Heterojunction material based on high-purity semiconducting single-walled carbon nanotubes and cubic indium oxide, and manufacturing method thereof

High-Power Supercapacitor Electrode Material Using Semiconducting Carbon Nanotube and Indium Oxide Heterojunction

This technology features a heterostructure material created by bonding >99% pure semiconducting single-walled carbon nanotubes (s-SWCNTs), separated from metallic types, with cubic indium oxide (In2O3) via hydrothermal synthesis. The carbon nanotubes are distributed within and on the surface of the oxide, inducing lattice contraction to enhance the properties of the supercapacitor electrode active material.

While In2O3 is a promising metal oxide semiconductor with a wide bandgap and high transparency, it has historically been limited by low power density and poor long-term cycle reliability when used alone. Furthermore, conventional methods relied on adding crude carbon nanotubes containing a mix of metallic and semiconducting types, making it difficult to optimize material design due to the ambiguity regarding which component drove performance improvements.

This technology utilizes a one-step hydrothermal process to introduce pure s-SWCNTs in situ during In2O3 synthesis, providing a simple and scalable method for producing heterojunction electrode materials. The resulting solid-state symmetric supercapacitor demonstrated a specific capacitance of 898 F/g at 1.8 A/g, a maximum power density of 3900 W/kg, and a 91.8% capacity retention after 5000 cycles. It is well-suited for high-power energy storage applications, such as wearable devices, flexible IoT security systems, and auxiliary power for electric vehicles, facilitating the development of power components that require both rapid charging/discharging and long lifespans.

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Key Features:

• A composition for supercapacitor electrodes comprising a heterojunction material with a heterostructure where pure semiconducting single-walled carbon nanotubes and cubic indium oxide are bonded together
• A structure where single-walled carbon nanotubes exist inside and on the surface of indium oxide, inducing lattice strain to exhibit a smaller lattice parameter than pure indium oxide
• A manufacturing step for heterojunction materials involving mixing NaOH into an InCl3 solution, followed by the sequential addition of a semiconducting carbon nanotube solution and the surfactant hexamethyldisilazane
• A solid-state symmetric supercapacitor comprising an electrode that uses the heterojunction material as an active material, with the addition of a conductive agent and a binder

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This invention was developed with support from the Ministry of Education, Science and Technology for the project on low-dimensional transition metal chalcogen-aligned CNT-based nanostructure heterojunctions and wafer-scale smart sensor applications.

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