Zhengyu Bai

3-Dimensional porous N-doped graphene foam as a non-precious catalyst for the oxygen reduction reaction

Nitrogen-doped graphene materials have been demonstrated as promising alternative catalysts for the oxygen reduction reaction (ORR) in fuel cells and metal–air batteries due to their relatively high activity and good stability in alkaline solutions. However, they suffer from low catalytic activity in acid medium. Herein, we have developed an efficient ORR catalyst based on nitrogen doped porous graphene foams (PNGFs) using a hard templating approach. The obtained catalyst exhibits both remarkable ORR activity and long term stability in both alkaline and acidic solutions, and its ORR activity is even better than that of the Pt-based catalyst in alkaline medium. Our results demonstrate a new strategy to rationally design highly efficient graphene-based non-precious catalysts for electrochemical energy devices.

Flexible High‐Energy Polymer‐Electrolyte‐Based Rechargeable Zinc–Air Batteries

A thin-film, flexible, and rechargeable zinc-air battery having high energy density is reported particularly for emerging portable and wearable electronic applications. This freeform battery design is the first demonstrated by sandwiching a porous-gelled polymer electrolyte with a freestanding zinc film and a bifunctional catalytic electrode film. The flexibility of both the electrode films and polymer electrolyte membrane gives great freedom in tailoring the battery geometry and performance.

A Lithium-Sulfur Battery using a 2D Current Collector Architecture with a Large-Sized Sulfur Host Operated under High Areal Loading and Low E/S Ratio

While backless freestanding 3D electrode architectures for batteries with high loading sulfur have flourished in the recent years, the more traditional and industrially turnkey 2D architecture has not received the same amount of attention. This work reports a spray-dried sulfur composite with large intrinsic internal pores, ensuring adequate local electrolyte availability. This material offers good performance with a electrolyte content of 7 µL mg-1 at high areal loadings (5-8 mg cm-2 ), while also offering the first reported 2.8 µL mg-1 (8 mg cm-2 ) to enter into the second plateau of discharge and continue to operate for 20 cycles. Moreover, evidence is provided that the high-frequency semicircle (i.e., interfacial resistance) is mainly responsible for the often observed bypassing of the second plateau in lean electrolyte discharges.

Batteries: Flexible High‐Energy Polymer‐Electrolyte‐Based Rechargeable Zinc–Air Batteries (Adv. Mater. 37/2015)

On page 5617, L. Yang, Z. Chen and co-workers report the development of solid-state, flexible, and rechargeable zinc-air batteries with high energy density using a porous-gelled polymer electrolyte. The highly promising battery is ultrathin, yet mechanically robust and capable of operating under extreme bending conditions, which is particularly interesting for emerging portable and flexible electronic applications.