Recently, Prof. Guo Yiping and Prof. Liu Hezhou of the State Key Laboratory of Metal Matrix Composites of Shanghai Jiaotong University have made important progress in the field of ultra-flexible nano-power composites.
With the rapid development of smart devices (ie, self-driven portable electronic devices, multi-energy harvesters and sensors), self-powered nano-power generation / power supply technology designed to obtain energy from the environment has become increasingly important and urgent. Piezo nano-generators have become a research hotspot because of their highly efficient electromechanical conversion efficiency, light weight, and fast response. Piezoelectric ceramics and single crystals have an extremely high piezoelectric effect, but due to their rigidity and brittleness, they cannot meet the design requirements of flexible and wearable electronic devices. Although there have been many studies to obtain super-flexibility by mixing piezoelectric ceramic powder and polymer, the design of the piezoelectric structure of the discontinuous phase leads to low energy collection efficiency. Although the piezoelectric film can be deposited and then transferred to a flexible substrate, although it can maintain good energy collection and maintain a certain flexibility, its complicated process and high cost are not conducive to commercial large-scale production. Therefore, it is particularly important and challenging to design and develop a piezoelectric nano-power generation material that is ultra-flexible, can efficiently perform energy harvesting, and can achieve large-scale production.
This study proposes to use a layered electronic-grade glass fiber cloth material system as a substrate and deposit a nano-piezoelectric generation material with a layered structure on the substrate by a dipping method. In the prepared piezoelectric fiber cloth composite material, the surface of each fiber is covered with a layer of nano-thickness PZT material, and the PZT between each fiber is connected to each other to form a kind of glass fiber cloth. Multi-level structure. The macro-ultra-flexibility and micro-rigidity of electronic-grade glass fiber cloth itself give this piezoelectric fiber cloth high-efficiency energy transfer, conversion, and super flexibility. In addition, the piezoelectric fiber cloth can realize the design of a finger electrode mask and an upper and lower flexible electrode bonding package design. For example, a 3.5cm × 1.5cm nano-piezoelectric fiber cloth can produce ~ 60 V and ~ 500 nA output under the standard test by using a finger electrode. An 8cm × 8cm nano-piezo fiber cloth uses ultra-flexible conductive polyethylene carbon film as the upper and lower electrodes to easily light up 20 commercial green LED lights under the condition of simulating human movement.
At the same time, using the micro-rigidity of glass fiber cloth, it was found for the first time that the deformation of the piezoelectric nanogenerator has a linear relationship with the signal output, which is expected to gain important applications in the field of flexible sensing. In addition, depositing a broad-spectrum absorption high-voltage electroactive piezoelectric material on the glass fiber cloth substrate of this multilayer structure is also expected to be able to collect light energy, thermal energy and mechanical energy at the same time. This work provides a new perspective for manufacturing high-performance, ultra-flexible, low-cost nano-generators and flexible sensors, and is expected to find applications in the field of flexible wearable devices.