Cobalt Nickel Boride Nanocomposite as High-Performance Anode Catalyst for Direct Borohydride Fuel Cell

Similar to MXene, MAB is a group of 2D ceramic/metallic boride materials which exhibits unique properties for various applications. However, these 2D sheets tend to stack and therefore lose their active surface area and functions. Herein, an amorphous cobalt nickel boride (Co–Ni–B) nanocomposite is prepared with a combination of 2D sheets and nanoparticles in the center to avoid agglomeration. This unique structure holds the 2D nano-sheets with massive surface area which contains numerous catalytic active sites. This nanocomposite is prepared as an electrocatalyst for borohydride electrooxidation reaction (BOR). It shows outstanding catalytic activity through improving the kinetic parameters of BH4− oxidation, owing to abundant ultrathin 2D structure on the surface, which provide free interspace and electroactive sites for charge/mass transport. The anode catalyst led to a 209 mW/cm2 maximum power density with high open circuit potential of 1.06 V at room temperature in a miniature direct borohydride fuel cell (DBFC). It also showed a great longevity of up to 45 h at an output power density of 64 mW/cm2, which is higher than the Co–B, Ni–B and PtRu/C. The cost reduction and prospective scale-up production of the Co–Ni–B catalyst are also addressed

Hierarchical and lamellar porous carbon as interconnected sulfur host and polysulfide-proof interlayer for Li–S batteries

A robust three-dimensional (3D) interconnected sulfur host and a polysulfide-proof interlayer are key components in high-performance Li–S batteries. Herein, cellulose-based 3D hierarchical porous carbon (HPC) and two-dimensional (2D) lamellar porous carbon (LPC) are employed as the sulfur host and polysulfide-proof interlayer, respectively, for a Li–S battery. The 3D HPC displays a cross-linked macroporous structure, which allows high sulfur loading and restriction capability and provides unobstructed electrolyte diffusion channels. With a stackable carbon sheet of 2D LPC that has a large plane view size and is ultrathin and porous, the LPC-coated separator effectively inhibits polysulfides. An optimized combination of the HPC and LPC yields an electrode structure that effectively protects the lithium anode against corrosion by polysulfides, giving the cell a high capacity of 1339.4 mAh g−1 and high stability, with a capacity decay rate of 0.021% per cycle at 0.2C. This work provides a new understanding of biomaterials and offers a novel strategy to improve the performance of Li–S batteries for practical applications