How Twisting Graphene Layers Improves Batteries express
Two sheets of graphene — carbon film one atom thick — without a twist resemble a harbor clogged with shoals: lithium ions either run aground or rush past without stopping. But a 9.43° twist lays out a perfect fairway. The ion ships dock securely to carbon 'piers' and immediately cast off without losing speed.
The driving force is entropy — the eternal push toward disorder — urging ions to spread like water across a table. The principle of twisting lattices was first applied by Leo Esaki to semiconductors, and now machine learning finds safe 'straits' in molecular structures without long calculations, like a pilot reading a map.
Original abstract
as written by the authors arXiv:2603.27453
Controlling ion transport is a fundamental challenge for advanced energy storage. Bilayer graphene offers a unique platform for modulating ion diffusion via twist-angle-dependent moire superlattices, yet conventional stacking configurations face an inherent trade-off: AA stacking provides stable Li intercalation but high diffusion barriers, while AB stacking enables fast diffusion but poor intercalation stability. Twisted bilayer graphene (tBLG) offers potential to overcome this limitation, yet systematic understanding across different twist angles remains limited. Here, we investigate Li intercalation in tBLG using first-principles density functional theory, evaluating intercalation energies and diffusion barriers across multiple twist angles through potential energy surface (PES) mapping. The Sigma 37 structure (9.43 degrees) simultaneously achieves the most favorable intercalation energy (-2.39 eV) and the lowest diffusion barrier (0.14 eV) among all structures examined, resolving the conventional stacking trade-off. Furthermore, using the Smooth Overlap of Atomic Positions (SOAP) descriptor, we demonstrate that the PES is governed by local atomic environments and that a model trained on limited structures predicts the PES of untested configurations with high accuracy. This transferability enables efficient screening without exhaustive first-principles calculations, establishing a systematic framework for twist-angle engineering of ion transport in two-dimensional layered materials.
A 1.1° angle makes graphene a superconductor, and a 9.43° angle turns it into a speed tunnel for lithium ions. Same material, different twists — and such unalike marvels.
Science fiction writers dreamed of a material whose properties depend on twisting; twisted graphene is the first harbinger of that dream.