Effect of a ZrO[sub 2] Coating on the Structure and Electrochemistry of Li[sub x]CoO[sub 2] When Cycled to 4.5 V

Abstract

Recently, Cho et al. studied the effects of a coating on the electrochemical behavior of cells. They found that the capacity retention to 4.4 V was significantly improved for cells having electrodes incorporating coated material compared to those with uncoated They suggested that the thin coating suppressed the lattice expansion of during cycling, leading to improved behavior. Our results on coated with reported here, confirm the improved cycling behavior. X-ray diffraction (XRD) patterns collected with long counting times show that the coated material is nanocrystalline In situ XRD results indicate that the lattice of coated expands and contracts in exactly the same way as uncoated during charge and discharge. These results prove that the coating does not affect the lattice expansion of in contrast to the results reported by Cho et al. We believe that the improved cycling behavior is caused by a reduction in the contact area between and electrolyte. © 2002 The Electrochemical Society. All rights reserved.