Free-standing Monolithic Nanoporous Graphene Foam as High Performance Aluminum-ion Battery Cathode

Xiaodan Huang, Yang Liu, Hongwei Zhang, Jun Zhang, Owen Noonan, Chengzhong Yu*

Australian Institute for Bioengineering and Nanotechnology,
The University of Queensland,
Brisbane QLD 4072, Australia

Aluminum-ion battery (AIB) is emerging as an attractive new electrical energy storage system. Despite of the recent breakthroughs in AIB technology, state-of-the-art cathode materials suffer from mediocre volumetric capacity (~0.74 mAh cm^-3) and AIB in the widely-used coin-cell configuration is rarely reported. Here we present the synthesis of free-standing monolithic nanoporous graphene foam with a high density and a new strategy to stabilize coin-cell type AIB. A new AIB cathode material with significantly improved volumetric capacity and high gravimetric capacity has been developed. Free-standing monolithic nanoporous graphene foam with well-defined nanopores (94.2 nm), high surface area (762 m² g^-1), large pore volume (2.45 cm³ g^-1) and improved weight density (81.0 mg cm^-3) has been produced by a hydrothermal hard-templating approach and in-situ hydrophobicity induced silica/GO self-assembly. A new coin-cell based AIB configuration has also been developed by applying conductive polymer PEDOT coating to prevent the corrosion. With our design, free-standing NGF has demonstrated promising electrochemical performances, including significantly improved volumetric capacities up to 12.2 mAh cm^-3 together with a high gravimetric capacity (up to 151 mAh g^-1), and good low temperature property. This novel cathode material and the novel cell configuration present new opportunities for the advancement of AIB.