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Heterostructure NaMnO2–Li0.5Mn2O4 cathode materials were prepared by adjusting the molar ratio of sodium in the materials by a solid phase method. X-ray diffraction (XRD) analysis showed that the prepared samples were a layered-spinel heterostructure NaMnO2–Li0.5Mn2O4. The lattice fingerprint region of NaMnO2–Li0.5Mn2O4 was studied by electron microscopy, and the results showed the (111) plane of Li0.5Mn2O4 and the (001) plane of NaMnO2. The heterostructure 0.5NaMnO2–0.5Li0.5Mn2O4 exhibits superior high-rate capability and excellent cycling performance. The proposed heterostructure 0.5NaMnO2–0.5Li0.5Mn2O4 cathode is investigated by in situ XRD and impedance analysis. The rate of discharge of heterostructure 0.5NaMnO2–0.5Li0.5Mn2O4 was 108.8 mA h g−1 at 500 mA g−1. The initial discharge of 0.5NaMnO2–0.5Li0.5Mn2O4 was 61.69 mA h g−1, and after 1000 cycles the discharge capacity remained 51.13 mA h g−1 at a current of 2 A g−1. The heterogeneous structure combines the advantages of high capacity of the layered structure NaMnO2 and the structural stability of the spinel Li0.5Mn2O4, which exert a synergistic effect and improve the electrochemical performance of the lithium-free layered NaMnO2 cathode material. [ABSTRACT FROM AUTHOR]

In this study, polyacrylonitrile and boric acid are used as the nitrogen source and boron source, respectively. The Na3V2(PO4)2F3 cathode material with a carbon layer coated by nitrogen and boron was successfully synthesized by using a mechanical ball milling assisted sol–gel method (represented as NVPF@NBC). Simultaneously, Na3V2(PO4)2F3 materials with single-atom-doped carbon have been successfully prepared in this study by using the same method. Among the above materials, NVPF@NBC exhibits appreciable electrochemical performance because of the synergistic effect of diatoms in carbon. NVPF@NBC shows an outstanding specific discharge capacity of 127.2 mA h g−1 at 0.2C, and the capacity retention after 100 cycles is 97.6%. In particular, NVPF@NBC exhibits a discharge specific capacity of 106.3 mA h g−1 at 5C, and the capacity retention after 500 cycles is 90.59%. The X-ray diffraction analysis of the synthesized materials shows that the NVPF@NBC material has good crystallinity, indicating that the diatoms of N and B do not change the crystal structure of the material. TEM shows that the NVPF@NBC material exhibits uniform distribution of particles and a uniform carbon coating of about 4 nm. Nitrogen–boron co-doping does not influence the valence state of V3+ in the material. The results indicate that the co-doping of nitrogen and boron reinforces the crystallinity of the material and strengthens the sodium storage performance of the material, thereby greatly ameliorating the electrochemical performance of the material. [ABSTRACT FROM AUTHOR]

The heterostructures, xNa0.7MnO2–yLi4Mn5O12(0 < x < 1, 0 < y ≤ 1), were synthesized by a solid-phase method. X-Ray diffraction (XRD) analyses revealed that the as-prepared samples were heterostructures Na0.7MnO2 and Li4Mn5O12. Electron microscopy was used to study the lattice fingerprint area of 0.6Na0.7MnO2–0.4Li4Mn5O12 that showed (111) crystal surface of Li4Mn5O12 and (002) crystal surface of Na0.7MnO2. With different molar ratios of lithium and sodium, Li4Mn5O12 and Na0.7MnO2 in the formed heterostructure will change accordingly, during the synthesis process. The XPS data also showed that Mn3+/Mn4+ in the materials presented different ratios. The heterostructure, 0.6Na0.7MnO2–0.4Li4Mn5O12, exhibits superior high-rate capability and excellent cycle performance. The rate discharge capacity of 0.6Na0.7MnO2–0.4Li4Mn5O12 was maintained at 163.25 mA h g−1 at 500 mA g−1. When cycled at 100 mA g−1, the discharge capacity was maintained at 189.80 mA h g−1 after 50 cycles. The construction of heterostructure can take the advantage of the high capacity of the layered structure of Na0.7MnO2 and the stable spinel structure of Li4Mn5O12, which can form a synergistic effect and improve the electrochemical performance of cathode materials. [ABSTRACT FROM AUTHOR]

The recycling of cathode materials from batteries has an impact on reducing energy consumption. In this study, a green recycling method without secondary pollution was adopted to directly reutilize spent lithium manganate materials. The stripping rate achieved for these spent materials reached 91.1%. This excellent stripping rate was attributed to the synergistic effects of stirring and sonication. The molecular formula of the stripped cathode materials was determined to be LiMn1.85O4. Infrared spectroscopy was used to demonstrate that the organic adhesive in the cathode materials was completely removed after calcination and that the asymmetric stretching peak of the MO6 groups was enhanced. Comparative experiments showed that the electrochemical properties of the re-utilized materials were dramatically improved. The discharge capacity of the sample calcined at 800 °C for 12 h was 131.7 mAh g−1 at the first cycle, and 91.7% of the capacity was maintained after 200 cycles at 0.2C (1C = 148 mAh g−1). Importantly, this recycling strategy not only requires no toxic or hazardous solvents but also has no harmful effects on the environment and reduces waste accumulation effectively, thus providing a new possibility for the recycling of similar batteries. [ABSTRACT FROM AUTHOR]

Europium-modified TiO2 with different valence states was prepared by a hydrothermal method and calcined in air. Microscopic analyses revealed that the average particle size of europium-modified TiO2 nanoparticles is approximately 11.03 nm, and the particle size distribution is narrow. In addition, defects were introduced into TiO2 by doping with europium. X-ray photoelectron spectroscopy (XPS) showed different valence states of Eu3+/Eu2+ in Ti1−xEuxO2 (x = 0.04). A mechanism for europium-modified TiO2 with different valence states is proposed. Europium-modified TiO2 features excellent rate performance and long-term stability. The discharge capacity of Ti1−xEuxO2 (x = 0.04) reached 417.5 mA h g−1 at the initial cycle and retained 219.1 mA h g−1 at 5C after 600 cycles. When it is cycled at 50C, the rate discharge capacity is maintained at 134.9 mA h g−1. The electronic conductivity of TiO2 was significantly improved by doping with different valence states of europium (Eu3+/Eu2+) due to the existence of mixed valence states of Ti4+/Ti3+. [ABSTRACT FROM AUTHOR]

Chemodynamic therapy (CDT) with selective therapeutic and minimal side effects has attracted increasing attention in recent years. Nevertheless, the limited H2O2 and acid contents in the tumor microenvironment suppress the efficiency of the Fenton reaction. To overcome these issues, photothermal therapy (PTT) is employed to amplify the CDT effect and realize synergistic PTT/CDT. Herein, MoS2 sheets are functionalized with copper (Cu2O–MoS2), which integrates enhanced CDT and PTT to combat tumor cells. The 808 nm light activated Cu2O–MoS2 nanoplatform appears to be a potential candidate to improve the synergistic effect on the enhanced Fenton-like reaction and photothermal performance. [ABSTRACT FROM AUTHOR]

A two-step method is developed for the preparation of nanocomposite LiFePO4/C cathode materials for lithium ion batteries. Water is used as a solvent in the sintering process, with Fe(CH3COO)2·4H2O and H3PO4 as the raw materials and citric acid as the carbon source. The synthesis of the resultant grain-size precursor is then performed at 700 °C for 1 h in order to obtain a lithiation reaction precursor via ball milling. The crystal structure and morphology of the samples are characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The electrochemical properties of the material are assessed using charge–discharge and cyclic voltammetry testing. Based on the test results, the discharge capacity of LiFePO4/C reaches 163.3 mA h g−1 in the first cycle, which is close to the theoretical value (170 mA h g−1). After 50 charge–discharge cycles, a capacity of 154.4 mA h g−1 is obtained. The capacity retention ratio is 94.5%. [ABSTRACT FROM AUTHOR]

In this study, (1 −x)LiFePO4·xLi3V2(PO4)3/C (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1) composite cathode materials are synthesized using CH3COOLi·2H2O, Fe(CH3COO)2·4H2O, V2O5, and H3PO4 as starting materials with N,N-dimethyl formamide as a dispersing agent using a novel sol–gel method. The structure, morphology, and electrochemical properties of the composites are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge–discharge measurements. XRD patterns of the compound indicate the coexistence of LiFePO4 and Li3V2(PO4)3. Compared to pristine LiFePO4 and Li3V2(PO4)3, the composite materials exhibit smaller particle size, which can facilitate Li+ extraction and insertion, thereby leading to an improvement in the electrochemical properties. Among all the composites synthesized, 0.8LiFePO4·0.2Li3V2(PO4)3/C exhibits the best electrochemical performance with an initial specific discharge capacity of 158.7 mA h g−1 at 0.1C in the voltage range of 2.5–4.3 V. When the current rate is increased to 5C and 10C, the capacity of 0.8LiFePO4·0.2Li3V2(PO4)3/C is retained at 125.8 and 110.8 mA h g−1, respectively, indicating the cycling stability of the composite. [ABSTRACT FROM AUTHOR]

Six new coordination complexes, [AgL]CF3SO3(1and 2), [Ag2L2](NO3)2·4CH3NO2(3), [AgL]NO3·0.5CH3OH (4), [AgL]BF4(5) and [Cu4L2(OCH3)2(OH)2(NO3)2](NO3)2·0.32H2O (6), were obtained by reactions of the corresponding metal salts with ligand N,N′-bis[4-(4,5-dihydrooxazol-2-yl)-benzyl]ethane-1,2-diamine (L). The results of X-ray crystallographic analysis indicate that complexes 1and 2are supramolecular isomers with a wavelike cationic two-dimensional network structure of 1and a double-stranded helical chain of 2. Complexes 4and 5also have helical chain structures with Pand Mforms. Differing from polymeric structure of 1, 2, 4and 5, complexes 3and 6are a M2L2molecular rectangle and a M4L2cage, respectively. The results show that the flexible ligand L can have different conformation and coordination modes leading to complexes with varying structures. Magnetic data show that there are antiferromagnetic interactions in the dimeric unit of complex 6. [ABSTRACT FROM AUTHOR]