2D materials have attracted a great deal of attention for their unique electrical and magnetic properties, but may also play important roles in applications for energy storage and conversion. Here, our efforts towards the synthesis of functional 2D nanosheets comprising Li-ion battery cathode materials such as LiCoO2 and LiNi1/3Mn1/3Co1/3O2, as well as methods for their reassembly into bulk cathode materials with novel properties (Scheme 1), will be presented. Many conventional battery materials have layered structures, and hence can be readily exfoliated into 2D nanosheet materials. The high surface area and short ionic diffusion distances in the 2D nanosheets may improve the charging/discharging rates and result in more lithium insertion or surface adsorption. Furthermore, hybrid electrode materials comprised of layers of different cathode materials may be possible by reassembling different nanosheets. However, the synthesis of Li rich materials into 2D nanosheets is challenging due to the strong interlayer electrostatic interactions and binding by protons during osmotic swelling processes, which can block Li sites. Our modified exfoliation approach circumvents these problems and allows for the synthesis of 2D nanosheets from Li rich materials that can be restacked and display the expected electrochemical properties of bulk counterparts. Characterization of the reassembled materials using X-ray diffraction and electrochemical methods will be discussed, including the challenges of characterizing the structures of composite materials prepared with different types of nanosheets. Our work is a firm step forward for improving understanding of exfoliation processes for the synthesis of nanosheets, as well as the design and fabrication of high performance hybrid electrodes for energy storage applications.

Characterization of composite materials prepared by controlled reassembly of functional nanosheets

253rd National Meeting (2017)

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