18650 lithium battery 3.7 v

　　Overview of power battery industry technology: 18650 lithium battery 3.7 v will remain the mainstream

　　The development of new energy vehicle power battery systems involves materials, chemistry, mechanics, thermodynamics, heat transfer, fluid mechanics, electricity, systems and control. Its key technologies include battery assembly technology, thermal management technology, power management technology and safety Management technology, etc. Vehicle power battery system technology has become a bottleneck for the popularization of electric vehicles, requiring exploration and breakthroughs from many aspects such as material development, battery design, manufacturing, system integration, and business models.

　　1. Classification of new energy vehicle power batteries

　　New energy vehicle power batteries can be divided into two categories: batteries and fuel cells. Batteries are used in pure electric vehicles (EV), hybrid electric vehicles (HEV) and plug-in hybrid electric vehicles (PHEV); fuel cells are dedicated to fuel battery vehicle (FCV).

　　1.1 Battery

　　Batteries are the only power source for the drive system in pure electric vehicles, mainly including nickel, nickel metal hydride and lithium-ion batteries. Currently, lithium-ion batteries are in a stage of rapid development, and are used in new energy vehicles such as the Nissan Leaf, Toyota Prius plug-in, Tesla Model S, GM Volt, Ford Focus EV and BMW i3. In addition, lithium resources are relatively abundant and the price is not expensive. It can be said that lithium-ion batteries are currently the most promising power batteries in the market. The performance comparison of Category 4 batteries is shown in Figure 1.

　　1.2 Fuel cells

　　A fuel cell is a device in which a fuel reacts with an oxidant to directly convert its chemical energy into electrical energy through electrode reactions. Fuel cells do not require charging and have the advantages of high specific energy, long service life, less maintenance work, and continuous high-power power supply. In addition, fuel cell vehicles can achieve the same driving range as fuel vehicles.

　　According to different electrolytes, fuel cells can be divided into five categories: alkaline fuel cells, phosphoric acid fuel cells, proton exchange membrane fuel cells, molten carbonate fuel cells and solid oxide fuel cells. At present, proton exchange membrane fuel cells are widely used in fuel cell vehicles and are a very competitive battery type in the field of new energy vehicle power batteries in the future.

　　2. Overview of new energy power battery industry technology

　　Since the use of vehicle power batteries is quite different in different types of new energy vehicles, their performance requirements are quite different. HEV has a gasoline engine as the power source, which places more emphasis on acceleration performance and climbing ability, so it pays more attention to the specific power of the battery (requiring up to 800 to 1200W/kg); PHEV and EV are completely powered by batteries, and place more emphasis on continued driving after charging. capacity, so more attention is paid to the specific energy of the battery (required to reach 100-160Wh/kg) (see Table 1).

　　Due to significant differences in performance, materials, costs, etc., different types of power batteries have different prospects. At present, the most mature technology is nickel-metal hydride power batteries, but the most successful commercialization is lithium-ion batteries, and fuel cells are widely regarded as a long-term goal.

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