Improved electrochemical stability of Zn-doped LiNi 1/3Co 1/3Mn 1/3O 2 cathode materials

Abstract

Highly stable Li(Ni 1/3Co 1/3Mn 1/3) 1-xZn xO 2 (x=0, 0.02, 0.05) cathode materials doped with Zn are synthesized by solid-state reactions with co-precipitated precursors. Cyclic voltammetry (CV) curves reveal that the potential difference between oxidation and reduction decreases to 0.09 V, and from electrochemical impedance spectra (EIS) curves, the impedance of LiNi 1/3Co 1/3Mn 1/3O2 cathode materials is reduced from 266 to 102 Ω. The diffusion coefficients of Li + ions in intercalation processes increase from 1.20×10 -11 to 2.54×10 -11 cm 2· s -1. Li(Ni 1/3Co 1/3Mn 1/3) 0.98Zn 0.02O 2 is stable at 0.3C (constant charge/discharge) at a high cut-off potential of 4.6 V vs Li/Li +. It has a second discharge capacity of 176.2 mAh· g -1 at 0.3C and 142 mAh· g -1 at 3C, and keep almost no decay after 100 cycles at room temperature. Furthermore, its average capacity loss per cycle at 55 ° C is 0.20%, which is lower compared with 0.54% for LiNi 1/3Co 1/3Mn 1/3O2 and 0.38% for Li(Ni 1/3Co 1/3Mn 1/3) 0.95Zn 0.05O 2 after 100 cycles. The improved electrochemical stability of Zn-doped LiNi 1/3Co 1/3Mn 1/3O2 is attributed to the reduced electrode polarization and impedance values, and an increased Li + ion diffusion coefficient. © Editorial office of Acta Physico-Chimica Sinica.