Hybrid energy cells for simultaneously harvesting multi-types of energies

Harvesting multi-mode energies from our living environment is an effective approach for solving the power source issue of the sensors and some personal electronics. Usually, the mechanical, thermal, and solar energies can be extensively found in our living environment. However, these energies are not always available at the same time, which is depending on the weather, working conditions, and some other cases. The concept of a hybrid energy cell is to develop a technology to individually or simultaneously scavenge multi-mode energies from environment, so that the sensors or other devices can sustainably work without the external power sources. In this article, we review the investigations about the hybrid energy cells that include the energy harvesting units such as the piezoelectric nanogenerator, triboelectric nanogenerator, pyroelectric nanogenerator, thermoelectric generator and solar cells. The fabricated hybrid energy cells have been utilized to light up some electronics and for some self-powered electro-chemical applications. The obtained energies can be also stored in Li-ion battery, where the hybrid structure between the nanogenerator and the Li-ion battery exhibits the better charging performance than that of the conventional charging method. These investigations are of critical importance for sensing, medical science, environmental monitoring, defense technology, and even personal electronics. (C) 2014 Elsevier Ltd. All rights reserved.