Why doesn't Tesla use lithium iron phosphate batteries?

Discussion: Why not lithium iron phosphate? Are the lithium batteries used in Tesla electric vehicles safe? Why not use lithium iron phosphate batteries? The following answers come from lithium battery practitioners. As an engineer working in a research institute, I finally have the opportunity to say a few words in my field. First, correct a concept. Lithium battery is the abbreviation of what we usually call lithium battery, and what you call ferroelectricity is actually a lithium battery that uses lithium iron phosphate as the positive electrode data. It is a lithium battery. Now let us start from the superficial abstract and simple version: Tesla uses Panasonic 18650 lithium batteries with NCA as the positive electrode to plan a complex battery management system to ensure and improve the efficiency and safety of battery operation. As for whether it is definitely safe, this cannot be answered. If you want to talk about spontaneous combustion, the author also wants to say that gasoline cars also spontaneously ignite in summer. Regarding pure electric vehicles, what are we most worried about? Distance anxiety is not far away, because the energy density that the battery can store is too low. Nowadays, the energy density of car battery packs is generally 100~150Wh/kg, and the value of gasoline is about 10,000. So, even if you carry a pile of batteries like a tortoise, you can’t fix it. Let's make fun of what to do if an electric car is charged halfway every day without electricity, because the energy density is too low and it is not harmful. The biggest weakness of current battery technology is that the energy density is too low, which is far behind Moore's Law. Don’t talk about empty lithium. Even if their energy density is not high enough, this is far from useful. So the important reason for not using lithium iron phosphate batteries is that the capacity is low and the energy is low (lithium iron phosphate is slightly less than 3, the voltage Lower, 3.4V, so the energy is lower). In practical applications, all automotive battery packs are combined in series and parallel, requiring a series connection to increase the voltage. At this time, the voltage of a single cell and the consistency of the capacity between different batteries become very important. It is not prudent to say that the capacity is low. In order to compare several positive data, we must introduce this graph, which is five important functional standards: electricity, life, cost, safety and energy. The comparative data is NMC/NCA triad data/NCA, LCO lithium cobalt oxide, LFP lithium iron phosphate, LMO lithium manganese acid. NCA and NCM are close relatives, so they are grouped here. From this picture, we can see that the data energy of the league is the lowest (unfortunately, low capacity is one aspect, low voltage is a problem of 3.4v, for example, 4.7v lithium NMC spinel). Space is limited, do not put charge and discharge curves here. The power is not low at all (in the pilot test of lithium iron phosphate, 5C can reach a drop of 130mAh/g (of course PHOSTECH can also) carbon package + nano data multiplier function is still very powerful!. The life and safety of life are the best Yes, this is important because it is guessed that the polyanion PO43-In addition, the combination of oxygen and electrolyte is better, and the reactivity is lower. Unlike ternary data, it is easier to show oxygen bubbling and other phenomena. In terms of life, it is generally considered to be OK Do 4000 cyclesu003e. The cost cost, lithium iron phosphate is good, the cost is second only to LMO lithium manganese (this thing, air combustion, manganese source and cheap), the second most competitive. Lithium iron phosphate materials, Lithium phosphorus is relatively cheap, but it requires some cost to make nano powders, heat treatment and lazy atmosphere, and various process requirements, resulting in the cost of data (about 10w/t in China) is not as low as LMO (6~ 7w/t), but compared to NMC (13w/t), LCO (more expensive) is still cheaper. Reasons: cobalt is more expensive than nickel, nickel is more expensive than ferromanganese, what material is used, and what cost. Then compare and analyze the following NCM/NCA data energy is the biggest advantage (electric vehicles just want to go further, this is the most important). In addition, with the development of high-nickel NCM data, the energy density of the data can be further improved and the power is possible ( In fact, for pure electric vehicles, energy is more important than power characteristics, but for hybrid vehicles like Toyota Prius, power characteristics are more important, but only if the energy is not too bad). Some pictures and content of the article are from the Internet. If there is any infringement, please contact to delete the previous article: Daily use of laptop batteries