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Since LiFePO _4 batteries play a major role in the transition to safe, more affordable and sustainable energy production, numerous strategies have been applied to modify LFP cathode, with the aim of improving its electrochemistry. In this contribution, a highly vanadium-doped LiFe _0.9 V _0.1 PO _4 /C composite (LFP/C-10V) is synthesized using the glycine combustion method and characterized by x-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Thermogravimetry Differential Thermal Analysis (TGDTA) and Cyclic Voltammetry (CV). It is shown that 10wt.% of vanadium can substitute Fe positions, thus decreasing unit cell volume, which is followed by generation of Li _3 V _2 PO _4 traces, as detected by CV. High vanadium doping does not change the carbon content in the composite (≈13 wt%) but improves its electronic conductivity and electrochemical performance in both aqueous and organic electrolytes. The reversibility and current response are increasing following the trend: LFP/C, LFP/C -3mol%V, LFP/C - 5 mol % and LFP/C-10 mol %. The best specific capacity is obtained for the most highly doped olivine, which exhibits a reversible process at 1 mV s ^−1 in an aqueous electrolyte, thus showing a peak-to-peak distance of 56 mV. The high capacity of LFPC-10V is measured in both LiNO _3 and NaNO _3 electrolytes amounting to around 100 mAh g ^−1 at 20 mV s ^−1 . Still, the material is only stable in LiNO _3 electrolyte, making it more suitable for Li than Na-ion aqueous rechargeable batteries. |
