High-yield production of non-layered 2D carbon complexes: Thickness manipulation and carbon nanotube branches for enhanced lithium storage properties

Non-layered two-dimensional（2 D） carbon complexes manifest great potential in energy-related applications owing to their exotic electronic structures, large electrochemically active surface, and intriguing synergistic effects. However, reliable method for mass production and thickness manipulation of 2 D carbon complexes remains great challenges. Here, inspired by blowing chewing gum into bubbles, a ‘‘tailored gel expanding" strategy is proposed for high-yield synthesis of non-layered 2 D carbon complexes with tailored thickness from ～12 nm to ～1 lm, by controllable pyrolysis of metal-polymeric gel with adequate crosslinking degree. The key feature for thickness manipulation is introducing NH4 NO3 in sol–gel process, which tailors the expansion behavior of gel precursor during subsequent pyrolysis. Various of 2 D sheets with intimately coupled N,O-doped carbon（NOC） and Ni Co-based(Ni Co,（Ni Co）S2,（Ni Co）Se2,Ni Co2 O4,（Ni Co）(PO3)2) nanocrystals are obtained on a large scale and without any impurities.Moreover, these 2 D products are branched with in-situ grown CNTs on the surface, accelerating electrons transfer and preventing the nanosheets from stacking. As a demonstration, the 2 D（Ni Co）S2/NOC with optimized thickness manifests excellent lithium storage properties in both half and full cells. This method paves a new path for massive and controlled production of non-layered 2 D materials with tailored thickness and robust structure stability for energy-related applications.