Effect of Titanium Content in MWCNT@Sn1‐xTixO2 Composites on the Lithium Ion Storage Process

• Published in: ChemistrySelect (Weinheim) 2017-08, Vol.2 (23), p.6850-6856
• Main Authors: Ramírez‐Vargas, Mirna, Calva, Julio C., de la Fuente, Mauricio Solís, Jaramillo‐Quintero, Oscar A., Herrera‐Garza, José R., Acevedo‐Peña, Próspero, Rincón, Marina E.
• Format: Article
• Language: English
• Subjects: Li insertion process; Li-ion Batteries; Sn1-xTixO2 solid solutions
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.201701284

We report the synthesis of multiwall carbon nanotubes@metal oxide composites (MWCNT@Sn1‐xTixO2) and explore the lithium storage capacity and mechanisms in a broad range of compositions. The composite structures were synthesized by hydrothermal method using SnCl4 and TiCl4 as Sn and Ti sources, respectively. Oxide adherence on the carbon surface, as well as an optimum ratio between surface area and porosity, seem to be promoted by Sn content, with MWCNT@Sn0.75Ti0.25O2 showing the best performance in terms of Li capacity and structure stability. Cycled in a potential range of 3 to 1 V vs Li/Li+, the composite shows an insertion mechanism reported for solid solutions with low Sn content, whereas at cut off potential of 0 V vs Li/Li+ the alloying mechanism expected for SnO2 is dominant. Nevertheless, the presence of Ti during the transformation of the solid solution impacts positivily the performance of these electrodes. Lithium storage mechanism were studied in MWCNT@Sn1‐xTixO2 composites synthesized by hydrothermal method. MWCNT@Sn0.75Ti0.25O2 show the best performance in terms of Li capacity and structure stability (650 mAhg−1 at 0.04 C, after 28 cycles at several rates in a potential window of 0–3 V vs Li/Li+). It shows the insertion mechanism when cycled between 3 and 1 V vs Li/Li+, whereas at cut off potential of 0 V vs Li/Li+ the alloying mechanism is dominant.