Nanoholey MXene/LiMn 2 O 4 Composite with Superior Electroconductivity for Accelerated Direct Lithium Extraction

Direct lithium extraction (DLE) from brines has attracted increasing attention due to the growing demand for lithium-ion batteries. However, current DLE technologies often suffer from slow kinetics and long operational times. Here, we report a highly electroconductive nanoholey MXene/LiMn2O4 composite (ENMLC) designed to accelerate sustainable DLE via hybrid capacitive deionization (HCDI). A mild oxidative acid-etching strategy enlarges the interlayer spacing of MXene and generates abundant nanopores, thereby facilitating rapid Li+ transport. Coupling MXene with LiMn2O4 suppresses manganese dissolution and improves the cycling stability. The ENMLC electrode exhibits a high Li+ adsorption capacity of 36.08 mg g–1 at an ultrafast rate of 6.67 mg g–1 min–1 (1.0 V, 0.05 mol L–1 LiCl), outperforming most reported electrodes. Even at a low voltage (0.2 V, 0.05 mol L–1 LiCl), it achieves a Li+ adsorption capacity and rate of 23.20 mg g–1 and 4.30 mg g–1 min–1, respectively. After 50 cycles, nearly 90% of the initial performance is retained. Moreover, ENMLC demonstrates a high Li+/Mg2+ separation factor of 181.8 with a Mg2+/Li+ ratio of 20 and efficiently extracts Li+ from various brines while excluding interfering ions, highlighting its promise for sustainable lithium production.