Generally speaking, according to the nature of crystal defect engineering, the main roles of defects in energy storage and conversion systems can be summarized as follows ( Fig. 12 ): (I) Crystal defects can be exploited as energy storage/adsorption/active/nucleation sites.
Abovementioned chemical adsorption/absorption materials and chemical reaction materials without sorption can also be regarded as chemical energy storage materials. Moreover, pure or mixed gas fuels are commonly used as energy storage materials, which are considered as chemical energy storage materials.
The key factors for such kinds of chemical energy storage materials are as follows: Large density; Easy to store and transport; Compatible to the existing infrastructure; Easy to produce and high round-trip efficiency; Environment friendly. Different chemical energy storage materials are listed as follows. Hydrogen.
Defect engineering could modulate the structures of carbon materials, thereby affecting their electronic properties. The presence of defects on carbons may lead to asymmetric charge distribution, change in geometrical configuration, and distortion of the electronic structure that may result in unexpected electrochemical performances.
Chemical energy storage in the form of biomass, coal, and gas is crucial for the current energy generation system. It will also be an essential component of the future renewable energy system. With each facility ranging in the terawatt-hours, chemical energy storage has by far the largest capacity.
Some of the chemical storage systems which are not yet commercialised can also be listed, such as hydrated salts, hydrogen peroxide and vanadium pentoxide. It is vital to note that chemical energy storage also includes both electrochemical energy storage systems and the thermochemical energy storage systems .