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Ti, Cr dual-element-doped LiMn 1.5 Ni 0.5 O 4 (LNMO) cathode materials (LTNMCO) were synthesized by a simple high-temperature solid-phase method. The obtained LTNMCO shows the standard structure of the Fd 3 ®m space group, and the Ti and Cr doped ions may replace the Ni and Mn sites in LNMO, respectively. The effect of Ti-Cr doping and single-element doping on the structure of LNMO was studied by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) characteristics. The LTNMCO exhibited excellent electrochemical properties with a specific capacity of 135.1 mAh·g -1 for the first discharge cycle and a capacity retention rate of 88.47% at 1C after 300 cycles. The LTNMCO also has high rate performance with a discharge capacity of 125.4 mAh·g -1 at a 10C rate, 93.55% of that at 0.1C. In addition, the CIV and EIS results show that the LTNMCO showed the lowest charge transfer resistance and the highest diffusion coefficient of lithium ions. The enhanced electrochemical properties may be due to a more stable structure and an optimized Mn 3+ content in LTNMCO through TiCr doping., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Recently, nonclassical fullerene derivatives C 66 H 4 and C 70 Cl 6 , which both contain two negatively curved moieties of heptagons, have been successfully synthesized. Inspired by these experimental achievements, the structural and electronic properties of C 66 H 4 , C 70 Cl 6 , Li@C 66 H 4 , F@C 66 H 4 , Li@C 70 Cl 6 , and F@C 70 Cl 6 were systematical studied through density functional theory calculations in this work. Our results show that the reduction of the front molecular orbital gap of fullerene derivatives occurs with the introduction of Li and F atoms. After quantitative analysis of back-donations of charge between an encapsulated atom and an external carbon cage, it is found that C 66 H 4 and C 70 Cl 6 prefer to act as electron acceptors. It is interesting to note that the strong covalent nature of the interactions between a F atom and a carbon cage is observed, whereas the weak covalent and strong ionic interactions occur between a Li atom and a carbon cage. On the other hand, according to the first hyperpolarizability results, the encapsulation of the Li atom enhances the nonlinear optical response of fullerene derivatives. This work provides a strategy to improve nonlinear optical properties of C 66 H 4 and C 70 Cl 6 , reveals the internal mechanism of the contribution from Li and F atoms to endohedral fullerene derivatives, and will contribute to the designation of endohedral fullerene derivative devices., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

A new trend is emerging that flexible batteries will play an indispensable role in the progress of social science and technology. However, flexibility exists only in a single direction for the existing electrode material. Searching for flexible battery materials has attracted more and more attention from researchers. In this article, the lattice structural stability, electronic structure modulation, and the Li adsorption properties of the heterostructures designed by assembling GeP 3 and NbX 2 (X = S, Se) together were methodically explored based on van der Waals. We found that diffusion barrier of the GeP 3 /NbS 2 heterostructure with metallic properties is 0.21 eV for Li. It greatly improves the charge and discharge performance of the battery. The predicted heterostructure shows quite high theoretical specific capacity with 540.24 mA h/g, which is higher than the traditional graphite anode (372 mA h/g). It demonstrates superior isotropic flexibility with a considerable small Young's modulus (151.98-159.02 N/m), which has promising application as flexible electrodes for rechargeable battery equipment., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

The lead-free 0.5(Ba 0.7 Ca 0.3 )TiO 3 -0.5Ba(Ti 0.8 Zr 0.2 )O 3 (BCTZ) ceramics with Er doping have shown good upconversion photoluminescence (PL) and desirable optical temperature sensing properties. To bridge a relationship between the structure/intrinsic defects and properties of rare-earth-doped ferroelectrics, we designed and fabricated a series of BCTZ ceramics doped with 1 mol % Er 3+ by combining the first-principles calculations and experimental measurements. Theoretically, we discovered that Er can occupy both A sites (i.e., replacing Ba or Ca) and B sites (i.e., replacing Ti or Zr) in the BCTZ lattice and highlighted that the Er-doping-induced vacancy concentration decreases for both the oxygen vacancies ( V o ) and cation vacancies ( V c ). Experimentally, the enhanced PL performance and the dielectric, ferroelectric, and piezoelectric properties of the Er-doped BCTZ ceramics have been observed. Finally, the physical origin of Er-induced property enhancement in BCTZ has been elaborated according to the charge density and chemical bonding analysis. These results open up a path to investigate the effects of site substitution and vacancies on optoelectronic properties of multifunctional rare-earth-doped ferroelectrics., Competing Interests: The authors declare no competing financial interest.

Anisotropic two-dimensional materials with direction-dependent mechanical and optical properties have attracted significant attention in recent years. In this work, based on density functional theory calculations, unexpected elastic anisotropy and optical isotropy in van der Waals (vdW) heterostructures have been theoretically proposed by assembling the well-known anisotropic black phosphorene (BP) and transition-metal trisulfides MS 3 (M = Ti, Hf) together. It is interesting to see that the BP/MS 3 vdW heterostructures show anisotropic flexibility in different directions according to the elastic constants, Young's modulus, and Poisson's ratio. We have further unraveled their physical origin of the type-II band structure nature with their conduction band minimum and valence band maximum separated in different layers. In particular, our results on the optical response functions including the excitonic effects of the BP/MS 3 vdW heterostructures suggest their unexpected optical isotropies together with the enhancements of the solar energy conversion efficiency., Competing Interests: The authors declare no competing financial interest.