Li-ion battery anodes printed by rotogravure

Abstract

 Inks for Li-ion battery anodes were formulated for printing with the rotogravure printing process. Graphite powders with different particle sizes were used as conductive materials along with nanoparticle carbon black fillers. As polymer binders, polyvinylidene fluoride (PVDF) (commercial names Kureha 9100 and Kureha 9300) and polyvinyl pyrrolidone (PVP) were tested. Inks were printed using proprietary gravure engraving. Ink solid content of 30–70 % was examined. At 70 % solids, ink layers were 25–27 μm thick with mass loading of 2.1–2.5 mg/cm². A solids content of 50 % was found the highest that produced a smooth uniform film. Half cells were made using print with 1 000 μm holes or they were bar coated. Half cells were charged and discharged in order to measure irreversible capacity loss (ICL). Inks with mixed binders Kureha/PVP were performing better than sole polymers. Half-cell testing revealed that PVP as a sole binder has not good electrical performance, thus it was mixed with PVDF. The ICL was lower when mixed PVDF/PVP binder was employed in anode ink.