Nano-propping effect of residual silicas on reversible lithium storage over highly ordered mesoporous SnO2 materials

Abstract

Highly ordered mesoporous SnO 2 materials with residual silica species were successfully synthesized from a mesoporous silica template (SBA-15) via nano-replication and simple etching processes. A tin precursor, SnCl 2 $2H 2 O, was infiltrated spontaneously within the mesopores of the silica templates by melting the precursor at 353 K without using a solvent. After the heat-treatment of composite materials at 973 K under static air conditions, the controlled removal of silica templates using NaOH or HF solutions with different concentrations results in the successful preparation of mesoporous SnO 2 materials, where the amounts of residual silica species are in the range 0.9-17.4 wt%. The residual silica species induce a nano-propping effect enabling the mesoporous SnO 2 material (containing 6.0 wt% of silica species) to remain stable up to 973 K without any significant structural collapse. More importantly, the optimum amount of residual silica species (3.9-6.0 wt%) results in a dramatic reduction in capacity fading after prolonged charging-discharging cycles in Li-ion battery. The mesoporous SnO 2 material with 3.9 wt% of silica species still exhibits a large capacity (about 600 mAh g À1 ) after the 30 th cycle, which is probably because the residual silica species act as a physical barrier to suppress the aggregation of Sn clusters formed in the mesoporous SnO 2 materials during the reversible lithium storage.

Porous Electrode Materials for Lithium‐Ion Batteries – How to Prepare Them and What Makes Them Special

“…Although it is usually desirable to remove all of the silica template from the electrode material because silica does not contribute to lithium ion storage and is electronically insulating, residual silica can provide some mechanical stabilization. For instance, in the case of mesoporous SnO 2 templated from SBA‐15 by melt‐infiltration of SnCl 2 ·2H 2 O, a small amount (6 wt%) of residual SiO 2 resulting from incomplete etching was believed to prop up the SnO 2 phase 61. As a result, the mesoporous SnO 2 was structurally stable up to 700 °C.…”

Tin Oxide with Controlled Morphology and Crystallinity by Atomic Layer Deposition onto Graphene Nanosheets for Enhanced Lithium Storage

“…Ning et al34 reviewed the use of mechanical‐chemical methods (e.g., micromilling) to fabricate alloys and composites (including graphite) of Sn or SnO 2 for negative electrodes. To stabilize SnO 2 electrodes, various approaches have been attempted, including using nanosized SnO 2 ,35–38 SnO 2 ‐matrix composites39, 40 and special nanostructured SnO 2 such as nanotubes41, 42 and nanowires 43–45…”

Discovery of abnormal lithium-storage sites in molybdenum dioxide electrodes

“…Mesoporous materials are excellent nanoscale-engineered candidates for numerous applications because of their high surface areas, tunable pore sizes, adjustable framework thickness and compositions, and diverse surface properties 19 20 21 22 23 . Recently, various novel mesoporous metal oxides have been widely investigated as electrode materials for LIBs 24 25 26 27 28 . These studies have opened up a possibility for the development of anode materials with significantly improved Li-storage performance.…”