Charge without friction?

With a colleague from Xi'an, Yanbo, and a colleague from the lab, Thomas, Li and Laurent just had their work on the coupling between surface charge and friction accepted in Physical Review Letters, and selected as a reading suggestion by the Editors.

Porous materials confining salt water can be used to generate electricity from the osmotic energy of sea water or from waste heat. To that aim, the pore surfaces must be charged to attract ions into the material. However, the friction of liquids is larger on charged surfaces, which limits the electric current produced. Using atomic-scale simulations, the authors have shown that the charge-friction relationship strongly depends on how the surface charge is generated. For polarized conductive surfaces, the friction increases very little in the presence of charge. For example, they predict that polarized graphene must produce giant currents. More generally, the authors have developed models for the charge-friction relationship, which can guide the search for high performance materials.