Electrochemical mechanism of recovery of nickel metal from waste lithium ion batteries by molten salt electrolysis

Abstract

With the widespread use of lithium-ion batteries, the cumulative amount of used lithiumion 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.