The Effects of Acid Treatment on the Electrochemical Properties of 0.5 Li[sub 2]MnO[sub 3]⋅0.5 LiNi[sub 0.44]Co[sub 0.25]Mn[sub 0.31]O[sub 2] Electrodes in Lithium Cells

The electrochemical properties of electrodes, when preconditioned and activated with acid for , have been studied in lithium cells. Powder X-ray diffraction data and electrochemical measurements provide supporting evidence for an intergrown, composite electrode structure from which can be leached from the component with acid, thereby mimicking the electrochemical charge process at high potentials . The -rich domains generated by acid treatment are reduced during electrochemical discharge at a lower potential than electrochemically generated -rich domains. With prolonged cycling between 4.6 and , plots of untreated and acid-treated electrodes develop similar, but not identical, character, suggesting a coalescence and redox interaction of the manganese ions in -rich and regions of the structure. Acid treatment eliminates the first-cycle capacity loss of the electrodes, consistent with earlier reports for related systems, but it damages their cycling stability and rate capability.