Cerium-Modified Diatom Biosilica for Lithium-Ion Anodes

Diatom frustules offer hierarchically porous biosilica templates for sustainable electrode design; however, their low electrical conductivity and limited electrochemically accessible sites constrain lithium-storage performance. In this study, a two-stage cultivation strategy was used to introduce Ce-related species into Cyclotella cryptica frustules, followed by purification and pyrolysis to obtain Ce-functionalized biosilica/carbon anodes. Ce-200 provided the best balance among biological tolerance, cerium enrichment, structural retention, pore evolution, and electrochemical performance. SEM, ICP-MS, XPS, Raman, and nitrogen sorption analyses confirmed cerium enrichment, preservation of the frustule morphology, formation of defect-containing carbon, and an approximately 3-fold increase in specific surface area. In half-cells, DBS/C@Ce200 delivered 932.8 mAh g^-1 after 200 cycles at 0.1 A g^-1 and retained 527.0 mAh g^-1 at 2 A g^-1. CV, EIS, and postcycling SEM results were consistent with improved charge-transfer behavior and structural stability. This work demonstrates bioassisted cerium modification as a promising route for diatom-derived lithium-ion battery anodes.