Electrochemical performance of honeycomb graphene prepared from acidic graphene oxide via a chemical expansion method

•Simple, low-energy and scalable one-step chemical expansion of graphene.•High-yield (>90%) preparation of of nanocrystalline chemically expanded graphene.•Specific capacity of 283.8F·g−1 at 1 A·g−1, and excellent rate capability.•Excellent capacity retention of ≈87% after 5000 cycles at 20 A·g−1.