Electrochemical Exfoliation to Produce High-Quality Black Phosphorus

To obtain high-quality two-dimensional (2D) materials from the bulky crystals, delamination under an externally controlled stimulus is crucial. Electrochemical exfoliation of layered materials requires simple instrumentation yet offers high-quality exfoliated 2D materials with high yields and features straightforward upscalability; therefore, it represents a key technology for advancing fundamental studies and industrial applications. Moreover, the solution processability of functionalized 2D materials enables the fabrication of (opto)electronic and energy devices via different printing technologies such as inkjet printing and 3D printing. This paper presents the electrochemical exfoliation protocol for the synthesis of black phosphorus (BP), one of the most promising emerging 2D materials, from its bulk crystals in a step-by-step manner, namely, cathodic electrochemical exfoliation of BP in the presence of N(C4H9)4∙HSO4 in propylene carbonate, dispersion preparation by sonication and subsequent centrifugation for the separation of flakes, and morphological characterization by scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM)

Ionic liquid electrolyte additive regulates the multi-species-insertion titanium sulfide cathode for magnesium batteries

Benefiting from the appealing Mg metal anodes, magnesium batteries (MBs) present attractive potential as sustainable batteries of tomorrow. However, the Mg metal anode-compatible electrolytes generally contain large-size and strongly bonded Mg-clusters (i.e., MgxCly2x-y), resulting in the inefficient cathode chemistries associated with the sluggish Mg-species insertion. Here, using the iconic TiS2 cathode, we demonstrate the pronounced effect of ionic liquid on regulating MgxCly2x-y clusters in the MB electrolyte and promoting the high-kinetics multi-Mg-species insertion into TiS2. Specifically, the addition of 1-butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide (PP14TFSI) ionic liquid into the conventional Mg bis(hexamethyldisilazide)/4MgCl2 electrolyte induces a nontrivial two-plateau charge/discharge profile of the TiS2 electrode, in which Mg2+ insertion is mainly disclosed at the high-potential plateau and MgCl+ insertion dominates the low-potential plateau. Molecular dynamic simulations indicate that the PP14TFSI additive can dissociate large MgxCly2x-y clusters to produce MgCl+, which can be effectively stabilized by PP14+ and TFSI–. Meanwhile, PP14TFSI catalyzes the Mg-Cl dissociation, thus creating the desirable Mg2+ species. These electrolyte-regulation effects consequently enable the TiS2 cathode with a decent specific capacity (81 mAh g–1 at 10 mA g–1), high rate capability (63 mAh g–1 at 200 mA g–1), and long-term durability (86% capacity retention after 500 cycles)