On the electrochemical behavior of LiMXFe1 − XPO4 [M = Cu, Sn; X = 0.02] anodes – An approach to enhance the anode performance of LiFePO4 material

An attempt, for the first time, has been made to explore the possible electrochemical activity of partially substituted LiFePO4 as negative electrode for lithium battery applications. In this regard, cationic substitution of Cu and Sn to the native LiFePO4/C electroactive material has been made individually via. ball milling treatment. This simple procedure has resulted in the formation of metal substituted LiFePO4 powders of phase pure nature and finer crystallite size (<1 μm) with better distribution of particles. Herein, 2% of metals such as Cu (transition) and Sn (non-transition) were chosen as dopants with a view to understand the effect of transition and non-transition metals upon LiFePO4 individually. It is interesting to note that irrespective of the nature of the dopant metal, the simple route of cationic substitution via. ball milling endowed with improved conductivity of LiFePO4, as evidenced by the augmented reversible specific capacity values of substituted LiFePO4 anodes. In other words, the LiCu0.02Fe0.98PO4/C anode delivered a reversible capacity of ∼380 mAh/g with an enhancement in the capacity retention behavior and excellent coulumbic efficiency value compared to that of LiFePO4. In contrast, LiSn0.02Fe0.98PO4/C anode displayed an appreciable reversible capacity of ∼400 mAh/g with a significant steady discharge profile. Results of Fourier Transform Infra Red (FTIR) spectroscopy and Cyclic Voltammetric studies of LiMXFe1 − XPO4 (M = Cu, Sn)/C composites are also appended and correlated suitably.