Why can nickel-metal hydride batteries become the first choice for Toyota hybrids?

1. There are tens of thousands of batteries, safety first. The reason why Ni-MH batteries can become the first choice for all cars is that they have unparalleled safety and reliability. On the one hand, the nickel-hydrogen battery electrolyte is a non-flammable aqueous solution. On the other hand, the specific heat capacity and heat of evaporation of the nickel-metal hydride battery are relatively high, while the energy density is relatively low, which means that even if extreme abnormal conditions such as short circuit and puncture occur, the temperature rise of the battery will not cause combustion . In the end, as a relatively mature battery product, the product quality of Ni-MH battery is less difficult to control, and the yield rate is higher. By the end of 2014, more than 73% of the world's hybrid cars used nickel-metal hydride batteries, with a total of more than 8 million. These hybrid cars have experienced serious safety accidents caused by batteries during their use. As the representative of commercial hybrid cars, Toyota Prius, thanks to the excellent charging and discharging procedures, the batteries of these cars have not shown a significant life decline after ten years of use. Therefore, the mature Ni-MH battery is currently the most commercially valuable battery. Foreign testers conducted artificial uninterrupted charging tests on Prius battery packs, and the battery packs did not cause serious safety accidents. 2Shallow charge to create longevity, followed by nickel-metal hydride batteries with good fast charge and discharge functions. The battery capacity of hybrid cars is not large. For example, the latest eighth-generation Camry dual engine has a battery capacity of only 6.5 kWh, which is more than half the capacity compared to plug-in hybrids, which can easily exceed 10 kWh. However, due to the working mode of the hybrid power system, the battery needs to be continuously charged and discharged quickly. Under this working condition, the nickel-hydrogen battery has more advantages than the lithium battery. Although the energy density of NiMH batteries is only 60-80% of that of lithium batteries (Lithium batteries is 100J/m3), the characteristics of NiMH batteries have lower requirements for safety protection, temperature control, etc., so they can easily be used without large volume. Find a place in the hybrid car. The special power system of a hybrid car, under a reasonable power output strategy, generally only uses 10% of the battery capacity during the journey. Even in the most extreme case, the maximum battery usage can only be about 40%. In other words, about 60% of the battery's power is permanently unavailable. This battery management strategy called shallow charging is related to the improvement of nickel-chromium batteries and the greatly improved battery recall effect. Greatly extend its service life, the number of charge and discharge cycles can reach more than 10,000 times. The US 'Customer Statement' inquired over 36,000 Prius owners and concluded that the vehicle has high reliability and very low operating costs. In this regard, 'Customer Statement' used a first-generation Prius that had traveled 330,000 kilometers for 10 years and a new first-generation Prius that had traveled only 3,200 kilometers a decade ago to perform the same standard fuel consumption test and function test. The results show that the old car and the new car that have traveled 330,000 kilometers for 10 years have maintained the same level in terms of fuel consumption and power functions, indicating that the nickel-hydrogen battery pack and hybrid system are still working normally. Many overseas media have highly rated the Prius hybrid car that uses nickel-metal hydride batteries. Since 2015, new energy cars (pure electric and plug-in hybrid) have spread throughout the domestic market. Because this type of car with lithium batteries has been used for a certain period of time, the battery life will be reduced, and the power will be low in winter. Shows a significant attenuation, causing many car owners to have significant endurance anxiety in use. And such results are formed by the characteristics of lithium batteries. Therefore, a new energy car with a vehicle age of 3-4 years has the highest value retention rate of only 45%, which is much lower than the lowest 60% of a fuel vehicle (same age). 3. Environmentally-friendly batteries can make environmentally-friendly cars. Although lithium batteries have no recall effect, the number of charge and discharge cycles is generally only about 600, and in the chaotic application environment of high current fast charge and fast discharge and overcharge and overdischarge, the battery life The number has dropped significantly. In addition, due to the choice of organic electrolyte solutions for lithium batteries, the resistance increases rapidly at low temperatures, and the function has been greatly attenuated at 0°C, which cannot meet the normal operating requirements at -10°C. In contrast, nickel-metal hydride batteries, due to the use of alkaline electrolyte solution, their working temperature can be as low as -40 ℃, so in winter, the power and economic functions of hybrid cars have not changed significantly. Ultimately, because Ni-MH batteries do not contain highly toxic substances, they are more environmentally friendly. The important components of nickel-metal hydride batteries are nickel and rare earths. They have high recovery value (with residual value) and low recovery difficulty. They can basically be fully recovered and reused to realize the continued development of materials and are known as the most environmentally friendly batteries. In contrast, lithium batteries are much more difficult to recover. The vivid chemical characteristics of the lithium battery itself is that the technical path of its recovery is appropriately chaotic. The battery must be pre-solved first, which includes discharge, disassembly, crushing, and sorting. The plastic and metal shells after disassembly can be recovered, but the cost is high: because the remaining voltage is still as high as hundreds of volts (18650 batteries are not included), and there is a certain degree of danger; the battery shell is not self-removable for safety reasons. It takes quite a lot of effort to open it; in addition, the materials for the positive electrode of lithium batteries are also varied and require high levels of acid and alkali solutions for recovery. With current skills, the recovery of lithium batteries is undoubtedly a loss-making business. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous article: Characteristics of power lithium batteries and market status