Analysis of common types of lithium batteries for electric vehicles

Today's mainstream electric vehicles (including plug-in hybrid models) have mostly switched to the embrace of lithium batteries. Investigating the reasons, better energy-to-weight ratio (the amount of electricity that a battery can store per unit weight), better high-temperature and low-temperature charge and discharge performance, and longer life are all important factors for lithium batteries to become mainstream. In order of energy efficiency, the types of lithium batteries currently used in mainstream electric vehicles are lithium cobalt oxide batteries, lithium manganese oxide batteries, and lithium iron phosphate batteries. As a high-performance sports car in electric vehicles, Tesla's requirements for batteries are of course also performance-oriented. This is why it chooses lithium cobalt oxide battery technical efficiency first, with large discharge current, high charging speed, and light weight. In fact, lithium cobalt oxide batteries are not unfamiliar to ordinary people. This kind of battery technology has been popularized in small electrical appliances such as flashlights and notebooks. To a certain extent, everyone is the beneficiary of this advanced lithium battery technology. However, high returns are often accompanied by high risks, and the stability of lithium cobalt oxide batteries is relatively poor. This is why it is difficult for this battery technology to produce large-capacity battery cells. The safety technical problems have not been fully resolved. Therefore, Tesla chose a very magical technical solution. Taking the P85 model as an example, it used more than 8000 encapsulated 18650 battery cells to combine, thus circumventing the technology of processing large-capacity battery cells with lithium cobalt oxide battery technology. Gap. Then use extremely complex battery management technology and peripheral circuits to balance the charging and discharging process of so many battery packs, and isolate the batteries by several independent battery compartments, and then use high-strength aluminum alloy guard plates and frame structures. Carry out physical protection to minimize the possibility of security issues. The choices of Japanese manufacturers are relatively balanced. The technology of lithium manganese oxide batteries is not as radical as lithium cobalt oxide batteries. Since metal cobalt is not used, the cost is much lower. This sounds like a continuation of the Japanese economically applicable strategy. . In fact, lithium manganese oxide batteries appeared as a low-cost alternative technology for lithium cobalt oxide batteries. Sacrificing a little efficiency and a little stability, in exchange for the advantages of easier popularization, this transaction is very cost-effective. Another important feature of lithium manganate batteries is that they are beneficial to the processing of large and medium-sized batteries. Therefore, for battery packs for electric vehicles, fewer battery cells can be used, and the requirements for power management are not like lithium cobalt oxide batteries. That's complicated. Lithium manganate battery has better low temperature performance and is more suitable for use in cold areas. However, the high temperature stability is not good enough, it is easy to swell, and the cycle life decays quickly are its shortcomings. Therefore, the actual battery capacity of Japanese electric vehicles is often much larger than the theoretical capacity calculated according to the calibrated power and cruising range. The larger redundant space is to allow electric vehicles to maintain the nominal endurance in the latter part of the life cycle. . The last type of lithium iron phosphate battery is known as the safest vehicle battery technology, because compared with lithium cobalt oxide batteries and lithium manganese oxide batteries, the stability of lithium iron phosphate batteries, especially the stability at high temperatures It is much more stable, and the chances of accidents such as fires when encountering unexpected situations are also smaller. However, the efficiency of lithium iron phosphate batteries is not as good as the aforementioned two battery technologies. The weight required to store the same energy is about twice that of lithium cobalt oxide batteries. It is no wonder why this new battery technology is difficult to become the choice of high-performance electric sports cars. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: Why do pure electric vehicles do not need lower-cost lead-acid batteries, but use high-cost lithium batteries?