Highly Doped 3D Graphene Na‐Ion Battery Anode by Laser Scribing Polyimide Films in Nitrogen Ambient

Conventional graphite anodes can hardly intercalate sodium (Na) ions, which poses a serious challenge for developing Na‐ion batteries. This study details a novel method that involves single‐step laser‐based transformation of urea‐containing polyimide into an expanded 3D graphene anode, with simultaneous doping of high concentrations of nitrogen (≈13 at%). The versatile nature of this laser‐scribing approach enables direct bonding of the 3D graphene anode to the current collectors without the need for binders or conductive additives, which presents a clear advantage over chemical or hydrothermal methods. It is shown that these conductive and expanded 3D graphene structures perform exceptionally well as anodes for Na‐ion batteries. Specifically, an initial coulombic efficiency (CE) up to 74% is achieved, which exceeds that of most reported carbonaceous anodes, such as hard carbon and soft carbon. In addition, Na‐ion capacity up to 425 mAh g−1 at 0.1 A g−1 has been achieved with excellent rate capabilities. Further, a capacity of 148 mAh g−1 at a current density of 10 A g−1 is obtained with excellent cycling stability, opening a new direction for the fabrication of 3D graphene anodes directly on current collectors for metal ion battery anodes as well as other potential applications. Laser scribing is used to directly form expanded and highly doped (≈13 at% N) 3D graphene anodes on Cu foil without the need for a binder or conductive filler. The simultaneous graphitization and doping of the 3D graphitic anodes in this process result in exceptional electrochemical storage of Na‐ions.