SUPERCAPACITOR FROM POLYMER DERIVED SILICON OXYCARBIDE
Publication Date: 2012-Nov-21
The IP.com Prior Art Database
This publication discloses potential for a new class of materials, commonly known as polymer derived ceramic (PDC) as material for supercapacitors. A suitable polymer precursor, typically a silicone polymer such as polydimethylsilane (PDMS) is subjected to crosslinking and pyrolysis to form amorphous silicon oxycarbide ceramic. The amorphous ceramic is then etched chemically using HF, leading to formation of a highly nanoporous carbonaceous skeleton of oxycarbide units surrounded by graphitic carbon, with very high surface area. The measurements show surface area of 980 m2/g for a structure produced using polydimethylsilane. Specific electrochemical capacitance was shown to be of the order of 18 F/g. Using the methods illustrated, the nanoporous capacitor structures can be formed to suit various needs and specifications.
This publication relates to supercapacitors used for energy storage applications. In recent years, super capacitors have drawn tremendous attention from technologists because of high power density, useful for numerous energy storage applications in hybrid vehicles, PC cards, digital cameras etc. Carbonaceous activated carbon, graphene, carbon nanotubes, carbon aerogels, conductive polymers etc. have been successfully demonstrated as potential supercapacitor materials. Many of these materials are difficult to manufacture in large quantity, expensive and susceptible to damage in harsh environments and/or at elevated temperatures. This publication discloses a new material, based on polymer derived ceramic (PDC) for supercapacitors. Chemical composition along with electrical conductivity and surface area, are important parameters for electrochemical capacitance. The publication also discloses a process to optimize these parameters to achieve higher values of capacitance.
BRIEF DESCRIPTION OF DRAWINGS
Supercapacitor from polymer derived silicon oxycarbide is described further with reference to the following drawings in which:
Figure 1 illustrates the process map to make nanoporous, high surface area SiOC.
Figure 2 shows (a) cyclic voltammogram and (b) galvanostatic charge-discharge of electrochemical cell made from etched SiOC.
This publication discloses potential for a new class of materials, commonly known as polymer derived ceramic (PDC) as material for supercapacitors. It also discloses a process of making in large quantity suitable for industrial production and economically viable. Polymer derived ceramic (PDC) is a group of materials generally manufactured via pyrolysis of silicon based polymer. Silicon oxycarbide is one many important PDC materials being currently investigated for multifunctional applications. This material is a non-stoichiometric combination of parent elements of silicon, carbon, oxygen. Structurally, amorphous silicon oxycarbide consists of three components; silica tetrahedra, different oxycarbide units and free graphitic carbon. The building block for silicon oxycarbide is a silica domain surrounded by oxycarbide units; silica domains encapsulated with oxycarbide units are separated by graphene sheets. This unique material exhibits high electrochemical capacitance as will be illustrated further in the example.
A process flow diagram for producing the novel silicon oxycarbide structures is illustrated in Fig. 1. As shown in the flow diagram, a suitable polymer precursor, typically a silicone polymer such as polydimethylsilane (PDMS) is subjected to crosslinking and pyrolysis to form amorphous silicon oxycarbide ceramic as is well known in the art (US4981820). The amorphous ceramic is then etched chemically using HF. Chemical etching of SiOC with HF leads to formation of a highly nanoporous...