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Polymer Nanocomposite-Based Solid Electrolytes for Lithium-Ion Batteries
Published in Prasanth Raghavan, Fatima M. J. Jabeen, Polymer Electrolytes for Energy Storage Devices, 2021
Prasad V. Sarma, Jayesh Cherusseri, Sreekanth J. Varma
Anti-perovskites or inverse perovskites, as the names indicate, have the same structure as perovskite, with the general formula ABX3, but where the cations take the place of the anions and vice versa, generally denoted as A3BX [78]. Unlike the sulfide-type electrolytes, anti-perovskites are stable against contact with Li metal, resulting in low interfacial resistance. Considerable interest in this material took hold with the report on superionic conductivity observed in Li-rich anti-perovskites (LiRAP), which displayed ion conductivities greater than 10−3 S cm−1 at room temperature and activation energies as low as 0.2–0.3 eV [79]. A superionic conductivity of 10−2 S cm−1 was attained when the temperature reached the melting point of the material. Zhao et al. have also prepared a range of anti-perovskites, like Li3OCl, using efficient synthesis methods and have modified the structure by replacing Cl− with Br- or by using mixed anions to raise the tolerance factor for the formation of the more stable pseudo-cubic phase [79]. These kinds of structural reformations bring about the superionic conduction in anti-perovskites through a mechanism called Frenkel interstitial transport. A similar approach was adopted to increase the ionic conductivity by cationic doping in the anti-perovskite, supporting the ionic mobility (“hopping”) through the Schottky channel [79]. In this study, they have obtained ionic conductivities of 0.85×10−3 and 1.94×10−3 S cm−1 for the Li3OCl and Li3OCl0.5Br0.5 anti-perovskites, respectively, at room temperature, which then increased to 4.82×10−3 and 6.85×10−3 S cm−1, respectively, as the temperature was increased to 250°C. The synthesis methods described in this article give a clear idea on tailoring the characteristics of anti-perovskites to the desired values to suit specific practical applications. Goodenough and co-workers [80] reported the fabrication of an all-solid-state LiFePO4/Li battery, using a fluorine-doped Li2(OH)X (X=Cl, Br) anti-perovskite-based solid-state electrolyte. The cells were found to be unstable above 3 V due to the hygroscopic nature of the anti-perovskites. To rectify the moisture instability and the high interfacial resistance problems, polymer composites of these materials, which exhibit all the advantages of the filler and the ion-conducting polymer, can be used as the solid-state electrolyte in batteries. Now, there is ample scope for developing efficient and stable flexible solid-state electrolytes, as recent research has now uncovered a range of doped and undoped anti-perovskites [80, 81], double anti-perovskites [82, 83], and those with superionic conductivities [84] in the range of 10−2–10−1 S cm−1.
Structural, elastic, electronic, and magnetic properties of ferromagnetic inverse-perovskite Pr3InO
Published in Philosophical Magazine, 2022
F. Saadaoui, T. Djaafri, M. Zemouli, F. Z. Driss Khodja, A. Kafi, M. Driss Khodja, A. Djaafri, A. Bendjedid
Antiperovskite alloys are an important class of materials due to their interesting and useful physical properties not found in perovskite compounds, namely superconductivity, giant magnetoresistance (GMR), metal–insulator transition and magnetism [1–11], piezomagnetic effects [12] and giant magnetostriction [13]. Strong electron–electron correlation [14], giant negative thermal expansion [15–17], magnetocaloric effect (MCE) are induced by the strong relationship between lattice, spin and charge [18,19] and optical devices applications [20,21] since these antiperovskites particularly have small band gaps. The antiperovskite and the perovskite alloys have the same structure; however, the anion and cation positions are switched. The antiperovskite alloys are generally depicted by a generic formula M3XY, where M is metal, X = metalloid and Y is B, N, O or C. Synthesis of single crystals of tripraseodinium indium oxide Pr3InO alloy has been realised by a flux of Pr–Cu eutectic mixture at high temperature. The X-ray diffraction diagram of the investigated alloy powder revealed that the product of the reaction was Pr3In with the long-known cubic AuCu3 structure. However, the use of single-crystal X-ray diffraction data confirm that it is rather an oxygen-stabilised inverse-perovskite Pr3InO. This structure is constituted from corner-sharing Pr6O octahedra with the In atoms occupying the cube–octahedral sites [22]. M. Kirchner et al. [23] synthesised the cubic inverse-Perovskite Eu3OIn from the metals and Eu2O3. The crystal structure analysis was realised on single-crystal X-ray diffraction data (space group Pm-3 m). In addition, magnetic susceptibility measurements and X-ray absorption spectroscopic data at the Eu LIII edge show that the compound contains europium in the 4f7 (Eu+2) electronic state. A few theoretical investigations of similar Eu3InO present a ferromagnetic character at 185(5) K and behaves as metallic conductors in electrical resistivity measurements. In 2015, on the other hand, a series of M3TtO (M = Ca, Sr, Ba, Eu; Tt = tetrel element: Si, Ge, Sn, Pb) compounds were studied by means of single-crystal X-ray diffraction experiments [24], and it is found that they are crystallised as ‘ideal’ inverse-perovskites at room temperature. Some compounds similar to Pr3InO are cited in the literature such as (Eu3O)In which is realised by Zahid Ali et al. [25], they revealed that (Eu3O)In was ferromagnetic and magnetoresistive with a metallic nature bonding. Although the cubic anti-perovskite Pr3InO was only manufactured to determine its lattice constants and some characteristic such as electrical conductivity [22], no theoretical or experimental study has been devoted to the electronic and elastic properties of Pr3InO alloy.