Accelerating Gas Escape in Anion Exchange Membrane Water Electrolysis by Gas Diffusion Layers with Hierarchical Grid Gradients.

At high current densities, gas bubble escape is the critical factor affecting the mass transport and performance of the electrolyzer. For tight assembly water electrolysis technologies, the gas diffusion layer (GDL) between the catalyst layer (CL) and the flow field plate plays a critical role in gas bubble removal. Herein, we demonstrate that the electrolyzer's mass transport and performance can be significantly improved by simply manipulating the structure of the GDL. Combined with 3D printing technology, ordered nickel GDLs with straight-through pores and adjustable grid sizes are systematically studied. Using an in situ high-speed camera, the gas bubble releasing size and resident time have been observed and analyzed upon the change of the GDL architecture. The results show that a suitable grid size of the GDL can significantly accelerate mass transport by reducing the gas bubble size and the bubble resident time. An adhesive force measurement has further revealed the underlying mechanism. We then proposed and fabricated a novel hierarchical GDL, reaching a current density of 2 A/cm2 at a cell voltage of 1.95 V and 80 °C, one of the highest single-cell performances in pure-water-fed anion exchange membrane water electrolysis (AEMWE).

A Samarium-Doped Carbon Aerogel Cathode with Anchored Polysulfides for Lithium-Sulfur Batteries with High Electrochemical Performance: A Metal-Organic Framework Template Method.

A samarium-doped carbon aerogel cathode (CA-Sm) for high-performance lithium-sulfur batteries was successfully synthesized from a Sm-containing metal-organic framework (MOF) as a template through a sol-gel reaction and a carbonization process. Sm-MOF doping plays an important role in regulating the structure of the gel and promoting the formation of samarium oxide in an amorphous state that is uniformly dispersed among the carbon spheres. A CA/S/Sm electrode delivers an initial discharge capacity of 1322 mAh g-1 at a rate of 0.2 C. Furthermore, it possesses an initial discharge capacity of 1212 mAh g-1 at 0.5 C and still maintains a value of 866 mAh g-1 after 300 cycles. Both the anchoring of polysulfides to uniformly doped Sm and the influence of the Sm-MOF on the CA structure lead to the excellent performance of the battery, and effectively prevent polysulfides escaping from cathode, while suppressing the shuttle effect and enhancing the utilization of sulfur.