classify
According to the different energy storage mechanism, supercapacitors can be divided into three categories: 1) electrochemical double-layer capacitors (electric double-layer capacitors), which use adsorbed anion and cation to store energy; 2) Pseudocapacitor, which stores energy through rapid surface redox reaction; 3) Asymmetric supercapacitor.
principle
Principle of electric double layer supercapacitor
Also known as non-Faraday supercapacitor. Its performance comes from the so-called electric double layer capacitance, and the charge accumulated by the capacitance of the electric double layer capacitor device is stored in the electric double layer formed as the interface between the high surface area electrode and the electrolyte. Several key factors of electric double layer capacitor materials are specific surface area (SSA), electrical conductivity, pore size and distribution. Graphene provides a good substitute for the electrode materials of electric double layer capacitors in the past. Compared with traditional porous carbon materials, graphene has very high conductivity, large surface area and a large number of interlayer structures. Therefore, graphene-based materials are very beneficial to its application in electric double layer capacitors.
Supercapacitor principle
Pseudocapacitor supercapacitor, also known as Faraday supercapacitor, stores energy through Faraday process, which involves rapid reversible redox reaction between electrolyte and electroactive material on electrode surface. The most widely studied electroactive materials include three types: a) transition metal oxides or hydroxides, such as ruthenium oxide, manganese oxide and nickel hydroxide; B) conductive polymer, c) material with oxygen-containing and nitrogen-containing surface functional groups. The pseudo capacitance can reach a higher pseudo capacitance than the electric double layer capacitance. Graphene is considered to be the most suitable carrier material for preparing electrode active components of quasi-capacitors.