Mitigating mechanical failure of crystalline silicon electrodes for lithium batteries by morphological design.

Although crystalline silicon (c-Si) anodes promise very high energy densities in Li-ion batteries, their practical use is complicated by amorphization, large volume expansion and severe plastic deformation upon lithium insertion. Recent experiments have revealed the existence of a sharp interface between crystalline Si (c-Si) and the amorphous LixSi alloy during lithiation, which propagates with a velocity that is orientation dependent; the resulting anisotropic swelling generates substantial strain concentrations that initiate cracks even in nanostructured Si. Here we describe a novel strategy to mitigate lithiation-induced fracture by using pristine c-Si structures with engineered anisometric morphologies that are deliberately designed to counteract the anisotropy in the crystalline/amorphous interface velocity.

Kirigami-based stretchable lithium-ion batteries.

We have produced stretchable lithium-ion batteries (LIBs) using the concept of kirigami, i.e., a combination of folding and cutting.

Unique aspects of a shape memory polymer as the substrate for surface wrinkling.

Typical bilayer wrinkle systems employ soft elastomers as the substrates. In contrast, shape memory polymers have recently emerged as attractive alternatives. Besides the shape fixing capability, shape memory polymers distinguish from elastomers in that they are rigid at room temperature, but experience significant modulus drop upon heating.