Engineering of [(2D MoS2/CNTs)1(Ti3C2Tx/CNTs)2]x3 Heterostructures via Layer-by-Layer Spray Deposition: towards tailored high-performing energy storage devices

In this work, we engineer 2D/3D hybrid architectures or heterostructures using cost-effective and scalable layer-by-layer spray deposition methods using 2D MoS2, Ti3C2Tx as building blocks. We assemble heterostructure using a simple-to-complex strategy and systematically optimize the architecture to improve charge storage performance. The architecture and performance of the heterostructures are investigated using imaging and a variety of electrochemical methods. The optimized [(2D MoS2/CNTs)1(Ti3C2Tx/CNTs)2]x3 heterostructure showed remarkable synergystic effects in terms of capacity achieved (up to 800 mAh g-1 at 0.05 A g-1), surpassing the sum of capacities of the constituting building blocks, excellent cycling stability from low to very high rates, e.g. up to 2000 cycles at 5 A g-1 with 100 % Coulombic efficiency and capacity retention. This performance and determined predominant pseudocapacitive charge storage processes suggest applications for Li-ion capacitors. We demonstrated that by adequate tailoring of heterostructures, the drawbacks of individual nanomaterials such as the low cycling stability of 2D MoS2 can be overcome while maintaining the benefits of its high capacity. The manufacturing methods and architecture design principles here established constitute a proof of concept of the powerful potential of heterostructures in surmounting the limitations of capacity, rate performance and cycling stability of current commercial energy storage devices.