On the low - speed electric vehicle power threshold

Low-speed electric vehicles, without the support of national policies and funds, are an industry completely dependent on market demand. Has played a role in the new energy electric vehicle industry. However, at present, the majority of low-speed electric vehicles are powered by developed lead-acid batteries, and lithium batteries are rarely used. Low-speed electric vehicles are powered by lead-acid batteries in large part because of their current competitive advantage in cost. And lead-acid battery development more mature, stable performance, better security. All of this has led to low-speed electric cars choosing lead-acid batteries over the technical route of power batteries.

For low-speed electric vehicles, lead-acid battery as the power source has great advantages in economic cost, but there is a huge risk of environmental pollution. As for the lifting of the ban on low-speed electric vehicles and the establishment of standards, on April 14, 2016, the national standardization administration of China publicly solicited opinions on the first batch of proposed national standard projects in 2016 on its website. In 2016, the first batch of proposed project standards, technical conditions for four-wheel low-speed electric passenger vehicles, was put in the project column. In the opinion column, it is clearly proposed that low-speed electric vehicles using lithium battery as power is the threshold. This opinion has two aspects: one is to support the lithium electrification of low-speed electric vehicles, and the other is to maintain the use of lead-acid batteries in low-speed electric vehicles. Both sides have sufficient and reasonable reasons to prove the rationality of technical route selection. In the choice of power battery this I prefer to choose lithium battery. No matter from the perspective of technology or operation management, the choice of lithium battery as power is bound to become the development trend of low-speed electric vehicles.

Lead-acid battery structure

The positive electrode material of lead-acid battery is mainly composed of PbO2, the negative electrode material is mainly composed of Pb, and the electrolyte is usually dilute sulfuric acid. PbSO4 grains are generated on both positive and negative electrode materials. The nominal voltage of lead-acid battery is 2V, the theoretical specific energy is 166.9Wh/kg, and the actual specific energy is 35 ~ 45Wh/kg. Due to the conductivity of the electrolyte, the self-discharge and charging of lead-acid batteries do not allow large current charging, so the general lead-acid battery charging is limited to less than 0.3c.

Lead-acid batteries or lithium batteries? On the low - speed electric vehicle power threshold

The production process of lead-acid battery is relatively mature. Although many companies have made innovations and breakthroughs in the preparation process of anode and cathode materials, the basic technology of using materials has not made fundamental innovations and breakthroughs. On the basis of the improvement and innovation of the preparation process, the storage capacity, self-discharge capacity and charging resistance of lead-acid batteries have been improved. But there was no qualitative change. Lead-acid batteries are made of materials that may pollute the environment. Under the complex working conditions of low-speed electric vehicles, electrolyte leakage is very likely to occur, or other circumstances may lead to the loss of positive and negative electrode materials in lead-acid batteries into the environment, causing certain pollution to the environment.

For now, the preparation of lead acid batteries from upstream of the lead, as well as a variety of processing industrial chain is perfect, the competition is more sufficient, coupled with the development of the industry technology maturity include industrial equipment localization rate is higher, so the product price is lower, in low-speed electric vehicle use very has a cost advantage.

Structure of lithium battery

Lithium batteries work by moving lithium ions between the positive and negative electrodes. During the charging and discharging process, Li+ is embedded and unembedded back and forth between the two electrodes. Anode materials are mainly lithium active materials, such as lithium manganate or lithium cobalt oxide, lithium nickel-cobalt manganate materials (commonly known as ternary), lithium iron phosphate and other active lithium compounds. Anode materials are mainly lithium-carbon interlayer compound LiXC6, which is basically carbon materials with good performance and chemical stability, such as graphite, carbon fiber, glass carbon, etc. In terms of anode materials, graphene has attracted more and more attention from various lithium battery manufacturers and investment institutions due to its excellent charge-discharge performance. Electrolytes are usually carbonate solvents with lithium hexafluorophosphate dissolved, while polymer electrolytes use gelatinous electrolytes. At present, the largest electrolyte manufacturer in China is a kind of manufacturer represented by polyfluorine. At present, the energy density of relatively hot lithium-ion batteries is about 100 ~ 150Wh/kg, which is obviously much higher than that of lead-acid batteries. Because the electrolyte USES an organic solvent, the conductivity is very weak. The self-discharge of lithium battery is very small. Allow high current charge while charging. So a typical lithium-ion battery can charge up to 1C.

At present, the production process of lithium battery has been very mature, but there is still a long way to go in the localization of core materials such as anode and cathode materials and diaphragm. With the continuous progress and development of assembly technology and a large number of domestic capital poured into the lithium battery industry chain. Breakthroughs in key raw materials, coupled with the recent two years of a large number of new lithium battery manufacturers will be built and put into production in the next two years, is bound to lead to lithium battery overcapacity, prices are bound to fall. With the intensive investment of capital and the improvement of upstream and downstream industrial chains, the price of lithium battery will surely reach a level acceptable to low-speed electric vehicles. What's more, the material structure of lithium battery itself determines that there is no great risk of environmental pollution.

The superior performance of lithium batteries, if they can compete head-on with lead-acid batteries in price, will have a profound impact on the range, charging and use of low-speed electric vehicles, and even the industry. I am optimistic about the price and cost advantages of lithium batteries for low-speed electric cars.

Lead-acid batteries or lithium batteries? On the low - speed electric vehicle power threshold

After comparing the structure of lead-acid battery and lithium battery, the pollution points generated by power battery in the use of low-speed electric vehicles are mainly as follows:

1. The car body is overturned or damaged by collision. In this case, lead-acid batteries are extremely prone to electrolyte leakage, leakage of some materials inside the lead-acid battery. However, due to the manufacturing process of lithium battery vehicles is quite different from that of lead-acid batteries, the leakage situation is very limited or even negligible.

2. Replace one or two batteries that have problems during use. In this link is very easy to replace the phenomenon of randomly discarded. In this case, the battery is very easy to become a source of pollution. Compared with lead-acid batteries and the materials they are made of, the absence of heavy metals in lithium-ion batteries has little impact on the environment. Lead, a heavy metal in lead-acid batteries, exerts great pressure on the environment.

3. Waste disposal after reaching the service life. Firstly, the charge and discharge times of lithium battery are much more than those of lead-acid battery. Lithium batteries are much slower to use than lead-acid ones. Even at the end of life or at the end of life. Lithium batteries still have a high capacitance rate. It can also be used to store energy for the next cycle. Although the residual value of lead-acid battery is relatively high, it is extremely easy to be discarded at will or circulated to some small renovation workshops in circulation links, especially in remote rural areas and specific use links, and it becomes completely out of control.

As the market of low-speed electric vehicles grows larger and larger, low-speed electric vehicles occupy a place in the new energy electric vehicle industry by virtue of their own advantages. At the same time, its practicality, low cost and convenience are increasingly favored by urban residents and rural residents, especially to improve the travel of urban and rural residents has played a huge role. The basic logistics and passenger flow between villages and towns objectively reduce the circulation cost. It plays a huge role in the proper use of space. The development direction of lightweight low-speed electric vehicles and the demand of large range also require the use of lithium battery as the driving power.

At present, the price of lithium battery cannot be reduced to the price competitive with lead-acid battery within a certain period of time, but it cannot be denied that the price of lithium battery is gradually falling. In addition, the policy tax increase of the state on lead-acid battery also promotes the accelerated development of lithium battery and occupies the rapidly growing market of low-speed electric vehicle. Domestic lithium battery manufacturers capacity expansion, into an orderly fierce competition will bring cheap power lithium battery. In the "technical conditions for four-wheel low-speed electric passenger vehicles" for comments, lithium battery as the basic requirements for power batteries. At the national level, China is also facing up to the market of low-speed electric vehicles, which can improve people's livelihood.

Low-speed electric cars have a big future.

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