Modifying Li+Transport and Interface Chemistry via Citric Acid-Treated Silica Carrier in Nanoparticle Colloidal Electrolyte toward Stable Li-Metal Batteries

Tailoring the lithium ion (Li+) microenvironment is essential for achieving rapid ionic transfer and a mechanically strong solid-electrolyte interphase (SEI). This is key to the stable cycling of lithium-metal batteries (LMBs). Beyond the conventional approach of adjusting salt and solvent compositions, this study introduces a novel method. It involves simultaneous modulation of Li+ transport and SEI chemistry through a citric acid (CA)-modified silica-based colloidal electrolyte (C-SCE). The CA-tethered silica (CA-SiO2) provides more active sites for attracting complex anions. This leads to a greater dissociation of Li+ from these anions, resulting in a high Li+ transference number (approximately 0.75). The intermolecular hydrogen bonds formed between solvent molecules and CA-SiO2, along with their migration, serve as nano-carriers. These nano-carriers are responsible for transporting additives and anions to the lithium surface, thereby strengthening the SEI through the co-implantation of SiO2 and fluorinated components. Notably, C-SCE has shown promise in suppressing lithium dendrite formation and enhancing the cycling stability of LMBs. This is a significant improvement over the CA-free SiO2 colloidal electrolyte. The study highlights that the surface properties of nanoparticles play a crucial role in the dendrite-inhibiting capabilities of nano colloidal electrolytes.