This technology is a top-down process that creates a porous metal compound structure with low oxygen content by heat-treating bulk metal oxides in a nitrogen atmosphere, followed by a second heat treatment in an oxygen atmosphere to produce a nitrogen-doped metal oxide structure with a high specific surface area and fine grains.
Conventional bulk materials have low specific surface areas and large grain sizes, leading to inefficient ion diffusion paths and limited electrochemical performance in lithium secondary batteries.
This technology controls the relative temperatures of the first and second heat treatments based on whether the metal element is in groups 4–8 or group 9. The first heat treatment in an ammonia atmosphere creates a porous precursor, such as an oxynitride, while the second heat treatment in an oxygen atmosphere induces nitrogen doping and forms metastable crystal structures like the anatase phase. It can be applied to titanium, niobium, cobalt, and iron oxide-based anode materials, as well as the production of porous oxides for photocatalysts and sensors. Its key advantage is the ability to obtain nanoporous structures from commercial bulk powder without the need for templates.
This invention was developed with support from the Samsung Science and Technology Foundation for research on developing high-capacity/fast-charging electrode materials using sequential gas-phase reactions.
US11084011B2, WO2017-209517A1
