configuration entropies exceed 1.5 R . This can enhance the likelihood of stabilizing a single-phase crystal structure, prompting the term “entropy-stabilized oxides” for such materials.…”

Low-temperature synthesis of high-entropy amorphous metal oxides (HEOs) for enhanced oxygen evolution performance

“…Recently, high-entropy materials (HEMs) have been used as a new class of electrode material for electrocatalytic applications due to their synergistic effect of five or multi-metallic elements, good electrical conductivity, high-entropy effects, and structural stability. 15–17 The material contains at least five principal elements, along with molar configurational entropy ( S config ) greater than 1.5 R, which is represented as the high-entropy material. 18 The general formula used for the calculation of molar configurational entropy is represented aswhere x i and x j represent the mole fraction of elements present in the cation and anion sites, respectively, and R is the gas constant.…”

Li-doped transition metal high-entropy oxides (Li/TM-HEOs) as Li-Ion batteries cathodes: a first report on capacity fading and cycling stability

“…With the availability of a wide range of crystal structures, cations, and combinations, HEOs offer an exceptional opportunity to design and engineer new functional materials. Particularly, rock salt and spinellike crystal structures have shown promise for various energy applications, ranging from conversion to storage [10,[19][20][21].…”