The introduction of high-performance friction nano-generators for green new energy

Recently, under the leadership of Professor Wang Zhonglin, the scientific research team jointly organized by the Beijing Institute of Nano Energy and Systems, Chinese Academy of Sciences and the Georgia Institute of Technology in the United States, designed and produced a high-power two-dimensional planar friction generator and successfully demonstrated its adoption. The ability to collect mechanical energy in the environment to drive conventional electronic products in real time. The high-performance friction generator created a practical process for self-driven portable electronic devices, and provided a brand-new idea for collecting mechanical energy over a large area. The relevant research results were published online in Nature - Communication (DOI: 10.1038/ncomms4426).

The frictional electrification effect is a phenomenon in which two different materials are charged to each other through contact with each other, and is one of the most common phenomena in the natural world. In 2012, Wang Zhonglin’s research team successfully developed a transparent friction generator made of organic materials for the first time. It originally used the coupling effect of frictional electrification and electrostatic induction to convert mechanical energy into electrical energy. In recent years, this type of transparent friction generator has been successively demonstrated. The basic operating mode of the device and its suitability for various mechanical movements. However, smaller output currents and lower output power have been hindering the practical application of this technology.

The main team composed of Dr. Zhu Guang and Ph.D. Chen Jun found in the latest research under the guidance of Wang Zhonglin that the amount of charge transfer between the electrodes can pass through the material during the sliding process of the two working parts of the friction generator. Surface patterning is greatly enhanced and is in a quasi-linear relationship with the pattern density. Therefore, they designed a patterned array structure that produced a qualitative leap in the output power of the friction generator. The generator consists of a planarized circular stator and a rotor. The pattern array on the surface of the contact material is composed of a circle of tiny sectors that are radially and closely packed. When the stator and rotor rotate relative to each other, the highest average output power of the generator is 1.5 watts, and the power density is as high as 19mW·cm-2. The corresponding energy conversion efficiency is 24%.

The research team successfully demonstrated the widespread use of this high-power friction generator in the collection of a variety of mechanical energy including air flow, water flow, and human activity. As a direct power supply, they can provide continuous power for everyday appliances such as spherical bulbs. In addition, through the combination of generators and power management circuits, researchers have further developed a complete small power supply system. The system has the functions of impedance reduction, rectification, energy storage and voltage regulation, and can provide constant voltage and stable DC output, thus providing real-time power or direct charging for various common electronic products including mobile phones.

Researchers said that compared to traditional electromagnetic generators, the friction generator has a series of unparalleled advantages due to the unique mechanism of surface electrification.

First, the friction generator is made of a thin film polymer material and a thin-film electrode material, has a very light weight and a very small volume, and its energy density has a great advantage compared with the electromagnetic generator. Therefore, it is particularly suitable for providing power to small appliances such as portable/wearable electronic devices or wireless sensor arrays.

Secondly, the materials used to make the friction generators are large-scale industrialized raw materials, combined with their simple structure and easy fabrication, making their production costs much lower than other power generation technologies, providing extremely favorable conditions for their wide application. Finally, the unique structure of the friction generator provides a viable and even unique solution for collecting the mutual sliding between two bodies, which is also beyond the reach of traditional generators. Not only that, the friction generator also has the potential to collect and transform the mechanical energy in the natural world on a large scale, and it is expected to become a new approach to the supply of green energy.

For this original innovative technology, experts from the same industry gave a high rating and considered that this type of friction generator has the advantages of high output, small size, and low cost through the delicate design of the structure, which is achieved by using mechanical energy in daily life. Self-powered electronic devices provide a practical method. In addition, for areas that do not have power grid coverage, it is expected that people's daily activities will be able to obtain enough energy to turn on the lights and power the mobile phones.