A big analysis of the development of power battery technology, why the rapid rise of new energy vehicles

　　From a practical point of view, after the ban on the sale of fuel vehicles in 2025, only new energy vehicles can be purchased. How important is the battery of a car? As the battery development mentioned in this article, the old battery types are gradually becoming In history, some new battery technologies are still in the conceptual stage, and some will come to everyone as long as they overcome technical and cost problems.

　　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, so that new energy vehicles can 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 batteries

　　Pure electric vehicles first used lead-acid batteries. Lead and its oxides were made as electrode materials, and sulfuric acid solution was 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.

　　NiMH batteries

　　Ni-MH batteries are very close to our daily lives. It is common to hear from the early days that small electrical appliances such as rechargeable toothbrushes are common. The positive electrode is a nickel-hydrogen compound and the negative electrode is a metal hydride. The energy density and the number of charge and discharge are compared. Lead-acid batteries have been greatly improved, the electrolyte is non-flammable, safety is guaranteed, and the manufacturing process is mature. Before making cars, BYD was the world's second largest manufacturer of nickel-metal hydride batteries.

　　However, because nickel-metal hydride batteries have general charging efficiency, have rechargeable memory effects, and have a low operating voltage (high-voltage fast charging cannot be used), they are not suitable for a single power source of a car and are suitable for auxiliary engine operation. The best in this regard is Toyota, whose hybrid power system uses Atkinson engine + Ni-MH battery pack. Atkinson engine itself has the advantage of high efficiency in the middle speed range, but it also has the problem of low speed and high speed weakness. , And nickel-hydrogen battery can just solve the problem of starting and high-speed power shortage.

　　After the widespread use of lithium batteries, nickel-metal hydride batteries also have a tendency to be 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 advantageous. The cost advantage has also been weakened under 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 batteries are 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 anode material. Its advantages are high energy density, small size, light weight, and charging efficiency. high. The main factor that determines the type or performance of a lithium battery lies in the materials of the two poles of the battery. The material of the positive electrode is the key at this stage, such as the mainstream lithium iron phosphate, lithium cobalt oxide, nickel cobalt manganese, etc. There are differences in multiple dimensions such as cost, low-temperature charge and discharge, and safety.

　　But 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 is different to a certain extent, 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: For electric vehicles equipped with lithium battery packs, the battery life in actual use in the northern winter can generally only reach more than 60% of the theoretical battery life, and at most about 70%.

　　The negative impact of low temperature is not easily solved by the battery itself, so many automakers have tried to heat the battery pack and increase the temperature control system for the power battery. Most of the brand models that adopt this approach have a certain mitigation effect, but The actual effect is not an excellent solution to the problem, because some electric vehicle temperature control systems consume more power than the low temperature loss.

　　What can be expected in this regard is that the General Motors Group has the intention to cooperate with the South Korean LG Group to purchase products that are directly equipped with multiple temperature control components inside the battery pack, which can not only dissipate heat from the battery as it is now, but also in the cold. The weather raises the temperature of the battery. 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 that H2+O2 burns the final water, so hydrogen is a very ideal clean energy. As far as hydrogen itself is concerned, combustion can release a large amount of energy and has excellent low temperature performance. The most important hydrogenation is high in efficiency. 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 of hydrogen fuel cell vehicles, Japanese and Korean car companies have already started research, and now they have invested in their respective countries' markets on a small scale, such as the Hyundai NEXO hydrogen fuel cell vehicles that the author tested before the Spring Festival. Used for the Pyeongchang Winter Olympics and went on sale.

　　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 is the graphene battery. The interpretation of some professional perspectives is "translation": there are two ways to use this material in combination with lithium batteries. Graphene composite material is used as the conductive agent of the lithium battery, and the second is directly used 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 batteries 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 yet announced plans to make efforts in this regard.

　　To put it simply, the working principle of a pure electric vehicle is to "recharge and use electricity directly", while a hydrogen fuel cell vehicle uses H2 + O2 to "fire" (chemical reaction) electricity and water, which is equivalent to "burning hydrogen" to generate electricity. Both types of "batteries" are also zero-emissions. The lithium battery of electric vehicles has a lower capacity density, poor low-temperature activity, which affects battery life, and the problem of slow charging speed. The reason why hydrogen is called high-quality energy.

　　Solid Lithium Battery

　　As the name suggests, solid-state lithium batteries no longer use liquid electrolytes and use solid electrolytes. Their 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 are charged. Compared with the current stage, the efficiency also has a qualitative leap. It is reported that an electric vehicle equipped with a solid-state battery can achieve an ideal charging speed of up to 800 kilometers in 1 minute. This can be said to be the best core component of a new energy vehicle.