一. What is a cylindrical lithium battery?

1.Definition of cylindrical battery

Cylindrical lithium batteries are divided into different systems of lithium iron phosphate, lithium cobalt oxide, lithium manganate, cobalt-manganese mixed, and ternary materials. The shell is divided into two types: steel shell and polymer. Different material systems have different advantages. At present, the cylinders are mainly steel-shell cylindrical lithium iron phosphate batteries, which are characterized by high capacity, high output voltage, good charge-discharge cycle performance, stable output voltage, high-current discharge, stable electrochemical performance, and use Safe, wide operating temperature range, environmentally friendly, widely used in solar lamps, lawn lamps, backup energy, power tools, toy models.

2.Cylindrical battery structure

The structure of a typical cylindrical battery includes: shell, cap, positive electrode, negative electrode, separator, electrolyte, PTC element, gasket, safety valve, etc. Generally, the battery shell is the negative electrode of the battery, the cap is the positive electrode of the battery, and the battery shell is made of nickel-plated steel plate.

3. Advantages of cylindrical lithium batteries

Compared with soft packs and square lithium batteries, cylindrical lithium batteries have the longest development time, higher standardization, more mature technology, high yield and low cost.

· Mature production process, low PACK cost, high battery product yield, and good heat dissipation performance

· Cylindrical batteries have formed a series of internationally unified standard specifications and models, with mature technology and suitable for large-scale continuous production.

· The specific surface area of the cylinder is large, and the heat dissipation effect is good.

· Cylindrical batteries are generally sealed batteries, and there is no maintenance problem during use.

· The battery shell has high pressure resistance, and there will be no swelling of square and soft-packed batteries during use.

4.Cylindrical battery negative electrode material

Cylindrical battery anode materials are roughly divided into six types: carbon anode materials, alloy anode materials, tin-based anode materials, lithium-containing transition metal nitride anode materials, nanoscale materials, and nanoscale anode materials.

Carbon nanoscale materials for anode materials: At present, the anode materials actually used in lithium-ion batteries are basically carbon materials, such as artificial graphite, natural graphite, mesocarbon microspheres, petroleum coke, carbon fiber, pyrolysis resin carbon, etc. .

Alloy-based anode materials: including tin-based alloys, silicon-based alloys, germanium-based alloys, aluminum-based alloys, antimony-based alloys, magnesium-based alloys and other alloys, and there are currently no commercial products.

Tin-based negative electrode material: Tin-based negative electrode material can be divided into two types: tin oxide and tin-based composite oxide. Oxides refer to oxides of metal tin in various valence states. There are currently no commercial products.

· Lithium-containing transition metal nitride anode materials, there are currently no commercial products.

· Nanoscale materials: carbon nanotubes, nano-alloy materials.

· Nano anode material: nano oxide material

二. Cylindrical lithium battery cells

1.Cylindrical lithium-ion battery brand

Cylindrical lithium batteries are more popular among lithium battery companies in Japan and South Korea, and there are also large-scale enterprises in China that produce cylindrical lithium batteries. The earliest cylindrical lithium battery was invented in 1992 by SONY Company of Japan.

Well-known cylindrical lithium-ion battery brands: Sony, Panasonic, Sanyo, Samsung, LG, Wanxiang A123, BAK, Lishen, etc.

2.Types of cylindrical lithium-ion batteries

Cylindrical lithium-ion cells are usually represented by five-digit numbers. Counting from the left, the first and second digits refer to the diameter of the battery, the third and fourth digits refer to the height of the battery, and the fifth digit represents a circle. There are many types of cylindrical lithium batteries, the more common ones are 10400, 14500, 16340, 18650, 21700, 26650, 32650, etc.

①10440 battery

The 10440 battery is a lithium battery with a diameter of 10mm and a height of 44mm. It is the same size as the "AAA battery" we often call it. The battery capacity is generally small, only a few hundred mAh. It is mainly used in mini electronic products. Such as flashlights, mini stereos, amplifiers, etc.

②14500 battery

The 14500 battery is a lithium battery with a diameter of 14mm and a height of 50mm. This battery is generally 3.7V or 3.2V. The nominal capacity is relatively small, a bit larger than the 10440 battery, generally 1600mAh, with superior discharge performance and the most application field. Mainly consumer electronics, such as wireless audio, electric toys, digital cameras and so on.

③16340 battery

The 16340 battery is a lithium battery with a diameter of 16mm and a height of 34mm. This kind of battery has a shorter ruler height and a smaller capacity, so it can be used in strong light flashlights, LED flashlights, headlights, laser lights, lighting fixtures, etc. occur frequently.

④18650 battery

The 18650 battery is a lithium battery with a diameter of 18mm and a height of 65mm. Its biggest feature is that it has a very high energy density, almost reaching 170 Wh/kg. Therefore, this battery is a cost-effective battery. We usually often Most of what I see are this kind of battery, because it is a relatively mature lithium battery, and the system quality is stable in all aspects. It is widely used in occasions with a battery capacity of about 10 kWh, such as in mobile phones, laptops and other small appliances. .

⑤21700 battery

The 21700 battery is a lithium battery with a diameter of 21mm and a height of 70mm. Because its volume increases, the space utilization rate increases, and the energy density of the battery cell and the system can be improved. Its volume energy density is much higher than that of the 18650 battery. It is widely used in digital, electric vehicles, balance vehicles, solar energy lithium battery street lights, LED lights, power tools, etc.

⑥ 26650 battery

The 26650 battery is a lithium battery with a diameter of 26mm and a height of 65mm, with a nominal voltage of 3.2V and a nominal capacity of 3200mAh. This battery has the characteristics of excellent capacity and high consistency, and has gradually become a trend to replace the 18650 battery. In terms of power batteries, many products will gradually favor this.

⑦ 32650 battery

The 32650 battery is a lithium battery with a diameter of 32mm and a height of 65mm. This battery has a strong continuous discharge capacity, so it is more suitable for electric toys, backup power supplies, UPS batteries, wind power generation systems, and wind-solar hybrid power generation systems.

三.Market Development of Cylindrical Lithium Batteries

The technological progress of cylindrical lithium-ion batteries mainly comes from the innovation research and application progress of key battery materials. Through the development of new materials, the battery performance is further improved, the quality is improved, the cost is reduced, and the safety is improved. In order to meet the requirements for improving the specific energy of batteries in downstream applications, on the one hand, materials with high specific capacity can be used, and on the other hand, high-voltage materials can be used by increasing the charging voltage.

Cylindrical lithium-ion batteries have developed from 14500 to Tesla 21700 batteries. In the near and mid-term development, while optimizing the existing lithium-ion power battery technology to meet the needs of large-scale development of new energy vehicles, a new type of lithium-ion power battery will be developed. Focusing on improving its key technologies such as safety, consistency and lifespan, and simultaneously carrying out forward-looking research and development of new system power batteries.

For the medium and long-term development of cylindrical lithium-ion batteries, while continuing to optimize and upgrade new lithium-ion power batteries, focus on research and development of new system power batteries, significantly improve specific energy, greatly reduce costs, and achieve practical and large-scale new system power batteries. application.

四. Comparison of cylindrical lithium battery and square lithium battery

1. Battery shape: Square size can be arbitrarily designed, while cylindrical batteries cannot be compared.

2. Rate characteristics: Due to the technological limitation of welding multi-pole tabs for cylindrical batteries, the rate characteristics are slightly worse than those for square multi-pole batteries.

3. Discharge platform: For lithium batteries using the same positive and negative materials and electrolyte, in theory, the discharge platform should be the same, but the discharge platform in the square lithium battery is slightly higher.

4. Product quality: The manufacturing process of cylindrical batteries is relatively mature, the probability of secondary slitting defects in the pole pieces is low, and the maturity and automation of the winding process are relatively high. The lamination process is still semi-manual. Battery quality is adversely affected.

5. Welding of tabs: the tabs of cylindrical batteries are easier to weld than square lithium batteries; square lithium batteries are prone to false welding and affect the quality of the battery.

6. Packing into groups: cylindrical batteries are easier to use, so the packing technology is simple and the heat dissipation effect is good; when the square lithium battery is packed, the heat dissipation problem should be solved.

7. Structural features: The chemical activity at the corners of the square lithium battery is poor, the energy density of the battery is easy to decay after long-term use, and the battery life is short.

五. cylindrical lithium battery and soft pack lithium battery comparison

1. The safety performance of the soft-pack battery is good. The soft-pack battery is structurally packaged with aluminum-plastic film. When a safety problem occurs, the soft-pack battery will generally burst and crack, instead of exploding like the steel shell or aluminum shell battery. ; Better than cylindrical lithium battery in safety performance.

2. The weight of the pouch battery is relatively light, the weight of the pouch battery is 40% lighter than that of the steel shell lithium battery of the same capacity, and 20% lighter than that of the cylindrical aluminum shell lithium battery; the internal resistance is small, and the internal resistance of the pouch battery is smaller than that of the lithium battery , which can greatly reduce the self-consumption of the battery;

3. The soft pack battery has good cycle performance, the soft pack battery has a longer cycle life, and the 100-cycle decay is 4% to 7% less than that of the cylindrical aluminum shell battery;

4. The design of the soft-pack battery is flexible, the shape can be changed to any shape, and it can be thinner. It can be customized according to the needs of customers, and new battery models can be developed. The cylindrical lithium battery does not have this condition.

5. Compared with cylindrical lithium batteries, soft pack batteries have the disadvantages of poor consistency, high cost and easy leakage. The high cost can be solved by large-scale production, and the leakage of liquid can be solved by improving the quality of the aluminum-plastic film.

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