Influence of sol-gel precursors on the electrochemical performance of NaMn0.33Ni0.33Co0.33O2 positive electrode for sodium-ion battery

Abstract

Among the various cathode materials explored for sodium-ion batteries (SIBs), NaMn0.33Ni0.33Co0.33O2, with a layered oxide structure, is a promising material due to its high theoretical capacity (240 mAhg−1). We have synthesized NaMn0.33Ni0.33Co0.33O2 using two different types of precursors, namely metal acetates and metal nitrates by the sol-gel method. XRD patterns confirm the formation of a stable phase of the material at 900 °C. Coupled TGA-FTIR analysis was used to optimize the calcination conditions and to understand the hydrolysis and condensation mechanism of the sol-gel precursors. FTIR spectra extracted at different temperatures reveal the polymer network-forming tendency of the acetate ligands whereas the polymerization is inhibited in the nitrate precursors. SEM analysis shows spherical and platelet morphologies of samples synthesized from nitrate and acetate precursors, respectively. Using in situ impedance and galvanostatic charge/discharge studies, we observed that the precursors used to synthesize the cathode material influence the electrochemical properties of the material, as in this case, where we observe a 20 % improvement in terms of capacity by using acetate precursors instead of nitrate precursors.