Li3V2(PO4)3 Addition to the Olivine Phase: Understanding the Effect in Electrochemical Performance

Several chemical compositions of (1 – x )LiFePO 4 – x Li 3 V 3 (PO 4 ) 3 with Li 3 V 2 (PO 4 ) 3 decorated LiFePO 4 morphology are synthesized via modified solid-state synthesis. The current study is undertaken to establish a relation between composite formation and their electrochemistry as an excellent cathode material. A detailed physical and structural investigation revealed the formation of a Li 3 V 2 (PO 4 ) 3 decorated LiFePO 4 composite. To investigate the electrochemical performance of LiFePO 4 –Li 3 V 2 (PO 4 ) 3 composites, a series of compositions are prepared with end member of LiFePO 4 and Li 3 V 2 (PO 4 ) 3 . A specific composition of 0.97LiFePO 4 –0.03Li 3 V 3 (PO 4 ) 3 shows a high reversible capacity of ∼163.8 mAh g –1 at 1 C current rate in the potential window of 2–4.5 V. The present study could provide a great physical insight into the stability of solid electrolyte interface and subsequent decrease in charge transfer resistance of composite materials and exhibits an excellent electrode kinetics and electrochemical stability compared to pristine LiFePO 4 . Electrode kinetics is studied at 100% depth of discharge at open circuit potential and continuous charge–discharge cycle by the electrochemical impedance spectroscopy technique. It is observed that the improvement of electrochemical performance is mainly controlled by the Li 3 V 2 (PO 4 ) 3 phase because of its unique three-dimensional open structure. Finally, understanding the physical and electrochemical behavior of the (1 – x )LiFePO 4 – x Li 3 V 3 (PO 4 ) 3 composite electrode is studied that could be useful to design new cathode materials further for lithium ion batteries.