Simultaneous double membrane electrolysis of sodium sulfate solution and preparation of hydroxide precursor for layered cathode materials

Abstract

In this paper, a material-oriented metallurgical electrolysis strategy, which is of such characteristics as short process, easy procedure, and nonpollution, is proposed to treat sodium sulfate wastewater and simultaneously prepare high value-added cathode material LiNi1/3Co1/3Mn1/3O2 for lithium-ion batteries. The strategy is divided into two parts. First, the Ni1/3Co1/3Mn1/3(OH)2 precursor is obtained by double membrane electrolyzing a mixed solution of Na2SO4, NiSO4, CoSO4, and MnSO4 under the optimum electrolysis conditions (60 °C, 1.0 A). Furthermore, LiNi1/3Co1/3Mn1/3O2 cathode is obtained through solid-sintering desulfurization. The change of sulfur content in the process and its effect on the morphology and electrochemical properties of the materials are investigated. Under optimum desulfurization conditions, the LiNi1/3Co1/3Mn1/3O2 electrode delivers a high initial specific discharge capacity of 195.0 mAh·g−1 and a satisfying capacity retention of 85.0% after 120 cycles at 0.1 C in 2.5–4.5 V. This innovative strategy can realize the comprehensive utilization of sodium sulfate wastewater for preparation of Ni, Co, Mn-contained layered cathode materials.