The use of electrolyte additives is one of the most effective and economical ways to improve battery performance by stabilizing the electrode/electrolyte interface. In this work, we identified that fluoroethylene carbonate (FEC), which is one of the important electrolyte additives, had different impacts on anode and cathode, by investigating a graphite anode and a LiMn₂O₄ cathode through electrochemical analyses at room and elevated temperatures. In the anode side, the solid electrolyte interphase (SEI) layer derived from FEC exhibited a lower interfacial resistance and excellent thermal stability, showing excellent rate capability and improved cycle retention of cells. In contrast, poor cycling retention and a rapid increase in the interfacial resistance of the cathode were observed at elevated temperature. The poorer performance of the cathode in the FEC-containing cell at elevated temperature was attributed to the formation of a thicker surface layer and to increased Mn dissolution catalyzed by HF, which resulted from FEC dehydrofluorination initiated or accelerated by elevated temperature. Accordingly, it is suggested that the amount of FEC in a full cell must be optimized to minimize the adverse effects of FEC on cathode.

With the rapid growth of the volume of spent Li-ion batteries (LIBs), recycling of spent LIBs has attracted significant attention in recent years for future sustainability. In particular, there remains a great need for the development of a scalable and environment-friendly separation process to recycle valuable cathode active materials from spent LIBs and electrode scraps. In this work, froth flotation technique was adopted to separate cathode active materials from a mixture of cathode and anode materials. To evaluate whether the recovered cathode materials maintain their functional integrity after the developed separation process, a variety of electrochemical analyses have been conducted systematically. The present work demonstrated that froth flotation process with kerosene enhanced separability of mixed electrode materials and the recycled cathode materials almost preserved their original electrochemical reactivity. Cycle performance (up to 200 cycles) and rate capability (up to 1 C) of the recycled cathodes were comparable to those of a pristine cathode. However, the higher polarization observed in the recycled cathodes was identified as a key challenge, and it needs to be addressed further. This work provides valuable insights into further development of a scalable froth flotation-based recycling process which can be implemented in a direct recycling process.

Pulsed laser exfoliation was successfully applied to fabricate few-layer phosphorene from high energy mechanical milling (HEMM) synthesized black phosphorus (BP) powders and crystals.