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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 investigation, a lithium-free cathode material, Na0.7MnO2.05–Na0.91MnO2, was synthesized by the solid phase method. The intercalation mechanism and partial phase transformation mechanism of NMO600 were clarified by in situ X-ray diffraction and impedance. The design of the heterostructure is favourable for improving the lithium ion storage of NMO600, which can deliver a discharge capacity of 83.12 mA h g−1 at 1 A g−1 and keep 61.71 mA h g−1 after 700 cycles. [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]

• LiTiOPO 4 /CeO 2 was synthesized by hydrothermal and solid phase method. • The different valence states of Ce3+/Ce4+ exist in LiTiOPO 4 /CeO 2. • The Ce3+-doped and CeO 2 modified LiTiOPO 4 enhance Lithium-Ion storage. LiTiOPO 4 /CeO 2 composites as high-performance anodes for lithium-ion batteries (LIBs) were synthesized by a simple hydrothermal and high-temperature solid-phase method. X-ray diffraction (XRD) analysis results showed that CeO 2 -motified LiTiOPO 4 was successfully prepared. Electron microscopy observation of the structural and morphological analysis data of the prepared materials further showed that CeO 2 was coated on the surface of LiTiOPO 4. X-ray photoelectron spectroscopy (XPS) showed different valence states of Ce4+/Ce3+ exist in LiTiOPO 4 /CeO 2. The Ce3+-doped LiTiOPO 4 with CeO 2 surface modification was used to enhance lithium-ion storage performance by mediating voltage from 0.01 to 3.0 V. The rate capacity of the LiTiOPO 4 /CeO 2 was maintained at 295.5 mAh g−1. The specific discharge capacity was maintained at 206.5 mAh g−1 after 1000 cycles, at 5 A g−1. The CeO 2 not only significantly enhances ion diffusion and charge transfer, but also reduces polarization, promotes transport of Li+ to more storage sites in LiTiOPO 4. [ABSTRACT FROM AUTHOR]