A slurry of the dry jellyfish biomass and silicon nanoparticles (Nanografi, average diameter 100 nm, crystalline) was prepared with a mass ratio of 10:3 in D.I. water. No binders or conductive additives were used. The slurry was sonicated for 20 minutes and vortexed for 5 minutes to prevent agglomeration of the SiNPs and homogenize the slurry. For thin-layer battery configurations, layers of the slurry was spin-coated onto a 316L stainless steel current collector (12 mm diameter, 0.5 mm thickness) or battery-grade copper foil (15 µm thick, then punched into 12 mm disks) at 400 rpm for 10 seconds and then 2000 rpm for 40 seconds. The film was hot baked for 5 minutes at 50℃ for 15 minutes at 100℃ after each layer. The thin film was then treated with 20 μL of 5 wt/wt % of boric acid (> 99.5%, Sigma-Aldrich) in D.I. water and hot baked for an additional 20 minutes at 100℃. The resulting dried layer deposited on the current collector was rastered with continuous visible laser irradiation (2.8 W, 450 nm wavelength, Zmorph Fab) using lasing parameters of 100% power, a spot size diameter of 10 μm, a lasing speed of 20 mm/s, and a hatch spacing of 0.1 mm. The anode was lastly washed with D.I. water and dried in order to remove residual salts inherent from the biomass and boric acid.