Conformal electrodeposition of manganese dioxide onto reticulated vitreous carbon for 3D microbattery applications

Reticulated vitreous carbon (RVC) has been used as a high aspect ratio substrate and current collector for 3D microbattery systems. A 100 ppi compressed RVC offered a 70x increase in surface area when a 2 mm thick piece was used. Deposition of electrolytic manganese dioxide (EMD) conformal films of thicknesses between 0.5 and 10 mm has been demonstrated. Thermal conditioning at 400 degrees C has been shown to remove water from the EMD films and allow for the reversible insertion and extraction of lithium. This treatment has not resulted in any observable damage to the 3D carbon substrate. A capacity per footprint area increase of 250 was seen in a comparison between planar films and those deposited on the 3D substrate. The utilisable capacity was seen to be extremely sensitive to film thickness. This indicates that the films are non-porous and the slow solid state diffusion is limiting the performance of the films.