Search

Ni-rich transition metal-based oxide materials have excellent electrochemical properties that make their specific discharge capacity and voltages suitable as cathodes in Li-ion batteries. The current investigation uses solid-state synthesis to create a variety of Ni-rich metal oxide cathode materials, including vanadium (V) and zinc (Zn) co-doped LiNiO2. XRD analysis demonstrates that the synthesized materials exhibit a stable hexagonal structure with an R3m space group. Scanning electron micrographs (SEM) reveal the production of well-shaped particles with different doping concentrations, while energy-dispersive spectroscopy (EDS) mapping validates the presence of Ni, V, Zn, and O with the appropriate compositions. Selected area electron diffraction (SEAD) and transmission electron microscopy (TEM) confirm that the synthesized polycrystalline LiNi0.80Zn0.06V0.14O2 cathode material has crystals organized in a hexagonal phase. Structural properties are also calculated by density functional theory (DFT) using Wien2K code. The spin-polarised electronic band structures and density of states (DOS) are calculated for all given compounds showing the ferromagnetic nature. The theoretical discharge capacity and intercalation voltages are determined by adding up the total energies of the optimized compounds. It claimed that LiNi0.52Zn0.16V0.32 O2 has a discharge capacity of 48–246 mAhg−1 with an intercalation voltage of 5.77–3.35 V, proving significant improvement in the redox properties. Theoretical calculations and experimental results both examined Ni-rich co-doped V and Zn transition metal oxides as potential materials for the fabrication of coin cells in future batteries. [ABSTRACT FROM AUTHOR]

In this paper, dual doped Li2Fe0.98Ag0.02(SiO4)1 − x(PO4)x/C and Li2Fe0.98Ag0.02(SiO4)1 − x(BO3)x/C (x = 0.01, 0.02, 0.03, 0.05) materials were synthesized by high temperature solid state method. Among all the materials dual-doped with Ag+ and PO43−, the initial discharge capacity of Li2Fe0.98Ag0.02(SiO4)0.97(PO4)0.03/C is the highest, which is 167.7 mAh/g, which is equivalent to 1.01 Li+ deintercalation, and its lithium-ion diffusion coefficient is also the largest. For the materials dual-doped with Ag+ and BO33−, the initial discharge capacity of Li2Fe0.98Ag0.02(SiO4)0.99(BO3)0.01/C is the highest , which is 150.8 mAh/g. After 10 cycles of charging and discharging at 0.1 C, the capacity becomes 131.2 mAh/g, and the retention rate is 87%. The above-mentioned materials which have good electrochemical performance were analyzed by SEM and XRD. According to the SEM images, no obvious agglomeration was found in Li2Fe0.98Ag0.02 (SiO4)0.97(PO4)0.03/C and Li2Fe0.98Ag0.02 (SiO4)0.99(BO3)0.01/C. Meanwhile, XRD analysis showed that the overall structure is still Li2FeSiO4 with monoclinic structure, but there are traces of Li2Fe3O4 characteristic peaks. [ABSTRACT FROM AUTHOR]

In this paper, the solid-phase method is adopted in the synthesis of Li2Fe0.98Mg0.02(SiO4)1−x(PO4)x/C and Li2Fe0.98Mg0.02(SiO4)1−x(BO3)x/C (x = 0.01, 0.02, 0.03, 0.05). The Li2Fe0.98Mg0.02(SiO4)0.97(PO4)0.03/C has an initial discharge capacity of 170.4 mAh/g. The initial discharge capacity of Li2Fe0.98Mg0.02(SiO4)0.95(PO4)0.05/C is 152 mAh/g. After PO43− is doped at the Si site, a peak appears at 3.1 V in the oxidation curve of the CV graph, indicating that more Li+ participate in the electrochemical reactions, which finally increases the peak area and the capacity of the modified material. The initial discharge capacity of Li2Fe0.98Mg0.02(SiO4)0.97(BO3)0.03/C is 138 mAh/g. The SEM shows the particle sizes of those two materials are uniform. According to the XRD, there is a weak characteristic peak of Li2Fe3O4 impurity found in the Li2Fe0.98Mg0.02(SiO4)0.97(BO3)0.03/C, while no characteristic peak of impurity is found in the Li2Fe0.98Mg0.02(SiO4)0.95(PO4)0.05/C, and its cell volume increases slightly which is beneficial to improve the electrochemical performance of the material. [ABSTRACT FROM AUTHOR]

In this research, the Pr-doped LiNi0.8Co0.1Mn0.1O2 material was prepared successfully via the solid-state method. The significant improvement on the material structural stability was confirmed by the experimental results (XRD, SEM, and XPS, etc.). What's more, the Pr-2500 sample exhibited the best electrochemical performance with the capacity retention rate 94.43% (3.0–4.4 V, 1 C (180 mA g−1), 25 °C, after 100 cycles), while the capacity retention rate of the Pristine was only 83.40%. Furthermore, the degree of the electrochemical polarization and the electrochemical impedance were reduced after modification. The excellent electrochemical properties were ascribed to the higher structure stability after modification, and the more stable structure may benefit from the higher bond dissociation energies (753 kJ mol−1) of Pr-O. [ABSTRACT FROM AUTHOR]

The Li2FeSiO4/Agx and Li2FeSiO4/Znx (x = 0.01, 0.02, 0.03, 0.05) were synthesized through high-temperature solid-state method. Constant current charging-discharging, cyclic voltammetry, and electrochemical impedance spectroscopy analysis were conducted on the materials mentioned above. According to the test data, the Li2FeSiO4/Ag0.02 shows stable electrochemical performance, and the initial discharge capacity is 161.2 mAh/g. After 10 cycles at 0.1 C, its capacity retention ratio is 91.4%. The diffusion coefficient of Li+ is higher than pure-phase materials by one order of magnitude, and it also has lower charge transfer resistance. The initial discharge capacity of Li2FeSiO4/Zn0.02 is 147.5 mAh/g, and its capacity could sustain at 118.4 mAh/g after 10 cycles at 0.1 C. The diffusion coefficient of Li+ is an order of magnitude higher than that of pure-phase materials. It can be observed from the SEM image that the particle size of the Li2FeSiO4/Ag0.02 is relatively uniform, and there is no obvious agglomeration. It can be seen from the XRD spectrum that there is no impurity peak in Li2FeSiO4/Ag0.02 while the characteristic peak of Li2Fe3O4 could be found in the Li2FeSiO4/Zn0.02. The cell volume of the Li2FeSiO4/Ag0.02 increases and is larger than that of the pure-phase material. [ABSTRACT FROM AUTHOR]

Li2FeSi0.98M0.02O4/C (M = Ti, Ag, Cu, V, Pb) was synthesized as cathode material for lithium-ion battery by the solid-state method. The electrochemical performance of Li2FeSi0.98M0.02O4/C was investigated by constant current charge–discharge test, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results show that the materials doped with Ti or Ag at the Si site deliver good initial discharge capacity. Li2FeSi1-xMxO4/C (M = Ti, Ag; x = 0.01, 0.02, 0.03, 0.05) was synthesized via the solid-state method. By comparing the electrochemical properties, it can be observed that Li2FeSi0.98Ti0.02O4/C and Li2FeSi0.98Ag0.02O4/C have good initial discharge capacity. The initial discharge capacity of Li2FeSi0.98Ti0.02O4/C is 164.1 mAh/g, which is equivalent to 0.98 Li+ deintercalation. The capacity of Li2Fe0.98Ti0.02SiO4/C is 155.8 mAh/g after 10 cycles under 0.1 C, and the capacity retention rate is 94.9%. The initial discharge capacity of Li2FeSi0.98Ag0.02O4/C is 166.6 mAh/g, which is better than other materials. The capacity of Li2Fe0.98Ag0.02SiO4/C is 132.8 mAh/g after 10 cycles under 0.1 C, and the capacity retention rate is 79.7%. The charge–discharge cycle performance of Li2FeSi0.98Ti0.02O4/C is more stable than Li2FeSi0.98Ag0.02O4/C. The Li+ diffusion coefficient of Li2FeSi0.98Ti0.02O4/C is higher than that of pure phase material by two orders of magnitude. The Li2FeSi0.98Ti0.02O4/C and Li2FeSi0.98Ag0.02O4/C were tested by XRD and SEM. The XRD patterns show that there are no characteristic peaks of Fe or Li2SiO3 impurities in the materials, which indicates that the crystal structure of Li2FeSiO4 has not been changed after doping metal ion at the Si site. The SEM images indicate that the particle size of materials is quite uniform and no obvious agglomeration is detected in the materials. Li2FeSi0.98Ti0.02O4/C was analyzed by EDS, ICP, XPS, and FT-IR spectra since it delivers better performance when compared with other materials. EDS and ICP show that the values which were measured according to the ratio of each element are found to be similar to the theoretical values. The XPS spectrum confirms the existence of the characteristic peaks of Li, Fe, Si, and O in samples, which could also prove that Si4+ is successfully replaced by Ti4+ in the crystal structure of Li2FeSiO4. The position of each absorption peak in the infrared spectrogram coincides with that reported in the literatures, which indicates that the stable materials are formed. [ABSTRACT FROM AUTHOR]

Li2Mn4O9 and molybdenum-doped Li2Mn4O9 have been prepared by simple solid-state method. Molybdenum is used as a dopant since it is resistant to both corrosion and high-temperature creep deformation. The structural, morphological, and electrical performances of the samples have been analyzed. The material exhibits a cubic structure with the fd3m space group. Using EDAX, the chemical compositions of the samples have been identified. The dc electrical conductivity of the Mo-doped (LM2) sample is found to be increased to 7.44 × 10−6 S cm−1 at 393 K. The enhanced electrical property of the molybdenum-doped Li2Mn4O9 reveals it as a feasible cathode material for rechargeable Li-ion batteries. [ABSTRACT FROM AUTHOR]

In this present work, we have successfully synthesized highly pure phases of Na6Mg1-xCox (SO4)4 vanthoffite powder ceramics denoted as NMCoSx using the solid-state reaction method. Refinement of structural parameters confirmed that the Co2+ dopant can replace the magnesium in this structure with a slight increase of the lattice parameters. The spectroscopic studies by means of infrared (IR) and visible (Vis) spectroscopies revealed the vibrational mode of sulfate groups and verified the amount of cobalt inserted in the host lattice. Electrical conductivity was studied by impedance spectroscopy in the [553-733 K] temperature range and results show that the materials present a semiconductor ionic character and the conductivity increases when the Co2+ dopant content x increases. Results also show that at low temperatures, NMCoSx (x = 0.5) has the highest electrical conductivity representing a candidate that may be used as an electrode in sodium-ion batteries. [ABSTRACT FROM AUTHOR]

In this paper, Li2Fe1−yMgySiO4/C (y = 0, 0.01, 0.02, 0.03, 0.05), a cathode material for lithium-ion battery was synthesized by solid-state method and modified by doping Mg2+ on the iron site. The effects of Mg2+ doping on the crystal structure and electrochemical performance Li2FeSiO4 was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical tests. Electrochemical methods of measurement were applied including constant current charge-discharge test, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), to determine the electrochemical performance of the material and the optimal doping ion and ratio. The results showed that Li2Fe0.98Mg0.02SiO4/C has the higher specific capacity and better cycle stability as well as lower impedance and better reversibility. The enhanced electrochemical performance can be attributed to the increased electronic conductivity, the decreased charge transfer impedance, and the improved Li-ion diffusion coefficient. Then, further study on the synthesis conditions was performed to find the optimal combustion temperature and time. According to the study, the material which has the best electrochemical performance, shows initial discharge specific capacity of 142.3 mAh g−1 at 0.1 C (1 C = 166 mA g−1) and coulomb efficiency of 95.6%, under the condition that the temperature is 700 °C and the calcining time is 10 h. [ABSTRACT FROM AUTHOR]

The layered LiMnNiCoO lithium-rich manganese-based solid solution cathode material has been synthesized by a simple solid-state method. The as-prepared material has a typical layered structure with R-3m and C2/m space group. The synthesized LiMnNiCoO has an irregular shape with the size range from 200 to 500 nm, and the primary particle of LiMnNiCoO has regular sphere morphology with a diameter of 320 nm. Electrochemical performances also have been investigated. The results show that the cathode material LiMnNiCoO prepared at 900 °C for 12 h has a good electrochemical performance, which can deliver a high initial discharge capacity of 233.5, 214.2, 199.3, and 168.1 mAh g at 0.1, 0.2, 0.5, and 1 C, respectively. After 50 cycles, the capacity retains 178.0, 166.3, 162.1, and 155.9 mAh g at 0.1, 0.2, 0.5, and 1 C, respectively. The results indicate that the simple method has a great potential in synthesizing manganese-based cathode materials for Li-ion batteries. [ABSTRACT FROM AUTHOR]

Spinel structured LiTiO was synthesized by a solid-state method using TiO and LiCO as starting materials. High-energy ball milling was used to obtain the LiCO samples with different particle size. Then, the effects of LiCO particle size on the structure, morphology, and electrochemical performance of LiTiO samples were investigated in detail. The samples were characterized by TG/DTA analysis, X-ray diffraction, scanning electron microscopy and electrochemical tests, respectively. The results indicate that fine LiCO particles will promote the interfacial reaction between LiCO and TiO in solid-state reaction. The crystallinity and particle size of LiTiO depend on the particle size of LiCO. Electrochemical tests show that LiTiO samples synthesized by fine LiCO particles exhibit better rate capacity and cycle performance. [ABSTRACT FROM AUTHOR]

The titanate spinel LiNiTiO is proposed for the first time as a new anode for lithium-ion batteries and successfully synthesized via a facile ball-milling assisted solid-state reaction method. The sample is characterized by X-ray diffraction patterns (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), galvanostatic charge-discharge tests, cyclic voltammetry (CV) tests, and electrochemical impedance spectroscopy (EIS). The results reveal that the LiNiTiO nanoparticles have well-distributed morphology, and the particle size ranges between 100 and 300 nm. Although the initial coulombic efficiency is only 56.3 %, the LiNiTiO electrode still exhibits a high rate capability and excellent cycling stability. The LiNiTiO anode provides a large capacity of 212.3 mAh g at 0.1 A g after 10 cycle, which is close to its theoretical capacity (223.6 mAh g). Even after 100 cycles, it still delivers a quite high capacity of 203.98 mAh g, with no significant capacity fading. This indicates that the as-synthesized LiNiTiO material is a promising anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]