Ab initio diffuse-interface model for lithiated electrode interface evolution.

The study of chemical segregation at interfaces, and in particular the ability to predict the thickness of segregated layers via analytical expressions or computational modeling, is a fundamentally challenging topic in the design of novel heterostructured materials. This issue is particularly relevant for the phase-field (PF) methodology, which has become a prominent tool for describing phase transitions. These models rely on phenomenological parameters that pertain to the interfacial energy and thickness, quantities that cannot be experimentally measured.

From ab initio calculations to multiscale design of Si/C core-shell particles for Li-ion anodes.

The design of novel Si-enhanced nanocomposite electrodes that will successfully mitigate mechanical and chemical degradation is becoming increasingly important for next generation Li-ion batteries. Recently Si/C hollow core-shell nanoparticles were proposed as a promising anode architecture, which can successfully sustain thousands of cycles with high Coulombic efficiency. As the structural integrity and functionality of these heterogeneous Si materials depend on the strength and fracture energy of the active materials, an in-depth understanding of the interface and their intrinsic mechanical properties, such as fracture strength and debonding, becomes critical for the successful design of such and similar composites.

Li segregation induces structure and strength changes at the amorphous Si/Cu interface.

The study of interfacial properties, especially of their change upon lithiation, is a fundamentally significant and challenging topic in designing heterogeneous nanostructured electrodes for lithium ion batteries. This issue becomes more intriguing for Si electrodes, whose ultrahigh capacity is accompanied by large volume expansion and mechanical stress, threatening with delamination of silicon from the metal current collector and failure of the electrode. Instead of inferring interfacial properties from experiments, in this work, we have combined density functional theory (DFT) and ab initio molecular dynamics (AIMD) calculations with time-of-flight secondary ion mass spectrometry (TOF-SIMS) measurements of the lithium depth profile, to study the effect of lithiation on the a-Si/Cu interface.