Non-woven electrode materials or new options for smart wearable products

Smart bracelets, smart mattresses, rechargeable heating warm pants... More and more smart wearable products are springing up, but these products basically rely on batteries, charging treasures, or using alternating current, how to make conductive materials The soft fit and the simplification of the energy supply device are still issues that need to be solved for wearable products.

Recently, the Chen Su group of Nanjing University of Technology created a non-woven electrode material through microfluidic spinning technology. The supercapacitor constructed with this material may provide a better power supply option for smart wearable products.

According to reports, microfluidic spinning technology is based on the traditional wet spinning rapid prototyping, combined with the laminar flow effect of microfluidic technology, to prepare micron-sized fiber technology, which has many advantages that traditional spinning technology does not have. It is a fiber preparation technology with no high voltage current, energy saving, safety and easy operation.

Schematic diagram of preparation of black phosphorus composite fiber nonwoven fabric based on microfluidic spinning technology

More specifically, the microfluidic spinning technology can utilize the diffusion and laminar effects of microfluids to control the composition and structure of the spinning solution, and to simulate the operation of the bio-spinner to prepare a structure with adjustable structure and regularity. fiber. Microfluidic spinning technology is widely used in biology, medical, energy, defense and other fields due to its fast mass transfer and heat transfer, precise control, easy parallel amplification, and highly controllable continuous production.

Electrode and Preparation of Black Phosphorus Composite Fiber Nonwovens Prepared by Microfluidic Spinning Technology

The research team greatly improved the efficiency of electron conduction between layers by in-situ bridging one-dimensional carbon nanotubes (CNTs) in a two-dimensional black phosphorus (BP) sheet layer between layers of poorly conductive black phosphorous materials; Moreover, since black phosphorus is similar to graphene, the layers are easily deposited. After the addition of carbon nanotubes, the accumulation of black phosphorus layers is effectively alleviated, the specific surface area is increased, the ion adsorption surface is increased, and the ion diffusion rate and the accumulation amount are improved. The black phosphorus has a large ion diffusion channel.

(a) Schematic diagram of the structure of a flexible supercapacitor

(b) Comparison of energy density between flexible supercapacitors and other capacitors

(c) Charge distribution of three different structural electrodes

(d) Accurate charge distribution of three different structural electrodes

Then the research team passed the black phosphorus composite spinning solution through the microfluidic spinning technology to draw, solidify and fuse the black phosphorus micro/nano composite fiber nonwoven electrode material, which has high conductivity, high energy density and excellent flexible supercapacitor function. . The flexible supercapacitor constructed with the nonwoven material has high flexibility and deformability, and can be integrated into the fabric to provide more stable and long-lasting energy supply for the wearable device. It has been successfully applied in electronic devices such as LEDs, smart watches, and color displays.

Schematic diagram of construction and application of flexible supercapacitors

Professor Chen Su said: "The non-woven electrode material made by microfluidic spinning technology is used to construct a supercapacitor whose energy density is currently based on the maximum value of the fiber material electrode supercapacitor and has a higher The flexibility and deformability can be integrated into the fabric to provide stable energy supply under deformation conditions."

Flexible supercapacitors power the deformation of LEDs at different bending angles

Flexible supercapacitors power smart watches

Two capacitor packs are connected in series to power the color display

This method not only provides new ideas for the design of advanced electrode materials, but also greatly promotes the development of flexible supercapacitors in the field of wearable electronics. It is expected to replace microbatteries and be widely used in new energy energy storage fields. The research results were published on November 1, 2018 in "Microfluidic-spinning construction of black-phosphorus-hybrid microfibres for non-woven fabrics toward a high energy density flexible supercapacitor, 2018, 9: 4573. "Nature Communications."