Everyone should be familiar with supercapacitors. We talked about the application of supercapacitors in-car startups, and also talked about the working principle of energy storage capacitors. But have you heard of lithium-ion batteries? Don’t worry if you haven’t, let’s talk about the difference between supercapacitors and lithium-ion capacitors.
Supercapacitors are divided into three types: organic (activated carbon-based, including graphene, which is now highly hyped). The principle is to polarize the electrolyte under electric potential. The positive and negative ions of the electrolyte and the positive and negative electrons on the conductive material form an electric double layer. The porous and high specific surface area of u200bu200bthe activated carbon material can store a large amount of electrolyte positive and negative ions. The process is physical energy storage (of course, it is not pure, there are some chemical reactions, otherwise its cycle may not be 1 million times but an infinite life)
The water system is an electrochemical capacitor for energy storage by means of 'pseudocapacitance' produced by the Faraday reaction on the surface of the active material. The 'pseudocapacitor' electrode material uses lithium ions or protons in the three-dimensional or quasi-two-dimensional lattice of the material. The storage in the three-dimensional structure achieves the purpose of storing energy. Although its charging and discharging characteristics are very similar to that of an electric double-layer capacitor, its energy storage mechanism is quite different from the two-dimensional adsorption on the surface of activated carbon materials. Therefore, pseudocapacitors have large currents. While charging and discharging characteristics, it also has a large capacity that ordinary electric double-layer capacitors do not have.
Asymmetric Super Capacitor Example: Asymmetric super capacitor developed by ACT Company. The positive electrode adopts the material 'carbon nano' developed by Japan Electronics, which can greatly increase the energy density, the negative electrode adopts graphite, and the negative electrode is pre-coated with lithium ions, that is, a lithium-ion capacitor.
(Activated carbon, metal oxides, conductive polymers can all become electrode materials for supercapacitors)
Other energy storage, let’s talk about the new energy storage that we are doing now, which cannot be replaced in the next 20 years. Lithium-ion batteries. Lithium-ion batteries are different from lithium batteries. There should be no confusion between the two.
The charging principle of lithium-ion battery: a power supply charges the battery. At this time, the electron e on the positive electrode runs from the external circuit to the negative electrode, and the positive lithium ion Li+ 'jumps' into the electrolyte from the positive electrode and 'climbs over' The small tortuous hole in the diaphragm 'swims' to the negative electrode and combines with the electrons that have run over.
Discharge principle: Discharge has a constant current discharge and constant resistance discharge. Constant current discharge is actually adding a variable resistance to the external circuit that can change with the voltage. The essence of constant resistance discharge is to add resistance to the positive and negative electrodes of the battery. Let electrons pass.
It can be seen that as long as the electrons on the negative electrode cannot run from the negative electrode to the positive electrode, the battery will not discharge. Both electrons and Li+ act at the same time, with the same direction but different paths. When discharging, the electrons run from the negative electrode to the positive electrode through the electronic conductor, and the lithium-ion Li+ 'jumps' from the negative electrode into the electrolyte, and 'climbs' over the diaphragm. 'Swimming' to the positive pole in the small hole, combined with the electrons that ran over long ago.