Analysis the advantages and disadvantages of lithium sulfur batteries

Source: 2020 - 03 - He hits: 30 pros and cons here is not particularly easy to summarize the advantages and disadvantages of, because they are still in the experimental stage listed two aspects. The advantage of 1) Theory of large capacity, fantasy space is large; 2) Convenient access to information, the price is low, determines the commercial products prices are low; On the downside, due to the interval of batch production is relatively far, natural major shortcomings, is only four. 1) Electrodes and electrolyte mutual echo, simple constitute a high resistivity and low coulomb power interface materials; 2) Generated in the process of discharge product lithium sulfide is adiabatic insoluble, irreversible component is contained in reaction process, poor circulation function; 3) Lithium electrode production of small changes can lead to change batteries all functions, and there are a lot of uncontrollable factors; 4) There is continuous effects, self-discharge rate is very large. The three lithium sulfur batteries lithium-sulfur battery technology has been around for a long time, but for various reasons, it has never reached the level of business applications. In the anode of sulfur, first of all the following difficulties: active centrosome dissolved lead to loss of active material. In the center of the circulation process, long chain disulfide ( Li2S4 ~ Li2S8) Brief dissolved in ether base electrolyte, lead to loss of active material in the electrolyte. Some active substances will remain dissolved state, these substances will not have the effect of charge and discharge, reduce the energy density and power density of the battery. 2) The positive data for sulfur, reflects the low conductivity of lithium sulfide. Low sulfur and sulfide lithium ionic conductivity leads to the poor transport ion electrode, and lithium sulfide accumulation in the anode discharge form a layer of the anode surface insulation interface, make the positive cycle is even worse. 3) Lithium sulfur in large volume change. Because there is a certain density difference lithium sulfur and sulfide ( 2. 3 and 1. 66 g cm & minus; 3) Has huge volume expansion rate, sulfur in the process of complete sulfide lithium, lithium in the reverse process, dramatically reduced, which may lead to collapse and damage the electrode structure. In terms of the lithium cathode, first face the following difficulties: 1) Continuous flow effect. This is a well-known lithium sulfur batteries. Continuous effect refers to the long chain dissolved in electrolyte lithium sulfide, it can reach the lithium cathode, recovery by chemical method, formation of cheap compounds. These compounds are not restricted by the polarity, the positive, some of the low sulfur compounds can once again return to again by oxidation. This is called the constant current effect. This polysulphide cascade effect occurs in batteries, reduce the charge and discharge capacity of the system in the process of circulation, reduce the coulomb's power; Lithium sulfur batteries during rest will produce serious self-discharge, makes the application of lithium sulfur batteries value is reduced greatly. 2) Solid electrolyte center ( SEI) The accumulation of uneven. Lithium metal anode, the interface between the metal and the electrolyte, electrolyte and cathode of data between the reverberation, and to form the SEI at the cathode surface. The SEI ions can pass, but not electronic. In most cases, SEI is not even and dense, and all kinds of holes, the electrolyte and anode material can still contact and reverberation. Lithium metal and the electrolyte battery reversibility of continuous consumption is poor, reduce the service life of the battery. 3) Metallic lithium dendrite growth. Heterogeneous accumulation formation of metallic lithium lithium dendrite growth, lead to massive SEI fracture, further consumption lithium metal and the electrolyte, affect the battery life. Part of the conductivity increases gradually, the impedance increases, the coulomb power reduction.