Synthesis and electrochemical properties of layered Li[Li(1/3−x/3)CrxMn(2/3−2x/3)]O2 prepared by sol–gel method

The Li[Li(1/3−x/3)CrxMn(2/3−2x/3)]O2 (0.15 ≤ x ≤ 0.3) cathode materials were synthesized by sol–gel process using aqueous solutions of metal acetates and citric acid as the chelating agent. The precipitate of metal citrate was dried in a vacuum oven for 10 h at 100 °C. After drying, the gel precursor was calcined at 300 °C for about 10 h. The resulted powder was ground and heated at 900 °C. The structural characterization was carried out by fitting the XRD data with Rietveld program. The samples exhibited a well defined layered structure and the unit cell parameters linearly increased with increasing chromium contents in Li[Li(1/3−x/3)CrxMn(2/3−2x/3)]O2 Surface morphology was determined by SEM and HRTEM and it is found that the cathode material consisted of highly ordered single crystalline particles with layered-hexagonal structure. Test cells were assembled and cycled in the voltage range of 2.0–4.9 V with a current density of 7.947 mA/g. Electrode with (x = 0.2) delivered a high reversible capacity of around 280 mA h/g in cycling.