Biomimetic nanostructuring of copper thin films enhances adhesion to the negative electrode laminate in lithium-ion batteries.

Thin films of copper are widely used as current collectors for the negative electrodes in lithium-ion batteries. However, a major cause of battery failure is delamination between the current collector and the graphite anode. When silicon or tin is used as active material, delamination becomes a key issue owing to the large volume changes of these materials during lithation and delithation processes. Learning from Nature, we developed a new biomimetic approach based on the adhesion properties of the feet of geckos. The biomimetic approach improves adhesion between the laminate and the copper surface by introducing an array of Cu(OH)2 nanorods, which increases the surface area of the current collector. When graphite anode laminate is casted onto regular and a modified copper surfaces, the modified current collector displays superior adhesion to graphite and the PVDF binder-based electrode. The electrochemical performance of the batteries using these electrodes is not compromised by the additional chemistry of the Cu(OH)2 on the copper surface. The technique can lead to enhanced battery lifetimes over long-term cycling.