Why does the development of energy-saving and environmentally friendly lithium batteries often appear predicament?

After 10 years of development, the electric bicycle will gradually return to the road of lightweight, miniaturization, and help. Lightweight should be the mainstream trend of the development of electric bicycles.

Many people think that the weight of lead-acid batteries is too large, which directly affects the weight control of the vehicle. The use of lithium-ion batteries can effectively reduce the load of the frame and control the quality of the vehicle. Therefore, lithium-ion batteries should be the best power source for the new generation of electric bicycles.

The industry pointed out that taking the batteries commonly used in the market as an example, 36V/10Ah lithium-ion batteries weigh only 3.5 to 5 kilograms, while lead-acid batteries of the same capacity weigh 12 to 14 kilograms.

In the survey of some electric bicycle stores in Beijing, the author saw that some ultra-lightweight lithium-ion battery electric bicycles have appeared on the market. Such electric vehicles use lithium-ion batteries of 24V/10Ah, and the weight of the vehicle is controlled within 10 kilograms. The mileage has reached 30 kilometers. Perfect performance of lithium-ion battery lightweight, high specific energy characteristics.

Although the characteristics of lithium-ion batteries show great potential in the electric bicycle industry, the position of lithium-ion batteries in the electric bicycle industry has always been somewhat awkward. Lithium-ion batteries have appeared on some manufacturers 'electric bicycles since 2003, but they have never really shaken the dominance of lead-acid batteries. After lithium-ion batteries entered the field of electric bicycles, several ups, and downs, why have the "spring" of lithium-ion batteries not yet arrived?

Price and security are the biggest bottlenecks.

"One of the most important reasons why lithium-ion batteries have not been able to open up sales in the field of electric bicycles is the price. Due to the high price of raw materials for lithium-ion batteries and the high manufacturing process requirements, the cost of lithium-ion batteries has been at a disadvantage relative to lead-acid batteries. Domestic consumers are more sensitive to prices. Market surveys show that the first factor in consumers 'purchase of bicycle batteries is the price. The current market price of lithium-ion batteries is 3 to 4 times that of lead-acid batteries. High prices often make consumers look forward. sigh. In addition to prices, lithium-ion batteries have failed to meet consumer expectations, according to people concerned. Lithium-ion batteries themselves have a series of advantages such as high specific energy, high output power, and long cycle life. However, electric bicycle lithium-ion batteries do not fully reflect their own advantages, although the weight of lithium-ion batteries is only one third of that of lead-acid batteries., It is compact and light, but it usually reaches only 300-500 times in cycle life, which is less than double the cycle life of 300 lead-acid batteries. Yemao pointed out that the combination of performance indicators, compared to the price of lead-acid batteries more than 3 times, lithium-ion batteries have also been given a negative evaluation.

Yuhongtao, another technician at the company, said safety was a "sword of Damocles" hanging over lithium-ion batteries compared to the first two. In recent years, with the popularity of mobile phones and notebook computers, the safety of lithium-ion batteries in use has gradually attracted public attention. The safety accident of fire and even explosion has made everyone feel quite "talk about lithium color change". Some electric car manufacturers also have many doubts about the safety of lithium-ion batteries and are afraid to launch lithium battery production projects. The shadow of the safety problem of lithium-ion batteries is always lingering, which seriously restricts the further development of lithium-ion batteries.

Safety and standards are indispensable

Under the new situation of the electric bicycle industry, how should the application of lithium-ion battery in the electric bicycle field develop? At the third electric bicycle industry summit forum, many experts in the industry believe that the use of high-safety materials should be vigorously promoted. lithium iron phosphate is one of the more mature ones. The cycle life of lithium iron phosphate batteries has reached more than three times that of lead-acid batteries, and its weight-to-energy ratio has also reached 90 Wh / kg, which is about three times that of lead-acid batteries. The safety performance is that lithium iron phosphate differs from other lithium-ion batteries. The advantage is. From the material cost point of view, with the improvement of the domestic production of lithium iron phosphate materials and the gradual expansion of the production scale, the price of lithium iron phosphate materials is gradually declining, and the price difference between lead-acid batteries is gradually shrinking. The price of lithium iron phosphate power supply of the same capacity may be reduced to 1.5 to 2 times the price of lead acid power supply in the short term, and the high price of lithium-ion batteries will be expected to change.

An expert from the China Battery Industry Association pointed out that another major reason why lithium-ion batteries have not been widely used in the field of electric bicycles is that they have not formed standard models like lead-acid batteries. The shape and electrical performance specifications of the core are not uniform among various manufacturers.. The interchangeability is poor and can not form a size advantage. According to the report, a major feature of bicycle batteries different from portable electronic products such as mobile phones is high capacity, Gaodianya, so it is usually necessary to use multiple batteries in series. When Multi-segment batteries are used in series, the most poorly performing batteries often become bottlenecks for the entire group of power supplies. Due to the "short plate effect", the batteries with the worst performance are usually filled earlier than other batteries, and they are also earlier than other batteries. In repeated charge-discharge cycles, this gap will gradually expand, eventually resulting in the entire group of batteries. Performance deterioration. If the consistency of lithium-ion cells in the production process and the distribution group cannot be guaranteed, the battery life will also be greatly affected. Therefore, the electric bicycle battery must eventually use automatic production equipment, effectively improve the consistency of the battery, and conduct a strict distribution group before the battery is used to ensure the consistency of the battery.

It is a systematic project to give full play to the advantages of lithium batteries. Firstly, we should increase the technical innovation in the three aspects of the matching of lithium battery material, the design of lithium battery structure and the power management system. The goal is to continuously improve the suitable performance of the battery matching, improve the power supply efficiency, and continuously push the battery cost down in a technological innovation manner.; Secondly, the horizontal system integration of the motor and power supply of low-power electric vehicles should be carried out. Not only should the lithium battery and its management system be better matched with the motor and controller, but also the lithium battery should be further included in the industrial design of the electric vehicle, and the complete vehicle should be integrated., in pursuit of the consistency of the service life of the vehicle.

Lithium battery enterprises need to unswervingly advance the process of universality and standardization. Under the premise of maintaining the advantages of individual applicability of lithium batteries, for the mainstream products in the industry, The standardization of product application and various specifications, main and auxiliary materials and accessories, components and connectors, equipment and instrumentation, and fixture are the necessary conditions and marks for the healthy development of the industry. -Yeah.

Industry insiders have called for the use of low-power electric vehicles for lithium batteries is a huge segment of the market with tens of billions of yuan or even hundreds of billions of yuan after lithium batteries for digital products such as mobile phones. The state should include the lithium battery industry for electric vehicles in the major industries of new energy and low-carbon emission reduction, and give industrial policy support in all aspects.

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