Comparison of the La-doped and Gd-doped Li3V2(PO4)3/C via electrochemical tests and first-principle calculations for lithium-ion batteries

Abstract The Li3V2-xMx(PO4)3/C (x=0.01,0.03,0.05; M=Gd, La; abbreviated as LVP-G/C, LVP-L/C) materials were purposely prepared without changing the original of Li3V2(PO4)3/C (abbreviated as LVP/C)through the sol-gel method. Characterization by XRD confirmed that injecting doping makes no difference in the crystal of LVP/C material. The results of the electrochemical performance test showed that both Gd and La doping can effectively improve the electrochemical properties of LVP/C materials to a different extent. Li3V1.97Gd0.03(PO4)3/C and Li3V1.97La0.03(PO4)3/C display the best initial discharge specific capacity of 120.3mAh/g and 117.3mAh/g at 0.1C in the voltage range of 3.0–4.3 V, with a capacity retention rate of 83.8% and 79.4% after 50 cycles. First-principles for assisting the experiment described after doping LVP/C material stability and electrochemical performance. The results show that LVP-G/C is the most stable, and substitute V by Gd or La has a positive effect on the electronic conduction of LVP.