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In order to develop lithium-ion batteries with high energy density, prelithium technology has attracted extensive attention. Li5FeO4was successfully prepared by molten salt method with LiNO3-LiOH mixed lithium salt as reaction medium and lithium source, and nano Fe2O3 as iron source in this work. Li5FeO4 as cathode prelithiation additive is applied to lithium-ion batteries. The synthesis conditions of Li5FeO4 were optimized by orthogonal experiment, and the effect of synthesis conditions on the electrochemical properties of the material was discussed. Li5FeO4 was added to the surface of LiFePO4 positive electrode and assembled with graphite negative electrode to form a full cell. Its effect on the electrochemical performance of the full cells and the mechanism of reducing the initial capacity loss of lithium-ion batteries were studied. The results show that Li5FeO4 cathode prelithiation additives with high purity, small particle size and outstanding electrochemical performance can be prepared by molten salt method. When Li5FeO4 with a mass fraction of 2.8%(based on the percentage of active materials mass) was added, the discharge specific capacity of first cycle for the LiFePO4/graphite full cell was 150 mAh·g-1 at 0.05 C, which was 8.5% higher than that without adding, after 100 cycles at 0.2 C. the capacity still increased by 7.1%, and the irreversible capacity of the svstem was restored.

LiMn2O4 batteries have been widely used as power batteries due to the advantages of high safety, low cost, and higher capacities as compared to their LiFePO4 counterparts. However, their cycling stabilities under elevated temperatures remain a significant challenge in practical applications. We herein report an effective electrolyte additive of (3-(N, N-dimethylamino) diethoxypropyl) pentamethyldisiloxane (DSON) to improve the high-temperature electrochemical performance of LiMn2O4 cells. The LiMn2O4/graphite cell using an optimized addition level of 0.5 wt% shows an increased capacity retention of 56.8% compared to 36.8% for that using the baseline electrolyte after 50 cycles at 60 °C. X-ray photoelectron spectra reveal that DSON compound can also form a robust cathode electrolyte interface on the surface of LiMn2O4 cathode. The dissolution of Mn from LiMn2O4 cathode is effectively suppressed in LiMn2O4/Li cell after 200 cycles at 60 °C, due to the formed cathode electrolyte interface and the inhibited hydrolysis of LiPF6 salt in the electrolyte at the presence of DSON additive. This work demonstrates that DSON is a promising electrolyte additive for improving the cycling stability of LiMn2O4 batteries at high temperatures. [ABSTRACT FROM AUTHOR]

Abstract: V2O5 and Al0.2V2O5 nanoparticles were prepared by an oxalic acid assisted soft-chemical method. X-ray photoelectron spectroscopy confirmed the V5+ oxidation state of V2O5, whereas an intermediate state between V5+ and V4+ of Al0.2V2O5. Raman scattering showed that the Al3+ ions existed in an [AlO6] octahedral environment. The doping of Al3+ increased the cohesion between the V2O5 slabs, which enhanced the structural stability of the material. The chemical diffusion coefficients of the Al0.2V2O5 nanoparticles were a little bit smaller than those of V2O5. Charge–discharge cycling showed that the Al0.2V2O5 nanoparticles exhibited much better capacity retention than the un-doped V2O5, which was attributed to the enhanced structural stability of the material. [Copyright &y& Elsevier]

Abstract: Pure phase of Cr x V2O5 (x =0.05 and 0.1) cathode materials were prepared by an oxalic acid assisted sol–gel method. A combination study of X-ray diffraction, thermogravimetric analysis and Raman scattering confirmed a slight of V4+ ions in both materials. Cyclic voltammetry and galvanostatic charge–discharge cycling were employed to investigate their electrochemical properties. Cr0.1V2O5 exhibited much better electrochemical performance with respect to that of Cr0.05V2O5. The reversible capacities of Cr0.1V2O5 were 200mAhg−1, 170mAhg−1 and 120mAhg−1 after 50 cycles when cycled at C/10, C/2, and 1C rates, respectively. The good electrochemical performance of Cr0.1V2O5 was attributed to its structural stability and high electronic conductivity, both of which were closely related to the high Cr concentration in the material. [Copyright &y& Elsevier]