In Situ Exfoliated Graphene-Like Carbon Nanosheets Strongly Coupled with the Biochar Tube as the Cathode for an Application- Ready Zn-Air Battery

The Zn-air battery (ZAB) is a new generation energy storage and conversion device, but its applications are still hampered by the slow oxygen reduction reaction (ORR) dynamics of cathode materials. Here, a strategy for in situ exfoliation of graphene-like carbon nanosheets (GCNs) from a biochar tube is reported, which combines carbon activation, carbonization, and N doping in a one-pot process. The exfoliated GCNs are endowed with a remarkable half-wave potential (0.85 V @ 3 mA cm-2) and high stability toward the ORR of NPC-900, outperforming most of the reported N-doped carbon materials. In terms of practical applications, three different forms of ZAB were assembled for different practical application scenarios using three-dimensional (3D) printed devices to simulate. This work provides a simple and sustainable way to synthesize N-doped biochar catalysts with excellent ORR properties, offering a broad potential for their application as ZAB cathodes.