Different strategies of introduction of lithium ions into nickel‑manganese‑cobalt carbonate resulting in LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode material for Li-ion batteries

Abstract

The new strategies of introducing lithium ions into nickel‑manganese‑cobalt carbonate resulting in LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode material for Li-ion batteries were described. The proposed novel method is based on the co-precipitation of nickel‑manganese‑cobalt carbonate followed by wet impregnation with solutions of selected lithium salts (hydroxide, acetate or nitrate). The results of detailed characterization studies using nitrogen physisorption, TGA-MS, PXRD, SEM and DLS analysis indicate that wet impregnation using different lithium salts formed cathode materials of well-ordered layered structure with chemical composition and microstructure similar to that obtained using solid state reaction method. Galvanostatic cell cycling revealed promising electrochemical activity of all the NMC622 materials prepared using the proposed method. The first cycle discharge capacities of the materials obtained using lithium hydroxide, acetate, nitrate and carbonate are 177, 181, 180 and 187 mAh g−1at 0.05C rate to 4.4 V vs. Li/Li+, whereas the discharge capacity retentions are 88, 91, 93 and 91% at 0.5C rate after 30 cycles, respectively. The best performance in the range of 0.1C-10C rates exhibited the cathode materials synthesized by wet impregnation method using lithium acetate and lithium nitrate as Li ions precursor.