Flexible graphite film with laser drilling pores as novel integrated anode free of metal current collector for sodium ion battery

• Advanced laser drilling technique is applied to prepare porous polyimide graphite film.
• The porous graphite film is directly used as an integrated anode for NIBs by Na+-solvent co-intercalation mechanisms.
• A full cell was built in a diglyme-based electrolyte and delivered higher energy density and much improved cycle life.

In this work, flexible polyimide graphite films with laser drilling pores were prepared by laser drilling pore technique. Then a full cell was built based on the porous graphite film anode, Na3V2(PO4)3 cathode, and NaPF6 in diglyme electrolyte. This unique battery system makes the best of co-intercalation mechanism of Na+-solvent into porous graphite film host. Moreover, the porous graphite film is directly served as an integrated anode with no electrochemically inactive components, such as binders, conductive agents and metallic current collectors. The above merits allow remarkable progress in electrochemical performance, especially the high energy density and much improved cycle life, which will significantly boost the high energy batteries. Our sodium-ion system is potentially promising power sources for promoting the substantial use of low-cost energy storage systems.