TiO2 nano-particles in polymer electrolytes: surface interactions

Artikel i vetenskaplig tidskrift, 2004

The effect of nano-sized oxide particles, especially TiO 2 , on the structure and dynamics of polymeric electrolytes such as LiX/PEO has previously been shown to be profound. Here a first attempt is made to investigate the local surface interactions affecting the macroscopically observed properties using a rutile TiO 2 -cluster via ab initio Hartree-Fock (HF) and density functional theory (DFT) (B3LYP) type calculations. As an exploratory work, we use a small Ti 11 O 22 atomistic cluster embedded in point charges (PCs) and the (110) surface for the adsorption process. Out of lithium cations (Li + ), tetrafluoroborate anions (BF 4 - ), and dimethyl ethers (O(CH 3 ) 2 ), BF 4 - is found to be the preferred adsorbate. The ether has comparable energy of adsorption when adjusting for bi-dentate coordination. The present results support the creation of new diffusion pathways for the lithium ion at the nano-particle surfaces and emphasises the possible role of anion adsorption. © 2003 Elsevier B.V. All rights reserved.