A very thin layer of hexagonal boron nitride (h-BN) is an important 2D nanomaterial, sometimes called 'white graphene', with many properties distinct from graphene. However, the lack of controlled synthesis of high quality and wide-area films largely prevents realisation of the full potential of this material. In this review article, a comprehensive overview of the current status of the synthesis, growth mechanism using chemical vapour deposition, structure and electronic properties to tune the bandgap is covered. In particular, the progress towards achieving the improved quality and functionalities of the h-BN films via epitaxial growth and control of grain size, number of layers, morphology and orientation have been critically reviewed. In addition to synthesis and properties of the atomically thin (mono and few layer) h-BN, the applications in possible and emerging areas are also described and discussed.

Silicon is a promising anode material for lithium ion batteries. However, lithiation of silicon generates stress that is known to be the primary reason for the failure of the anode. This study explored the existence of residual stress in single crystalline silicon electrodes after full de-lithiation, i.e., under no mechanical or electrical load. The magnitude of residual stress and its evolution with the number of lithiation-delithiation cycles is measured by Raman spectroscopy and a simple mechanics based approach. It is shown that the residual stress is tensile in nature and increased from 69 ± 11 MPa after the 1st cycle to ∼291 ± 56 MPa after 50 cycles of lithiation and de-lithiation. Concurrently, microstructural studies were performed to demonstrate the consequence of the evolution of residual stress on failure by the fracture of the silicon anode. These results provide understanding on the progressive failure mechanism of single crystalline-based silicon electrodes upon lithiation-delithiation.

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