Tunable Recycling of Sodium–Ion Batteries Cathode by Dual‐Regulation of Basicity and Hydrophobicity of Green Solvents

The regulation strategy to tune the recovery of cathode from sodium-ion batteries (SIBs) is of great significance. However, traditional strategies involving temperature, duration, and additives often lead to high energy demands, time deficiencies, notable environmental pollution, or complicated separation processes. Here, we propose a sustainable strategy based on the synergistic regulation of basicity and hydrophobicity to regulate the cathode recycling from SIBs using amino acid-based deep eutectic solvents (DESs) with low energy consumption, high time efficiency and simple process. The metal leaching efficiency from SIBs cathode could be tuned by dual-regulation of high basicity and moderate hydrophobicity. The basicity of amino acid-based DESs shows a weak positive correlation with the metal leaching efficiency, while hydrophobicity of amino acid exhibits a trend of initially increasing and then decreasing with metal leaching efficiency. After reasonable tunability of basicity and hydrophobicity, DESs glycine:lactic acid (1:12) is capable of recycling 87.5% Na and 83.3% Fe from the sodium iron phosphate cathode of SIBs at a mild temperature of 80°C for 24 h with a liquid-to-solid ratio of 50:1.