The scalable preparation of graphene in control of its structure would significantly improve its commercial viability. Despite intense research in this area, the size control of defect-free graphene (df-G) without any trace of oxidation or structural damage remains a key challenge. Here, we propose a new scalable route for generating df-G with a controllable size of submicron to micron through sequential insertion of potassium and pyridine at low temperature. Structural and chemical analyses confirm that the df-G perfectly preserves the intrinsic properties of graphene. The Co3O4 (<50 nm) wrapped by ∼ 10.5 μm(2) df-G has unprecedented capacity, rate capability, and cycling stability with capacities as high as 1050 mAh g(-1) at 500 mA g(-1) and 900 mAh g(-1) at 1000 mA g(-1) even after 200 cycles, which suggests enticing potential for the use in high performance lithium ion batteries.