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A cubic Li 5 La 3 Nb 2 O 12 phase with a garnet framework was synthesized by the sol–gel process, in which lithium hydroxide, niobium oxide and acetic lanthanum were used as starting materials, while water was used as solvent. Pure garnet-like Li 5 La 3 Nb 2 O 12 powders were obtained after heating the gel precursor at 700 °C for 6 h with 10 % excess lithium salt. The calcination temperature is nearly 250 °C lower than that by the solid state reaction. The phase transforms from cubic to tetragonal symmetry with loss of lithium at 717 °C, but the garnet framework remains stable to above 900 °C. A pellet annealed at 900 °C for 6 h had a room-temperature Li + -ion conductivity σ Li (22 °C) = 1.0 × 10 −5  S cm −1 , a little higher than that attained by solid-state synthesis. The Li 5 La 3 Nb 2 O 12 compound was chemically stable against two commonly used cathode materials, LiMn 2 O 4 and LiCoO 2 , up to 900 °C and against metallic lithium.

Fused‐ring acceptors based on an electron‐deficient core, such as Y6, have become a successful strategy in bulk heterojunction (BHJ) organic solar cells (OSCs) for high power conversion efficiencies (PCEs). Here, five fused‐ring electron acceptors (Y9, Y9‐2F, Y9‐2Cl, i‐Y9‐2F, i‐Y9‐2Cl) are synthesized using fused dithienothiophen[3,2‐b]pyrrolobenzotriazole and halogenated 1,1‐dicyanomethylene‐3‐indanone (IC) to investigate the effect of end‐group (EG) halogenation and structural isomerism on BHJ photovoltaic performance. Due to the strong electronegativity of halogens, all the acceptors with halogenated terminal units possess redshifted absorption spectra and deeper frontier energy levels compared with Y9. Different from asymmetric molecules i‐Y9‐2F and i‐Y9‐2Cl, Y9‐2F and Y9‐2Cl exhibit slightly lower bandgaps. Moreover, the devices based on fluorinated acceptors show more efficient charge collection, obtaining relatively high short‐circuit current density (J sc) and fill factor (FF). The lowest unoccupied molecular orbital energy levels of halogenated acceptors are similar. As a result, OSCs based on poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithio‐phene))‐alt‐(5,5‐ (1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethyl‐hexyl) benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione))] (PBDB‐T):Y9‐2F obtain more balanced J sc and open‐circuit voltage (V oc), and thus an optimal PCE of 15.49% is demonstrated with a V oc of 0.84 V, J sc of 26.30 mA cm−2, and FF of 70.05%. Five fused‐ring electron acceptors (Y9, Y9‐2F, Y9‐2Cl, i‐Y9‐2F, i‐Y9‐2Cl) were synthesized to investigate the effect of end‐group halogenation and structural isomerism on bulk heterojunction (BHJ) photovoltaic performance. Organic solar cell (OSC) based on Y9‐2F shows the best performance with power conversion efficiency (PCE) of 15.49%, and fill factor (FF) of 70.05%.

Lithium–ion batteries have become a vital component of the electronic industry due to their excellent performance, but with the development of the times, they have gradually revealed some shortcomings. Here, sodium–ion batteries have become a potential alternative to commercial lithium–ion batteries due to their abundant sodium reserves and safe and low-cost characteristics. As power sources for various civilian and military equipment, they have received widespread attention from the scientific research community. However, currently both lithium–ion batteries and sodium–ion batteries have encountered some problems like low electrode energy density and poor cycling efficiency. It is precisely these shortcomings that lead to the current application status of batteries being inadequate. Coincidentally, metal organic frameworks have the characteristics of high surface area, flexible chemical structure, and easy modification, and have been widely used in fields such as gas absorption, drug carriers, and sensors. Its derivatives have also been widely reported as electrode materials for batteries. This article reviews the various application status of metal organic frameworks and their derivatives (oxides, selenides, phosphides and porous carbon) in lithium–ion batteries and sodium–ion batteries. Finally, their limitations and future improvement methods were briefly explained.

In this paper, taking Nb-Mo alloy system as an example, the equations of concentration of characteristic atoms of alloys in BCC structure were obtained on the basis of the idea of systematic science of alloys and the number of coordination atoms. The concentrations of characteristic atoms in B2-NbMo type ordered alloys were calculated as functions of ordering degree(s) and composition xMo. When s=smax, the concentrations of characteristic atoms of stoichiometric B2-NbMo intermetallic compound are equal to that of alloys, that is, Nb8Nb = 0.5 at., x0Mo = 0.5 at. As ordering degree decreases, characteristic atoms A8Nb and A0Mo of B2-NbMo type ordered alloy split. And the degree of splitting of characteristic atoms increases with the ordering degree decreasing. Therefore, disordered alloys and various types of ordered alloys can be designed.

Based on the idea of systematic science of alloys, we derived the interaction equations of binary alloys in BCC structure in this paper. According to the basic information of characteristic atoms sequences and characteristic crystals sequences of Nb-Mo alloy system and the concentrations of characteristic atoms of Nb-Mo alloy system, the properties of DO3-Nb3Mo type ordered alloys, B2-NbMo type ordered alloys and DO3-NbMo3 type ordered alloys and disordered alloys were calculated. The results show that the properties of ordered alloys exhibit stronger variations than those of disordered Nb(1−x)Mox alloys when approaching the stoichiometric ratio, whereas the opposite trend occurs when deviating from the stoichiometric ratio. The main reason is that the ordering degree is maximal at the stoichiometric ratio while it decreases linearly when deviating from stoichiometric ratio. On the contrary, the number of bonding electrons among atoms increases with the simultaneous decreasing of the nearly free electrons, which shortens the bond lengths and thus strengthens the crystal bonding.

Recent advances in material design for organic solar cells (OSCs) are primarily focused on developing near-infrared non-fullerene acceptors, typically A-DA′D-A type acceptors (where A abbreviates an electron-withdrawing moiety and D, an electron-donor moiety), to achieve high external quantum efficiency while maintaining low voltage loss. However, the charge transport is still constrained by unfavorable molecular conformations, resulting in high energetic disorder and limiting the device performance. Here, a facile design strategy is reported by introducing the “wing” (alkyl chains) at the terminal of the DA′D central core of the A-DA′D-A type acceptor to achieve a favorable and ordered molecular orientation and therefore facilitate charge carrier transport. Benefitting from the reduced disorder, the electron mobilities could be significantly enhanced for the “wing”-containing molecules. By carefully changing the length of alkyl chains, the mobility of acceptor has been tuned to match with that of donor, leading to a minimized charge imbalance factor and a high fill factor (FF). We further provide useful design strategies for highly efficient OSCs with high FF.

In this paper, it is pointed out that the descriptions of alloy phase structures are dependent on structural unit sequence. In the systematic science of alloys (SSA), the alloy phase structures are described by means of the symmetry element sequence combining with characteristic atom sequence. It is named the characteristic atom arranging structure, which can display the characteristic atoms at the lattice sites and the micro-inhomogeneity, besides the symmetry. Each characteristic atom has its own characters: neighboring configuration, potential energy, volume and electronic structure. The micro-inhomogeneity of alloy phases can be described by concentrations and short-range ordered parameters of characteristic atoms. The differences between the electronic structures of alloy phases and electronic structures of characteristic atoms in the alloy phases are also discussed.

In this paper, we report low temperature, fast synthesis of Li 6 MLa 2 Nb 2 O 12 (M = Ca, Sr, Ba) with the cubic garnet structure by sol–gel process. The optimized synthesis condition is 775 °C for 6 h with 10% excess lithium salt. The calcination temperature is nearly 125 °C lower than that in the solid state reaction, and the calcination time(~6 h) is shorter than in the solid state reaction(~24 h). Qualitative phase analysis by X-ray powder diffraction patterns combined with the Rietveld method reveals garnet type compounds as major phases. The cubic lattice parameter is found to increase with increasing size of the alkaline earth ions under the same preparation conditions. The density was found to be increasing with increasing ionic radius of the alkaline earth elements. In comparison, the ionic conductivity decreases with decreasing ionic radius of the alkaline earth elements. Among the compounds, the Li 6 BaLa 2 Nb 2 O 12 exhibits the highest ionic conductivity of 1.2 × 10 −5  S cm −1 at room temperature. Graphical Abstract

Using the one-atom theory (OA), the atomic state of Pt-electrocatalyst with fcc structure was determined as follows: [Xe] (5dn)6.48 (5dc)2.02 (6sc)1.48(6sf)0.02. The atomic states of this metal with hcp and bcc structures of primary characteristic crystals and liquid state was also studied. According to its atomic states, the relationship between the atomic states and crystalline structure, catalytic performance and conductivity was explained qualitatively. The potential curve, the temperature dependence of bulk modulus and linear thermal expansion coefficient of fcc-Pt were calculated quantitatively.

A new small molecule acceptor, m‐ITIC‐OR, based on indacenodithieno[3,2‐b]thiophene core with meta‐alkoxyphenyl side chains, is designed and synthesized. The m‐ITIC‐OR film shows broader and redshift absorption compared to its solution and matched energy levels with a hexafluoroquinoxaline‐based polymer donor‐HFQx‐T. Here, polymer solar cells (PSCs) by blending an HFQx‐T donor and an m‐ITIC‐OR acceptor as an active layer deliver the power conversion efficiency (PCE) of 6.36% without any posttreatment. The investigations demonstrate that the HFQx‐T:m‐ITIC‐OR blend films possess higher and more balanced charge mobility, negligible bimolecular recombination, and nanoscale interpenetrating morphology after thermal annealing (TA) treatment. Through a simple TA treatment at 150 °C for 5 min, an impressive PCE of 9.3% is obtained. This efficiency is among one of the highest PCEs for additive free PSCs. This is the first time alkoxyphenyl side chain is introduced into nonfullerene electron acceptor; more interestingly, the new electron acceptor (m‐ITIC‐OR) in this work shows a great potential for highly efficient photovoltaic properties. A new electron acceptor (m‐ITIC‐OR) with meta‐alkoxyphenyl side chains is designed and synthesized. A power conversion efficiency of 9.3% is achieved in nonfullerene polymer solar cells, demonstrating that the meta‐alkoxyphenyl side chain is promising for constructing a high‐performance electron acceptor due to its simplicity and low cost. m‐ITIC‐OR shows a great potential for photovoltaic applications.