A well-designed CoTiO_3 coating for uncovering and manipulating interfacial compatibility between LiCoO_2 and Li_(1.3)Al_(0.3)Ti_(1.7)(PO_4)_3 in high temperature zone

摘要

The unexpected chemical reaction between LiCoO2 (LCO) and Li1.3Al0.3Ti1.7(PO4)(3) (LATP) in high temperature sintering process was studied by a well-designed stoichiometric ratio method. The species, content, color, interface morphology, element distribution and electrode impedance were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Various electrochemical analyses such as charge/discharge, cycle life test and electrochemical impedance spectroscopy (EIS) were conducted to evaluate the cell performance. Based on the understanding of the interaction between the cathode material (LCO) and the ceramic electrolyte (LATP), the four key steps involved in the reaction mechanism were discussed in detail. We found that the high-temperature chemical reactions between LCO and LATP could be well suppressed by introducing CoTiO3 as an efficient inhibition coating. High-density solid-state electrodes were prepared at high temperature, which exhibited high electrochemical performance in LCO-LATP-LiIn solid-state batteries.