리튬이온전지 양극활물질 NCA(LiNiCoAlO2) 공정부산물로부터 수산화리튬과 유가금속 회수 연구

Abstract

Lithium ion batteries are widely used throughout real life and industry due to their high output and high energy density. The cathode active material, which greatly affects the performance of a lithium ion battery, determines the capacity and average voltage of the battery as a storage of lithium ions. LCO (LiCoO2)-based cathode active materials have been used in most small electronic devices such as smartphones and laptops. Research is progressing in the direction of high power and high energy density. Currently, major countries are encouraging the production and distribution of eco-friendly electric vehicles by strengthening automobile fuel efficiency regulations and carbon dioxide emission standards. It is expected that more than 30% of global vehicles will be electric vehicles by 2040, and a rapid increase in supply is expected accordingly. Accordingly, it is expected that the number of batteries will exceed 80,000 after using domestic electric vehicles in 2029, and it is predicted that there will be problems with battery disposal after rapidly increasing use. Currently, recycling of used lithium ion batteries is mostly a process of leaching valuable metals using acid or alkali, which may cause secondary environmental pollution as well as treatment costs due to process by-products such as waste liquid. Therefore, in this study, research was conducted to develop an eco-friendly dry process for recovering lithium and valuable metals from lithium ion battery cathode active materials, and H2 thermal reaction, water leaching, and magnetic separation from process by-products of lithium ion battery cathode active materials NCA (LiNiCoAlO2). Lithium hydroxide, Ni, and Co were recovered through the process. First, NCA was phase-separated and reduced through H2 thermal reaction, and at this time, the effect of reaction temperature and holding time was investigated. Second, the phase-separated Li, Ni, and Co were water-leached using the difference in solubility in water, followed by filtration and drying to recover lithium hydroxide powder. At this time, the effect of water leaching time and solid-liquid ratio was investigated. Finally, Ni and Co mixture powders, which are water leaching residues, were separated through magnetic separation. As a result, lithium hydroxide was recovered from the by-products of the NCA process, and the recovery rate of Li was calculated as 92.30%. It was confirmed that the purity of the Ni powder was 95.44% and the purity of the Co powder was 95.98%.