Demonstration of Co/Ni exchange in exfoliated LiCoO2 nanosheets: a new approach for upcycling spent Li-ion battery cathodes

Abstract

In response to growing concerns over the limited availability of cobalt sources for lithium-ion battery cathodes, this study explores a novel method for upcycling LiCoO₂ (LCO) materials. Traditional LCO recycling approaches like pyrometallurgy and hydrometallurgy are energy intensive. Here, we propose a new direct upcycling approach that leverages the high surface area of nanosheets to facilitate cobalt extraction and cation exchange. The method involves exfoliation of bulk LCO into nanosheets, which are subsequently mixed with aqueous solutions to carry out cobalt extraction and replacement by nickel. The effectiveness of the cation exchange is investigated using various characterization techniques, including Raman spectroscopy, electron microscopy, X-ray diffraction, and soft X-ray absorption spectroscopy. In addition, the reassembly of the nanosheets into functional cathode materials is accomplished using heat treatment and the electrochemical characteristics evaluated. The results show the successful synthesis of Ni-doped LCO (LiCo_1−xNi_xO₂, x = 0.11) using this approach. Mn ion exchange into the exfoliated LCO is also investigated with the same method. This study establishes how nanosheet processing can be leveraged for recycling critical materials used in batteries and establishes a new pathway that can be used for converting LCO or low-Co materials to Ni-rich cathodes.