Pressure-Induced Molding of Black Phosphorus@Ti₃C₂T_<i>x</i> Composite Electrode and Its Implications on the Lithium Storage

For the first time, an innovative pressure quenching technique is used to create the integrated electrode of the black phosphorus (BP) @Ti₃C₂T_<i>x</i> composite material, doing away with the requirement for adhesive additives and simplifying time-consuming processes. Through the formation of Ti-O-P bonds with BP, Ti₃C₂T_<i>x</i> MXenes can function as conductive additives and affect the interlayer gap. Additionally, we have found that there is a critical synthetic pressure threshold (300 kN) at which the performance of BP@Ti₃C₂T_<i>x</i>-integrated electrodes can be improved: too high of a pressure prevents lithium-ion transport because of mesopore reduction; too low of a pressure prevents Ti-O-P chemical bond formation between the two components; and suboptimal pressure does not allow for density enhancement for better electron conduction. The integrated electrode produced at 300 kN shows a discharge capacity of about 724.9 mA h/g at 0.1 A/g current density after 100 cycles, which is much larger than that obtained at 50 kN (270.2 mA h/g). Furthermore, the capacity can remain steady at 560.74 mA h/g even after 500 lengthy cycles at the high current density of 0.5 A/g. Significantly lower resistance (1.10 × 10² Ω at 300 kN; 2.02 × 10³ Ω at 50 kN) and faster reaction kinetics are responsible for this improvement. This study offers a new, straightforward, and broadly useful technique for creating integrated electrodes and BP-based composite materials.