Research for Electrochemical & Structural Properties of Recycling Cathode Materials for End of Life Lib

Abstract

Demand for lithium-ion batteries (LIBs) has increased dramatically over the years due to the rapid market expansion of electric vehicles. However, many of the essential components of cathode materials, such as cobalt, nickel, manganese and lithium, are resource-limited and expensive[1]. Therefore, recycling of used LIB cathode materials is very important to conserve resources and the environment. Currently, the lithium secondary battery recycling technology mainly uses wet and dry smelting, but there is a disadvantage of high energy consumption due to the use of strong acid and the smelting process[2-3].In this study, the cathode active material was separated from a pouch-type lithium secondary battery separated from a portable tablet that was over 10 years old and the chemical, structural, and electrochemical characteristics thereof were investigated. The cathode active materials were dismantled from a pouch-type LIB, which was removed from the tablet produced in 2011. The pouch cell was in a swelling state and the OCV was 0V due to internal short is expected. As a result of TGA analysis, the electrode composition was confirmed to be 92wt% of the cathode active material, 3wt% of the conductive agent, and 3wt% of the binder, respectively. The recovery rate of the active material is the best when a mixed solvent including NMP, heating, and ultrasonic, respectively. Through SEM and EDS analysis, copper metal due to dissolution of the negative electrode current collector was found on the surface of the positive electrode. As shown in Fig. 1, It can be seen that the positive electrode active material recovered using the composite solvent is a positive electrode active material that is a mixture of NCM active material and LMO active material. The XRD results shows a well layered structure and a Co3O4 phase due to lithium deficiency. In order to examine the electrochemical characteristics of the recovered electrode, it was reassembled into a 2032 coin type cell and evaluated, and the discharge capacity of approximately 150mAh/g was recovered as shown in Fig. 2. The positive active material recovered according to the experimental results is estimated to be in a state of insufficient lithium, and a lithium compensation process is planned to be additionally performed in the future.