Energy storage devices

For improving the energy storage efficiency, ECP/CNM nanocomposites are widely used in electrochemical energy storage devices. These include lithium-ion batteries and supercapacitors. Polyaniline/CNM nanocomposites and polypyrrole/CNM nanocomposites are the major composite nanostructures used for this piupose due to their superior electrochemical properties, low cost and easy processing methods. 

Lithium-ion batteries require novel materials for increasing their cychng stability and power delivering capability. Polypyrrole/reduced graphene oxide nanocomposite is used as cathode in a lithium-ion battery and enhanced electrochemical properties are observed such as high rate capability and improved cycling stability [71 ]. 

Supercapacitors require electrode materials that have good electrical conductivity, good electrochemical properties, high chemical and environmental stabilities, etc. Various ECP/CNM nanocomposites such as polyaniline/carbon nanofiber [31,32,34], polyaniline/graphene [62,67-69], and polypyrrole/graphene [73,75] are widely used as electrode materials in supercapacitors. 

---

A Ragone plot (Figure 7) compares the power and energy density of electrical energy storage devices. Electrolytic capacitors, based on an oxide dielectric, for example, arc associated with high-power densities... 

These results illustrate that electrochemical techniques can be employed to synthesize a vast range of [Si(Pc)0]n-based molecular metals/conductive polymers with wide tunability in optical, magnetic, and electrical properties. Moreover, the structurally well-defined and well-ordered character of the polymer crystal structure offers the opportunity to explore structure/electro-chemical/collective properties and relationships to a depth not possible for most other conductive polymer systems. On a practical note, the present study helps to define those parameters crucial to the fabrication, from cheap, robust phthalocyanines, of efficient energy storage devices. 

Mayer S.T., Pekala R.W., Kaschmitter J.L. The aeorocapacitor an electrochemical double-layer energy-storage device. J Electrochem Soc 1993 140 446-51. 

S. Dietz, V. Nquyen, in Proceedings of the 11th International Seminar on DLC and Similar Energy Storage Devices, Dec. 3-5, 2001, Deerfield Beach, FL, USA. 

In order to be competitive in the market of energy storage devices SC must demonstrate the specific power output of about 10 kW/kg for a charge/discharge at 95% efficiency. 

Burke AF, Miller M. Characteristics and Applications of Advanced Ultracapacitors. Proceedings of the 12th International Seminar on Double Layer Capacitors and Similar Energy Storage Devices, Deerfield Beach, Florida, USA, Dec. 9-11, 2002. 

Pushparaj VL, Manikoth SM, Kumar A, Murugesan S, Ci L, Vajtai R, Linhardt RJ, Nalamasu O, Ajayan PM (2007) Flexible nanocomposite thin film energy storage devices. Proc Natl Acad Sci USA 104 13574-13577. 

Gwon, H., et al., Flexible energy storage devices based on graphene paper. Energy Environmental Science, 2011. 4(4) p. 1277-1283. 

Lithium ion batteries (LIBs) and electrochemical capacitors (ECs) are two important energy storage devices that can complement each other. LIBs work slowly but provide high energy density whereas ECs offer high power density, but suffer from lower energy density [30],... 

ECs are another promising electrical energy storage device with a higher energy density than electrical capacitors, and a better rate capability and cycling stability than LIBs [32]. Carbon-based electric double layer capacitors and metal oxide- or polymer-based pseudocapacitors are two main types of ECs. The charge-... 

The power is created by batteries and other electricity sources. Batteries are energy storage devices, but tmlike batteries, fuel cells convert chemical energy to electricity. Fuel cell vehicles use electricity produced from an electrochemical reaction that takes place when hydrogen and oxygen are combined in the fuel cell stack. The production of electricity using fuel cells takes place without combustion or pollution and leaves only two byproducts, heat and water. Benefits include no emissions and fewer parts to be serviced and replaced. Electricity is also cheaper than gasoline. 

Figure 25. (A) Comparison of the energy storage capability of fuel cells and batteries. Only after several refueling operations are fuel cells more efficient energy storage devices on a Wh/L and Wh/kg basis. (B) Fuel cells have a set volume and weight for the fuel cell stack and peripherals to supply the reactants to the stack. The small incremental fuel volume to continue operation supplying energy makes them more efficient for longer operations.

---