Analyze the advantages and disadvantages of lithium-sulfur batteries

The advantages and disadvantages here are not particularly easy to summarize, because they are still in the experimental stage. List two general aspects. The advantages of 1) large theoretical capacity and large fantasy space; 2) convenient information acquisition and low price determine the low price of commercial products; the disadvantage is that due to the relatively long interval of batch processing, there are natural major shortcomings, which can only be summarized into four points. 1) The electrode and the electrolyte interact with each other to simply form an interface material with high resistivity and low Coulomb power; 2) The product lithium sulfide generated during the discharge process is adiabatic and insoluble, contains irreversible components during the reaction, and has poor circulation function; 3) Small changes in the output of lithium electrodes will lead to changes in all functions of the battery, and there are many uncontrollable factors; 4) There is a continuous effect, and the self-discharge rate is very large. Three problems with lithium-sulfur batteries Lithium-sulfur battery technology has existed for a long time, but due to various reasons, it has never reached the level of commercial application. In the sulfur cathode, the following difficulties are first encountered: the dissolution of the active center body leads to the loss of the active material. During the circulation process, the central long-chain polysulfide (Li2S4~Li2S8) dissolves briefly in the ether-based electrolyte, causing the active material to be continuously lost to the electrolyte. Some active materials will remain dissolved, these materials will not play the role of charging and discharging, reducing the energy density and power density of the battery. 2) The positive electrode data is sulfur, which reflects the low conductivity of lithium sulfide. The low conductivity of sulfur and lithium sulfide ions leads to poor transport of ion electrodes, while the accumulation of lithium sulfide on the positive electrode discharge forms a layer of insulating interface on the positive electrode surface, making the positive electrode cycle worse. 3) The volume of sulfur in lithium metal changes greatly. Because there is a certain density difference between sulfur and lithium sulfide (2.03 and 1.66g cm−3), sulfur has a huge volume expansion rate in the process of completing lithium sulfide, and the amount of lithium decreases sharply in the opposite process, which may cause collapse and damage的electrode structure. In terms of lithium anode, the following difficulties are first faced: 1) Continuous flow effect. This is a well-known problem of lithium-sulfur batteries. Sustained effect refers to the long-chain lithium sulfide dissolved in the electrolyte, which can reach the cathode of lithium and be recycled by chemical methods to form cheap compounds. These compounds are not limited by polarity. Some low-priced compounds can return to the sulfur cathode again and be oxidized again. This is the constant current effect. This polysulfide cascade effect occurs in the battery, which reduces the charge and discharge capacity of the system during the cycle and reduces the coulomb power; the lithium-sulfur battery will have serious self-discharge during the rest period, which makes the application value of the lithium-sulfur battery Greatly reduced. 2) The accumulation of the solid electrolyte central phase (SEI) is not uniform. The lithium metal negative electrode, the interface between the metal and the electrolyte, the data reverberation between the electrolyte and the negative electrode, and the SEI is formed on the surface of the negative electrode. These SEI ions can pass, but electrons cannot. In most cases, SEI is uneven and dense, and there are various pores, so that the electrolyte and anode raw materials can still contact and reverberate. The continuous consumption of lithium metal and electrolyte leads to poor reversibility of the battery, which reduces the service life of the battery. 3) Dendritic growth of metallic lithium. The heterogeneous accumulation of metallic lithium forms the growth of lithium dendrites, which leads to large-scale SEI fracture, which further consumes metallic lithium and electrolyte, and affects battery life. Part of the conductivity gradually increases, the impedance increases, and the Coulomb power decreases. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.