Lead germanate-graphene nanosheets (PbGeO3-GNS) composites have been prepared by an efficient one-step, in-situ hydrothermal method and were used as anode materials for Li-ion batteries (LIBs). The PbGeO3 nanowires, around 100–200 nm in diameter, are highly encapsulated in a graphene matrix. The lithiation and de-lithiation reaction mechanisms of the PbGeO3 anode during the charge-discharge processes have been investigated by X-ray diffraction and electrochemical characterization. Compared with pure PbGeO3 anode, dramatic improvements in the electrochemical performance of the composite anodes have been obtained. In the voltage window of 0.01–1.50 V, the composite anode with 20 wt.% GNS delivers a discharge capacity of 607 mAh g−1 at 100 mA g−1 after 50 cycles. Even at a high current density of 1600 mA g−1, a capacity of 406 mAh g−1 can be achieved. Therefore, the PbGeO3-GNS composite can be considered as a potential anode material for lithium ion batteries.
Yttrium doped spinel LiMn2−yYyO4 with single phase was synthesized and characterized. The data of the XRD show that the limit for Y solubility is y≤0.02. The beneficial effect of Y is evident by way of improved cyclability. The electrode of LiMn1.98Y0.02O4 shows excellent electrochemical properties with a first discharge capacity of 118 mA·h·g−1 and retaining 98% of the initial capacity after 100 cycles at the current rate 0.2 C.
A nonstoichiometric spinel phase (Li1.02Mn1.90Y0.02O4-yF0.08) was synthesized using natural polymer net method. It was characterized by XRD and XPS. The particle size and shape of the expected compounds were observed by Transmission Electron Microscopy technique. The composition of new spinel phase was checked by ICP. The electrochemical properties of the new spinel phase (Li1.02Mn1.90Y0.02O4-yF0.08) were also investigated. The results showed that the Li1.02Mn1.90Y0.02O4-yF0.08 behaved excellent recharge ability to compare with stoichiometric LiMn2O4. The initial discharge capacity of the battery was 128.5 mAh/g when current density was 1 mA·cm-2 over voltage range of 4.4 to 3.0V. The discharge capacity could retain about 96% after 100 cycles when metallic lithium was anode. The outstanding electrochemical properties of Li1.02Mn1.90Y0.02O4-yF0.08 make it possible as a promising cathode material. The novel synthesis method provides a simple and effective route for inorganic material synthesis.
KMn8O16 nanorods were prepared by a rheological phase method using KMnO4 and Mn (CH3COO)2•4H2O as reactants. The samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that the morphology of the samples was nanorods with a diameter of about 5~15 nm. The electrochemcial testing showed that the KMn8O16 nanorods annealed at 400 °C for 4 h exhibited good lithium storage properties, with a high reversible capability (143 mAh/g at current density of 50 mA/g) and stable lithium-ion insertion/de-insertion reversibility.
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