Synthesis and characterization of Na-substituted LiMnPO4 as a cathode material for improved lithium ion batteries

The present study, report the sodium (Na) substituted lithium (Li) in LiMnPO4/C structure as an active material for lithium-ion batteries, and its effect on structure, morphology and electrochemical performances. Sodium with different concentrations has been substituted in the LiMnPO4 system using the solution combustion method. The XRD analysis confirmed a pure orthorhombic structure well indexed, which confirms a good substitution of Li+ ions by Na+. A maximum discharge capacity of 136.7 mAh g−1 was achieved for Li0.97Na0.03MnPO4/C composite cathode material compared to LiMnPO4/C (126.9 mAh g−1) with a coulombic efficiency of 93.8% higher than that of LiMnPO4/C (82.3%). It can be observed that the irreversible loss of capacity has been reduced by adding sodium (x = 0.03) Li0.97Na0.03MnPO4/C compared to LiMnPO4/C. With remarkable stability achieved, for the three doped samples (x = 0.01, 0.03 and 0.05 compared to x = 0.00), during the charge/discharge process.