Analysis of the characteristics of several common battery technologies
NiCd and Metal Hydride Batteries
Nickel oxide or nickel hydroxide is the positive electrode, potassium hydroxide or sodium hydroxide is the electrolyte, and cadmium or metal hydride is the negative electrode. Metal hydride batteries were developed in the late 1980s from the electrochemical reversibility of hydrogen-absorbing alloys and hydrogen-releasing reactions. It is the leading product of small secondary batteries.
Lithium Ion Battery
Lithium metal lithium or lithium compound as the active material of the battery is called lithium ion battery, which is divided into primary lithium ion battery and secondary lithium ion battery.
Batteries that enable lithium-ion intercalation and de-intercalation of carbon data can replace pure lithium as the negative electrode, lithium compounds as the positive electrode, and mixed electrolytes as the electrolyte.
The data of the positive electrode of the lithium-ion battery is generally composed of the active compound of lithium, while the negative electrode is carbon with a special molecular structure. A common important component of the positive data is LiCoO2. When charging, the potential at the north and south poles of the battery forces compounds in the positive electrode to release lithium ions, and the negative electrode molecules intercalate into the carbon in a layered structure. During discharge, lithium ions detach from the layered carbon and recombine with positively charged compounds. The movement of lithium ions produces an electric current.
Although the principle of chemical reaction is very simple, in actual industrial production, there are many practical issues to be considered: the data of the positive electrode should be additive to adhere to repeated charging activities, and the data of the negative electrode should contain more lithium ions at the molecular structure design level; The electrolyte filled between the positive and negative electrodes, in addition to stability, also has excellent electrical conductivity to reduce the resistance of the battery.
Although lithium-ion batteries have little recall effect, their capacity will still drop after repeated charging, mainly due to changes in the positive and negative data themselves. At the molecular level, the cavity structure of lithium ions on the positive and negative electrodes gradually collapses and plugs. From a chemical point of view, it is the data active passivation of the positive electrode and the negative electrode, and the secondary reaction appears to stabilize other compounds. There are also physical conditions, such as the gradual stripping of positive electrode data, that ultimately reduces the number of lithium ions in the battery, allowing it to move freely during charge and discharge.
Overcharging and discharging can cause permanent damage to the electrodes of lithium-ion batteries. From a molecular level, it can be intuitively understood that anode carbon emissions will lead to excessive release of lithium ions and their layer structure will decline. Overcharging will put too much The lithium ions harden into the structure of the cathode carbon, and some of the lithium ions can no longer be released. This is why lithium-ion batteries are generally equipped with charge and discharge control circuits.
fuel cell
A device that uses a fuel (such as hydrogen or hydrogen-containing fuel) and an oxidant (such as pure oxygen or oxygen in air) to directly connect to generate electricity. It has the characteristics of high efficiency, electrochemical reaction conversion rate of more than 40%, and no pollution.
-
