Technology Commercialization and Partnerships | BSA 11-08: Nanoscale Magnéli Phases of Titanium Oxide Increase Electrode Capacity

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Categories: advanced materials, nanotechnology

BSA 11-08: Nanoscale Magnéli Phases of Titanium Oxide Increase Electrode Capacity

BNL Reference Number: BSA 11-08

Patent Status: Application Number 20120251887 was published on October 4, 2012

Summary

This transmission electron micrograph shows typical carbon-coated Magnéli phase titanium oxide nanowires.

Titanium dioxide (TiO₂) is a robust, dynamic material used for photocatalysis of water splitting, in solar cells, and as an electrode in batteries, fuel cells, and supercapacitors. Unfortunately, it suffers from high resistivity, which limits its applications. Magnéli phases of oxides of titanium overcome that obstacle, but until now have been available only at the microscale. Carbon coating precursors produces nanowires 30- to 45-nm in diameter, a previously impossible achievement. The innovative carbon coating does not interfere with the advantageous electrical and optical properties of these titanium suboxides.

Description

Reduced oxides of titanium, the Magnéli phases, have lower bandgaps and higher conductivity than TiO₂. Until now, however, Magnéli phases could not be fabricated with dimensions smaller than micrometers �" too coarse to take advantage of the changes to electrical and optical properties that happen on the nanoscale. Nanoparticles of TiO₂ or hydrogen titanates are first coated with carbon using either wet or dry chemistry methods. During this process the size and shape of the nanoparticles are "locked in." Subsequently, the carbon-coated nanoparticles are heated in a reducing atmosphere. This results in the transformation of the original TiO₂ or hydrogen titanates to Magnéli phases without coarsening, so that the original size and shape of the nanoparticles are maintained to a precise degree.

Benefits

Nano-sized particles of titanium oxide Magnéli phases exhibit twice the capacity of macro-sized structures of the same composition for lithium ions in battery coin cells. Stability has been demonstrated over 600 charge-discharge cycles.

Applications and Industries

These nanoparticles can increase efficiency and energy output for lithium ion batteries, solar cells, and other devices that use titanium dioxide electrodes.