Improvement of Degradation at Elevated Temperature and at High State-of-Charge Storage by ZrO[sub 2] Coating on LiCoO[sub 2]

A uniform coating on cathode materials for rechargeable lithium batteries was applied by a spray coating technique. The cells showed improved cycle performance and better durability of storing the cell (calendar life) under a high-voltage charging condition (4.2 V-313 K). X-ray diffraction and calorimetric study revealed that no marked change was observed in the bulk properties, such as crystal structure and phase transition, in the cathode during charge and discharge. The suppression of the increase of cathode/electrolyte interfacial impedance was observed by coating. Thus, the improved electrochemical performance in the higher voltage region is ascribed to the stabilization of the interface between the cathode and electrolyte materials.