Nitrate-melt synthesized HT-LiCoO₂ as a superior cathode-material for lithium-ion batteries

Abstract

An electrochemically-active high-temperature form of LiCoO₂ (HT-LiCoO₂)is prepared by thermally decomposing its constituent metal-nitrates at 700°C. The synthetic conditions have been optimized to achieve improved performance with the HT-LiCoO₂cathode in Li-ion batteries. For this purpose, the synthesized materials have been characterized by powder X-ray diffraction, scanning electron microscopy, and galvanostatic charge-discharge cycling. Cathodes comprising HT-LiCoO₂ exhibit a specific capacity of 140 mAhg^-1 with good capacity-retention over several charge-discharge cycles in the voltage range between 3.5 V and 4.2 V, and can sustain improved rate capability in contrast to a cathode constituting LiCoO² prepared by conventional ceramic method. The nitrate-melt-decomposition method is also found effective for synthesizing Mg-/Al- doped HT-LiCoO₂; these also are investigated as cathode materials for Li-ion batteries.