Last year, the global release of the timetable for the ban on the sale of fuel vehicles made people realize that the era of new energy vehicles is coming, and why pure electric vehicles, plug-in hybrids, fuel cell vehicles, etc., will become the future in just a few years The main theme? On the one hand, it is the support of global strategy and policy, on the other hand, the continuous improvement of power battery technology. Longer battery life and shorter charging time are directly related to the commuting needs of users. Only when new energy vehicles come to us , Will replace traditional fuel vehicles in the future, and are inseparable from everyone's daily travel. So there is what people say: "The development of new energy vehicles is the development of battery technology."

　　Lead-acid battery　　The earliest pure electric vehicles used lead-acid batteries. Lead and its oxides are made as electrode materials, and sulfuric acid solution is used as electrolyte. This is the power source of most electric bicycles now, and low cost is its biggest advantage. However, because the energy density of lead-acid batteries is low, it brings problems such as large size and small capacity, which cannot meet the control of a car's own weight, the consumption of driving force, and the service life of more than 10,000 kilometers per year. It could not be used in mass-produced cars on a large scale and was eventually eliminated by automakers.

　　Sealed lead-acid battery pack Ni-MH battery Ni-MH battery is very close to our daily life. From the early sound, it is very common to hear rechargeable toothbrushes and other small electrical appliances. The positive electrode is a nickel-hydrogen compound and the negative electrode is a metal hydride. Compared with lead-acid batteries, its energy density and number of charge and discharge have been greatly improved, and the electrolyte is non-flammable, its safety is guaranteed, and its manufacturing process is mature. Before making cars, BYD was the world’s second largest manufacturer of nickel-metal hydride batteries. .

　　Ni-MH battery pack 　　 However, because the Ni-MH battery has general charging efficiency, has a rechargeable memory effect, and has a low working voltage (high-voltage fast charging cannot be used), it is not suitable for a single power source of a car and is suitable for auxiliary engine operation. The best in this regard is Toyota. Its hybrid power system uses Atkinson engine + Ni-MH battery pack. The Atkinson engine itself has the advantage of high efficiency in the intermediate speed range, but it also has the problems of low speed and high speed. , And nickel-metal hydride batteries are just a big help to solve the starting and high-speed power shortage.

　　After the widespread introduction of lithium batteries, nickel-metal hydride batteries have also been completely replaced in automobiles. For example, Toyota's new-generation hybrid system uses a more efficient engine + lithium battery combination. Compared with lithium batteries, the capacity of nickel-metal hydride batteries, cycle charging life and environmental protection are not dominant. The cost advantage has also been weakened by the vigorous development of lithium batteries. This is the reason why nickel-metal hydride batteries have gradually withdrawn from the automotive field. Where. Lithium battery Lithium battery is the mainstream choice for new energy vehicles at this stage. Lithium compounds (lithium manganate, lithium iron phosphate, etc.) are used as electrode materials, and graphite is used as negative electrode material. Its advantages are high energy density, small size, light weight, High charging efficiency. The main factor that determines the type or performance of lithium batteries lies in the materials at the two poles of the battery. The material of the positive electrode is the key at this stage, such as mainstream lithium iron phosphate, lithium cobalt oxide in ternary materials, nickel cobalt manganese, etc. There are differences in multiple dimensions such as cost, low-temperature charge and discharge, and safety.

　　General Group Lithium Battery Pack 　　 However, no matter what type, all lithium battery packs will face the "natural enemy" of low temperature. Although the optimal operating temperature of different lithium battery types has certain differences, the decrease in the activity of lithium ions that accompanies the lower than the optimal range has a greater impact on the cruising range, which is also reflected in our previous tests: The battery life of electric vehicles equipped with lithium battery packs in actual use in winter in the north can generally only reach more than 60% of the theoretical battery life, and at most about 70%.

　　The negative impact of low temperature in the test results of the DENZA EV400 limit mileage is not well solved by the battery itself, so many automakers have tried to heat the battery pack and added a temperature control system for the power battery alone. Most of the brand models that adopt this approach All have a certain mitigation effect, but the actual effect is not an excellent solution to the problem, because the power consumption of some electric vehicle temperature control systems is greater than the loss of low temperature.

　　Emgrand EV450 is equipped with version 2.0 of the ITCS battery intelligent temperature control management system. What can be expected in this regard is that General Motors has the intention to cooperate with South Korea’s LG Group to purchase multiple temperature control components directly installed in the battery pack. The product can not only dissipate heat to the battery as it does now, but also increase the temperature of the battery in cold weather. The landing of this technology is worth looking forward to. It is reported that the next round of pure electric and plug-in hybrid new cars of GM will be used to replace the battery packs currently supplied by the Hitachi brand.　　Hydrogen fuel cell　　Everyone knows the water that is finally obtained by H2+O2 combustion, so hydrogen is a very ideal clean energy. As far as hydrogen itself is concerned, combustion can release a large amount of energy, and it performs well at low temperatures. The most important thing is that hydrogenation is highly efficient. It only takes 5 minutes to drive more than 600 kilometers, and there is room for improvement in this data. These are far superior to existing lithium batteries.

　　Regarding the investment in hydrogen fuel cell vehicles, Japanese and South Korean car companies have already started research, and have now invested in their respective countries in a small scale. Used for the Pyeongchang Winter Olympics and went on sale.

　　Hyundai NEXO hydrogen fuel cell vehicle　　 And hydrogen is such a good energy source, why not promote it? Because it is too difficult to obtain hydrogen with current technology. Everyone has learned that hydrogen can be obtained by electrolyzing water, but it consumes electricity to electrolyze the water, and then burn the hydrogen to finally turn into water. The power consumption and loss of this process is not as good as directly charging the lithium battery, and the cost is too high. The cost and process are more appropriate to extract from oil and natural gas, but the amount is not large, so fuel cell vehicles "only get their name and are difficult to promote."

　　Graphene battery. For the discussion of the power battery of new energy vehicles in the future, the most reliable and most discussed one is the graphene battery. The interpretation of some professional perspectives is "translation": there are two uses for combining this material with lithium batteries. The method is to use the graphene composite material as the conductive agent of the lithium battery, and the other is to directly use it as the negative electrode. The effect is to increase the activity of the lithium battery, thereby improving the cruising range and charging speed of the electric vehicle.

　　Graphene-carbonized sponge lithium-oxygen battery　　graphene battery can effectively solve the shortcomings of lithium batteries, and the product characteristics are directly linked to the use of new energy vehicle users. The benefits of this material are indeed great, and South Korea’s Samsung has also announced that it has mastered this technology, but the cost is a major bottleneck. Graphene is not easy to obtain. It was a material used in the aerospace field in the early days. When, How to reduce costs will be a big problem for this high-quality product to "fly into the homes of ordinary people." Various automakers have not announced plans to make efforts in this regard.

　　Graphene lithium battery renderings To put it simply, the working principle of pure electric vehicles is to "charge directly with electricity", while hydrogen fuel cell vehicles use H2 + O2 to "fire" (chemical reaction) electricity and water, which is equivalent to "burning hydrogen". Power generation. Both types of "batteries" are also zero-emission. The lithium battery of electric vehicles has a lower capacity density, poor low-temperature activity, which affects battery life, and slow charging speed. Hydrogen fuel cells have no problems at all, and the work efficiency is much higher. The reason why hydrogen is called high-quality energy. Solid-state lithium battery Solid-state lithium battery, as its name implies, no longer uses liquid electrolyte and uses solid electrolyte. Its capacity density is far higher than that of current mainstream lithium batteries. This means that pure electric vehicles have a higher range and even reach the range of energy-saving gasoline vehicles. , And the charging efficiency also has a qualitative leap compared with the current stage. It is reported that the optimal charging speed of electric vehicles equipped with solid-state batteries can reach an increase of 800 kilometers in 1 minute. This can be said to be the best core component of new energy vehicles.