Conventional separators applied in lithium batteries face limitations like low porosity, poor electrolyte wettability, lower cation selectivity, and thermal instability, which impact battery performance and safety characteristics. Besides the challenge in separator design, transition metal ion migration from positive electrodes during cycling greatly accelerates capacity fading because of unrestricted diffusion of transition metal cation across the separator. This study explores an innovative strategy for the separator design by incorporating MXene (spraying MXene solution on both sides of the separator), a two-dimensional material, into electrospun Polyacrylonitrile/Polyetherimide membranes with the function of cation selection. Li+ can be accelerated, and its transference number increases along with the anion limitation in the MXene layer. Ni, Co, and Mn ion dissolution from the positive electrode is inhibited due to the cation selectivity of the MXene layer. Leveraging electrospinning advantages, the resultant membranes exhibit high porosity, excellent liquid absorption, mechanical strength, and superior thermal properties. Benefiting from MXene's layered structure and excellent adsorption ability, the membrane significantly inhibits the dissolution of transition metal ions while enabling smooth lithium deposition due to its cation selectivity. Eventually, the Li||NMC811 batteries deliver outstanding cyclic performance (91.3% capacity retention after 200 cycles) and robust lithium dendrite suppression (800 hours of stable cycling). Moreover, the MXene-modified membrane demonstrates exceptional electrolyte wettability, significantly improving ionic transference number (0.67) and conductivity (1.6 mS cm-1). Modification of membrane surfaces with MXene offers insights into addressing transition metal ion migration from the positive electrode material perspective, providing a promising avenue for high-performance LIBs.

Graphite is one of the main components of lithium-ion batteries (LIBs) because of its good recycling performance and uniform layers suitable for lithium intercalation. This study focused on the separation of spent LIBs, the isolation of the anode and the washing of its surface to remove the solid electrolyte interphase that leads to an increase in the electrical resistance. The spent graphite was incubated in a nitric acid/ethanol solution which cleans the spent graphite anode while retaining its original morphology. The regenerated graphite anode has a better electrochemical performance when used in a new lithium-ion battery than does the spent graphite, with no capacity loss at a current density of 50 mA·g -1 for 60 cycles. A full battery using regenerated graphite as the anode and lithium iron phosphate as the cathode has a capacity retention of 92% at 0.5 C after 100 cycles. Our work provides a new strategy for regeneration of the anode graphite.

Graphite is one of the main components of lithium-ion batteries (LIBs) because of its good recycling performance and uniform layers suitable for lithium intercalation. This study focused on the separation of spent LIBs, the isolation of the anode and the washing of its surface to remove the solid electrolyte interphase that leads to an increase in the electrical resistance. The spent graphite was incubated in a nitric acid/ethanol solution which cleans the spent graphite anode while retaining its original morphology. The regenerated graphite anode has a better electrochemical performance when used in a new lithium-ion battery than does the spent graphite, with no capacity loss at a current density of 50 mA.g(-1) for 60 cycles. A full battery using regenerated graphite as the anode and lithium iron phosphate as the cathode has a capacity retention of 92% at 0.5 C after 100 cycles. Our work provides a new strategy for regeneration of the anode graphite.