Crystallization-Induced Morphological Tuning Toward Denim-like Graphene Nanosheets in a KCl-Copolymer Solution

Although nucleation and crystallization in solution-processed materials synthesis is a natural phenomenon, the morphology design of graphene nanosheets by controlling the dual crystallization has not been established. In this work, we systematically demonstrate how the dual crystallization of ice and potassium chloride induces the morphological variation of the freeze-dried scaffold from fractal structure toward stepped sheet-like structure. A denim-like graphene nanosheet (DGNS) has been fabricated by annealing the F127-coated stepped sheet-like scaffold in nitrogen. DGNS shows parallel and straight stripes with an average stripe spacing of 10 nm. When used as a lithium-ion battery anode, DGNS possesses a superhigh reversible capacity of 1020 mAh g^-1 at the current density of 1 A g^-1 after 600 cycles. This work reports the control of dual crystallization of ice and salt crystals and provides an efficient way to design the morphology of two-dimensional materials by adjusting the crystallization.