Laser-induced graphene as an effective supporting structure for high performance Ge anode applied in Li-ion batteries.

Germanium is considered a promising anode material for advanced lithium-ion batteries (LIBs) owing to its high theoretical capacity and electrochemical performance. However, the intrinsically large volume expansion and shrinkage during cycling limit its application scope. Three-dimensional (3D) supporting structures combined with an effective thin-film deposition technique can help enhance the mechanical integrity of Ge anodes and improve their cycle life. In this work, a 3D interconnected graphene (Gr) skeleton-supported Ge was successfully prepared via a facile direct laser ablation process using a polyimide (PI) substrate. The 3D Gr framework with high surface area, sufficiently large space, and short electron/ion transport distance acts as an effective interlayer for Ge anodes to achieve superior Li-ion storage ability and excellent cycle life. Owing to the high adsorption energy, which was determined via first-principles calculations, and favourable 3D configurations, the as-prepared solid-state Li||solid polymer electrolyte||3D Ge/Gr and full 3D Ge/Gr||LiPF||LiCoO batteries exhibited high reversible specific capacity and cyclability. The impressive structural stability and Li-ion storage mechanism of the 3D Ge/Gr electrode were systematically investigated using cycled electrodes and in situ Raman spectroscopy, and the positive effects of the 3D Gr-supported structures were verified.