Cathode materials with high energy density for Li ion batteries have received great attention due to the high demand in transportation applications. Although several crystal structures have been demonstrated and shown reversible capabilities during lithiation/delithiation processes in cathode of Li ion batteries; oxides with layered/spinel structure still remain the ones that provide higher energy densities.However, higher energy density means the creation of more ionic/electronic defects in both cation and/or anion sublattices of layered/spinel structures. Higher defect concentration in either cation or anion sublattices tend to destabilize its crystal structure. As a result, the phase change is frequently observed in repeatedly cycled cathode. Furthermore, the phase-changing cathode tends to show the capacity fading after cycling tests. Based on defect consideration, the stability of highly defective materials may be enhanced by using dopant and/or better processing routes. In this study, the electrical/electrochemical/structural properties of oxide cathodes will be investigated.First, the electrical measurement of spinel/layered oxides are conducted using sintered disc. Assembled cells using above-mentioned cathode and Li anode with desired liquid electrolyte will be tested and cycled. XPS, SEM and XRD analyses will be conducted on as-assembled as well as cycled cells. The analyzing results will be illustrated based on the processing parameters and defect chemistry of doping ions and the accompanying defects created.