Perpustakaan Digital ITB

Core?shell structures offer opportunities to overcome challenges to thedurability of Li-ion batteries with high energy density due to instability at the cathode/electrolyte interface. Achieving complete stability requires fundamental understanding ofthe role of the shell in providing passivation without compromising carrier transport, bytuning surface chemistry and structural features in a highly conformal barrier layer. Here,individual LiCoO2nanoplates were employed as the core, and passivating shells weregrown at a tailored thickness and composition, through different Al loadings andannealing temperatures. Depending on the annealing conditions, the sub-5 nm shellswere shown to vary from amorphous aluminum oxide layers to LiAlxCo1?xO2gradients,resulting in an Al-rich outer layer on a Co-rich core. This control revealed the differingbalance between effective minimization of redox-active Co3+at the surface and transportproperties of the two types of shell. Based on correlations with electrode performance,the requirements in thickness of the layers were proposed to critically depend on theirchemical composition, with epitaxial shells based on surface substitution being favored. The outcomes of the studysimultaneously advance the ability to assemble complex oxides into heterostructures and refine the rules of design for tunablepassivation through a barrier layer, so as to maximize electrode properties in practical batteries