•Hierarchical Li4Ti5O12 particles composed of numerous nanocrystals were prepared.•Li4Ti5O12 particles were co-modified by carbon and nitrogen successfully.•These Li4Ti5O12 particles exhibit excellent performance in lithium-ion batteries.•The amount of C&N-modifying is a critical parameter for improving the final properties.Carbon and nitrogen, (C&N), co-modified hierarchical Li4Ti5O12 (LTO) particles with excellent perfomance in lithium-ion batteries were prepared via a facile synthesis with the proper modifying of C and N successfully reducing the polarization and enhancing the conductivity of LTO while also giving rise to Ti3+ sites due to the reduction ability of C&N. Together, with primary nanocrystals less than 10 nm and a relatively high specific surface area (16.9 m2 g−1), as-prepared samples exhibit excellent electrochemical performance, such as a high capacity around 174.7 mAh g−1 at the current rate of 0.1 C and reversible capacity over 171 and 150 mAh g−1 after 100 cycles at the current rate of 1 and 10 C (1 C = 175 mAh g−1). More importantly, the optimal amount of C&N modifying in LTO was investigated for the first time. It was found that excessive modifying of C&N can introduce a lot of amorphous TiONx and also create undesirable Ti2+ to induce a structural transformation of LTO, directly leading to a low rate capacity.

In this study, Co3O4 with different morphologies (leaf, sheet, and cube) are successfully synthesized by a facile hydrothermal method followed by calcination treatment. Representative samples with different morphological structures are compared and evaluated as anode materials in lithium-ion batteries. Relative to the Co3O4-sheet and Co3O4-cube samples, the Co3O4-leaf samples exhibit excellent electrochemical performance with high storage capacity (1245 mA h g−1 after 40 cycles at 0.1 C) and superior rate capability (0.1, 0.2, 0.5, 1, and 2 C for 1028, 1085, 1095, 1038, and 820 mA h g−1, respectively); interestingly, the thinner the samples are, the better their performance. Moreover, assisted by characterization by cyclic voltammetry and electrochemical impedance spectroscopy, we draw a conclusion that the ultra-thin structures result in shorter path lengths for the transport of lithium ions and electrons, benefiting conductivity and fast charge–discharge rates. More importantly, for Co3O4, the respective structure's degree of thickness has a great effect on the electrochemical performance in lithium-ion batteries. This new concept might be extended to prepare other anode and cathode materials for advanced energy storage and conversion devices.

A series of LiMn1-xVxPO4 samples have been synthesized successfully via a conventional solid-state reaction method. The active materials are characterized by x-ray diffraction, x-ray photoelectron spectroscopy, and scanning electron microscopy. The electrochemical performances of the samples are tested using cyclic voltammetry, electrochemical impedance spectroscopy, and charge/discharge measurement techniques. It is confirmed that the samples are in single phase when the content of vanadium (x) is lower than 0.05. If that content is higher than 0.1, the samples are shown to contain an additional conductive phase of Li3V2(PO4)3. The vanadium doping significantly enhances the electrochemical properties of LiMnPO4. It is underlined that the optimal ratio for a low-vanadium doping with the best electrochemical performance is 0.1 and this material exhibits a corresponding initial charge and discharge capacity of 98.9 and 98.1 mAh g−1 at 0.1 C under 50 °C. The capacity retention is higher than 99 % after 30 cycles. The dramatic electrochemical improvement of the LiMnPO4 samples is ascribed to the strengthened ability of lithium-ion diffusion and enhanced electronic conductivity for the V-doped samples.

Tin dioxide (SnO2) attracts considerable attention as an anode material due to its high theoretical capacity compared with graphite. However, the practical use of a SnO2 anode is significantly hampered by its large volume changes during lithium insertion and extraction processes, which leads to poor cyclic performance. To overcome this problem, a simple and efficient method was employed to fabricate SnO2-based nanocomposites with controlled titanium nitride (TiN) modification. The as-prepared samples were characterized by XRD, Raman, XPS, TEM and electrochemical measurements. Compared with the pristine SnO2, the appropriate TiN modified SnO2 nanocomposite electrodes exhibited improved lithium storage performance. Particularly, the hybrid anode with 2 wt% TiN delivered a high first capacity of 1580.6 mA h g−1 and a stable capacity of 404 mA h g−1 after 50 cycles at a charge–discharge rate of 0.1 C. The improved lithium storage performance was attributed to the inactive TiN matrix, which significantly enhanced the structural stability and electronic conductivity of the SnO2–TiN nanocomposites.