Preparation of orthorhombic LiMnO2 material via the sol–gel process

Orthorhombic LiMnO2 was synthesized via the sol–gel process using citric acid as a chelating agent. The effect of varying the molar acid to metal ions ratio (R) on the structural and electrochemical properties of the synthesized compound was studied. Samples with high R (R=1,2) contain large amount of MnO impurity phase, which is electrochemically inactive and thus is detrimental to the electrochemical activity of the electrode. Therefore, the acid to metal ions ratio “R” should not be high. Samples with low R (R=0.5) exhibited a high initial capacity, above 190 mAh/g when cycled at a current density of 0.4 mA/cm2 at room temperature. The ac impedance results show that the initial capacity was improved (compared with ss-o-LiMnO2) due to the smaller particle size and good homogeneity, which improves the Li+ diffusion in the cathode.