Multi-responsive supercapacitors: Smart solution to store electrical energy

With increasing demand for economic and eco-friendly energy conversion and storage system, smart devices integrating both energy conversion and storage have received increasing attention as a key breakthrough for efficient energy utilization. In recent years, significant attempts are made in the integration of the two technologies taking all possible means into account to convert energy efficiently. Among the options, multi-responsive supercapacitors which can be charged using diverse renewable resources, e.g. mechanical force, temperature or light, are widely considered as a promising energy integrated system because of the unique characteristics of supercapacitors, such as fast charging/discharging rate, high power density, simple configuration. In this review, we provide insights into the mechanism of converting mechanical force, temperature and light into electrochemical energy. We shed light on various alternatives to store electrical energy using an electrochemical energy storage unit to realize multi-responsive supercapacitors. In addition, other means of enabling electrochemical energy storage are also discussed in brief. The challenges of the integrated system for simultaneous realization of energy conversion and storage are highlighted. (c) 2017 Elsevier Ltd. All rights reserved.