Although the list of new energy vehicles in China does not include many non-plug-in hybrid vehicles, it is undeniable that such hybrid vehicles do not need to change the user’s habits, but can bring a lot of fuel economy and driving quality. , More and more popular with users.

Speaking of hybrid power, apart from Honda, a latecomer, it is reliable in the domestic market that Toyota was the first to bring this technology to China. Toyota is clearly taking advantage of this. In January 2019, sales of the eighth-generation Camry reached 19,720, of which hybrid models accounted for 21%. The cheaper, compact model Leeling sold 26,681 units in January, with hybrid vehicles accounting for 20% of sales.

However, many consumers still have questions about hybrid vehicles. Why is Toyota blindly focusing on the use of nickel-metal hydride batteries when most new energy vehicles (such as Tesla, NIO, BYD, etc.) are in use? Lithium batteries have been used in the use of our daily necessities Today, the use of nickel-metal hydride batteries is obsolete. Is this the factory to reduce production costs? In fact, the use of nickel-metal hydride batteries in hybrid vehicles has considerable advantages, not only Toyota, but also hybrids of many brands such as Ford and General Motors. Most power cars choose nickel-metal hydride batteries as the storage medium for electric energy.

The voltage we use daily is 1.2V, which is a nickel-metal hydride battery.

1.22. Thousands of batteries, safety first

Ni-MH battery has become the first choice for many cars because of its unparalleled safety and reliability. On the one hand, the electrolyte of nickel-metal hydride batteries is a non-flammable aqueous solution. On the other hand, the specific heat capacity and heat of evaporation of the nickel-metal hydride battery electrolyte are relatively high, while the energy density is relatively low, which means that even in the case of short-circuit, puncture and other extreme abnormal conditions, the temperature rise of the battery is not enough to cause combustion. Finally, as a mature battery product, Ni-MH battery has low quality control difficulty and high yield.

As of the end of 2014, more than 73% of the world’s hybrid vehicles use nickel-metal hydride batteries, a total of more than 8 million vehicles. These hybrid vehicles have had serious battery safety accidents during their use. As a representative of commercial hybrid vehicles, Toyota Prius has no obvious loss of battery life due to its excellent charging and discharging procedures after 10 years of use. Therefore, mature nickel-metal hydride batteries are the most valuable batteries for commercial applications.

The battery pack of Prius did not have any serious safety accidents. The battery pack was artificially charged by foreign testers.

Shallow charging, long life

Secondly, Ni-MH batteries have good fast charge and discharge performance. For example, the battery capacity of the latest eighth-generation Camry twin-engine car is only 6.5 kWh, which is less than half of the capacity of plug-in hybrid vehicles above 10 kWh. Ni-MH batteries are more advantageous than lithium batteries because the hybrid system’s working method requires batteries to be charged and discharged quickly.

Although the energy density of Ni-MH batteries is only 60-80% of that of lithium batteries (100J/m lithium batteries), Ni-MH batteries have lower requirements for safety protection and temperature control, and are easy to find in small hybrid vehicles. Own position.

Under a reasonable power output strategy, the special power system for hybrid electric vehicles can only use 10% of the battery capacity during driving. Even in the most extreme cases, the maximum capacity of the battery can only reach 40%. In other words, about 60% of the electricity has never been used. This battery management strategy is called shallow charging, which can greatly extend the life of nickel-chromium batteries, and its memory effect is greatly improved, with more than 10,000 charge-discharge cycles.

Consumer Reports surveyed more than 36,000 Prius owners and concluded that the car is reliable and very cheap to use. To this end, Consumer Reports conducted the same fuel economy performance on a 10-year-old Prius with a mileage of 330,000 kilometers and a 10-year-old Prius with a mileage of 3,200 kilometers. And performance testing. The results show that the old and new cars that have been used for 10 years and have driven 330,000 kilometers have maintained the same level of fuel consumption and power performance, indicating that the nickel-metal hydride battery pack and hybrid power system can still work normally.

Since the popularization of new energy vehicles (pure electric and plug-in hybrid) in the domestic market in 2015, new energy vehicles using lithium batteries have a reduced battery life after a certain number of years of use, and their power is significantly reduced in low temperature environments in winter, causing many car owners There is obvious endurance anxiety during use. This is caused by the characteristics of lithium batteries. Therefore, in the 3-4 years of new energy vehicles, the highest warranty rate is only 45%, compared with the lowest fuel vehicle with only 60% (same vehicle age), which is much lower.

3. Environmentally friendly battery manufacturing environmentally friendly cars

Although the lithium battery has no memory effect, the charge and discharge cycle is generally only about 600 times. In the complex environment of high current rapid charge and discharge and overcharge and overdischarge, the battery life is greatly reduced. In addition, due to the use of organic electrolyte solutions, the resistance of the lithium battery increases rapidly at low temperatures, and its performance is greatly attenuated at 0°C, which cannot meet the requirements of normal use at -10°C. In contrast, due to the use of alkaline electrolyte solutions, the operating temperature of nickel-metal hydride batteries can be as low as -40°C. Therefore, the power and economy of hybrid vehicles do not change significantly in winter.

Finally, Ni-MH batteries are more environmentally friendly because they do not contain highly toxic substances. The important components of nickel-metal hydride batteries are nickel and rare earths, which have high recovery value (residual value) and low recovery difficulty. Basically all can be recycled and reused to realize the sustainable development of materials. Known as the most environmentally friendly battery.

On the other hand, lithium batteries are more difficult to recycle. The chemical activity of the lithium battery itself makes the technical route of its recycling very complicated. The battery must be pre-processed, including discharge, disassembly, crushing and sorting. The disassembled plastic and metal casing can be recycled, but the cost is high: the residual voltage is still several hundred volts (not included) and dangerous; the battery casing is safe, the packaging is self-disassembly, and considerable effort is open; in addition, the lithium battery cathode The materials are also different, with high demand for acid and alkaline solutions for recovery. With current technology, the recycling of lithium batteries is a loss-making business.

In addition to the above advantages, Ni-MH batteries also have the advantages of stable discharge characteristics, smooth discharge curves, and low calorific value. Therefore, before a major breakthrough in battery technology, this relatively low-energy density Ni-MH battery is still the best partner for hybrid vehicles that do not require high battery power. The PCB board that integrates control modules such as instrumentation, air conditioning, audio, and smart buttons is also an integrated solution. It is important to reduce weight, save costs (including reducing parts, reducing assembly processes, reducing vehicle wiring harnesses, etc.), and reducing space. At present, the functions of each part of the vehicle are realized through their own independent modules, such as smart buttons, air conditioning, audio, instrument panel, radar, tire pressure monitoring, etc. These modules are independent of each other and realize their own functions. The integration of low-voltage electrical appliances not only greatly reduces the cost of electrical appliances, but also reduces the cost of product diagnosis, production, testing, modification, and after-sales, optimizes the passenger car system, and is beneficial to the lightweight of the entire vehicle. The integrated EEA is also the basis for automakers to master their core competitiveness.