Abstract
With the widespread use of lithium-ion batteries, the cumulative amount of used lithium-ion batteries is also increasing year by year. Since waste lithium-ion batteries contain a large amount of valuable metals, the recovery of valuable metals has become one of the current research hotspots. The research uses electrometallurgical technology, and the main methods used are cyclic voltammetry, square wave voltammetry, chronoamperometry and open circuit potential. The electrochemical reduction behavior of Ni3+ in NaCl-CaCl2 molten salt was studied, and the electrochemical reduction behavior was further verified by using a Mo cavity electrode. It is determined that the reduction process of Ni3+ in LiNiO2 is mainly divided into two steps: LiNiO2 → NiO → Ni. Through the analysis of electrolysis products under different conditions, when the current value of LiNiO2 is not less than 0.03 A, the electrolysis product after 10 h is metallic Ni. When the current reaches 0.07 A, the current efficiency is 77.9%, while the Li+ in LiNiO2 is enriched in NaCl-CaCl2 molten salt. The method realizes the separation and extraction of the valuable metal Ni in the waste lithium-ion battery.
Highlights
No oxidation–reduction reaction occurs, and this range can be used as the scanning range after adding LiNiO2 to the NaCl-CaCl2 molten salt
The electrochemical reduction behavior of LiNiO2 in NaCl-CaCl2 molten salt and on the Mo cavity electrode was investigated by cyclic voltammetry, square wave voltammetry, chronoamperometry and open-circuit potential at 750 ◦ C
The electrochemical reduction process of Ni3+ in the two research systems is an irreversible–quasi-reversible reaction process, and the electro-chemical reduction process is divided into two steps
Summary
The recovery of valuable metals in waste lithium-ion batteries has major significance for the comprehensive utilization of waste resources [3,4]. Previous studies mainly adopted hydrometallurgical technology [5,6,7,8,9,10,11], which realized the recovery and utilization of Ni and other valuable metals through leaching, roasting and other processes. The method has a higher metal recovery and lower energy consumption, the entire process requires excessive acid-base solution and produces too much waste. The biological leaching method [12,13] has problems such as a long cycle and harsh microbial culture conditions. Molten salt electrolysis technology continues to develop, mainly through electro-chemical methods to control the reduction process to prepare metals or alloys
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